WO2024227212A2 - Drive system for a driverless transport vehicle - Google Patents

Abstract

The invention relates to a drive system (1) for a driverless transport vehicle (2), which drive system comprises at least one drive axle (3) with a first wheel unit (4) and with a second wheel unit (5) situated opposite the first wheel unit in the axial direction of the drive axle (3), wherein the at least one drive axle (3) comprises a first electric drive unit (6) for driving the first wheel unit (4) and a second electric drive unit (7) for driving the second wheel unit (5), wherein the drive system (1) comprises at least one control unit (8) for controlling the first drive unit (6) and for controlling the second drive unit (7), wherein the at least one drive axle (3) comprises a vertical first rotation axis (10) situated centrally between the two wheel units (4, 5), wherein the at least one drive axle (3) can be attached to a chassis (11) of the transportation vehicle (2) such that it can be deflected relative to the chassis (11) through a steering angle (α) about the first rotation axis (10), wherein the drive system (1) comprises a steering angle determination device (12) for determining an actual value (α_actual) of the steering angle (α) of the at least one drive axle (3), and wherein the at least one control unit (8) is designed to use the actual value (α_actual) of the steering angle (α) and a predefined target value (α_target) for the steering angle (α) for determining a first actuating variable (S1) for the first drive unit (6) and a second actuating variable (S2) for the second drive unit (7) and to actuate the first drive unit (6) and the second drive unit (7) using the determined actuating variables (S1, S2), so that the steering angle (α) can be adjusted to the predefined target value (α_target), wherein the first electric drive unit (6) and the second electric drive unit (7) are both in the form of an axial flux motor.

Description

DRIVE SYSTEM FOR A DRIVER-LOADED TRANSPORT VEHICLE

The invention relates to a drive system for a driverless transport vehicle, wherein the drive system comprises at least one drive axle with a first wheel unit and with a second wheel unit opposite the drive axle in the axial direction, wherein the at least one drive axle comprises a first electric drive unit for driving the first wheel unit and a second electric drive unit for driving the second wheel unit, that the drive system comprises at least one control unit for controlling the first drive unit and for controlling the second drive unit, that the at least one drive axle comprises a first axis of rotation located centrally between the two wheel units, wherein the at least one drive axle can be fastened to a chassis of the transport vehicle in such a way that the first axis of rotation is aligned vertically and the drive axle can be deflected relative to the chassis at a steering angle about the first axis of rotation, that the drive system comprises a steering angle determination device for determining an actual value of the steering angle of the at least one drive axle and that the at least one control unit is designed to use the actual value of the steering angle and a predetermined target value for the steering angle to determine a first manipulated variable for the first drive unit and a second control variable for the second drive unit and to control the first drive unit and the second drive unit with the determined control variables so that the steering angle can be set to the predetermined target value. The invention also relates to a driverless transport vehicle with such a drive system and a use of the driverless transport vehicle.

Automated Guided Vehicles (AGVs) are floor-mounted conveyors with their own drive, which are automatically controlled and usually guided without contact. Automated Guided Vehicles are often used to transport materials and are used, for example, to pull unpowered load-handling devices on which the goods to be transported are arranged, similar to a trailer operation. It is of course also possible to carry goods directly with an automated guided vehicle.

Automated guided vehicles are often used for internal material transport, usually in buildings. For example, automated guided vehicles are used in manufacturing processes to transport certain goods, components or to transport tools between process stations. Driverless transport vehicles are also increasingly being used in logistics, for example in automated high-bay warehouses, to transport packages or containers between different locations. Driverless transport vehicles are also increasingly being used in other areas, for example in agriculture or for passenger transport.

The drive systems of known driverless transport vehicles usually have one or more electric motors for the drive. The drive force is usually transferred to the ground via drive wheels. Steering systems with geometric steering angle are often used, in which the steered wheels are connected to the vehicle via suitable wheel suspensions. Each wheel can be steered separately or the wheels on one axle can be steered together. The necessary steering forces are usually generated by electromechanical actuators provided in addition to the drive motors and transferred to the steered wheels, which can also be drive wheels, via a suitable steering linkage. Steering systems with geometric steering angle are relatively complex and therefore expensive to manufacture.

There are also steering systems without geometric steering angle, known as differential steering. Here, the direction of the vehicle changes, similar to a tracked vehicle, through different speeds of the drive wheels. The wheels are connected to the vehicle via fixed wheel suspensions. There is no steering angle of the wheels. Although these systems are simpler in design than steering systems with geometric steering angle, the flexibility of the steering process is limited.

US 2016/167706 A1 discloses a self-propelled transport vehicle for luggage, which comprises two pivoting axles, each of which has two wheels driven by drive motors at the outer ends. The transport vehicle has a control unit which is designed to control the drive motors for changing the direction of the vehicle in such a way that, in addition to the basic drive torque, an equal but opposing steering torque is applied to the associated wheels.

The object of the present invention was to overcome the disadvantages of the prior art and to provide a drive system for a driverless transport vehicle which is of simple construction and which enables the most flexible steering process possible and which has the highest possible efficiency, the highest possible torque and the has a low weight. This object is achieved in that the first electric drive unit and the second electric drive unit of the at least one drive axle are designed as axial flux motors. An axial flux motor requires little installation space in the axial direction, is relatively light and highly efficient, and can provide a relatively high torque. A conventional electric motor with comparable torque, for example, is approximately twice as heavy. The drive system according to the invention enables both drive and steering in a simple manner, without the need for complex steering geometry as in the prior art. The desired steering angle can be set in a simple manner by a differential speed of the electric drive units. The drive system can therefore be manufactured much more simply and therefore more cost-effectively, since one or more separate steering actuators are not required in addition to the drive units, as was previously the case. Since the drive system is essentially a self-sufficient system, it can be very easily retrofitted to existing transport vehicles. Compared to pure differential steering, more complex steering processes can be carried out, for example the so-called "crab steering".

It can be advantageous if the at least one drive axle comprises at least a second axis of rotation, wherein the drive axle can be fastened to the chassis of the transport vehicle in such a way that the second axis of rotation is aligned parallel to a direction of travel of the drive axle and wherein the drive axle can be deflected relative to the chassis at a pivot angle about the second axis of rotation. This allows, for example, uneven ground to be better compensated for.

The at least one drive axle can comprise at least part of a first central joint that forms the first axis of rotation, preferably additionally the second axis of rotation, wherein the first central joint preferably comprises a rotary joint, universal joint or ball joint. This makes it possible to provide a simple structural embodiment for realizing the first and second axes of rotation. However, separate joints can also be provided for the first and second axes of rotation.

The at least one drive axle can be designed as a rigid axle, wherein a wheel suspension of the first wheel unit and a wheel suspension of the second wheel unit are connected to one another via a rigid axle body and wherein the rigid axle body supports the first rotation axis, in particular at least a part of the first central joint, and preferably additionally comprises the second rotation axis. This provides a robust, simple and consequently cost-effective embodiment.

Alternatively, the at least one drive axle can be designed as a pendulum axle having a central axle body that includes the first axis of rotation, in particular the at least part of the first central joint, wherein a wheel suspension of the first wheel units or a first wheel axle body connected to the wheel suspension of the first wheel units is connected to the central axle body via a first pendulum joint and a wheel suspension of the second wheel units or a second wheel axle body connected to the wheel suspension of the second wheel units is connected to the central axle body via a second pendulum joint, wherein the first pendulum joint and the second pendulum joint each have a pivot axis aligned parallel to a direction of travel of the respective wheel unit.

This allows an advantageous independent suspension to be provided.

The wheel units of the at least one drive axle can each comprise a wheel drive with at least one drive wheel for transmitting a driving force to the ground. Alternatively, the wheel units of the at least one drive axle can each comprise a crawler drive with at least one drive crawler or a chain drive with at least one drive chain for transmitting a driving force to the ground. This can enable advantageous power transmission to the ground depending on the area of application. While a wheel drive can be advantageous on smooth ground, for example, a crawler drive or chain drive can be advantageous on off-road surfaces, as this has greater traction.

The drive system can also comprise an electrical energy storage device and/or a current collector for supplying energy to the electrical drive units, the at least one drive axle and/or the at least one control unit and/or the steering angle determination device. An energy storage device can enable autonomous operation without an external energy supply. The electrical energy storage device can comprise, for example, a battery and/or a supercapacitor. A current collector enables an external energy supply without the need for an energy storage device, which can be advantageous, for example, in small installation spaces. A combination of energy storage device and current collector can also be provided. This means that, for example, the energy storage device can be connected to the Current collectors can be used to charge the battery. The current collector can be designed as a sliding contact or alternatively as an inductive current collector for contactless energy transfer.

The steering angle determination device can, for example, comprise a rotation angle sensor, preferably a photoelectric incremental encoder, a magnetic incremental encoder or an incremental encoder with sliding contacts. The steering angle determination device can, however, have another suitable sensor for detecting a measurement variable representative of the steering angle. The steering angle could then be determined by the control unit from the corresponding measurement variable.

In a simple embodiment, the wheel units of at least one drive axle can be driven by a direct drive from the respective electric drive unit. Compared to known drives that have a gear between the drive and the wheels, the direct drive enables improved controllability and thus greater accuracy in setting the steering angle and a faster response to a change in the target value of the steering angle. This also enables acceleration commands to be implemented more quickly, since there are no or lower mechanical losses in the power transmission. In addition, the lack of a gear means that the drive system can be designed more compactly, meaning that the drive system can be used in relatively small vehicles in particular. Alternatively, the wheel units can be driven by the respective electric drive unit via a gear. This means that an advantageous gear ratio can be provided depending on the application.

Preferably, at least one of the electric drive units of the at least one drive axle is designed for energy recovery. This advantageously allows braking energy to be converted into electrical energy.

Preferably, the at least one drive axle comprises a service brake that can be controlled by the at least one control unit, wherein the service brake preferably comprises an electric or electromechanical disc brake or drum brake for at least one wheel unit. The electromechanical disc brake is preferably designed as a fixed calliper brake. Alternatively or additionally, the at least one drive axle can comprise a parking brake, wherein the parking brake is preferably integrated in at least one of the electric drive units. This allows sufficient braking energy which is advantageous, for example, for transporting heavy loads and/or on a slope. A parking brake prevents unwanted movement of the drive axle or the transport vehicle.

