WO2025201631A1

WO2025201631A1 - Method of coupling a charging robot to an electrically chargeable industrial vehicle, and charging robot

Info

Publication number: WO2025201631A1
Application number: PCT/EP2024/058123
Authority: WO
Inventors: Max ASTRAND; Elinne SANCHEZ; Mattias HALLEN
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2024-03-26
Filing date: 2024-03-26
Publication date: 2025-10-02
Anticipated expiration: 2026-09-26

Abstract

A method (300) of coupling a charging robot (100) to an electrically chargeable industrial vehicle (400), comprising: moving a charging plug (120) mounted on a robot arm (110) of the charging robot (100) from an initial position of the charging plug to a first position closer to or within a charging socket of the vehicle; calibrating a force sensor (130) of the charging robot after moving the charging plug to the first position, the force sensor being configured for determining a force acting on the charging plug; measuring the force acting on the charging plug coupled to the charging socket, wherein the force is measured using the calibrated force sensor; and adjusting, by the charging robot, a second position of the charging plug coupled to the charging socket, wherein the second position is adjusted based on the force measured by the calibrated force sensor.

Description

METHOD OF COUPLING A CHARGING ROBOT TO AN ELECTRICALLY CHARGEABLE INDUSTRIAL VEHICLE, AND CHARGING ROBOT

FIELD

Aspects of the invention relate to a method of coupling a charging robot to an electrically chargeable industrial vehicle, particularly for charging the industrial vehicle. Further aspects relate to a charging robot for electrically charging an industrial vehicle.

BACKGROUND

In industrial operations, the use of electrically chargeable vehicles such as battery-electric vehicles or trucks is increasing. Electric industrial vehicles may be charged for example by a stationary charging device. Manual charging of an industrial vehicle by a driver or other personnel may have disadvantages. For example, as the power of charging devices for charging industrial vehicles increases, particularly for charging large industrial vehicles, the cables become very bulky, heavy, and hard to manually lift and insert into a charging socket. When electrifying large industrial vehicles such as large mining vehicles, particular issues arise which may not occur with personal cars. For instance, getting out of the industrial vehicle and down from the vehicle can be cumbersome and cost time that could otherwise be used for productive work. As the number of stops for charging increases, the interruptions of the industrial operations can become a significant economic factor. Further, getting out of an industrial vehicle to manually insert a charging plug into a charging socket of the vehicle may even be dangerous in active production areas with active machines or other vehicles. If the industrial vehicle is remote controlled or autonomously controlled, there not even be any human present for a manual insertion of the charging plug into the charging socket.

However, automating the charging of industrial vehicles may be challenging, for instance automating the charging using a robot to connect a charging cable to an industrial vehicle for charging the vehicle. For example, in mining industry, industrial vehicles such as a dump truck may be transporting large masses that may suddenly shift, for instance a boulder sliding in the bed of the truck, thereby effectively changing the truck center of mass. Further, ground conditions in the area, where the industrial vehicle is parked for charging, may be unstable, bumpy, muddy, or generally non-stiff These ground conditions may cause the vehicle to settle in place or slide slightly. Such situations can lead to a sudden movement of the vehicle, which may result in damage to the charging device, to the vehicle and/or to nearby equipment. Thus, there is a need for improved methods and apparatuses for the charging of industrial vehicles.

DISCLOSURE OF THE INVENTION

In view of the above, a method of coupling a charging robot to an electrically chargeable industrial vehicle, and a charging robot for electrically charging an industrial vehicle according to the independent claims are provided.

According to an aspect, a method of coupling a charging robot to an electrically chargeable industrial vehicle is provided. The method includes moving a charging plug mounted on a robot arm of the charging robot from an initial position of the charging plug to a first position closer to or within a charging socket of the vehicle. The method includes calibrating a force sensor of the charging robot after moving the charging plug to the first position, the force sensor being configured for determining a force acting on the charging plug. The method includes measuring the force acting on the charging plug coupled to the charging socket, wherein the force is measured using the calibrated force sensor. The method includes adjusting, by the charging robot, a second position of the charging plug coupled to the charging socket, wherein the second position is adjusted based on the force measured by the calibrated force sensor. It should be understood that the method and/or the charging robot used in the method may include any of the additional features described herein.

According to a further aspect, a charging robot for electrically charging an industrial vehicle is provided. The charging robot includes a robot arm. The charging robot includes a charging plug mounted on the robot arm, the charging plug configured to be plugged into a charging socket of the vehicle. The charging robot includes a force sensor configured for determining a force acting on the charging plug. The charging robot includes a controller configured to perform a method according to any of the embodiments described herein.

According to embodiments of the present disclosure, an electrically chargeable industrial vehicle is a vehicle suitable for industrial operations, and may be specialized for industrial operations. A personal electric vehicle, such as vehicles intended for personal transport, e.g. electric cars, electric motorcycles, recreational vehicles, golf carts, etc. are not considered industrial vehicles. The industrial vehicle may be a battery electric vehicle (BEV), or a hybrid vehicle having (plug-in) charging capabilities. Industrial vehicles may include trucks such as dump trucks, diggers, haulers, drillers, bulldozers, earthmovers, forklifts, agricultural vehicles such as harvesters or tractors, mining vehicles, construction site vehicles, mobile robots or drones. Industrial operations may include operations associated with mining, agriculture, construction, stockyard logistics, or similar industries or industry-related operation. In some embodiments, an industrial vehicle may be an off-highway vehicle. According to some embodiments, the industrial vehicle is a mining vehicle. In embodiments, the industrial vehicle is a heavy-duty vehicle, particularly an industrial vehicle with a gross vehicle weight rating of at least about 12 metric tons. In some embodiments, the industrial vehicle may be a batteryelectric mining truck, particularly a heavy-duty battery-electric mining truck.

