HK1190374B

HK1190374B - Towbarless airplane tug

Info

Publication number: HK1190374B
Application number: HK14103367.3A
Authority: HK
Inventors: 阿里．佩里; 兰．布莱尔
Original assignee: 以色列宇航工业有限公司
Priority date: 2008-11-25
Filing date: 2012-01-06
Publication date: 2017-01-27

Abstract

A towbarless airplane tug configured for receiving a landing gear of an airplane and towing it thereby is provided. The tug comprises a chassis configured for receiving thereon at least a portion of the landing gear, a propulsion arrangement configured to move the tug in a direction along a trajectory, at least one force sensor configured to measure, directly or indirectly, a force exerted by the chassis on the landing gear in at least the direction due to a speed differential between the tug and the airplane, and a controller in communication with the force sensor and being configured to alter one or more parameters of movement of the tug such that the force exerted by the chassis on the landing gear is maintained below a predetermined value.; The propulsion arrangement comprises a variable angle swash plate hydraulic pump coupled to a variable angle swash plate hydraulic motor and to a controllable bypass path valve. The controller alters the parameters by regulating at least the power available to the propulsion arrangement, the pump and motor swash-plates, and the state of the bypass path valve.

Description

Towbar-free airplane trailer

The application is a divisional application of an invention patent application with the application number of 200980147257.7, the international application date of 2009, 11 and 25 and the invention name of "towbarless airplane trailer".

Technical Field

The present invention relates generally to systems for aircraft ground movement, and more particularly to methods of controlling ground vehicles in such systems.

Background

Aircraft trailers are commonly used to tow aircraft between airport ground locations, thereby eliminating the need for the aircraft to move under its own power, thereby saving fuel. The trailer may be equipped with a tow bar connecting the landing gear and the trailer, or it may be towbar-less, in which case no tow bar is provided, wherein the landing gear is usually provided directly on the trailer chassis.

Disclosure of Invention

According to an aspect of the present invention there is provided a towbarless aircraft trailer for receiving landing gear of an aircraft for towing the aircraft, the trailer comprising:

a chassis for receiving at least a portion of a landing gear thereon;

propulsion means arranged for moving the trailer in a track direction, comprising a variable angle swash plate hydraulic pump connected to a variable angle swash plate hydraulic motor and a controllable bypass valve for circulating hydraulic fluid between the pump and the motor when the bypass is in a closed state, thereby activating the propulsion means to increase at least one of the speed and the tractive effort of the trailer, and circulating at least a major part of the hydraulic fluid through the motor via the bypass valve when the bypass is in an open state, thereby reducing at least one of the rotational speed and the tractive effort of the trailer;

at least one force sensor for directly or indirectly measuring the force exerted by the chassis on the landing gear at least in that direction, due to the speed difference between the trailer and the aircraft; and

a controller in communication with the force sensor for varying one or more parameters of movement of the trailer so as to maintain the force exerted by the chassis on the landing gear below a predetermined value (e.g. during trailer movement) by adjusting at least the power available to the propulsion means, the pump and the motor swash plate and the state of the bypass valve.

It will be apparent that the term "towbarless" as used in the present specification and claims relates to a class of aircraft trailers without a tow bar (i.e. a rod or other connection means connected between the trailer chassis and the aircraft landing gear). In towbarless aircraft trailers, the landing gear is typically located directly on the chassis, or its weight is directed into a region within the chassis.

It is clear that the term "controller" as used in the present description and claims may be understood in a broad sense to include, but is not limited to, two or more controllers, e.g. each implementing a specific function.

The towbarless aircraft trailer also includes a hydraulic motor diverter valve that allows hydraulic fluid to freely flow through the motor when the bypass is closed for free trailer movement.

The bypass may also be associated with a braking period after the bypass is opened, wherein hydraulic fluid is diverted from a swashplate pump (swashplate pump), the controller being further configured to control a state of the bypass, the valve being characterized by: the response period is much shorter than the braking period.

The propulsion drive module also includes a valve for controlling the bypass state, the valve characterized by a response period that is substantially less than a resonant period of the hydraulic pump swash plate and the motor.

The controller is also configured to regulate a displacement of the hydraulic motor.

The controller is also configured to adjust a control angle of the swash plate pump. In this way, the speed of the trailer and hence the force exerted on the landing gear can be controlled.

The controller may also be configured to cause rapid changes in the swash pump control angle. This allows it to prevent forces exerted on the aircraft landing gear from exceeding a force threshold.

The controller is also configured to cause the swash plate pump control angle to vary slowly. This may be advantageous, for example, for obtaining a desired speed for a towbarless aircraft trailer.

The controller may also be configured to adjust the control angle of the swash plate pump using a feed forward approach (i.e., a control scheme in which inversions (upsets) in the system input can be used to adjust the system equipment in advance or at the same time as those inversions arrive).

The towbarless aircraft trailer also includes an energy absorber positioned between the landing gear and the chassis for absorbing energy.

The change in one or more motion parameters may have an effect so as to and/or be directed to cause the trailer to slow and/or reduce tractive effort.

The chassis may include a support assembly configured to receive the landing gear portion and mounted on the chassis so as to be moveable on the chassis at least in that direction. In this case, the force sensor may be arranged to measure a force exerted by the support assembly on the chassis in at least that direction.