The at least one drive axle can be designed as a portal axle, with rotation axes of the electric drive units being spaced apart in the vertical direction from wheel rotation axes of the wheel units. This advantageously makes it possible to realize either a high-floor vehicle or a low-floor vehicle.

Preferably, the at least one drive axle comprises at least one impact damper, wherein preferably at least one impact damper is directed in the direction of travel and/or at least one impact damper is directed against the direction of travel. This allows an impact from another vehicle or an impact on an obstacle to be dampened, whereby the transport vehicle and possibly also the load can be protected from damage.

The impact damper can also comprise a contact device that is electrically connected to the at least one control unit and that is designed to transmit a contact signal to the control unit upon contact with a contact device of another drive axle. This makes it easy to detect contact with another vehicle and to take a corresponding action, e.g. acceleration or braking.

The at least one drive axle can also comprise a first guide device for laterally guiding the drive axle, wherein the first guide device preferably comprises, at least in the region of a wheel unit, a number of first rolling bodies and/or a number of first sliding elements which are designed to interact with a stationary first guide rail. The drive axle can thus be guided by an external guide, which, for example, facilitates positioning during a loading or unloading process.

It may be advantageous if an outer contour of the first guide device is spaced apart from the first axis of rotation in a radial direction with respect to the first axis of rotation at a guide distance which corresponds at least to a turning radius of the drive axis.

This ensures that the first guide device is contacted first and there is no contact with the wheel unit. It can be advantageous if the at least one drive axle comprises at least one distance sensor and that the at least one control unit is designed to use a sensor signal from the at least one distance sensor to control the electric drive units of the at least one drive axle and/or to control the service brake. Preferably, at least one distance sensor is directed in the direction of travel and/or at least one distance sensor is directed against the direction of travel. This makes it possible, for example, to detect obstacles and initiate a braking process or, if necessary, a steering maneuver. A desired distance from another transport vehicle, e.g. a specified minimum distance, can also be achieved in this way.

According to an advantageous embodiment, the drive system comprises a plurality of drive axles that can be fastened to the chassis of the transport vehicle such that the first axes of rotation are spaced apart from one another in a longitudinal direction of the transport vehicle by a fixed first axle distance. The at least one control unit can be designed to control the electric drive units of the plurality of drive axles or each of the plurality of drive axles can comprise a separate control unit to control its electric drive units. This makes it possible to realize multi-axle transport vehicles with steered drive axles.

It can be advantageous if the at least one control unit is designed to simultaneously operate at least one of the drive units of the first drive axle in a drive mode in which the respective electric drive unit exerts a drive torque on the respective wheel unit, and to operate at least one of the drive units of the second drive axle in a braking mode in which the respective electric drive unit exerts a braking torque on the respective wheel unit. This enables very flexible operating modes, e.g. an anti-lock braking system or an electronic stability program.

It may be advantageous if the drive system comprises at least one non-driven axle with a third wheel unit and a fourth wheel unit located opposite the non-driven axle in the axial direction, wherein the at least one non-driven axle can be fastened to the chassis of the transport vehicle in such a way that it is located in a longitudinal direction of the transport vehicle at a fixed second axle distance from the first axis of rotation of the at least one drive axle. This makes it possible to provide a transport vehicle with a drive axle and a non-driven and non-steered axle.

The at least one non-driven axle can comprise a vertical third axis of rotation located centrally between the two wheel units and can be fastened to the chassis of the transport vehicle in such a way that it can be rotated about the first axis of rotation relative to the chassis and that the at least one non-driven axle is connected to the at least one drive axle via a mechanical coupling device which is designed to transmit the steering angle from the at least one drive axle to the at least one non-driven axle. The at least one non-driven axle preferably has at least part of a second central joint which comprises the third axis of rotation. This makes it possible to provide a transport vehicle with a drive axle and a non-driven axle with forced steering. This allows more flexible steering maneuvers than a fixed axle.

The at least one drive axle can comprise an axle suspension device for spring-loaded attachment to the chassis of the transport vehicle and/or an axle damping device for damped attachment to the chassis of the transport vehicle. Alternatively or additionally, the at least one non-driven axle can comprise an axle suspension device for spring-loaded attachment to the chassis of the transport vehicle and/or an axle damping device for damped attachment to the chassis of the transport vehicle. This can be particularly advantageous in rough terrain or on uneven ground in order to protect the goods being transported from vibrations.

Preferably, the at least one control unit of the drive system comprises a preferably wireless data interface for transmitting at least the target value for the steering angle. Preferably, a target value for a vehicle speed can also be transmitted. This allows desired steering maneuvers to be controlled wirelessly, e.g. via WLAN, Bluetooth, mobile communications, etc.

A curve center point can also be specified for the at least one control unit of the drive system and the control unit can be designed to determine the target value for the steering angle of the at least one drive axle from the specified curve center point. The curve center point can be specified in the form of coordinates, e.g. as a GPS signal, or e.g. as a distance from the first axis of rotation. The at least one drive axle can comprise a positive or non-positive coupling device for detachable coupling with another drive axle or with a non-driven axle. Alternatively or additionally, the at least one non-driven drive axle can comprise a positive or non-positive coupling device for detachable coupling with another drive axle or with a non-driven axle. This allows several transport vehicles to be coupled via the axles, making it possible to travel in a train consisting of several vehicles. One or more vehicles in the train can, for example, be without drive, at least temporarily.

The drive system is preferably used in a driverless transport vehicle, wherein the drive system is attached to a chassis of the transport vehicle. The chassis preferably has a frame or a base plate.

In a simple embodiment, the transport vehicle can comprise at least one support wheel for contacting the ground in addition to the drive axle of the drive system.

This makes it possible to provide, for example, a tricycle. Alternatively or additionally, the transport vehicle can comprise a second guide device for laterally guiding the transport vehicle, wherein the second guide device preferably comprises a number of second rolling bodies and/or a number of second sliding elements which are designed to interact with a stationary second guide rail. The second guide device is preferably attached to the chassis and thus cannot be moved with the steered axles.

According to a preferred method, a target value for the steering angle is specified for the at least one control unit of the at least one drive axle of the drive system of the driverless transport vehicle, or a curve center point is specified and the control unit determines the target value for the steering angle based on the curve center point, wherein an actual value of the steering angle is determined by the steering angle determination device and the control unit determines the first manipulated variable for the first drive unit and the second manipulated variable for the second drive unit from the actual value of the steering angle and the target value for the steering angle and controls the first drive unit and the second drive unit with the determined manipulated variables so that the steering angle is set to the specified target value. In addition, it can be advantageous that a target value for a vehicle speed is specified for the at least one control unit of the at least one drive axle of the drive system and that the control unit uses the target value for the vehicle speed to determine the first control variable for the first drive unit and to determine the second control variable for the second drive unit, so that the vehicle speed is set to the specified target value. An actual value of the vehicle speed can, for example, be measured or determined from the speeds of the drive units.

This allows the desired steering angle to be set at a desired speed.

For example, the control unit can be given the axle distance between the first axes of rotation of the at least two drive axles, the track widths of the at least two drive axles and the effective diameters of the first and second wheel units of the at least two drive axles, and the control unit can use this to determine the control variables for the first and second wheel units of the at least two drive axles, so that the first wheel units roll along the same first curve and the second wheel units roll along the same second curve. A lateral offset of the two axles would also be possible, e.g. by specifying a desired correction value.

For a better understanding of the invention, it is explained in more detail with reference to the following figures.

They show in a highly simplified, schematic representation:

Fig. 1 shows a drive axle of the drive system according to the invention in a first exemplary embodiment in a view in the direction of travel from the rear;

Fig. 2 shows the drive shaft of the first embodiment in a plan view;

Fig. 3 shows a drive axle of the drive system according to the invention in a second exemplary embodiment in plan view;

Fig. 4 shows the drive axle of the second exemplary embodiment in a side view; Fig. 5 shows a drive axle of the drive system according to the invention in a third exemplary embodiment in a view in the direction of travel from the rear;

Fig. 6 shows a drive axle of the drive system according to the invention in a fourth exemplary embodiment in a view in the direction of travel from the rear;

Fig. 7 shows the drive shaft of the fourth embodiment in a plan view;

Fig. 8 shows a drive axle of the drive system according to the invention in a fifth exemplary embodiment in a plan view;

Fig. 9 shows a driverless transport vehicle of a first exemplary embodiment in a plan view;

Fig. 10 shows a driverless transport vehicle of a second exemplary embodiment in a plan view;

Fig. 11 shows a driverless transport vehicle of a third exemplary embodiment in a plan view;

Fig. 12 shows an exemplary first operating mode of a driverless transport vehicle;

Fig. 13 shows an exemplary second operating mode of a driverless transport vehicle;

Fig. 14 two coupled driverless transport vehicles of an exemplary embodiment in a curve;

Fig. 15 shows a driverless transport vehicle of an exemplary embodiment during cornering;

Fig. 16 shows a driverless transport vehicle of another exemplary embodiment in a plan view;

Fig. 17 shows a driverless transport vehicle of another exemplary embodiment in a plan view.

By way of introduction, it should be noted that in the various embodiments described, identical parts are provided with identical reference symbols or identical component designations. The disclosures contained in the entire description can be transferred analogously to the same parts with the same reference symbols or the same component designations. The position information chosen in the description, such as top, bottom, side, etc., also refers to the figure directly described and shown, and these position information must be transferred analogously to the new position if the position changes. Unless expressly excluded, the various embodiments can be combined as desired.

In Fig.l and Fig.2, a drive system 1 according to the invention for a driverless transport vehicle 2 is shown in a first exemplary embodiment. The drive system 1 comprises a drive axle 3 with a first wheel unit 4 and with a second wheel unit 5 opposite the drive axle 3 in the axial direction. The drive axle 3 can be attached to a chassis 11 of the driverless transport vehicle 2. Fig.l shows the drive axle 3 in a view in the direction of travel from the rear and Fig.2 shows the drive axle 3 in a top view. For the sake of simplicity, the entire transport vehicle 2 is not shown in Fig.l, only the chassis 11 is indicated by dashed lines. The chassis 11 can, for example, comprise a suitable frame or a suitable base plate, wherein the drive axle 3 is preferably attached to an underside of the base plate or frame facing the ground 15. The specific embodiment of the chassis 11 can vary depending on the application of the transport vehicle 2.