According to embodiments of the present disclosure, a charging robot is provided. The charging robot is configured for electrically charging an industrial vehicle. The charging robot includes a robot arm. The robot arm may include a plurality of arm segments connected by joints. In particular, each of the plurality of arm segments may be rotatable with respect to a neighboring arm segment. The arm segments of the robot arm may form a kinematic chain. In particular, the robot arm may be an at least 3-axis robot arm, particularly at least 4-axis robot arm, at least 5 axis robot arm or at least 6-axis robot arm. For example, the robot arm may be a 6-axis robot arm or a 7-axis robot arm. The number of axes particularly denotes the number of rotatable joints or degrees of freedom.

In embodiments, the charging robot includes a charging plug mounted on the robot arm. The charging plug is configured to be plugged into a charging socket of the industrial vehicle. The charging plug can be mounted on a plug-mounting segment of the plurality of arm segments of the robot arm. The plug-mounting segment may be the final segment of a kinematic chain of arm segments of the robot arm. In embodiments, the charging plug is rigidly connected to the plug-mounting segment. The charging plug may be rigidly connected to the plug-mounting segment throughout charging cycles, a charging cycle particularly including a plugging-in phase, charging and an unplugging phase. In contrast to releasable charging plugs, which may be released after plugging a charging plug into the charging socket, a rigidly connected charging plug may facilitate an operation of the charging robot and/or allow for connection of the charging plug to the charging socket in a larger variety of angles. In some embodiments, the charging plug may be a megawatt charging system (MCS) plug.

According to some embodiments, the charging robot may include at least one further charging plug mounted on the robot arm. In particular, the at least one further charging plug may be mounted together with the charging plug on the plug-mounting segment of the robot arm. The at least one further charging plug may be rigidly connected to the plug-mounting segment. For example, the charging plug may include a mechanical bracket for mounting the charging plug and the at least one further charging plug to the plug-mounting segment of the robot arm. The at least one charging plug may particularly be one further charging plug or two further charging plugs. In particular, the charging robot may include two or three charging plugs in total. In embodiments, the charging plug and the at least one further charging plug may be MCS plugs.

According to embodiments of the present disclosure, the charging robot may be particularly adapted for industrial vehicles, particularly for large or heavy-duty vehicles and/or vehicles with large electrical charging capacity. In particular, electrical components of the charging robot may be adapted to provide high output power for charging the industrial vehicle and/or withstand high currents for charging industrial vehicles. Further, mechanical components of the charging robot, such as the robot arm, may be adapted to support the electrical components, e.g. to at least partially support a weight of a charging cable used in charging industrial vehicles with a high charging power.

According to embodiments, the charging robot includes a charger module. It should be understood that the charger module of the charging robot as well as some further components of the robot may be stationary with respect to movable components of the robot arm, particularly not arranged on the robot arm. In embodiments, the charger module is configured for receiving an input power from a primary power source. The primary power source may be an electrical grid, a high, medium or low voltage substation, a generator, such as a diesel electric generator or a fuel cell, a photovoltaic installation, a windfarm, an intermediate energy store such as a battery installation, fly wheels, supercapacitors, or any other source of electrical power. The input power may be provided by a direct current (DC) or an alternating current (AC).

According to embodiments, the charger module is configured for converting the input power into an output power for charging the industrial vehicle. The output power may be a DC output power. In further embodiments, the output power may be an AC output power. In embodiments, the charging robot, particularly the charger module, is configured to provide an output power of at least 600 kW, particularly of at least 1 MW, at least 3 MW or at least 4 MW. For example, the charger module may be configured to provide an output power for charging the industrial vehicle of about 4.5 MW. Herein, the output power of the charger module may also be referred to as charging power. The charger module may include at least one transformer for converting the input power to the output power. The charger module may include at least one rectifier for rectifying the input power, particularly if the input power is an AC input power. The charger module may include at least one inverter, particularly if the output power is an AC output power. The transformer, the rectifier and/or the inverter may include solid-state devices, and/or be implemented as a converter, such as a solid-state converter. The charging robot may include a controller communicatively coupled to the charger module. The controller may be configured for controlling the charger module to electrically charge an industrial vehicle. In particular, the controller may be configured for regulating the output power provided by the charger module according to charging requirements of the industrial vehicle.

According to embodiments, the charging robot includes a charging cable. The charging cable may provide an electrical connection between a charger module of the charging robot and the charging plug. An end of the charging cable may be electrically connected to and particularly directly physically attached to the charging plug. A further end of the charging cable may be electrically connected to and particularly directly physically attached to a charger module of the charging robot. In embodiments with more than one charging plug on the robot arm, each charging plug may be electrically connected via a respective charging cable to the charger module. In further embodiments, more than one charging plug may be connected via one charging cable to the charger module.