The motion parameter is selected from the group consisting of speed, direction, acceleration and deceleration.

The controller is further configured for calculating a (predicted) resulting force exerted by the chassis on the landing gear based at least on one or more external factors. These external factors may be selected from the group consisting of:

relevant grade data for various locations along the aircraft running surface that the trailer is to traverse;

relevant wind data affecting the aircraft and trailer;

relevant rolling friction data for the aircraft and/or trailer at various locations along the aircraft running surface; and

relevant obstacle data.

The relevant grade data may be provided by a grade detection function.

The associated grade data may be predetermined and stored as grade data in a database, the controller being further configured for determining a position of the trailer on the aircraft travel surface and for correlating the grade data with the position.

The associated rolling friction data may be predetermined and stored as friction data in a database, the controller being further configured for determining a position of the trailer on the aircraft running surface and for correlating the friction data with the position.

The trailer may also be configured to detect obstacles in the path of the aircraft.

The controller may be configured to wirelessly communicate with a remote command center, for example, via an electronic flight bag.

The towbarless airplane trailer also comprises an electronic flight bag which is used for wirelessly communicating with the similar equipment in the airplane.

According to another aspect of the invention there is provided a method of towing an aircraft, the method comprising providing a towbarless aircraft trailer comprising:

a chassis for receiving at least a portion of an aircraft landing gear thereon; and

propulsion means for moving the trailer in the direction of the track, comprising a variable angle swash plate hydraulic pump connected to a variable angle swash plate hydraulic motor and a controllable bypass valve for circulating hydraulic fluid between the pump and the motor when the bypass is in the closed state, thereby energising the propulsion means to increase at least one of the speed and the tractive effort of the trailer, and circulating at least a major portion of the hydraulic fluid through the motor via the bypass valve when the bypass is in the open state, thereby reducing at least one of the speed and the tractive effort of the trailer;

the method further comprises the following steps: the trailer is caused to tow the aircraft while one or more parameters of movement of the trailer are varied to maintain the force exerted by the chassis on the landing gear below a predetermined value by adjusting at least the power obtained by the propulsion means, the pump and the motor swash plate, and the state of the bypass valve.

The trailer may be provided as described above.

According to another aspect of the present invention there is provided a towbarless aircraft trailer for receiving landing gear of an aircraft for towing the aircraft, the trailer comprising:

a chassis for receiving at least a portion of a landing gear thereon;

-a propulsion device for moving the trailer in a direction of the trajectory; and

a controller for comparing the actual speed of the towbarless aircraft trailer with its predetermined desired speed, and instructing the propulsion means to maintain the actual speed of the towbarless aircraft trailer if the following conditions are met:

the actual speed is lower than the desired speed; and

the actual speed is kept within the predetermined speed range for a predetermined period of time before the comparison.

The controller is further configured to detect aircraft pilot control braking and aircraft deceleration, and is further configured to command the propulsion devices to maintain actual speed when the following conditions are met:

the actual speed is higher than the desired speed; and

detecting at least one of aircraft pilot control braking and aircraft deceleration.

The controller may be further configured to instruct the propulsion device to change the actual speed of the towbarless aircraft trailer to match a desired speed if aircraft pilot controlled braking is detected.

The towbarless aircraft trailer may also be configured to provide positive tractive effort at all times during towing of the aircraft.

The towbarless aircraft trailer is also configured to prevent the landing gear from exceeding its maximum allowable fatigue load in real time.

The controller is further configured to calculate a desired speed.

The controller is further configured to calculate a desired tractive effort corresponding to the desired speed.

The controller is further configured to calculate a desired speed based at least on the trailer position.

The controller is further configured to calculate a desired velocity based at least on the position of the trailer and the position of the at least one other trailer.

The controller is further configured to calculate a desired velocity based at least on the position of the trailer and the position and velocity of at least one other trailer with which the at least one path is shared.

The controller is further configured to calculate a desired velocity based at least on the position of the trailer and its desired time to reach one end of the towing position.

The controller is further configured to calculate a desired velocity based on at least the position of the trailer, an estimated time of arrival of another trailer at an end of the tow point, and a desired time of arrival of the trailer at the end of the tow location.

The towbarless airplane trailer also includes a transmitter for transmitting information regarding trailer speed and position. The information may be transmitted, for example, to an aircraft cockpit, to at least one other trailer, or to a remote command center.

The towbarless airplane trailer also includes a receiver for receiving velocity and position information associated with at least one other trailer from a remote command center.

The towbarless airplane trailer further comprises a detector which detects the speed and position of at least one other trailer by means of a sensor; the controller is configured to calculate a desired speed based at least on the speed and the position of the other trailer.

The controller is further configured to calculate the desired speed based on the desired time to reach one end of the tow location and estimated times for other trailers to reach one end of the tow point.

According to a further aspect of the present invention there is provided a method of controlling a towbarless aircraft trailer, the method comprising:

obtaining relevant speed and position information for at least one other trailer that is expected to share at least part of the towing path with the trailer; and

calculating a desired speed of the trailer based at least on the speed, the position and the information.

The method of towing also includes calculating a desired speed based on a desired time for the trailer to reach an end of the towing location.

The method also includes calculating a desired velocity of the towbarless aircraft trailer based on estimated times for other trailers to reach an end of the tow point.