In the simplest case, the drive system 1 of the transport vehicle 2 can, for example, also comprise just one of the drive axles 3 described in more detail below. In this case, the drive system 1 can additionally comprise at least one support wheel or one support roller for contacting the ground 15. This could, for example, in principle also make it possible to create a three-wheeled transport vehicle 2. The support wheel or the support roller can, for example, be mounted freely on the chassis 11 so that it can rotate. Several support rollers or support wheels would of course also be possible.

Within the scope of the invention, the drive axle 3 has a first electric drive unit 6 for driving the first wheel unit 4 and a second electric drive unit 7 for driving the second wheel unit 5. The first electric drive unit 6 and the second electric drive unit 7 are each designed as an axial flux motor. The structure and function of an axial flux motor are known, which is why no detailed description is given here. Description is given. Compared to conventional electric motors, axial flux motors have the advantage that they have a relatively short length in the axial direction and that they have a comparatively high maximum torque.

The drive system 1 further comprises at least one control unit 8 for controlling the first drive unit 6 and for controlling the second drive unit 7. The control unit 8 can have suitable hardware and/or software. The structure and function of a control unit 8 are known per se, which is why no further description is given here.

Furthermore, the drive axle 3 comprises a first axis of rotation 10 located centrally between the two wheel units 4, 5. The drive axle 3 can be attached to the chassis 11 of the transport vehicle 2 in such a way that it can be deflected relative to the chassis 11 at a steering angle a about the first axis of rotation 10, as indicated in Fig. 2. The first axis of rotation 10 is aligned vertically in the assembled state of the drive axle 3 and thus corresponds to a vertical axis of the transport vehicle 2. The maximum steering angle a of the drive axle 3 can, for example, be limited by the available installation space or deliberately limited to a certain maximum angle. For example, the maximum steering angle a can be up to 45°.

The at least one control unit 8 can be arranged on the drive axle 3 and thus be moved with the drive axle 3 when the drive axle 3 is deflected. Alternatively, the at least one control unit 8 could also be designed to be attached to the chassis 11 or to another location on the transport vehicle 2. In this case, the control unit 8 would not be moved with the drive axle 3 during a steering movement.

The at least one control unit 8 can also comprise several separate control units. The separate control units could be autonomous or they can communicate with each other in a suitable manner. For example, the drive axle 3 could comprise a higher-level axle control unit and each drive unit 6, 7 could have its own drive unit control unit, which communicates with the axle control unit, for example via a suitable wireless or wired communication connection. However, for example, a further system control unit could also be provided for the entire drive system 1, which is higher than the axle control unit and which can communicate in a suitable manner. communicates with the axle control unit and/or with the drive unit control units. This can be particularly advantageous if the drive system 1 comprises more than one drive axle 3.

The drive system 1 further comprises a steering angle determination device 12 for determining an actual value a_ist of the steering angle a of the drive axle 3. The steering angle determination device 12 is indicated in Fig. 1 and can, for example, have one or more suitable sensors for detecting an actual value a_ist of the steering angle a or a measured variable representative of the actual value a_ist of the steering angle a.

In an advantageous embodiment, the steering angle determination device 12 can comprise, for example, a rotation angle sensor. The rotation angle sensor can be designed, for example, as an incremental encoder, preferably as a photoelectric incremental encoder, magnetic incremental encoder or incremental encoder with sliding contacts. Optical or capacitive detection of the steering angle a would also be conceivable. The steering angle determination device 12 could, however, also be designed to determine the steering angle a from another measured variable, e.g. from a path. The steering angle determination device 12 could in this case comprise a path sensor. A logic could also be implemented in the control unit 8 that determines the steering angle a from a measured variable of a sensor.

Within the scope of the invention, the control unit 8 is designed to use the actual value a_ist of the steering angle a determined by the steering angle determination device 12 and a predetermined target value a_soll for the steering angle a to determine a first manipulated variable S 1 for the first drive unit 6 and a second manipulated variable S2 for the second drive unit 7. The control unit 8 can control the first drive unit 6 with the determined first manipulated variable S 1 and the second drive unit 7 with the determined second manipulated variable S2, so that the steering angle a can be set to the predetermined target value a_soll.

To determine the control variables SI, S2, a suitable controller can be implemented in the control unit 8, for example, e.g. a known PI controller, PID controller, etc. The controller can preferably be implemented as software. The desired predetermined steering angle a can thus be set by determining and controlling different speeds of the first drive unit 6 and the second drive unit 7. The control variables Sl, S2 can, for example, comprise a current signal or voltage signal that is suitable to set the corresponding speed of the drive units 6, 7. The control variables Sl, S2 can each be a PWM signal (PWM = pulse width modulation).

Furthermore, the control unit 8 can, for example, comprise a wireless data interface 46 for transmitting the target value a_soll for the steering angle a. The wireless data interface 46 is indicated schematically in Fig.2. The wireless data interface 46 can, for example, comprise a receiving unit for WLAN, radio, Bluetooth, or similar. The target value a_soll for the steering angle a can, for example, be transmitted to the control unit 8 via an external signal, such as an RTK signal (“real time kinematic”). The target value a_soll for the steering angle a can also be specified by a manual (remote) control, e.g. using a suitable input device such as a joystick or similar.

Alternatively or in addition to the wireless data interface 46, the control unit 8 can also comprise a physical data interface (not shown) for wired data transmission. This can be advantageous, for example, to carry out a software or firmware update.

The target value a_target for the steering angle a could, however, also be determined, for example, from a guidance device on the ground 15 over which a driverless transport vehicle 2 comprising the drive system 1 travels. Such guidance devices are known in the prior art and can, for example, comprise codes such as barcodes, data matrix codes or QR codes, a painted dot grid, a magnetic tape or an induction loop.

Depending on the technology, the drive system 1 can include suitable sensors to determine the target value a_soll for the steering angle a from the respective control devices. For example, one or more optical sensors (not shown), e.g. suitable cameras, could be provided on the drive axle 3 to read the codes or to identify the dot matrix, which can communicate with the control unit 8 in a suitable manner. A GPS sensor for global positioning would also be conceivable. The target value a_soll for the steering angle could be determined by the control unit 8 from a predetermined target position.

In addition to the target value a_soll for the steering angle a, a target value for a vehicle speed of the transport vehicle 2 can also be transmitted to the control unit 8. The control unit 8 can then use the target value a_soll for the Steering angle a the setpoint for the vehicle speed calculates control variables SI, S2 for the drive units 6, 7 and controls the drive units 6, 7 with them in order to set the desired vehicle speed and the desired steering angle a. An actual value of the vehicle speed can, if necessary, be measured using a suitable sensor (not shown) or determined from the speeds of the drive units 6, 7. A suitable sensor can, for example, be a GPS sensor. A suitable sensor could also be, for example, a speed or angle of rotation sensor for detecting a speed or angle of rotation of the wheel units 4, 5 or a speed or angle of rotation of the drive units 6, 7. The control unit 8 can determine the vehicle speed from the speed signal or the angle of rotation signal.

The drive system 1 can preferably also comprise a suitable electrical energy storage device 17 and/or a current collector (not shown) for supplying energy to the electrical drive units 6, 7 of the drive axle 3, the control unit 8, the steering angle detection device 12 and possibly other electrical consumers, e.g. the available sensors. The energy storage device 17 can, for example, comprise a rechargeable battery and/or a super capacitor (so-called “super cap”). The drive system 1 can, for example, have a suitable charging socket for charging the energy storage device 17. The energy storage device 17 could, for example, be part of the drive axle 3. In this case, the charging socket can, for example, be arranged directly on the drive axle 3. However, a central energy storage device 17 could also be provided for several drive axles 3.

The current collector enables an external energy supply. The current collector can, for example, be arranged at a point on the drive axle 3 facing the floor 15 during operation and interact with corresponding contacts on the floor 15. The current collector can, for example, comprise a first sliding contact that interacts with a corresponding stationary second sliding contact. Alternatively, the current collector can also comprise a first induction unit that interacts with a stationary second induction unit for inductive, contactless energy transmission. The structure and function of both technologies are basically known, which is why no detailed description is given here.

The current collector can be connected directly to the electric drive units 6, 7 via suitable electrical cables, e.g. if no energy storage device 17 is used. is provided. Alternatively, the current collector could also be indirectly connected to the electric drive units 6, 7 via the energy storage unit 17. This allows the energy storage unit 17 to be supplied with energy and charged via the current collector, for example in sections at designated locations. At locations where no current collection is possible, the drive units 6, 7 of the drive axle 3 can then be operated for a certain time without an external energy supply, with the energy being supplied via the energy storage unit 17. When the energy storage unit 17 is discharged, a charging process can take place again, etc. This operation can be advantageous, for example, when using supercapacitors.

However, the current collector can also be connected to the drive units 6, 7 as well as to the energy storage unit 17. In this case, for example, a selective energy supply can take place, i.e. either directly via the current collector or via the energy storage unit 17. The selective energy supply can be controlled, for example, by the control unit 8 via a suitable switch.

The electric drive units 6, 7 of the drive axle 3 can also be advantageously designed for energy recovery or recuperation. In this case, the electric drive units 6, 7 can be operated in a generator mode to convert braking energy into electrical energy. The electrical energy generated can be used, for example, to charge the energy storage device 17. The recuperation mode can also be used only as an electrical braking device. The electrical energy generated can also be fed directly back into the energy supply of the transport vehicle 2.

As indicated in Fig.l and Fig.2, the wheel units 4, 5 of the drive axle 3 can be driven, for example, by a direct drive from the respective electric drive unit 6, 7. A direct drive is understood to mean a direct drive without an intermediate gear. If necessary, the wheel units 4, 5 of the drive axle 3 could also be driven indirectly by the respective electric drive unit 6, 7 via a suitable gear (not shown in Fig.l+Fig.2).

The wheel units 4, 5 of the drive axle 3 can, for example, each comprise a wheel drive with at least one drive wheel 14 for transmitting a driving force to the ground 15. The drive wheels 14 can, for example, comprise a rim and a tire. In a In a simple embodiment, the tire can be made of solid rubber, for example. However, the tire could also be designed as a pneumatic tire in a known manner. Depending on the application area of the transport vehicle 2, suitable drive wheels 14 can be selected for the wheel drive.