In embodiments, the robot arm is configured to support at least a portion of a weight of the charging cable, particularly during charging of the industrial vehicle. For example, the robot arm may support the end of the charging cable connected to the charging plug. According to some embodiments, the charging cable has a weight per length of at least 2 kg/m, particularly of at least 3.5 kg/m or at least 4 kg/m, and/or maximum 10 kg/m, particularly maximum 8 kg/m or maximum 7 kg/m. For example, the charging cable may have a weight per length between 3 kg/m and 7 kg/m, particularly between 3.5 kg/m and 6 kg/m or between 4 kg/m and 5 kg/m. The charging cable may have a length of at least 1 m, particularly of at least 2 m, and/or of maximum 10 m, particularly maximum 7 m or maximum 5 m. In particular, charging cables according to embodiments may be adapted for charging with a high power for efficiently charging industrial vehicles described herein.

In embodiments, the charging cable may include a positive wire and a negative wire for conducting current for charging the industrial vehicle, particularly a positive copper wire and a negative copper wire. In some embodiments, the charging cable includes a cooling hose for cooling the charging cable using a cooling fluid. The charging cable may further include a return hose for returning the warmed-up cooling fluid. Cooling the charging cable may be used particularly to avoid an overheating of the charging cable, e.g. when charging an industrial vehicle with a high power. For example, a charging cable may include a positive wire and a negative wire for charging the vehicle, a cooling hose for cold cooling fluid for cooling the positive and negative wires, and a return hose for warmed-up cooling fluid. The cooling hose and the return hose may be part of a cooling cycle for cooling the charging cable. The cooling cycle may include a cooling source for cooling the warmed-up cooling fluid from the return hose before re-circulating the cooling fluid through the cooling hose and the return hose. In some embodiments, the charging robot may include the cooling cycle for cooling the charging cable.

According to embodiments, the charging robot includes a vision system. The vision system may be positioned next to the robot arm and/or on the robot arm. The vision system may be configured to determine a socket position of a charging socket of an industrial vehicle. In some embodiments, the vision system may be configured to determine a position of the charging plug. The vision system can include or consist of one or more cameras, a LiDAR system and/or a time-of-flight sensor. The vision system may include multiple cameras, e.g. for stereo vision. The vision system can be communicatively coupled to a controller of the charging robot. In particular, the controller may be configured to control a motion of the robot arm based on information from the vision system.

According to embodiments of the present disclosure, the charging robot includes a force sensor. The force sensor is configured to determine a force acting on the charging plug. Forces acting on the charging plug may include for example supporting forces exerted by the robot arm on the charging plug, or forces from the industrial vehicle, such as forces exerted on charging plug by the charging socket of the industrial vehicle. Forces acting on the charging plug may include forces exerted on the charging plug by the charging cable, particularly due to the weight of the charging cable. Forces exerted by the charging cable on the charging plug may further be caused by a stiffness and/or inertia of the charging cable when the charging cable is moved or repositioned by the robot arm. Forces acting on the charging plug may include gravity acting on the charging plug itself. According to some embodiments, the force sensor may be a hardware force sensor. The force sensor may be arranged on the plug-mounting segment of the robot arm, particularly the final segment of the robot arm, and/or on the charging plug. In particular, the force sensor may be included into the plug-mounting segment, or the force sensor may be arranged at an interface connecting the charging plug and the plug-mounting segment. The force sensor may be an at least one-axis force sensor, particularly an at least two-axis or at least three-axis force sensor. For example, the force sensor may be a three-axis force sensor. The force sensor may for example include one or more strain gauges, and/or one or more piezoelectric force sensors. Hardware force sensors may provide a direct and accurate measurement of forces acting on the charging plug. In further embodiments, the force sensor may be a soft force sensor. The soft force sensor may be provided as software in a controller of the charging robot. The soft force sensor may be configured to calculate the force acting on the charging plug based on operational data of the charging robot, e.g. based on torque values of motors associated with the different axes of the robot arm. A soft force sensor may dispense with the use of one or more hardware force sensors.

Generally, industrial vehicles may be operated and electrically charged in industrial environments, in which the vehicles may be susceptible to sudden movements, for example as described above. Such sudden movements may result in damage to the charging robot, to a pedestal on which the robot arm is mounted, to the industrial vehicle itself or to other equipment near the vehicle or the charging robot. In particular, the charging plug and/or the charging socket may be damaged, which may be more brittle than other components of the charging robot or the industrial vehicle. In contrast to industrial vehicles, personal vehicles are generally assumed to stay stationary during electric charging. Further, charging devices for personal vehicles may be smaller and more flexible than a charging robot configured for charging industrial vehicles described herein. Embodiments of the present disclosure may use a forcebased control scheme to compensate sudden movements of the vehicle by a corresponding movement of the robot arm. In particular, the control scheme may include monitoring forces acting on the charging plug. In view of various forces acting on the charging plug, particularly forces by the vehicle, the charging cable and the robot arm, methods according to the present disclosure include a force sensor calibration such that specifically the forces exerted on the charging plug by the industrial vehicle can be identified. Based on the identified forces, e.g. forces caused by a sudden movement of the vehicle, the charging robot can reposition the charging plug to avoid damage, particularly by following a movement of the industrial vehicle. According to embodiments of the present disclosure, a method of coupling a charging robot to an electrically chargeable industrial vehicle is provided, particularly a method of electrically charging the industrial vehicle. Operations according to methods described herein may be performed automatically by the charging robot, particularly without human intervention. In particular, methods described herein may be performed fully automatically. The charging robot may be configured according to any of the embodiments described herein.

In some embodiments, the method includes determining a socket position of a charging socket of the industrial vehicle. The socket position may be determined by the charging robot, particularly by a controller of the charging robot. The socket position may be determined based on visual and/or position information provided by a vision system of the charging robot.