The method also includes transmitting the trailer-related speed and position information to other trailers.

The method also includes transmitting the associated speed and position information of the trailer to a remote command center and receiving the associated speed and position information of other trailers.

The trailer may also utilize sensors to obtain the relative speed and position information of at least one other trailer.

According to a further aspect of the present invention there is provided a towbarless aircraft trailer for receiving landing gear of an aircraft for towing the aircraft, the trailer comprising:

a chassis for receiving at least a portion of a landing gear thereon;

a controller configured to operate as described above.

Drawings

The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the accompanying drawings.

FIG. 1A is a schematic illustration of a towbarless aircraft trailer;

FIG. 1B is a cross-sectional view of the illustrated towbarless aircraft trailer taken along line 1B-1B of FIG. 1A;

FIG. 1C is a top view of the towbarless airplane trailer of FIG. 1A;

FIGS. 2A to 2J are perspective views of the towbarless aircraft of FIG. 1A at various stages of operation before and during towing operations;

FIGS. 3A through 3E are schematic illustrations of the towbarless aircraft trailer of FIG. 1A at various stages of pilot control of taxiing operations;

figures 4A to 4E are schematic views of the towbarless aircraft trailer of figure 1A at various stages of autonomous taxi operations;

figures 5A to 5E are schematic views of the towbarless aircraft trailer of figure 1A at various stages of autonomous return operation;

FIGS. 6A through 6C are schematic illustrations of the towbarless aircraft trailer steering function of FIG. 1A;

figures 7A to 7D illustrate an energy absorption system which reacts against the pilot controlled braking of the aircraft in order to control the load on the landing gear;

FIG. 8A is an input-output block diagram of a force control loop and a speed control loop that are part of the trailer controller of FIG. 1;

FIG. 8B is a block diagram of a multiple-input/multiple-output (MIMO) force control loop and a speed control loop that are part of the controller;

FIG. 9 illustrates a dynamic model of the towbarless trailer and aircraft, and the forces exerted on the aircraft and on the towbarless aircraft trailer shown in FIG. 1A;

FIG. 10 illustrates various control loops;

FIG. 11 illustrates a method of towing an aircraft;

FIG. 12 shows a towbarless trailer and corresponding aircraft cockpit Electronic Flight Bag (EFB) unit;

FIG. 13 shows a towbarless airplane trailer with two cameras;

FIG. 14 illustrates the movement of several towbarless trailers within a airport;

FIG. 15 illustrates a method of towing an aircraft;

FIG. 16 is a graph of speed, pilot braking, tractive effort, and motor RPM, each as a function of time, and related to a towbarless aircraft trailer desired and actual speed; and

figure 17 illustrates a method of controlling a towbarless aircraft trailer.

Detailed Description

A control system for an automatic or semi-automatic trailer is provided for taxiing an aircraft from an airport gate to a takeoff runway. To save fuel and reduce pollution, the trailer is designed to taxi the aircraft without using the aircraft's jet engine. The controller thus has the dual function of controlling the trailer traction speed (and thus replacing the aircraft engine) in real time and at all times, and of regulating the trailer traction (and thus preventing the aircraft landing gear, for example nose landing gear or NLG, from exceeding its static load limit and fatigue load limit), so that its life cycle is not affected. Thus, to direct the controller to function, a multi-input, multi-output (MIMO) control concept is provided, some of which are interrelated and interdependent in controlling and controlled variables.

The present description relates to automatic or semi-automatic trailers for taxiing aircraft from gates to takeoff runways without the use of aircraft jet engines. These trailers may operate in an airplane pilot controlled taxi mode in which the airplane pilot steers and brakes as if the airplane were moving under its own power, and trailer speed is controlled by its own controller. Once the taxi is over, the trailer can automatically return to the pre-tractor position at the doorway under the control of the airport command and control system. The trailer driver can complete the towing operation, after which he leaves the trailer, the aircraft pilot controlling the trailer during taxiing. The trailer may be operated in an autonomous mode of operation during taxiing of the aircraft. The term "autonomous" broadly includes operations under the control of airport command, control and communication systems, but with priority to the pilot of the aircraft.

Referring now to fig. 1A, 1B and 1C, a towbarless aircraft trailer 100 is shown. International publication WO2008/139440, which is assigned to the assignee of the present application, teaches many of the principles underlying the present specification, and is incorporated herein by reference in its entirety where appropriate to give appropriate teachings of additional or other details, features, and/or technical background. Referring to fig. 1A, 1B and 1C, a towbarless aircraft trailer 100 includes a chassis 102 supported on six wheels, including front steerable wheels 104 and 106, rear steerable wheels 108 and 110, and intermediate non-steerable wheels 112 and 114. It will be appreciated that alternatively, the wheels 112 and 114 may be steerable. The centers of rotation of the steerable wheels 104, 106, 108, and 110, indicated by reference numerals 115, 116, 117, and 118, respectively, may define the apex of a rectangle having a length a determined by the distance between the centers of rotation of the front and rear wheels on the same side of the trailer 100 and a width B determined by the distance between the centers of rotation 115 and 116 of the front wheels 104 and 106 and the centers of rotation 117 and 118 of the rear wheels 108 and 110, respectively.