According to an advantageous embodiment, the drive axle 3 can comprise a service brake 19, which can be controlled by the at least one control unit 8, as shown in Fig. 2. The service brake 19 can comprise, for example, a disc brake or a drum brake for at least one wheel unit 4, 5. The disc brake is preferably designed as a fixed calliper brake. The structure and function of a disc brake are known, which is why no detailed description is given here. Preferably, a separate disc brake or drum brake is provided for each wheel unit.

Particularly preferably, the disc brake or drum brake can be designed as an electromechanical brake, in which the kinetic energy is converted into heat in a known manner by means of friction by pressing brake pads onto the brake disc or brake drum. The brake pads can be actuated by electromechanical actuators that can be controlled by the control unit 8. As a result, in contrast to conventional hydraulic brakes, no hydraulic fluid is required to actuate the service brake.

The disc brake or drum brake could also be designed as electromagnetic brakes, in which the kinetic energy is converted into electrical energy like in a generator. The electrical energy can, for example, be fed to the energy storage device 17 or, if necessary, converted into heat via resistors.

The drive axle 3 can also comprise a parking brake (not shown), which can preferably also be actuated by the control unit 8. This can prevent undesired movement of the drive axle 3 or the transport vehicle 2, for example on uneven ground such as a slope or an incline. The mechanical parking brake can preferably be integrated into at least one of the electric drive units 6, 7. The parking brake can, for example, comprise a gear wheel that can be blocked by a locking element. The locking element can, for example, be actuated by an electrically controllable actuator that can be controlled by the control unit 8. The parking brake can also be implemented in the form of an electric or electromagnetic parking brake. To do this, the poles of the electric drive units, in particular the axial flux motors, can be short-circuited by the control unit 8 in order to achieve maximum recuperation. This form of electric parking brake does not allow the drive to be completely blocked due to its function, but this can be sufficient in certain cases, for example on a flat surface. The advantage of the electric parking brake is that it can be implemented purely via electrical control, so that no additional components are required. This results in a space-saving design and a reduction in manufacturing costs.

The drive axle 3 can further comprise at least one impact damper 23 for dampening an impact, as shown in Fig.2 and Fig.8 ff. By means of the impact damper 23, for example, an impact of a drive axle 3 of another transport vehicle 2 can be dampened or, if necessary, an impact of the drive axle 3 against an obstacle. The impact damper 23 can, for example, comprise a spring and/or a damper. The spring can, for example, comprise a coil spring or gas spring and the damper can, for example, comprise a hydraulic damper or a friction damper. Preferably, at least one impact damper 23 is directed in the direction of travel of the drive axle 3 and/or at least one impact damper 23 is directed against the direction of travel. An exemplary impact damper 23 is shown in Fig.2.

Optionally, the impact damper 23 could also comprise a contacting device 28 that is electrically connected to the at least one control unit 8. The contacting device 28 is designed to detect contact with a contacting device 28 of a further drive axle 3. In the event of contact, the contacting device 28 can send a corresponding contact signal to the control unit 8. The control unit 8 can use the contact signal to control the drive units 6, 7.

The contacting device 28 can, for example, comprise a curved or convex contact surface 66 on a free end of the impact damper 23 facing away from the drive axle 3, as is indicated in Fig.2. The contact surface 66 can, for example, have the shape of a spherical segment. This enables reliable contacting of convex contact surfaces 66 facing each other, even in the event of a lateral offset and/or an angular offset of two drive axles 3. The contacting device 28 can, for example, an electrical contact switch which generates or interrupts an electrical signal upon contact. The contacting device 28 can also comprise a suitable sensor, for example a pressure sensor or proximity sensor.

The contacting device 28 can be advantageous, for example, to form a train journey from two (or more) transport vehicles 2 traveling one behind the other, in which the impact dampers 23 of the transport vehicles 2 are in contact with one another “buffer to buffer”. The contact signal can be used, for example, to detect whether there is contact between two impact dampers 23 that are in contact with one another. If it is detected that there is no contact, the control unit 8 of the drive system 1 of the drive axle 3 of the front transport vehicle 2 can, for example, reduce the speed of the transport vehicle 2 until contact between the impact dampers 23 is re-established. This can be done, for example, by appropriately controlling the drive units 6, 7 and/or by actuating the service brake 19. Alternatively or additionally, the control unit 8 of the drive system 1 of the drive axle 3 of the rear transport vehicle 2 can increase the speed of the transport vehicle 2 until contact between the impact dampers 23 is re-established.

If a train consists of more than two transport vehicles 2, then one of the middle transport vehicles 2 can, for example, also be moved in the train without propulsion or, if necessary, even be operated in a recuperation mode.

Furthermore, it can be advantageous if the drive axle 3 comprises at least one distance sensor 35, which is connected to the control unit 8 via a suitable communication connection. The control unit 8 can use a sensor signal from the at least one distance sensor 35 to control the electric drive units 6, 7 and/or to control the service brake 19. Analogous to the collision damper 23, it can be advantageous if at least one distance sensor 35 is directed in the direction of travel and/or at least one distance sensor 35 is directed against the direction of travel.

For example, a minimum distance could be specified or can be specified in the control unit 8. The control unit 8 could then, for example, actuate the service brake and/or reduce a speed of the drive units 6, 7 if the distance sensor 35 detects that the specified minimum distance has been undershot. More complex dependencies could also be implemented in the control unit 8. For example a temporal change in a distance could be taken into account in order to initiate braking in advance if a certain value of the temporal change in the distance is reached or exceeded.

Various measuring principles are known in the prior art that can be used for the distance sensor 35. For example, the distance could be determined via the change in inductance or the change in capacitance. The distance sensor 35 can then be designed as an inductive sensor or capacitive sensor, for example. The distance could also be measured using a runtime measurement. The distance sensor 35 can then be designed as a laser rangefinder, PMD sensor or photonic mixer detector, LIDAR and sensor or radar sensors or ultrasonic sensors, for example. Of course, it would also be conceivable for several distance sensors 35 with the same or different measuring principles to be provided on the drive axle 3.

It can be advantageous if the drive axle 3, in addition to the vertical first axis of rotation 10, also comprises a second axis of rotation 60 which, during operation, is aligned parallel to a direction of travel of the at least one drive axle 3, as is indicated in Fig. 1 and Fig. 2. The drive axle 3 can be attached to the chassis 11 of the transport vehicle 2 in such a way that it can be deflected about the second axis of rotation 60 relative to the chassis 11. The second axis of rotation 60 is aligned essentially horizontally during operation and is perpendicular to the first axis of rotation 10. As is indicated in Fig. 1, the drive axle 3 can be pivoted at a pivot angle ß about the second axis of rotation 60. This allows, for example, uneven ground to be better compensated for.

The drive axle 3 can, for example, comprise at least a first part of a first central joint 9, which forms the first axis of rotation 10. A second part of the central joint 9, corresponding to the first part, can be arranged on the chassis 11 of the transport vehicle 2. The first part and the second part together form the first central joint 9. If the drive axle 3 comprises a second axis of rotation 60, then the first central joint 9 can, if necessary, also form the second axis of rotation 60. In principle, however, separate joints could also be provided for the first axis of rotation 10 and for the second axis of rotation 60, which can be arranged at a distance from one another on the drive axle 3. The first central joint 9 can, for example, be designed such that the steering angle a and/or the Swivel angle ß can be limited to a maximum value, for example by a mechanical stop.

If the drive axle 3 only comprises the first axis of rotation 10, then the first central joint 9 can be designed in a simple embodiment, e.g. as a rotary joint. The first part of the central joint 9 arranged on the drive axle 3 can be a cylindrical pin, for example. The second part of the central joint 9 arranged on the chassis 11 can in this case be a cylinder bushing corresponding to the cylindrical pin, in which the cylindrical pin can be received in order to form the rotary joint. If the drive axle 3 additionally comprises the second axis of rotation 60, then the first central joint 9 can be designed, e.g. as a universal joint or ball joint. In Fig. 1, the central joint 9 is indicated as a ball joint by way of example. Of course, the entire central joint 9 could also be arranged on the drive axle 3 or on the chassis 11.

In an exemplary embodiment, the drive axle 3 can be designed as a rigid axle, as shown in Fig. 1 and Fig. 2. A wheel suspension (not shown) of the first wheel unit 4 and a wheel suspension (not shown) of the second wheel unit 5 are essentially rigidly connected to one another via a rigid axle body 13. The rigid axle body 13 here comprises the first axis of rotation 10 and possibly also the second axis of rotation 60, in particular the first central joint 9 or at least part of the first central joint 9.

The rigid axle body 13 can, for example, be essentially cylindrical. The rigid axle body 13 can also comprise a cavity in which one or more components of the drive axle 3 or parts thereof are accommodated. For example, the drive units 6, 7 can be arranged within the cavity and be firmly connected to the axle body 13. The drive axles of the drive units 6, 7 can protrude from the front of the axle body 13 in the axial direction. Any sensors and/or the control unit 8 and/or the energy storage device 17 can also be accommodated in the cavity. Of course, this is only to be understood as an example and one or more components of the drive axle 3 or parts thereof can also be attached to the outside of the axle body 13.

In Fig.3 and Fig.4, a further embodiment of the drive axle 3 is shown. Fig.3 shows the drive axle 3 in a top view and Fig.4 shows the drive axle 3 in a side view. In this embodiment, the wheel units 4, 5 of the drive axle 3 comprise each have a crawler drive with at least one drive crawler 16 for transmitting a driving force to the ground 15. Alternatively, the wheel units 4, 5 can also comprise a chain drive (not shown) with at least one drive chain for transmitting a driving force to the ground 15. Apart from the wheel units 4, 5, the drive axle 3 can be designed essentially the same as the drive axle 3 in Fig.1+Fig.2. To avoid repetition, reference is made to the above statements with regard to the individual features.

Compared to the wheel drive (as shown in Fig. 1+2), the crawler drive and the chain drive have a higher traction, which improves off-road mobility. In addition, the crawler drive and the chain drive have a lower specific ground pressure. Since the weight of the transport vehicle 2 and any payload is distributed more evenly over a larger area, sinking is reduced on soft soils, which can reduce soil compaction, which is undesirable in agriculture and especially forestry.