According to embodiments, the method includes moving, particularly by the charging robot, a charging plug mounted on a robot arm of the charging robot from an initial position of the charging plug to a first position, the first position being closer to or within the charging socket of the industrial vehicle. In particular, the charging robot may move the charging plug from an initial position, e.g. a resting position of the charging plug between charging cycles, to the first position, wherein the first position is closer to the socket position or wherein the first position is at the socket position. According to some embodiments, in the first position, the charging plug is arranged outside the charging socket. In embodiments, the first position is at a distance of at least 1 mm, particularly at least 2 mm or at least 3mm, and/or maximum 40 cm from the charging socket, particularly maximum 30 cm, maximum 20 cm, maximum 10 cm or maximum 5 cm. For instance, the distance may be between 3 mm and 30 cm, e.g. about 5 cm. In further embodiments, the charging plug may be moved to a first position within the charging socket of the industrial vehicle such that the charging plug is at least partially inserted into the charging socket.

In some embodiments, moving the charging plug to the first position may include orienting the charging plug to an orientation suitable for inserting the charging plug into the charging socket. In particular, the charging plug may be oriented at least substantially perpendicular to the charging socket of the industrial vehicle. Moving the charging to the first position may include orienting the charging plug at least substantially perpendicular to the charging socket of the industrial vehicle at the first position or before arriving at the first position. The orientation of the charging plug may be maintained particularly during calibrating a force sensor and during coupling the force sensor to the charging socket according to embodiments described herein. By maintaining the orientation of the charging plug while calibrating the force sensor and while the charging plug is coupled to the charging socket, additional forces acting on the charging plug e.g. due to a rotation of the charging plug, for example torsional forces, may be avoided.

In embodiments, the method includes calibrating a force sensor of the charging robot after moving the charging plug to the first position, the force sensor being configured for determining a force acting on the charging plug. The force sensor may be provided in accordance with embodiments described herein. The calibration may be performed by the controller of the charging robot. Calibrating the force sensor may include activating the force sensor for the calibration. Activation of the force sensor may include switching the force sensor on and/or starting to read out force measurements from the force sensor. In further embodiments, the force sensor may be permanently activated.

In embodiments, calibrating the force sensor may include determining a reference force acting on the charging plug. The reference force may be a force measured by the force sensor after moving the charging plug to the first position. The reference force may be a reference force vector, particularly a three-dimensional reference force vector. The reference force vector and/or further force vectors described herein may be determined relative to an absolute coordinate system, for example relative to an orthogonal x-y-z coordinate system with the z- axis corresponding to the vertical direction with respect to gravity. Determining a reference force close to or within the charging socket may allow particularly for determining a force component exerted on the charging plug by the charging cable. Determining the force component caused by the charging cable can be particularly relevant with respect to the charging of industrial vehicles, since charging cables for the charging of industrial vehicles may be particularly large and heavy. The reference force may be used to distinguish forces exerted by the vehicle on the charging plug from the forces resulting from the charging cable. The calibration may advantageously be performed close to or within the charging socket to avoid significant changes in the forces caused by the charging cable, wherein such changes could result from changes in the spatial configuration of the charging cable due to a repositioning of the robot arm.

In some embodiments, the charging plug, particularly the entire robot arm, stands still at the first position while calibrating the force sensor. In particular, the charging plug may stand still for the duration of calibrating of the force sensor. In further embodiments, the robot arm may move the charging plug from the first position towards the socket position while calibrating the force sensor, particularly more slowly than the movement from the initial position to the first position. In some embodiments, calibrating the force sensor is performed while the charging plug is outside the charging socket of the industrial vehicle. Calibrating the force sensor outside the charging socket may avoid that a sudden movement of the vehicle results in a force being exerted by the charging socket on the charging plug while the force sensor is not yet calibrated or while the force sensor is being calibrated.

In embodiments, the method can include coupling the charging plug to the charging socket of the industrial vehicle, particularly after calibrating the force sensor. Coupling the charging plug to the charging socket may include positioning, particularly by the charging robot, the charging plug to a second position at which the charging plug is coupled to the charging socket of the vehicle. Coupling the charging plug to the charging socket may include plugging the charging plug into the charging socket. In some embodiments, the method may include electrically charging the industrial vehicle after plugging the charging plug into the charging socket. The second position may be a charging position. The charging position is a position of the charging plug in which the plug is plugged into the charging socket and charging of the industrial vehicle can be performed. In some embodiments, the charging cable may be cooled during charging of the industrial vehicle, particularly by flowing a cooling fluid through a cooling hose of a charging cable according to embodiments described herein. In some embodiments, methods described herein may also be performed without electrically charging the industrial vehicle, for example in case of a failure or a defect in the charging robot or in the industrial vehicle, wherein due to the failure or defect the electric charging may not be performed after coupling the charging plug to the charging socket. Embodiments may provide protection of the vehicle and the charging robot from damage due to sudden movements of the vehicle even in a situation of failed electric charging.

According to embodiments, the method includes measuring the force acting on the charging plug coupled to the charging socket, wherein the force is measured using the calibrated force sensor. In particular, measuring the force may be performed while charging the industrial vehicle. Measuring the force using the calibrated force sensor may be performed at the second position in which the charging plug is coupled to the charging socket of the industrial vehicle. Measuring the force may include continuously monitoring the force acting on the charging plug, particularly throughout a period in which the charging plug is coupled to the charging socket or throughout a charging period of charging the industrial vehicle. In some embodiments, the force measured by the calibrated force sensor may be a force vector, particularly a three- dimensional force vector.