Each wheel 104, 106, 108, 110, 112 and 114 is controllably driven by a respective hydraulic motor (not shown) powered by a respective hydraulic pump (not shown) driven by a vehicle diesel motor (not shown) in response to speed and torque control signals from a controller 119. Each of the steerable wheels 104, 106, 108, and 110 may be controlled by one or more steering pistons (not shown) in response to steering control signals from the controller 119. These wheels, hydraulic pump and diesel motor form part of a propulsion device for propelling the trailer in a track direction.

The operator control interface components, which may include steerable wheels 120, brakes (not shown), and optionally other controls as necessary, may interface with the controller 119 to allow the operator to control the operation of the towbarless aircraft trailer 100 prior to and during towing operations, and/or in the event of an emergency or in the event of a trailer control system failure. The towbarless aircraft trailer 100 may be operated in a "pilot control on the aircraft" (PIC) mode via a controller 119, taxiing to or near a takeoff point. Upon approaching the takeoff point, the controller 119 automatically or manually (by a safety pilot) disengages the trailer 100 from the aircraft, and in response to commands received from an airport command and control center or trailer position sensor 121 (such as a GPS sensor or any other suitable trailer position sensor), the trailer 100 operates under the control of the controller 119, autonomously or manually steered by a safety pilot, from the takeoff point back to the desired pre-tractor-operation position. The trailer 100 may also be equipped with a wind sensor 122, one or more obstacle detection sensors 123, such as radar and/or laser sensors, for exampleSold under the name HDL-64E, which is output to controller 119, and one or more drive cameras 124, which enable remote driving of trailer 100, such as by a remote command and control center. The drive camera 124 is rotatable to have selectable pan and tilt angles to enable the operator to view the trailer 100 and various nearby locations.

The rotatable landing gear wheel support assembly 125 is pivotally and rotatably mounted on the horizontal base assembly 126. The center of rotational stability of the support assembly 125, indicated by reference numeral 127, may be located at the rectangular geometric center defined by the centers of rotation 115, 116, 117, and 118 of the respective steerable wheels 104, 106, 108, and 110.

The horizontal base assembly 126 is attached to the chassis 102 in a manner that allows a limited amount of freedom of movement relative to the chassis and is engaged by an energy absorber assembly, which may include a plurality of energy absorbing pistons 128, each pivotally attached to the chassis 102 and the horizontal base assembly 126. A force sensor 129, which may be a load cell, may be associated with each energy absorbing piston 128, which outputs to the controller 119 and is therefore used to control vehicle acceleration and deceleration.

The horizontal base assembly 126 may include a circumferential base member 130 pivotally mounted to the chassis 102 by transversely extending support rods 131 that are suspended from a pair of front suspension supports 132, and suspended from a pair of rear supports 132 that are pivotally mounted to the chassis 102. The suspension supports 132 are engaged by a pivotally mounted energy absorbing piston 128. The circumferential base member 130 may be mounted on the suspension supports 132 by means of spindles 133, which may or may not be integrally formed with the base member 130.

Support assembly 125 is pivotally or rotatably mounted on base 126 by means of a pair of pivot shafts 134 extending outwardly to engage high load bearing 135, and high load bearing 135 correspondingly engaging a 360 degree circumferential bearing race 136 formed on base 126. This arrangement provides less rotational and tilting friction of the support assembly 125 relative to the base member 130, the horizontal base assembly 126, and the chassis 102.

A straight frame 140 is fixedly mounted to the support assembly 125 for aligning the aircraft landing gear wheels on the support assembly. An aircraft landing gear wheel stop rod 142 is selectively positionable relative to the straight frame 140 by means of a stop rod positioning piston 144 secured to the support assembly 125 for adapting the support assembly to aircraft landing gear wheels of different sizes. The direction of rotation of the support assembly 125 may be detected by a rotation sensor 145, such as a potentiometer, which provides a rotational direction input of the support assembly to the controller 119. The direction of rotation of support assembly 125 may be controlled by support assembly rotation motor 146.

A selectively positionable clamp assembly 147 may be mounted on the support assembly 125 and attached to the straight frame 140. The clamp assembly 147 is operative to selectively clamp the landing gear wheel to the support assembly 125 so that the centre of rotation of the landing gear wheel is located as closely as possible to the centre of rotation 127 of the support assembly, which as mentioned above, is located at the geometric centre of the rectangle defined by the centres of rotation of the steerable wheels 104, 106, 108 and 110.

Force sensors 148, such as force cells, are mounted on the front planing surface of the clamp assembly 147 and the rear planing surface of the stop bar 142 for engagement with the landing gear wheels to detect forces in the horizontal plane applied to the landing gear wheels and hence to the landing gear, such as due to differences in acceleration, deceleration, and/or velocity of the trailer 100 relative to acceleration, deceleration, and/or aircraft velocity due to towing.

A tilted aircraft landing gear wheel ramp loading device 150 may be mounted on the base member 130. A pair of landing gear wheels engaged with piston assembly 152 may be used to push or lift the aircraft landing gear and position the aircraft landing gear wheels on support assembly 125.