Fig. 4 shows an example of a first wheel unit 4 with a crawler drive. The first wheel unit 4 can have a transmission wheel 57 that can be driven by the first drive unit 6, for example via a direct drive or via a gear. The transmission wheel 57 is rotatably mounted on a carrier 58 and serves to drive the drive crawler 16. A number of rotatable running wheels 59 are also arranged on the carrier 58 and roll on the inner surface of the drive crawler 16. A chain drive is essentially constructed in a similar way, except that a drive chain is provided instead of the drive crawler 16. Since the crawler drive and the chain drive are basically known, no detailed description is given here.

Fig. 5 shows a further advantageous embodiment of the drive axle 3. Fig. 5 shows the drive axle 3 in a view in the direction of travel. The drive axle 3 is designed here as a portal axle 20. The axes of rotation 21 of the electric drive units 6, 7 are spaced vertically from the wheel axes of rotation 22 of the wheel units 4, 5 when the portal axle 20 is mounted. A portal axle can be used to either raise or lower the chassis 11. The wheel units 4, 5 here only have wheel drives as an example. The wheel units 4, 5 could of course in turn have a crawler drive or chain drive as shown in Figs. 3 and 4. In order to transmit the drive torque or braking torque of the drive units 6, 7 to the wheel units 4, 5, the drive units 6, 7 are each connected to the wheel units 4, 5 via a suitable gear 18. The gear 18 can, for example, comprise a known spur gear, a vertical shaft, a belt drive, a chain drive or the like.

In the example shown, the portal axle is designed for raising. In the assembled state, the rotation axes 21 of the electric drive units 6, 7 are located vertically above the wheel rotation axes 22 of the wheel units 4, 5. This allows a higher ground clearance between the chassis 11 of the transport vehicle 2 and the ground 15 to be achieved. In principle, however, lowering could also be made possible by having the rotation axes 21 of the electric drive units 6, 7 located vertically below the wheel rotation axes 22 of the wheel units 4, 5. This allows the ground clearance to be reduced, which can be advantageous, for example, for wheel units with a large effective diameter.

Apart from the design as a portal axle, the drive axle 3 according to Fig.5 can again be designed essentially the same as the drive axle 3 in Fig.1+Fig.2. In order to avoid repetition, reference is therefore made to the above statements with regard to the individual features.

The drive axle 3 can also comprise an axle suspension device 44 for the spring-loaded fastening of the drive axle 3 to the chassis 11 of the transport vehicle 2. Alternatively or additionally, the drive axle 3 can also comprise an axle damping device 45 for the damped fastening of the drive axle 3 to the chassis 11 of the transport vehicle 2. In this case, the drive axle 3 can be fastened to the chassis 11 in such a way that a certain relative movement in the vertical direction along the first axis of rotation 10 is possible. For example, the first central joint 9 can be designed in such a way that a certain amount of play in the direction of the first axis of rotation 10 is possible.

The axle suspension device 44 and the axle damping device 45 can also be designed as a common spring/damper unit. The axle suspension device 44 can have one or more suitable springs, for example mechanical springs such as coil springs, torsion springs or leaf springs, etc. or also gas springs, e.g. air springs. Likewise, the axle damping device 45 can also have one or more suitable dampers, for example hydraulic dampers, friction dampers, etc. Depending on Depending on the application, the person skilled in the art can select a suitable design of the axle suspension device 44 and/or the axle damping device 45.

Of course, the application of the axle suspension device 44 and/or the axle damping device 45 is not limited to the portal axle, but the axle suspension device 44 and/or the axle damping device 45 could of course be provided in the same way in the embodiments of the drive axle described above and below, as is indicated by way of example in Fig. 1.

A further advantageous embodiment of the drive axle 3 is shown in Fig.6 and Fig.7. Fig.6 shows the drive axle 3 in a view in the direction of travel from the rear and Fig.7 shows the drive axle 3 in a plan view. The drive axle 3 is designed here as a pendulum axle. The pendulum axle can have a rigid central axle body 24 which comprises the first axis of rotation 10 and possibly the second axis of rotation 60, in particular at least part of the first central joint 9. A wheel suspension (not shown) of the first wheel units 4 can be connected to the central axle body 24 via a first pendulum joint 25.

A wheel suspension (not shown) of the second wheel units 5 can be connected to the central axle body 24 via a second pendulum joint 26. The first pendulum joint 25 and the second pendulum joint 26 each have a pivot axis 27 aligned parallel to a direction of travel of the respective wheel unit 4, 5. The first wheel unit 4 and the second wheel unit 5 can thus be pivoted about the associated pivot axis 27 relative to the central axle body 24. The two pivot axes 27 can also be coaxial if necessary. The first pendulum joint 25 and the second pendulum joint 26 can be formed by a common joint.

The pendulum axle can, for example, comprise a first wheel axle body 62 for the first wheel unit 4, on which the first electric drive unit 6 is provided, and a second wheel axle body 63 for the second wheel unit 5, on which the second electric drive unit 7 is provided. The wheel suspension (not shown) of the first wheel unit 4 can be connected essentially rigidly to the first wheel axle body 62. The wheel suspension (not shown) of the second wheel unit 5 can also be connected essentially rigidly to the second wheel axle body 63. The first wheel axle body 62 can be connected to the central axle body 24 by means of the first pendulum joint 25, and the second Wheel axle body 63 can be connected to the central axle body 24 by means of the second pendulum joint 26.

It can be advantageous if the pendulum axle comprises a wheel suspension device 64 which is designed to cushion a pivoting movement of the first wheel unit 4, in particular of the first wheel axle body 62, about the pivot axis 27 of the first pendulum joint 25. Alternatively or additionally, the pendulum axle can comprise a wheel damping device 65 which is designed to damp a pivoting movement of the first wheel unit 4, in particular of the first wheel axle body 62, about the pivot axis 27 of the first pendulum joint 25. In the same way, the pendulum axle could comprise a wheel suspension device 64 which is designed to cushion a pivoting movement of the second wheel unit 5, in particular of the second wheel axle body 63, about the pivot axis 27 of the second pendulum joint 26 and/or comprise a wheel damping device 65 which is designed to dampen a pivoting movement of the second wheel unit 5, in particular of the second wheel axle body 63, about the pivot axis 27 of the second pendulum joint 26.

Analogous to the axle suspension device 44, the wheel suspension device 64 can, for example, have a suitable mechanical spring, for example a coil spring or torsion spring, or a gas spring. The wheel damping device 65 can, analogous to the axle damping device 45, e.g. comprise a suitable hydraulic damper or friction damper. The wheel suspension device or wheel damping device 64, 65 could, for example, also be integrated directly in the respective pendulum joint 25, 26, e.g. as a torsion spring or torsion damper.

Alternatively or additionally, the swing axle can in turn have an axle suspension device 44 and/or an axle damping device 45. The axle suspension device 44 and/or the axle damping device 45 can be arranged, for example, on the central axle body 24, as indicated in Fig.6. In principle, however, an axle suspension device 44 and/or an axle damping device 45 could also be provided on the wheel axle bodies 62, 63 in order to spring and/or dampen the respective wheel axle body 62, 63 in relation to the chassis in the vertical direction. For details, please refer to the explanations for Fig.1+Fig.2.

In Fig.8, a further advantageous embodiment of the drive shaft 3 is shown in a top view. The drive shaft 3 comprises a first guide device 29 for lateral guidance of the drive axle 3. The first guide device 29 can comprise, in the region of the first wheel unit 4 and/or in the region of the second wheel unit 5, a number of first rolling bodies 30 and/or a number of first sliding elements 31 which are designed to interact with a stationary first guide rail 32.

The first sliding elements 31 can, for example, be made from a suitable plastic with the best possible sliding properties. The first rolling bodies 30 can, for example, comprise suitable rollers, wheels, balls, or the like. In the example shown, three schematically indicated curved first sliding elements 31 are arranged on the first wheel unit 4 and three first rolling bodies 30 are arranged on the second wheel unit 5, each of which can rotate about a vertical axis of rotation here. If the guide device 29 comprises first sliding elements 31, then it is advantageous if rolling bodies are provided on the first guide rail 32, on which the first sliding elements 31 can slide. If the guide device 29 comprises first rolling bodies 30, then it is advantageous if the first guide rail 32 has a guide surface on which the first rolling bodies 30 can roll.

The first sliding elements 31 or the first rolling bodies 30 can, for example, be arranged in a vertical direction above the wheel units 4, 5. The first sliding elements 31 or the first rolling bodies 30 can be stationary with respect to the drive axle 3, so that they also carry out the steering movement of the drive axle 3. In the case of a rigid axle, the first sliding elements 31 or the first rolling bodies 30 could, for example, be firmly connected to the rigid axle body 13 of the rigid axle or to the wheel suspensions of the wheel units 4, 5. If the drive axle 3 is designed as a pendulum axle, then the first sliding elements 31 or the first rolling bodies 30 can, for example, be connected to the rigid central axle body 24 or in turn connected to the wheel suspensions of the wheel units 4, 5 or the wheel axle bodies 62, 63.

The first sliding elements 31 or the first rolling bodies 30 can optionally also be attached to the drive axle 3 in a spring-loaded and/or damped manner in order to cushion lateral contact with the guide rail 32. The attachment is only indicated schematically in Fig. 8. The expert can provide a suitable attachment depending on the application.

It may be advantageous if an outer contour of the first guide device 29 in a radial direction with respect to the first axis of rotation 10 is at a guide distance 34 from the first axis of rotation 10, which corresponds at least to a turning radius 33 of the drive axle 3. The turning circle is shown in Fig.8 and designates the smallest circle in relation to the parts of the drive axle 3 that protrude furthest outwards in the radial direction. Preferably, the guide distance 34 is slightly larger than the turning circle, so that it is ensured that the first guide rail 32 is first contacted by the guide device 29 and not by the respective wheel unit 4, 5.

Fig. 9 shows an advantageous embodiment of the drive system 1 according to the invention using a driverless transport vehicle 2 in a top view. The transport vehicle 2 has a chassis 11, which is only indicated schematically. The chassis 11 can, for example, have a rigid frame or a rigid base plate. The drive system 1 here comprises several, in particular two, drive axles 3a, 3b, which are fastened to the chassis 11 of the transport vehicle 2 in such a way that the first axes of rotation 10a, 10b are spaced apart from one another in a longitudinal direction of the transport vehicle 2 at a fixed first axle distance 36.