According to embodiments of the present disclosure, the method includes adjusting, by the charging robot, the second position of the charging plug coupled to the charging socket. In particular, the second position may be adjusted while the industrial vehicle is being charged. In embodiments, the second position is adjusted based on the force measured by the calibrated force sensor. In some embodiments, the second position is adjusted based on a comparison of the reference force measured during calibrating the force sensor with the force measured by the calibrated force sensor. In particular, the second position may be adjusted based on a difference between the force measured by the calibrated force sensor and the reference force. For instance, the forces acting on the charging plug may particularly include a force exerted by the charging cable on the charging plug, e.g. due to a gravitational force of the charging cable or due to a stiffness of the charging cable. The force caused by the charging cable may be part of or may at least substantially correspond to the reference force F_reference, particularly a reference force measured while the charging plug is positioned in front of the charging socket or after at least partially inserting the charging plug into the charging socket. Forces F_measured measured after coupling the charging plug to the charging socket may include or correspond to the force caused by the charging cable and may further include a force F_vehicle exerted on the charging plug by the vehicle, for example due to a sudden movement of the industrial vehicle. The force F_vehicie exerted on the charging plug by the vehicle may be determined by the difference Fvehicle ^— F_measured - F_ref_erence.

In embodiments, the second position may be adjusted based on the measured force and the reference force such that the charging plug is moved together with the industrial vehicle, particularly together with the charging socket. For example, the second position may be adjusted such that the charging plug remains coupled to the charging socket, e.g. during a sudden movement of the industrial vehicle. Adjusting the second position may include changing the second position of the charging plug in an absolute coordinate system. Adjusting the second position may include maintaining the position of the charging plug relative to the industrial vehicle, particularly relative to the charging socket of the industrial vehicle. Adjusting the second position may include continuously maintaining the position of the charging plug relative to the industrial vehicle, particularly throughout the period in which the charging plug is coupled to the charging socket, more particularly throughout electrically charging of the industrial vehicle. By following the industrial vehicle, for instance in case of a sudden movement, damage to the charging robot, particularly to the charging plug, and/or to the industrial vehicle, particularly to the charging socket, may be prevented.

In embodiments, the second position is adjusted such that the difference F_vehicie between the measured force and the reference force goes towards zero, particularly such that an absolute value of the difference F_vehicle is reduced to zero. A controller of the charging robot may use for example a proportional-integral-derivative (PID) control scheme to control the robot arm to adjust the second position such that the difference F_vehicie is adjusted towards zero, particularly at least substantially to zero.

According to some embodiments, the second position is adjusted if the difference between the force measured by the calibrated force sensor and the reference force exceeds a predetermined force threshold. The predetermined force threshold may be pre-determined for example based on experimental data or a simulation. The predetermined force threshold may be configured to account for negligible forces, e.g. minor fluctuations or changes in the forces acting on the charging plug. For example, minor fluctuations in forces may result from minor vibrations in the industrial environment. Minor changes in forces may result from minor forces acting on the cable. In embodiments, the second position is not adjusted if the difference between the force measured by the calibrated force sensor and the reference force is below the predetermined force threshold. The use of a predetermined force threshold may particularly prevent a movement of the charging plug by the charging robot in response to forces not resulting from the industrial vehicle, or in response to forces which may be too low to represent a danger to the charging robot and the industrial vehicle.

In some embodiments, the reference force measured during calibrating the force sensor is a reference force vector. Further, the force sensor may measure a force vector of the force acting on the charging plug coupled to the charging socket. The charging robot may adjust the second position of the charging plug in a direction of a difference between the force vector measured by the calibrated force sensor and the reference force vector, particularly in the direction of a difference vector between the force vector measured by the calibrated force sensor and the reference force vector. The force vector, the reference force vector and the difference (vector) may be three-dimensional vectors of an aligned coordinate system, for example an orthogonal coordinate system such as an orthogonal x, y, z system with the z-axis being a vertical axis with respect to gravity. The direction of the adjustment of the second position can be the same direction as the direction of the difference (vector). The second position may be adjusted such that the difference goes towards zero in accordance with further embodiments described herein. The second position may be adjusted if the difference between the force vector measured by the calibrated force sensor and the reference force vector exceeds a predetermined force threshold. In some embodiments, an absolute value of the difference may be compared to a predetermined force threshold, the predetermined force threshold being a scalar. In further embodiments, the predetermined threshold may be a vector threshold. If one or more components of the difference vector exceed the respective component of the predetermined threshold, the second position may be adjusted.

According to embodiments, the method may include uncoupling the charging plug from the charging socket of the industrial vehicle, particularly after charging the industrial vehicle. Uncoupling the charging plug may include deactivating the force sensor Uncoupling the charging plug may include unplugging the charging plug from the charging socket of the industrial vehicle. Further, the charging robot may remove the charging plug from the charging socket. The charging robot may move the charging plug to a resting position.

In embodiments, methods according to the present disclosure are performed during normal operation of the charging robot. In particular, a method may be performed repetitively for a plurality of consecutive charging cycles for charging one or more industrial vehicles. For example, the method may be used during normal operation and particularly not only during a calibration run, such as during a calibration run in a commissioning phase of the charging robot.