The force sensor 148 may be operable to detect a force applied to the landing gear at least in a generally horizontal direction along the trailer's track of travel. This force may be the result of an aircraft pilot-controlled braking of the aircraft, which decelerates the trailer or accelerates the trailer. The controller 119 is operative, at least in part, in response to the outputs of the force sensors, particularly the aircraft pilot controlled braking to cause deceleration of the aircraft, to provide speed and torque control signals to the hydraulic motors driving the wheels of the trailer 100. This control, for example, reduces and limits the force applied to the aircraft landing gear to the maximum allowable force that will not damage the aircraft landing gear as a result of the aircraft pilot controlling the brakes to cause the trailer to slow down and/or accelerate.

The rotation sensor 145 is operable to detect rotation of the support assembly 125 relative to the base assembly 126, which is caused by aircraft pilot piloting of the aircraft landing gear, and the controller 119 is operable to control steering of the steerable wheels 104, 106, 108 and 110 based on the output of the rotation sensor 145 and a response to aircraft pilot piloting commands.

The force sensors 129 and 148 may be operative to sense forces applied to the landing gear in at least a generally horizontal direction such that the controller 119 is operative to control trailer acceleration and deceleration using the output of the at least one force sensor, sensing pilot controlled braking, and at least one of the following inputs by employing at least one force feedback loop:

force indications caused by known gradients at a plurality of locations along the aircraft travel surface traversed by the trailer 100, these locations being identified to the controller by the position detection function;

an indication of the wind force exerted on the aircraft, information relating to the wind force being provided to the controller by the airport and/or trailer on which the wind sensor is mounted; and

known trailer and aircraft rolling friction indications at various locations along the aircraft running surface traversed by the trailer, these locations being identified to the controller by a position detection function.

The controller 119 is also operable to control the speed of the trailer 100 by employing at least one speed feedback loop based on known speed limits along the travel path traversed by the trailer and aircraft (e.g., using an appropriate airport map stored within the controller 119), and the output of trailer position sensors indicating the position of the trailer 100 along the travel path of the trailer 100 and aircraft.

One or a pair of laser rangefinders 154 may be mounted on the chassis 102 of the trailer 100 for determining the angular relationship between the longitudinal axis of the aircraft and the longitudinal axis of the trailer 100. The angular relationship between the longitudinal axis of the aircraft and the longitudinal axis of the trailer 100 is used in an autonomous taxi mode of operation, such as the modes described below and shown in figures 4A to 4E.

As shown in fig. 2A, the trailer 100 is propelled in the direction of arrow 200 under the control of the trailer driver toward an aircraft 202 awaiting operation by the tractor. Figure 2B shows the landing gear wheels 204 positioned on the ramp 150. Figure 2C shows piston assembly 152 engaged with a landing gear wheel, piston assembly 152 positioned to engage with landing gear wheel 204 for pushing and lifting the aircraft landing gear, and positioning the aircraft landing gear wheel on support assembly 125. Figure 2D shows the aircraft landing gear wheel detent rod 142 appropriately positioned relative to the straight frame 140 by means of the detent rod positioning piston 144 to accommodate a particular aircraft landing gear wheel 204 of a particular aircraft 202. Figure 2E shows the landing gear wheel 204 being pushed up the support assembly 125.

Figure 2F shows the landing gear wheel 204 pushed by the piston assembly 152 against the stop bar 142 positioned so that the axis of rotation of the landing gear wheel 204 is as close as possible to the centre of rotation 127 of the support assembly 125, which centre of rotation 127 is at or near the geometric centre of the rectangle defined by the centres of rotation of the steerable wheels 104, 106, 108 and 110, as described above.

Figures 2G and 2H show a sequence of retraction actions on the single piston assembly 152 disengaged from the landing gear wheel 204 and the engagement of the single clip of the clip assembly 147 with the landing gear wheel 204 to clip the landing gear wheel to the support assembly 125 so that the centre of rotation of the landing gear wheel is as close as possible to the centre of rotation 127 of the support assembly 125. Fig. 2I shows the trailer 100 towing the aircraft 202 back under control of the trailer driver. Fig. 2J shows the trailer driver leaving the trailer 100 after completion of the towing operation. During all or part of taxiing, the pilot may remain on the trailer 100, may participate in the disengagement of the trailer from the aircraft, and the engine may then be started.

Fig. 3A illustrates rotation of the landing gear wheels 204 as controlled by the aircraft pilot using a conventional aircraft steering column 206 or pedals (not shown), which in turn causes rotation of the support assembly 125 relative to the base member 130. The rotation of the support assembly 125 is immediately detected by the rotation sensor 145, the output of which is provided to the controller 119, causing the steerable wheels 104, 106, 108 and 110 of the trailer 100 to immediately rotate, as described in detail below with reference to fig. 6A-6B.

The controller 119 may effect steering of the trailer 100 according to a feedback control loop that receives an input from the rotation sensor 145 that is representative of the orientation of the landing gear wheels 204 as controlled by the aircraft pilot, i.e., the angle α between the orientation of the support assembly 125 and the longitudinal axis of the trailer as indicated at 210. As will be described below with reference to fig. 6A to 6C, the controller 119 turns the trailer steerable wheels 104, 106, 108, and 110 by angles β 1, β 2, β 3, and β 4, respectively, and drives the trailer 100 so that the angle α becomes zero.