The drive axles 3a, 3b can be designed according to one of the embodiments described so far. The drive axles 3a, 3b can be identical, but can also differ from one another if necessary. The first axle distance 36 is preferably set such that the first wheel units 4a, 4b or the second wheel units 5a, 5b do not touch one another at opposing maximum steering angles aa, ab of the two drive axles 3a, 3b.

The at least one control unit 8 of the drive system 1 can, for example, be designed to control the electric drive units 6a, 7a; 6b, 7b of both drive axles 3a, 3b (and possibly other components such as the service brakes, parking brakes, etc.). Alternatively, each drive axle 3a, 3b could also comprise a separate control unit 8a, 8b for controlling its electric drive units 6a, 7a; 6b, 7b, as indicated in Fig.9 and as already explained with reference to Fig.1+Fig.2. The control units 8a, 8b can, for example, be directly connected to one another via a suitable communication connection in order to exchange control signals. The control units 8a, 8b could, however, also each be connected to a higher-level control unit (not shown) via a suitable communication connection in order to exchange or receive control signals. The at least one control unit 8 can, for example, also be designed to simultaneously operate at least one of the drive units 6a, 7a of the first drive axle 3a in a drive mode in which the respective electric drive units 6a, 7a of the at least one first drive axle 3a exerts a drive torque on the respective wheel units 4, 5 and to operate at least one of the drive units 6b, 7b of the second drive axle 3b in a braking mode in which the respective electric drive units 6b, 7b of the at least one second drive axle 3b exerts a braking torque on the respective wheel units 4b, 5b. The braking mode can be used for energy recovery or recuperation. In addition, the function of a known anti-lock braking system (“ABS”) as well as a known electronic stability program (“ESP”) or a known “torque vectoring” can be implemented.

Fig. 10 shows a further advantageous embodiment of the drive system 1 according to the invention using a driverless transport vehicle 2 in a top view. In addition to the drive axle 3, the drive system 1 has a non-driven axle 37 with a third wheel unit 38 and a fourth wheel unit 39 opposite the non-driven axle 37 in the axial direction. The non-driven axle 37 is attached to the chassis 11 of the transport vehicle 2 such that it is spaced apart from the first axis of rotation 10 of the drive axle 3 in a longitudinal direction of the transport vehicle 2 by a fixed second axis distance 40. In a simple embodiment, the non-driven axle 37 can be firmly connected to the chassis 11 so that it cannot be deflected relative to the chassis 11. The third wheel unit 38 and the fourth wheel unit 39 can be rotatably mounted and driveless.

According to an advantageous embodiment, however, the non-driven axle 37, analogous to the drive axle 3, has a third axis of rotation 42 located centrally between the two wheel units 38, 39, which is vertically aligned in the assembled state. The non-driven axle 37 is attached to the chassis 11 of the transport vehicle 2 in such a way that it can rotate relative to the chassis 11 about the first axis of rotation 10. In this case, the non-driven axle 37 can be connected to the drive axle 3 via a mechanical coupling device 43, which is designed to transmit the steering angle a from the drive axle 3 to the non-driven axle 37. The mechanical coupling device 43 is shown in simplified form in Fig. 10 and comprises a handlebar, wherein a first end 43a of the handlebar is preferably connected in an articulated manner to the drive axle 3 and an opposite second end 43b of the handlebar is preferably connected in an articulated manner to the non-driven axle 37. In the example shown, the first end 43 of the handlebar is connected to a first articulation point of the drive axle 3, which lies in an area between the first axis of rotation 10 and the first wheel unit 4. The second end 43b of the handlebar is connected to a second articulation point of the non-driven axle 37, which lies in an area between the third axis of rotation 42 and the fourth wheel unit 39. This makes it possible to achieve an opposite steering angle of the two axles 3, 37.

In principle, however, the steering rod could also be aligned essentially parallel to the longitudinal direction of the chassis 11. The first articulation point could, for example, be in an area between the first axis of rotation 10 and the first wheel unit 4, and the second articulation point could be in an area between the third axis of rotation 42 and the third wheel unit 38. In this case, a parallel steering angle of the two axles 3, 37 can be achieved, whereby, for example, the so-called "crab steering" shown in Fig. 13 can be realized. The design of the mechanical coupling device 43 as a steering rod is of course only to be understood as an example. The mechanical coupling device 43 could also be designed differently, e.g. in the form of a suitable gear, a suitable belt drive or a suitable chain drive.

Analogous to the drive axle 3, the non-driven axle 37 can also have a fourth axis of rotation 61, which in the assembled state is aligned parallel to the direction of travel of the non-driven axle 37, as shown in Fig. 10. Analogous to the drive axle 3, the non-driven axle 37 can also have at least part of a second central joint 41, which forms the third axis of rotation 42 and possibly the fourth axis of rotation 61. In order to avoid repetition, with regard to the second central joint 41, reference is made to the above statements on the first central joint 9, which also apply in an analogous manner to the second central joint 41.

Analogous to the drive axle 3, the non-driven axle 37 can also comprise an axle suspension device 44 (not shown in Fig.10) for spring-loaded attachment to the chassis 11 of the transport vehicle 2 and/or a (not shown in Fig.10) Axle damping device 45 for damped attachment to the chassis 11 of the transport vehicle 2. In this regard, reference is made to the above statements regarding the drive axle 3, which also apply analogously to the non-driven axle 37.

The non-driven axle 37 could also be designed as a rigid axle or a swing axle. In this regard, reference is also made to the above statements on the drive axle 3, which also apply analogously to the non-driven axle 37.

As indicated in Fig. 10, the non-driven axle 37 can optionally also have a service brake 19, e.g. in the form of one or more disc brakes. The service brake 19 can be actuated via the control unit 8 of the drive system 1, which can e.g. be part of the drive axle 3. With regard to the service brake 19, reference is also made to the above statements on the drive axle 3, which also apply analogously to the non-driven axle 37.

In Fig. 11, a driverless transport vehicle 2 with a drive system 1 of a further embodiment is shown in a top view. In this embodiment, the drive system 1 comprises three drive axles 3a, 3b, 3c, each of which comprises at least one first axis of rotation 10a, 10b, 10c. The drive axles 3a-3c can in turn be designed according to one of the embodiments described. However, a non-driven axle 37 could also be provided instead of a drive axle 3a-3c. An additional non-driven axle 37 would of course also be conceivable.

The non-driven axle 37 could in turn be designed to be steerable or non-steerable. A collision damper 23 is arranged on the frontmost drive axle 3a in the direction of travel, which is aligned in the direction of travel, and a collision damper 23 is arranged on the rearmost drive axle 3c in the direction of travel, which is aligned against the direction of travel. It can be seen from this that the drive system 1 according to the invention can be adapted very flexibly to predetermined boundary conditions of the transport vehicle 2, wherein a desired number of drive axles 3 and, if necessary, a desired number of non-driven axles 37 can be combined.

Fig. 12 and Fig. 13 show two exemplary operating modes that can be implemented with a driverless transport vehicle 2 with two essentially identical drive axles 3a, 3b. The transport vehicles 2 are each shown in a top view. In the example according to Fig. 12, the steering angle aa of the first drive axle 3a and the steering angle ab of the second drive axle 3b are set in opposite directions by the control unit 8 of the drive system 1 (or possibly by the separate control units 8a, 8b of the drive axles 3a, 3b) by controlling the respective drive units 6a, 7a; 6b, 7b so that the first wheel unit 4a of the first drive axle 3a and the first wheel unit 4b of the second drive axle 3b roll on the same first curve 55 and the second wheel unit 5a of the first drive axle 3a and the second wheel unit 5b of the second drive axle 3b roll on the same second curve 56. The example shows a left turn as an example, but of course the operating mode can also be carried out for a right turn.

In the operating mode according to Fig. 13, the transport vehicle 2 is moved straight ahead, with a direction of travel of the transport vehicle 2 and a longitudinal axis of the chassis 11 of the transport vehicle 2 being aligned at an angle to one another. The two drive axles 3a, 3b are aligned parallel to one another here, but are offset from one another in the axial direction by a lateral offset 67. The operating mode is also referred to as so-called "crab steering". This can be advantageous in agricultural use, for example, in order to reduce soil compaction, since the wheel units 4b, 5b of the rear drive axle 3b do not travel in the same track as the wheel units 4a, 5a of the front drive axle 3a. In addition, better maneuverability is achieved. The operating mode shown can in principle also be carried out with a steered but not driven rear axle. A lateral offset 67 can of course also be realized in an analogous manner when cornering according to Fig. 12. In this case, each wheel unit 4a, 5a or 4b, 5b would roll on its own curve.

A further advantageous embodiment of the drive system 1 is described with reference to Fig. 14. Fig. 14 shows two transport vehicles 2a, 2b, each with a drive axle 3a, 3b and a non-driven axle 37a, 37b in a top view. The drive axles 3a, 3b and the non-driven axles 37a, 37b each have a coupling device 48 for detachable coupling with a further drive axle 3 or with a further non-driven axle 37. The coupling devices 48 can be designed for positive coupling or non-positive coupling. The coupling devices 48 are preferably designed identically. In the embodiment shown, the coupling devices 48 have, by way of example only, drawbars that can be detachably connected in a suitable manner, similar to known vehicle trailers. Of course, this is not to be understood as restrictive and the coupling devices 48 could also be designed differently. One possibility would be, for example, a permanent-magnetic coupling device 48 that automatically creates a magnetic coupling when another permanent-magnetic coupling device 48 approaches. One possibility would be, for example, an electromagnetic coupling device 48 that can be controlled by the control unit 8. In this case, the coupling with a permanent-magnetic electromagnetic coupling device 48 could be carried out selectively by the control unit 8. The coupling device 48 could also be designed in the manner of a, preferably automatic, central buffer coupling, as is known from railways.

As can be seen in Fig. 14, several transport vehicles 2 can be mechanically coupled to one another by means of the coupling devices 48 in order to form a train. In the example shown, the train is moved along a curve. In the coupled state, for example, only the front transport vehicle 2a could be driven and the rear transport vehicle 2b can be pulled without the drive being activated.