An adjustment of the second position based on measured forces as described herein may provide a force control of the position of the charging plug, particularly throughout a period in which the charging plug is coupled to the charging socket of the industrial vehicle, more particularly during a period of charging the industrial vehicle. During the period in which the charging plug is coupled to the charging socket or during charging, position control of the charging plug based on the vision system may be deactivated, or may be complementary to the force control, for instance for reasons of safety or redundancy. Before coupling the charging plug to the charging socket and/or after uncoupling the charging plug from the charging socket, the robot arm may be controlled based on signals from the vision system, particularly solely based on the vision system.

According to embodiments of the present disclosure, the charging robot includes a controller. The controller can be configured to perform any of the methods according to embodiments described herein. The controller may be configured to control the charging robot and particularly a plurality of subsystems of the charging robot. In particular, the controller may be communicatively coupled with the robot arm, with a vision system of the charging robot, with a cooling system for cooling the charging cable, and/or with a charger module of the charging robot. The controller may be configured to control a pose of the robot arm based on position information. The position information may be determined for example based on encoder data from encoders of motors configured for positioning the arm segments of the robot arm relative to each other. The position information may be determined based on the encoder data and based on a kinematic chain model of the robot arm. Additionally or alternatively, position information may be determined based on visual information or distance information provided by the vision system of the charging robot.

The controller may be configured to control the charging robot to automatically perform operations of a method described herein, particularly to perform all operations of a method automatically. The controller may include a processor. It is understood that the controller may include more than one controllers, each performing one or more operations according to the methods described herein. In particular, interoperating controllers of the charging robot may be distributed among various subsystems of the charging robot, for instance in the charger module, the vision system and/or the robot arm.

In embodiments, a processor of the controller may include a central processing unit (CPU). To facilitate performing operations according to embodiments described herein, the processor may be one of any form of general purpose computer processor that can be used in an industrial setting. A memory device containing a computer-readable medium may be coupled to the processor. The memory device and/or the computer readable medium may be one or more readily available memory devices such as random access memory, read only memory, hard disk, or any other form of digital storage either local or remote. The processor may be coupled to support circuits for supporting the processor in a conventional manner. These circuits may include cache, power supplies, clock circuits, input/output circuitry and related subsystems, and the like. For example, the processor may be configured to receive data from the vision system, the charger module and/or the robot arm. The processor may particularly output signals for controlling the robot arm and/or the charger module. The controller can include a human machine interface (HMI) or may be connectable to a human machine interface, e.g. for maintenance and/or monitoring of the charging robot. The human machine interface may be local at the industrial site or may be provided at a remote location. Instructions for operations of coupling a charging robot to an electrically chargeable industrial vehicle, particularly for charging the industrial vehicle, according to embodiments described herein may be stored in the computer-readable medium as a software routine typically known as a recipe. The software routine, when executed by the processor, transforms the general purpose computer into a specific purpose computer, and can cause the controller to carry out a method or any operations of controlling the charging robot according to embodiments of the present disclosure. Although the method of the present disclosure may be implemented as a software routine, some of the method operations that are disclosed herein may be performed in hardware as well as by the software. As such, the embodiments may be implemented in software as executed upon a computer system, and hardware as an application specific integrated circuit or other type of hardware implementation, or a combination of software and hardware. According to an example, an ABB 6-axis robot arm may be used as a robot arm for a charging robot. The ABB 6-axis robot may include integrated force control sensors for sensing forces at a tool mounted to the final segment of the robot arm, the tool herein being the charging plug. The controller of the charging robot may include software for force sensor calibration, load identification and gravity compensations. The controller may be configured for executing e.g. RAPID (programming language for ABB robots) force control instructions, the instructions being provided in accordance with methods described herein.

Embodiments of the present disclosure may advantageously provide for adaptively controlling the positioning of the charging plug based on forces exerted on the charging plug by an industrial vehicle, particularly when the charging plug is coupled to the industrial vehicle. In contrast to rigidly maintaining the robot arm in a pose while the charging robot is coupled to the industrial vehicle, the robot arm according to embodiments is controlled to adapt its pose in response to external forces, thus effectively providing a “flexible” or “free floating” connection between the charging robot and the industrial vehicle. The adaptive control may particularly avoid damage to the charging robot and/or the industrial vehicle, for example in case of a sudden movement of the industrial vehicle. The control of the robot arm of the charging robot according to embodiments can be performed using a force sensor that can measure the external forces that are applied to the charging plug. A calibration of the force sensor is performed particularly to isolate forces caused by the charging cable from forces caused by the industrial vehicle, which may be exerted on the charging plug by the charging socket of the vehicle. The isolation of the forces exerted on the charging plug by the vehicle from the forces caused by the charging cable is particularly advantageous in the charging of industrial vehicles such as mining vehicles, wherein large charging powers and heavy charging cables may be used. Embodiments provide corrective movements of the robot arm in order to compensate for the external forces exerted on the charging plug by the industrial vehicle. By following a movement of the industrial vehicle, damage such as a breaking of the charging plug can be prevented. Embodiments may provide improved automatic charging of industrial vehicles, particularly by increasing the safety of automatic charging using a charging robot, by reducing maintenance of charging robots due to damage or wear, and/or by avoiding a downtime of charging robots and industrial vehicles due to damage.