Fig. 3B illustrates an intermediate stage of movement of the trailer 100, wherein the trailer is oriented to cause the aircraft 202 to drag in a direction indicated by the aircraft pilot. At this stage, the angle α between the support assembly 125 and the longitudinal axis 210 of the trailer 100 is shown as half as shown in FIG. 3A. The angle between the longitudinal axis 210 of the trailer 100 and the longitudinal axis of the aircraft 202 to be towed (herein designated by reference numeral 220) is indicated by angle γ due to the rotation of the trailer 100 relative to the aircraft 202.

Fig. 3C shows trailer 100 oriented relative to landing gear wheels 204 of aircraft 202 such that a is zero. It is apparent that the angles β 1, β 2, β 3, and β 4 of the trailer steerable wheels 104, 106, 108, and 110, respectively, are typically non-zero. At this stage, the angle γ between the longitudinal axis 210 of the trailer 100 and the longitudinal axis 220 of the aircraft 202 towed by the trailer 100 is less than γ in fig. 3B, because the aircraft 202 has already started to turn. .

Fig. 3D shows the aircraft pilot stepping on pedal 222 to brake aircraft 202. Braking of the aircraft 202 is achieved by braking the main landing gear (not shown) of the aircraft 202, causing the aircraft 202 to slow down so that the applied force is immediately detected by the force sensor 148 on the clamp 147, the output of which is received by the controller 119, and the controller 119 accordingly immediately slows the trailer 100. Because of the time lag between the braking of the aircraft 202 and the corresponding deceleration of the trailer 100, forces are exerted on the rear energy absorbing piston 128, which are immediately detected by the force sensor 129. The rear energy absorbing piston 128 absorbs energy generated by braking of the aircraft 202 relative to the trailer 100. At this stage, force sensor 129 serves as a backup for force sensor 148.

Figure 3E shows the controlled acceleration of the trailer 100 controlled by the controller 119 in response to inputs from, inter alia, the force sensors 148 and 129, to provide a taxi speed to the aircraft, which speed is within predetermined speed limits for a predetermined position along the aircraft travel path, and to ensure that the force exerted on the landing gear does not exceed the predetermined limits, taking into account one or more of the following factors:

known ramp-induced forces at various locations along the aircraft's driving surface traversed by the trailer 100, these locations being communicated to the controller 119 by the location detection function identification, such as the GPS function provided here by the trailer mounting the trailer location sensor 121;

the wind force exerted on the aircraft 202, information relating to the wind force being provided to the controller 119 from wind sensors carried by the airport or trailer, such as the trailer-mounted wind sensor 122, optionally also by airport command and control functions; and

rolling friction of the trailer 100 and the aircraft 202 at various locations along the aircraft running surface traversed by the trailer 100, these locations being communicated to the controller 119 by the position detection function provided by the trailer position sensor 121, optionally also provided by airport command and control functions.

The controller 119 may also slow the trailer 100 in response to not only the braking of the aircraft 202 by the aircraft pilot, but also the detection of an obstacle by the obstacle sensor 123. The controller 119 controls the trailer to slow down in response to inputs from, inter alia, the force sensors 148 and 129, to ensure a coordinated reduction ratio between the aircraft and the trailer, so as to limit the force applied to the landing gear of the aircraft 202 to within predetermined force limits.

To distinguish between normal tractive effort on the landing gear and forces exerted by pilot braking, controller 119 may consider one or more of the factors described above, represented by data from various sensors, such as sensors 120, 121, 122, and 123 and camera 124.

The controller 119 is also operable to control the acceleration and deceleration of the trailer 100 to maintain a desired trailer speed by employing a speed control feedback loop. The controller 119 is also equipped with, or has access to, an embedded map of the airport for indicating the relevant trailer speed limits for each region of the trailer travel path. This speed limit information is coordinated with information provided by the trailer position sensor 121 indicating the immediate position of the trailer 100. The controller 119 also includes a navigation system that indicates the instantaneous speed of the trailer 100. The feedback loop operates to bring the actual speed as close as possible to and without exceeding the speed limit of the instant position of the trailer.

Controller 119 is also operable to control the acceleration and deceleration of trailer 100 so as to limit the horizontal force exerted on the landing gear of aircraft 202 to within an acceptable limit, such as 4% of the total weight of the aircraft, for example using a force control feedback loop. Controller 119 receives inputs from force sensors 148 and 129 that represent the sum of forces exerted on the landing gear of aircraft 202 due to, among other things, wind, hill, rolling friction, and acceleration or deceleration of aircraft 202 and/or trailer 100. The force feedback loop operates to accelerate or decelerate the trailer 100 so that the forces detected by the force sensors 148 and 129 remain below acceptable limits, optionally to allow for undesired acceleration and deceleration of the aircraft 202 or trailer 100.

Referring now to fig. 4A, 4B, 4C, 4D and 4E, the stages of autonomous taxi operation of the towbarless aircraft trailer 100 are illustrated. The autonomous taxi maneuver may be initiated by the driver of the trailer 100 or may be initiated automatically in response to instructions from the airport command and control center after the towing maneuver is completed.

In autonomous taxi operations, the support assembly 125 functions to reduce to zero the forces, and particularly the moments, exerted on the landing gear in the horizontal plane by maintaining the position of the landing gear wheels 204 in the position last selected by the pilot of the aircraft, which is generally parallel to the longitudinal axis 220 of the aircraft. Thus, the landing gear remains in this position while the trailer 100 changes its orientation along its travel path. This means that in most steering maneuvers of the trailer 100, the support assembly is steered in the opposite direction to the trailer 100.