Depending on the design of the coupling devices 48, the coupling can be carried out manually by a user, for example, or it can be carried out automatically, for example by a relative speed between two transport vehicles or, if necessary, by control via the control unit 8. The release can also be carried out manually or, if necessary, automatically; for example, the coupling device 48 could comprise an electrically controllable locking device that can be controlled by the control unit 8. It is clear that there are a large number of possible design embodiments from which the expert can select a suitable variant depending on the application.

As an alternative to the mechanical coupling via the coupling devices 48, two or more transport vehicles 2 can also be coupled via a virtual coupling. In this case, the drive units 6, 7 of the drive axles 3 of the transport vehicles 2 are controlled by the respective control unit 8 so that the transport vehicles 2 are moved directly one behind the other in one go. The distance control can be achieved, for example, via the contacting devices 28. As already described with reference to Fig.2.

Fig. 14 also shows a curve center point 47 of the curve along which the train is moved. The curve center point 47 does not have to be physically present, of course, but can be a virtual point. The curve center point 47 can be specified to the control unit 8 of the drive systems 1 of the two transport vehicles 2 and the control units 8 can use this to determine the target value a_target for the steering angle a of the drive axles 3a, 3b. The curve center point 47 can be specified, for example, as a distance from the first axis of rotation 10a, 10b or as coordinates of a fixed coordinate system. The curve center point 47 could also be transmitted to the control units 8 in the form of GPS data, for example via the wireless data interface 46 described with reference to Fig. 1 and Fig. 2.

Fig. 15 shows a transport vehicle 2 with a drive system 1 with two drive axles 3a, 3b in plan view. The transport vehicle 2 is moved along a curve with a curve center point 47. The control unit 8 (not shown) can be specified the axle distance 36 between the first axes of rotation 10a, 10b of the two drive axles 3a, 3b, the track width 53a between the wheel units 4a, 5a of the first drive axle 3a, the track width 53b between the wheel units 4b, 5b of the second drive axle 3b, the effective diameters 54a of the wheel units 4a, 5a of the first drive axle 3a and the effective diameters 54b of the wheel units 4b, 5b of the second drive axle 3b. The control unit 8 can determine the control variables SI, S2 for the drive units 6a, 7a of the first drive axle 3a and the control variables SI, S2 for the drive units 6b, 7b of the second drive axle 3b, so that the first wheel units 4a, 4b roll along the same first curve 55 and the second wheel units 5a, 5b roll along the same second curve 56.

If it is desired that the two drive axles 3a, 3b travel with a certain lateral offset 67 around the curve center 47 (see Fig. 13), then the control unit 8 can optionally additionally be given a correction factor by which the offset can be adjusted.

In Fig.16 and Fig.17, a further advantageous embodiment of a transport vehicle 2 is shown in plan view. The transport vehicle 2 has a second guide device 49 for lateral guidance of the transport vehicle 2. In contrast to the axle-fixed first Guide device 29 (see Fig.8), the second guide device 49 is fixed to the vehicle and therefore cannot be moved with the drive axle 3.

In the example according to Fig. 16, the second guide device 49 comprises a number of second sliding elements 51, each of which is designed to interact with a stationary second guide rail 52. The second sliding elements 51 can in turn be made of a suitable plastic with the best possible sliding properties. Rolling bodies (not shown) arranged one behind the other in the longitudinal direction can also be provided on the second guide rail 52, which interact with the second sliding elements 51. The transport vehicle 2 is here accommodated in the transverse direction between the two second guide rails 52 and is limited by them. This essentially enables forced guidance of the transport vehicle 2 to be implemented, for example during a loading or unloading process.

The second sliding elements 51 can be attached, for example, to a frame or a base plate of the chassis 11 of the transport vehicle 2. In the example shown, a second sliding element 51 with a rounded sliding surface is arranged on each side. Of course, this is only an example and the second sliding elements 51 could also have a different shape. Likewise, more than one second sliding element 51 could of course be provided per side.

In the example according to Fig. 17, the second guide device 49 comprises a number of second rolling bodies 50, each of which is designed to interact with a stationary second guide rail 52. For this purpose, a guide surface can be provided on the second guide rail 52, on which the second rolling bodies 50 can roll. The second rolling bodies 50 can, for example, be rotatably mounted on the frame or on the base plate of the chassis 11 of the transport vehicle 2. In the example shown, four second rolling bodies 50 are arranged on each side, each of which can rotate about a substantially vertical axis of rotation. Of course, this is only to be understood as an example and the second rolling bodies 50 could also have a different shape and/or a differently oriented axis of rotation. For example, spherical second rolling bodies 50 could be used. Likewise, more or fewer than four second rolling bodies 50 could of course be provided on each side. The embodiments show possible embodiment variants, whereby it should be noted at this point that the invention is not restricted to the specifically illustrated embodiment variants thereof, but rather various combinations of the individual embodiment variants with each other are also possible and this possibility of variation lies within the skill of the person skilled in the art in this technical field due to the teaching of technical action through objective invention.

The scope of protection is determined by the claims. However, the description and the drawings must be used to interpret the claims. Individual features or combinations of features from the different embodiments shown and described can represent independent inventive solutions in themselves. The task underlying the independent inventive solutions can be taken from the description.

All information on value ranges in the description in question is to be understood as including any range and all subranges thereof, e.g. the information 1 to 10 is to be understood as including all subranges starting from the lower limit 1 and the upper limit 10, i.e. all subranges start with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

Finally, for the sake of clarity, it should be noted that, in order to better understand the structure, some elements have been shown not to scale and/or enlarged and/or reduced.

REFERENCE SIGNS LISTING

Drive system 31 First sliding element

Transport vehicle 32 First guide rail

drive axle 33 turning radius

First wheel unit 34 guide distance

Second wheel unit 35 distance sensor

First drive unit 36 First axle distance

Second drive unit 37 Non-driven axle

Control unit 38 Third wheel unit

First central joint 39 Fourth wheel unit

First axis of rotation 40 Second axis distance

Chassis 41 Second central joint

Steering angle determination device 42 Third axis of rotation 43 mechanical coupling device