Further advantages, features, aspects and details that can be combined with embodiments described herein are evident from the dependent claims, the description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings relate to embodiments of the disclosure and are described in the following:

Fig. 1 schematically illustrates a charging robot according to embodiments of the present disclosure;

Fig. 2 schematically illustrates a portion of a robot arm of a charging robot, with a charging plug mounted on the robot arm according to embodiments described herein;

Fig. 3 shows a flow diagram of a method according to embodiments described herein;

Fig. 4 schematically illustrates a charging robot with a robot arm positioning the charging plug at a first position for calibrating a force sensor prior to coupling the charging plug to an industrial vehicle in accordance with embodiments of the present disclosure;

Fig. 5 schematically illustrates a charging robot with a charging plug coupled to a charging socket of an industrial vehicle; and

Fig. 6 schematically illustrates a sectional view of an industrial vehicle and a charging robot during charging of the industrial vehicle. DETAILED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to the same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not meant as a limitation of the disclosure. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

Fig. 1 illustrates a charging robot 100 according to embodiments described herein. The charging robot 100 includes a robot arm 110 including a kinematic chain. The kinematic chain includes a plurality of arm segments 112 mounted to a robot base 111. Neighboring arm segments 112 are rotatable (see curved arrows in Fig. 1) with respect to each other about a respective rotation axis. For example, the robot arm 110 of Fig. 1 is a 6-axis robot arm. The plurality of arm segments 112 includes a final segment 116 at a free end of the kinematic chain.

The charging robot 100 further includes a charging plug 120 mounted to the final segment 116. In particular, the charging plug 120 is rigidly mounted to the final segment 116 such that the charging plug 120 remains rigidly connected to the final segment 116 throughout a plurality of charging cycles of charging an industrial vehicle. For example, in Fig. 1, the charging plug 120 is an MCS plug. The charging plug 120 includes charging contacts 122 (see Fig. 2) to provide an electrical connection with corresponding further electrical contacts of a charging socket of an industrial vehicle. The charging plug 120 is connected to a charger module 119 via a charging cable 118. The charger module 119 is connected to a power source (not shown) and provides an output power to the charging cable 118 and the charging plug 120 for charging an industrial vehicle. The charging robot 100 further includes a controller 106. The controller 106 is communicatively coupled to the robot arm 110, particularly for controlling a motion of the robot arm 110, to a force sensor 130 mounted on the final segment 116 for measuring forces acting on the charging plug 120, and to the charger module 119, particularly for controlling the electric charging of an industrial vehicle. The controller 106 is configured to control the charging robot 100 in accordance with methods of the present disclosure, for example according to method 300 illustrated in Fig. 3. Fig. 2 illustrates a portion of the charging robot 100, specifically the arm segments 112 at the free end of the robot arm 110 and the charging plug 120 which is rigidly mounted to the final segment 116. In Fig. 2, the force sensor 130 is integrated into the final segment 116. The force sensor 130 is configured for determining force vectors in a first direction 132, in a second direction 134, and in a third direction 136, particularly force vectors in an orthogonal coordinate system. In Fig. 2, which shows the charging plug 120 in an uncoupled state, forces acting on the charging plug 120 are substantially caused by the gravitational force 124 acting on the charging cable 118.

Fig. 3 illustrates a flow diagram of a method 300 of coupling a charging robot to an electrically chargeable industrial vehicle according to embodiments described herein, particularly a method 300 of charging an electrically chargeable industrial vehicle. The method 300 uses a charging robot 100 according to embodiments described herein. The method 300 includes method operations which are automatically performed by the charging robot 100 during normal operation of the charging robot 100.

At block 310, the method 300 includes determining, by the charging robot 100, a socket position of a charging socket of the industrial vehicle. The socket position is determined using a vision system of the charging robot 100. At block 320, the method includes moving the charging plug 120 mounted on a robot arm 110 of the charging robot 100 from an initial position of the charging plug, particularly from a resting position, to a first position closer to the charging socket of the industrial vehicle. For example, the first position can be at a distance of about 5 cm from the charging socket. Referring to Fig. 4, a charging robot 100 is illustrated, wherein the robot arm 110 has been controlled to position the charging plug 120 at a first position in front of a charging socket 444 (see Fig. 5) of an industrial vehicle 400. The charging plug 120 is oriented for insertion into the charging socket 444, particularly perpendicular to the charging socket 444. Figs. 4 to 6 only illustrate a portion of the industrial vehicle 400, particularly a lower portion including wheels 442 of the industrial vehicle 400. For instance, the industrial vehicle 400 illustrated in Figs. 4 to 6 is a battery-electric haul truck for mining.

At block 330, the method 300 includes calibrating a force sensor 130 of the charging robot 100 after moving the charging plug 120 to the first position. At block 330, the force sensor 130 is for example activated and calibrated at the first position while the robot arm 110 stands still. At the first position, the force sensor 130 determines a three-dimensional reference force vector F reference of one or more forces acting on the charging plug 120, particularly with respect to the first, second and third directions 132, 134, 136 as illustrated in the magnified detail of Fig. 4. The reference force vector at least substantially corresponds to forces resulting from the gravitational force 124 acting on the charging cable 118.

At block 340, the method 300 includes coupling the charging plug 120 to the charging socket 444 of the industrial vehicle 400. Specifically, the charging plug 120 is plugged into the charging socket 444, particularly to establish an electrical connection between the charging robot 100 and the industrial vehicle 400. For example, Figs. 5 and 6 illustrate the charging robot 100 after having plugged the charging plug 120 into the charging socket 444 of the industrial vehicle 400 such that the charging plug 120 is in a second position (charging position) suitable for charging the industrial vehicle 400.

At block 350, the method 300 includes electrically charging the industrial vehicle 400 using a power of at least 600 kW, particularly more than 1 MW, e.g. using about 4.5 MW. During charging, the charging cable 118 is cooled using a cooling fluid provided through a cooling hose of the charging cable 118.