Autonomous trailer control may be immediately overridden by the aircraft pilot by manipulating the aircraft brakes on the main landing gear (which operation would be immediately detected by force sensors 148 and 129).

Autonomous taxi may employ the enhanced C4 (command, control, communication and computer) functionality of an airport command control center that coordinates and optimizes taxi travel paths and speeds of taxiing aircraft within the airport, for example, using some or all of the following inputs:

the position of all taxiing aircraft within the airport;

calculation of all aircraft taxi gaps and taxi driving paths; and

airport weather conditions and runway ground travel conditions.

The enhanced C4 function may provide some or all of the following functions:

avoidance of runway intrusion;

calculating the optimal taxi speed for all aircraft to ensure minimal start and stop during taxiing;

minimize slide traffic congestion; and

pilot control can be used immediately in the event of a malfunction or emergency.

Fig. 4A shows the initial orientation of the trailer 100 and aircraft 202 at the start of the autonomous taxi operation. The landing gear wheels 204 are parallel to the longitudinal axis 210 of the trailer 100 and the longitudinal axis 220 of the aircraft. The steerable wheels 104, 106, 108, and 110 of the trailer 100 are also parallel to the axles 210 and 220.

Fig. 4B illustrates the initial turning of the trailer 100 under the control of the controller 119, for example in response to traffic control commands received from an airport command and control system 250 based on the C4 system. As shown in fig. 4B, the aircraft pilot does not use a conventional aircraft steering yoke 206 or pedals (not shown) unless emergency braking occurs. The trailer 100 produces the desired steering by turning the wheels 104, 106, 108 and 110 of the trailer 100 in response to appropriate instructions from the controller 119. To avoid the application of torque to the landing gear of the aircraft 202, the support assembly 125 is caused to rotate by an angle- α, equal and opposite to the angle α between the trailer longitudinal axis 210 and the aircraft longitudinal axis 220, by the support assembly rotation motor 146. Rotation of the support assembly 125 is sensed by the rotation sensor 145 to provide a feedback output to the controller 119.

The controller 119 can steer the trailer 100 by steering the steerable wheels 104, 106, 108, and 110 and rotating the support assembly 125 via the support assembly rotation motor 146 according to two feedback control loops. A feedback loop ensures that the front of the trailer 100 follows the predetermined travel path established by the airport command and control system 250. The second feedback loop uses the laser rangefinder 154 to ensure that the landing gear wheels 204 are aligned parallel to the longitudinal axis 220 of the aircraft. The laser rangefinder 154 determines the angle a between the longitudinal axis 210 of the trailer 100 and the longitudinal axis 220 of the aircraft 202. The controller 119 ensures that the support assembly 125 is rotated by an angle-a relative to the longitudinal axis 210 to ensure that the landing gear wheels 204 are consistently aligned with the longitudinal axis 220 of the aircraft.

Fig. 4C shows yet another phase of turning of the trailer 100. At this stage, the angle α between the longitudinal axis 210 of the trailer 100 and the longitudinal axis 220 of the aircraft 202 and the angle α between the support assemblies 125 and the longitudinal axis 210 of the trailer 100 are twice the angle shown in FIG. 4B.

Fig. 4D shows that the automatic operating mode is replaced by the aircraft pilot, for example by depressing brake pedal 222. This alternative may be, for example, for emergency braking and/or to enable the aircraft pilot to control the steering of the trailer 100, as described above with reference to fig. 3A to 3E. Braking of the aircraft 202 is accomplished by brakes on the main landing gear (not shown) on the aircraft 202, causing the aircraft to slow down, so that the applied force is immediately detected by the force sensor 148 on the clamp 147, the output of which is received by the controller 119, which causes the trailer 100 to immediately slow down.

Controller 119 terminates the tractor mode of operation of trailer 100 and converts the trailer mode to aircraft pilot control operation as described above with reference to fig. 3A-3E.

Because there is a time lag between the braking of the aircraft 202 and the deceleration of the corresponding trailer 100, force is applied to the rear energy absorbing piston 128 and is immediately detected by the force sensor 129. The rear energy absorbing piston 128 absorbs energy generated by braking of the aircraft 202 relative to the trailer 100. At this stage, force sensor 129 serves as a backup for force sensor 148.

Returning to the autonomous operating mode typically requires input from the airport command and controller system 250 or pilot instructions transmitted by an Electronic Flight Bag (EFB), such as is commercially available from astronautics ltd.

Figure 4E shows controlled acceleration of the trailer 100 in an autonomous operating mode under control of the controller 119 in response to inputs from, inter alia, the airport command and control center 250 and the force sensors 148 and 129 to bring the aircraft taxiing speed within predetermined speed limits at predetermined locations along the aircraft travel path, ensuring that the force exerted on the landing gear does not exceed the predetermined limits, taking into account one or more of the following factors:

known ramp-induced forces at various locations along the aircraft's driving surface traversed by the trailer 100, these locations being communicated to the controller 119 by a location detection function identification, such as a GPS function provided here by the trailer mounting a trailer location sensor 121;

wind force exerted on the aircraft 202, information relating to the wind force being provided to the controller 119 from wind sensors carried by the airport or trailer, such as the trailer-mounted wind sensor 122, optionally via airport command and control functions; and

the rolling friction of the trailer and aircraft at various locations along the aircraft travel surface traversed by the trailer 100 are communicated to the controller 119 by the position sensing function provided by the trailer position sensor 121 and provided by the airport command and control functions.