axle beam

drive wheel 44 axle suspension device

Floor 45 axle damping device

drive track 46 data interface

energy storage 47 curve center

Gearbox 48 Mechanical coupling device

Service brake 49 Second guide device

Portal axle 50 Second rolling element

Rotation axis of the drive unit 51 Second sliding element

Wheel rotation axis 52 Second guide rail

shock absorber 53 track width

Central axle body 54 Effective diameter

First pendulum joint 55 First curve

Second pendulum joint 56 Second curve

swivel axis 57 transmission wheel

contacting device 58 carriers

First guide device 59 wheel

First rolling element 60 Second axis of rotation 61 Fourth axis of rotation

62 First wheel axle body

63 Second wheel axle body

64 wheel suspension system

65 wheel damping device

66 contact surface

67 Lateral offset

SI first manipulated variable

S2 Second control variable a Steering angle ß Swivel angle

Claims

patent claims 1. Drive system (1) for a driverless transport vehicle (2), wherein the drive system (1) comprises at least one drive axle (3) with a first wheel unit (4) and with a second wheel unit (5) opposite in the axial direction of the drive axle (3), wherein the at least one drive axle (3) comprises a first electric drive unit (6) for driving the first wheel unit (4) and a second electric drive unit (7) for driving the second wheel unit (5), that the drive system (1) comprises at least one control unit (8) for controlling the first drive unit (6) and for controlling the second drive unit (7), that the at least one drive axle (3) comprises a first axis of rotation (10) located centrally between the two wheel units (4, 5), wherein the at least one drive axle (3) can be fastened to a chassis (11) of the transport vehicle (2) in such a way that the first axis of rotation (10) is aligned vertically and the drive axle (3) is relative to the chassis (11) can be deflected at a steering angle (a) about the first axis of rotation (10), that the drive system (1) comprises a steering angle determination device (12) for determining an actual value (a_ist) of the steering angle (a) of the at least one drive axle (3) and that the at least one control unit (8) is designed to use the actual value (a_ist) of the steering angle (a) and a predetermined target value (a_soll) for the steering angle (a) to determine a first manipulated variable (Sl) for the first drive unit (6) and a second manipulated variable (S2) for the second drive unit (7) and to control the first drive unit (6) and the second drive unit (7) with the determined manipulated variables (SI, S2) so that the steering angle (a) can be set to the predetermined target value (a_soll), characterized in that the first electric drive unit (6) and the second electric drive unit (7) of the at least one drive axle (3) each designed as an axial flux motor. 2. Drive system (1) according to claim 1, characterized in that the at least one drive axle (3) comprises at least a second axis of rotation (60), wherein the drive axle (3) can be fastened to the chassis (11) of the transport vehicle (2) such that the second axis of rotation (60) is aligned parallel to a direction of travel of the drive axle (3) and the drive axle (3) can be deflected relative to the chassis (11) about the second axis of rotation (60). 3. Drive system (1) according to claim 1 or 2, characterized in that the at least one drive axle (3) comprises at least a part of a first central joint (9), which forms the first axis of rotation (10), preferably additionally the second axis of rotation (60), wherein the first central joint (9) preferably comprises a rotary joint, universal joint or ball joint. 4. Drive system (1) according to one of claims 1 to 3, characterized in that the at least one drive axle (3) is designed as a rigid axle, wherein a wheel suspension of the first wheel unit (4) and a wheel suspension of the second wheel unit (5) are connected to one another via a rigid axle body (13) and wherein the rigid axle body (13) comprises the first axis of rotation (10), in particular the at least part of the first central joint (9), and preferably additionally comprises the second axis of rotation (60). 5. Drive system (1) according to one of claims 1 to 3, characterized in that the at least one drive axle (3) is designed as a pendulum axle which has a central axle body (24) which comprises the first axis of rotation (10), in particular the at least part of the first central joint (9), wherein a wheel suspension of the first wheel units (4) or a first wheel axle body (62) connected to the wheel suspension of the first wheel units (4) is connected to the central axle body (24) via a first pendulum joint (25) and a wheel suspension of the second wheel units (5) or a second wheel axle body (63) connected to the wheel suspension of the second wheel units (5) is connected to the central axle body (24) via a second pendulum joint (26), wherein the first pendulum joint (25) and the second pendulum joint (26) each have a pivot axis (27) aligned parallel to a direction of travel of the respective wheel unit (4). 6. Drive system (1) according to one of claims 1 to 5, characterized in that the wheel units (4, 5) of the at least one drive axle (3) each comprise a wheel drive with at least one drive wheel (14) for transmitting a driving force to the ground (15) or that the wheel units (4, 5) of the at least one drive axle (3) each comprise a crawler drive with at least one drive crawler (16) or a chain drive with at least one drive chain for transmitting a driving force to the ground (15). 7. Drive system (1) according to one of claims 1 to 6, characterized in that the drive system (1) comprises an electrical energy storage device (17) and/or a current collector for supplying energy to the electrical drive units (6, 7) of the at least one drive axle (3) and/or the at least one control unit (8) and/or the steering angle determination device (12). 8. Drive system (1) according to one of claims 1 to 7, characterized in that the steering angle determination device (12) comprises a rotation angle sensor, preferably a photoelectric incremental encoder, a magnetic incremental encoder or an incremental encoder with sliding contacts. 9. Drive system (1) according to one of claims 1 to 8, characterized in that the wheel units (4, 5) of the at least one drive axle (3) are driven by a direct drive from the respective electric drive unit (6, 7) or that the wheel units (4, 5) of the at least one drive axle (3) are driven by the respective electric drive unit (6, 7) via a transmission (18). 10. Drive system (1) according to one of claims 1 to 9, characterized in that at least one of the electric drive units (6, 7) of the at least one drive axle (3) is designed for energy recovery. 11. Drive system (1) according to one of claims 1 to 10, characterized in that the at least one drive axle (3) comprises a service brake (19) which can be controlled by the at least one control unit (8), wherein the service brake (19) preferably comprises an electric or electromechanical disc brake or drum brake for at least one wheel unit (4, 5), wherein the electromechanical disc brake is preferably designed as a fixed calliper brake and/or that the at least one drive axle (3) comprises a parking brake, wherein the parking brake is preferably integrated in at least one of the electric drive units (6, 7). 12. Drive system (1) according to one of claims 1 to 11, characterized in that the at least one drive axle (3) is designed as a portal axle (20), wherein Rotation axes (21) of the electric drive units (6, 7) are spaced vertically from wheel rotation axes (22) of the wheel units (4, 5). 13. Drive system (1) according to one of claims 1 to 12, characterized in that the at least one drive axle (3) comprises at least one collision damper (23), wherein preferably at least one collision damper (23) is directed in the direction of travel and/or at least one collision damper (23) is directed against the direction of travel. 14. Drive system (1) according to claim 13, characterized in that the at least one impact damper (23) comprises a contacting device (28) which is electrically connected to the at least one control unit (8) and which is designed to transmit a contact signal to the control unit (8) upon contact with a contacting device (28) of a further drive axle (3). 15. Drive system (1) according to one of claims 1 to 14, characterized in that the at least one drive axle (3) comprises a first guide device (29) for laterally guiding the drive axle (3), wherein the first guide device (29) preferably comprises at least in the region of a wheel unit (4, 5) a number of first rolling bodies (30) and/or a number of first sliding elements (31) which are designed to interact with a stationary first guide rail (32). 16. Drive system (1) according to claim 15, characterized in that an outer contour of the first guide device (29) is spaced in a radial direction with respect to the first axis of rotation (10) at a guide distance (34) from the first axis of rotation (10) which corresponds at least to a turning radius (33) of the drive axis (3). 17. Drive system (1) according to one of claims 1 to 16, characterized in that the at least one drive axle (3) comprises at least one distance sensor (35) and that the at least one control unit (8) is designed to use a sensor signal of the at least one distance sensor (35) to control the electric drive units (6) of the at least one drive axle (3) and/or to control the service brake (19). use, wherein preferably at least one distance sensor (35) is directed in the direction of travel and/or at least one distance sensor (35) is directed against the direction of travel. 18. Drive system (1) according to one of claims 1 to 17, characterized in that the drive system (1) comprises a plurality of drive axles (3a, 3b) which can be fastened to the chassis (11) of the transport vehicle (2) such that the first axes of rotation (10a, 10b) are spaced apart from one another in a longitudinal direction of the transport vehicle (2) at a fixed first axle distance (36), wherein the at least one control unit (8) is designed to control the electric drive units (6a, 7a; 6b, 7b) of the plurality of drive axles (3a, 3b) or wherein each of the plurality of drive axles (3a, 3b) comprises a control unit (8a, 8b) for controlling its electric drive units (6a, 7a; 6b, 7b). 19. Drive system (1) according to claim 18, characterized in that the at least one control unit (8) is designed to simultaneously operate at least one of the drive units (6a, 7a) of the first drive axle (3a) in a drive mode in which the respective electric drive unit (6a, 7a) exerts a drive torque on the respective wheel unit (4, 5) and to operate at least one of the drive units (6b, 7b) of the second drive axle (3b) in a braking mode in which the respective electric drive unit (6b, 7b) exerts a braking torque on the respective wheel unit (4b, 5b). 20. Drive system (1) according to one of claims 1 to 19, characterized in that the drive system (1) comprises at least one non-driven axle (37) with a third wheel unit (38) and a fourth wheel unit (39) located opposite the non-driven axle in the axial direction, wherein the at least one non-driven axle (37) can be fastened to the chassis (11) of the transport vehicle (2) such that it is spaced apart from the first axis of rotation (10) of the at least one drive axle (3) in a longitudinal direction of the transport vehicle (2) at a fixed second axis distance (40). 21. Drive system (1) according to claim 20, characterized in that the at least one non-driven axle (37) comprises a vertical third axis of rotation (42) located centrally between the two wheel units (38, 39) and can be fastened to the chassis (11) of the transport vehicle (2) in such a way that it can rotate relative to the chassis (11) about the first axis of rotation (10). is rotatable and that the at least one non-driven axle (37) is connected to the at least one drive axle (3) via a mechanical coupling device (43) which is designed to transmit the steering angle (a) from the at least one drive axle (3) to the at least one non-driven axle (37), wherein the at least one non-driven axle (37) preferably has at least part of a second central joint (41) which comprises the third axis of rotation (42). 22. Drive system (1) according to one of claims 1 to 21, characterized in that the at least one drive axle (3) comprises an axle suspension device (44) for spring-loaded attachment to the chassis (11) of the transport vehicle (2) and/or comprises an axle damping device (45) for damped attachment to the chassis (11) of the transport vehicle (2) and/or that the at least one non-driven axle (37) comprises an axle suspension device (44) for spring-loaded attachment to the chassis (11) of the transport vehicle (2) and/or comprises an axle damping device (45) for damped attachment to the chassis (11) of the transport vehicle (2). 23. Drive system (1) according to one of claims 1 to 22, characterized in that the at least one control unit (8) of the drive system (1) comprises a preferably wireless data interface (46) for transmitting at least the target value (a_soll) for the steering angle (a), preferably in addition to transmitting a target value for a vehicle speed of the transport vehicle (2). 24. Drive system (1) according to one of claims 1 to 23, characterized in that a curve center point (47) can be specified for the at least one control unit (8) of the drive system (1) and that the at least one control unit (8) is designed to determine the target value (a _soll) for the steering angle (a) of the at least one drive axle (3) from the predetermined curve center point (47). 25. Drive system (1) according to one of claims 1 to 24, characterized in that the at least one drive axle (3) comprises a positive or non-positive coupling device (48) for releasable coupling with a further drive axle (3) or with a non-driven axle and/or that the at least one non-driven Drive axle (37) comprises a positive or non-positive coupling device (48) for releasable coupling with a further drive axle (3) or with a non-driven axle (37). 26. Driverless transport vehicle (2) with a chassis (11), characterized in that the driverless transport vehicle (2) comprises a drive system (1) according to one of claims 1 to 25, which is fastened to the chassis (11), wherein the chassis (11) preferably comprises a frame or a base plate. 27. Driverless transport vehicle (2) according to claim 26, characterized in that the transport vehicle (2) comprises at least one support wheel for contacting the ground (15) and/or that the transport vehicle (2) comprises a second guide device (49) for laterally guiding the transport vehicle (2), wherein the second guide device (49) preferably comprises a number of second rolling bodies (50) and/or a number of second sliding elements (51) which are designed to interact with a stationary second guide rail (52). 28. Method for operating a driverless transport vehicle (2) according to claim 26 or 27, characterized in that a target value (a_soll) for the steering angle (a) is specified to the at least one control unit (8) of the at least one drive axle (3) of the drive system (1), or that a curve center point (47) is specified to the control unit (8) and the control unit (8) determines the target value (a_soll) for the steering angle (a) based on the curve center point (47), that an actual value (a_ist) of the steering angle (a) is determined by the steering angle determination device (12), and that the control unit (8) determines the first manipulated variable (S1) for the first drive unit (6) and the second manipulated variable (S2) for the second drive unit (7) from the actual value (a_ist) of the steering angle (a) and the target value (a_soll) for the steering angle (a), and the first drive unit (6) and controls the second drive unit (7) with the determined control variables (SI, S2) so that the steering angle (a) is set to the specified target value (a_soll). 29. Method according to claim 28, characterized in that the at least one control unit (8) of the at least one drive axle (3) of the drive system (1) is a A target value for a vehicle speed is specified and that the control unit (8) uses the target value for the vehicle speed to determine the first manipulated variable (S1) for the first drive unit (6) and to determine the second manipulated variable (S2) for the second drive unit (7), so that the vehicle speed is set to the specified target value, wherein preferably an actual value of the vehicle speed is measured or determined from rotational speeds of the drive units (6, 7). 30. Method according to claim 28 or 29, wherein the transport vehicle (2) comprises a drive system (1) according to claim 18, characterized in that the control unit (8) is provided with the axle distance (36) between the first axes of rotation (10a, 10b) of the at least two drive axles (3a, 3b) and track widths (53a, 53b) of the at least two drive axles (3a, 3b) and effective diameters (54) of the first and second wheel units (4a, 5a; 4b, 5b) of the at least two drive axles (3a, 3b) and that the control unit (8) uses these to determine the control variables (SI, S2) for the first and second wheel units (4a, 5a; 4b, 5b) of the at least two drive axles (3a, 3b), so that the first wheel units (4a, 4b) preferably roll along the same first curve (55) and the second Wheel units (5a, 5b) preferably roll along the same second curve (56).