At block 360, the method 300 includes measuring the force acting on the charging plug 120 coupled to the charging socket 444, wherein the force is measured using the calibrated force sensor 130. The force acting on the charging plug 120 may be monitored particularly after coupling the charging plug 120 to the charging socket 444 and more particularly during charging of the industrial vehicle 400. In Fig. 5, the force monitored by the force sensor 130 is a three-dimensional force vector with respect to the first, second and third directions 132, 134, 136. Referring to Fig. 6, forces acting on the charging plug 120 are schematically illustrated. In particular, forces caused by the gravitational force 124 acting on the charging cable 118 are transmitted from the charging cable 118 to the charging plug 120. Further, in case of a sudden movement of the industrial vehicle 400, for example due to unstable ground conditions, the charging socket 444 exerts a further force 625 (F_vehicie) on the charging plug 120.

At block 370, the method 300 includes adjusting, by the charging robot 100, the second position of the charging plug 120 coupled to the charging socket 444, wherein the second position is adjusted based on the force measured by the calibrated force sensor 130. In particular, the controller 106 of the charging robot 100 determines a difference vector F_vehicie between the measured force vector F_measured and the reference force vector F_reference, the difference vector corresponding to a force exerted by the industrial vehicle 400 on the charging plug 120: F vehicle ⁼ F measured - F_ref_erence- The controller 106 controls the robot arm 110 to adjust the second position of charging plug 120 in the direction of the difference vector F_vehicle, particularly to follow the sudden movement of the charging socket 444 and the industrial vehicle 400. The second position is adjusted by the controller 106 via PID control to adjust the difference vector over a plurality of force measurement and position adjustment cycles at least substantially to zero. By adapting the second position of the charging plug 120 to follow the force exerted on the charging plug 120, damage may be avoided, particularly damage to the industrial vehicle 400, to the charging plug 120, to the robot arm 110 and/or to a robot base 604 which anchors the robot arm 110 to a pedestal 602 or floor beneath the robot arm 110. At block 380, particularly after finishing the charging of the industrial vehicle 400, the method 300 includes deactivating the force sensor 130 and unplugging the charging plug 120 from the industrial vehicle 400. The robot arm 110 and the charging plug 120 are positioned to a resting position before restarting the method 300 for charging a further industrial vehicle in a next charging cycle.

Claims

1. A method (300) of coupling a charging robot (100) to an electrically chargeable industrial vehicle (400), comprising:

- moving a charging plug (120) mounted on a robot arm (110) of the charging robot (100) from an initial position of the charging plug to a first position closer to or within a charging socket of the vehicle;

- calibrating a force sensor (130) of the charging robot after moving the charging plug to the first position, the force sensor being configured for determining a force acting on the charging plug;

- measuring the force acting on the charging plug coupled to the charging socket, wherein the force is measured using the calibrated force sensor; and

- adjusting, by the charging robot, a second position of the charging plug coupled to the charging socket, wherein the second position is adjusted based on the force measured by the calibrated force sensor.

2. The method according to claim 1, wherein calibrating the force sensor comprises determining a reference force acting on the charging plug; and wherein the second position is adjusted based on a comparison of the reference force with the force measured by the calibrated force sensor.

3. The method according to claim 2, wherein the second position is adjusted based on a difference between the force measured by the calibrated force sensor and the reference force.

4. The method according to claim 3, wherein the second position is adjusted if the difference between the force measured by the calibrated force sensor and the reference force exceeds a predetermined force threshold.

5. The method according to any of claims 2 to 4, wherein the reference force is a reference force vector, wherein the force sensor measures a force vector of the force acting on the charging plug coupled to the charging socket, and wherein the charging robot adjusts the second position of the charging plug in a direction of a difference between the force vector measured by the calibrated force sensor and the reference force vector.

6. The method according to any of the preceding claims, wherein the charging robot stands still at the first position while calibrating the force sensor.

7. The method according to any of the preceding claims, wherein the first position is at a distance of at least 1 mm and/or maximum 40 cm from the charging socket.

8. The method according to any of the preceding claims, wherein the socket position of the vehicle is determined by a vision system of the charging robot.

9. The method according to any of the preceding claims, wherein the vehicle is a mining vehicle.

10. The method according to any of the preceding claims, wherein the method is performed during normal operation of the charging robot.

11. The method according to any of the preceding claims, wherein the charging robot comprises at least one further charging plug mounted on the robot arm.

12. A charging robot (100) for electrically charging an industrial vehicle (400), comprising:

- a robot arm (110);

- a charging plug (120) mounted on the robot arm, the charging plug configured to be plugged into a charging socket (444) of the vehicle;

- a force sensor (130) configured for determining a force acting on the charging plug; and

- a controller (106) configured to perform a method (300) according to any of the preceding claims.

13. The charging robot according to claim 12, wherein the force sensor is arranged on a final segment (116) of the robot arm and/or on the charging plug.

14. The charging robot according to any of claims 12 or 13, wherein the charging robot is configured for charging the vehicle with a charging power of at least 600 kW.

15. The charging robot according to any of claims 12 to 14, further comprising a charging cable (118), wherein an end of the charging cable is electrically connected to the charging plug, and wherein the robot arm is configured to support at least a portion of a weight of the charging cable during charging of the vehicle.

16. The charging robot according to claim 15, wherein the charging cable has a weight per length of at least 2 kg/m.

17. The charging robot according to any of claims 15 or 16, wherein the charging cable includes a cooling hose for cooling the charging cable using a cooling fluid.