The controller 119 also decelerates the trailer 100 in response to not only the braking of the aircraft 202 by the aircraft pilot, but also to the detection of an obstacle by the obstacle sensor 123 or the detection of one of the drive cameras 124, or in response to control commands from the airport command and control center 250. The controller 119 controls the trailer to slow down in response to inputs from, inter alia, the force sensors 148 and 129, to ensure a coordinated reduction ratio between the aircraft and the trailer, so as to limit the force exerted on the landing gear of the aircraft 202 to within predetermined force limits.

To distinguish between normal tractive effort on the landing gear and forces exerted by pilot braking, controller 119 may consider one or more of the factors described above, which are represented by data from various sensors, such as sensors 120, 121, 122, and 123.

The controller 119 is also operable to control the acceleration and deceleration of the trailer 100 to maintain a desired trailer speed by employing a speed control feedback loop. The controller 119 is also equipped with or allows access to embedded maps of airports for indicating relevant trailer speed limits for various regions of the trailer travel path. This speed limit information is coordinated with the information provided by the trailer position sensor 121 indicating the instant position of the trailer. The controller 119 also includes a navigation system that indicates the instantaneous speed of the trailer. The feedback loop operates to bring the actual speed as close as possible to and without exceeding the speed limit of the instant position of the trailer.

Controller 119 is operative to control the acceleration and deceleration of trailer 100 so as to limit the horizontal force exerted on the landing gear of aircraft 202 to within an acceptable limit, such as 4% of the total weight of the aircraft, for example, using a force control feedback loop. Controller 119 receives inputs from force sensors 148 and 129 that represent the sum of forces exerted on the landing gear of aircraft 202 due to, among other things, wind, hill, rolling friction, and acceleration or deceleration of aircraft 202 and/or trailer 100. The force feedback loop operates to accelerate or decelerate the trailer 100 so that the forces detected by the force sensors 148 and 129 remain sufficiently below acceptable landing gear force limits, optionally to allow for undesirable acceleration and deceleration of the aircraft 202 or trailer 100.

When the trailer 100 is operating in the autonomous taxi mode of operation shown in fig. 4A to 4E, wherein the taxi speeds of the trailer 100 and towed aircraft 202 are generally those of the aircraft pilot controlled taxi mode of operation, the aircraft pilot can switch to the aircraft pilot controlled mode of operation by again turning the trailer by braking the aircraft and manipulating the aircraft joystick 206, instead of the autonomous system. The aircraft pilot may also brake the aircraft in an emergency.

Due to the fact that the ground movements of all the aircraft in the airport are managed centrally by the command and control system, an efficient taxi operation is provided in the autonomous taxi mode, thereby avoiding the waiting line for the aircraft to take off. As shown in fig. 4E, the command and control system 250 integrates the movement of all the aircraft, thereby maintaining the desired space between the aircraft during taxiing, avoiding start and stop movements as much as possible.

Reference is now made to fig. 5A, 5B, 5C, 5D and 5E, which are various schematic illustrations of the stages of operation of a towbarless aircraft trailer 100 in autonomous mode, under the control of a command and control system within an airport tower, controlling the towing movement of the trailer by a controller 119 and the return of the trailer 100 from a takeoff area to a position prior to towing operation.

Fig. 5A, 5B and 5C show the trailer 100 disengaged from the landing gear wheels 204. Obviously, the disengagement of the trailer 100 from the aircraft is typically performed after the aircraft pilot has started the aircraft engine. The command and control system 250 can instruct the trailer 100 to effect the disengagement. Alternatively, the disengagement of the trailer may be automatically triggered by the trailer sensing position at a predetermined disengagement position near the takeoff point. The disengagement command may be wirelessly communicated to the controller 119. In response to a command to disengage the trailer, the clamp assembly 147 disengages the clamp from the landing gear wheels 204 and the trailer 100 is pushed forward while the aircraft pilot brakes the aircraft 202 and controls the aircraft joystick 206 to cause the landing gear wheels to roll down the ramp 150 and maintain the landing gear parallel to the longitudinal axis of the aircraft 220 as if the ramp 150 were pushed relatively forward.

A safety driver may be present on the trailer 100, in which case disengagement may be performed by the safety driver in a conventional manner, typically with disconnection of the voice communication line by the safety driver.

Fig. 5D illustrates controlled acceleration and steering of the trailer by the controller 119 to control trailer travel speed within predetermined speed limits at predetermined locations of the predetermined autonomous trailer travel path from the takeoff area to the pre-tractor service position, taking into account one or more of the following factors:

the instantaneous position of the trailer 100 as indicated by the trailer position sensor 121;

obstacle detection information from the sensor 123 or the camera 124;

real-time information provided by the airport command and control system 250 of the location of other vehicles on the trailer's travel path; and

one or more trailer 100 predetermined travel path indicators from a takeoff position to a tractor pre-operative position; this information may be stored in the controller 119 or provided in real time by the airport command and control system 250.

Fig. 5E shows the controlled deceleration and mooring of the trailer by the controller at the pre-tractor service position.

Reference is now made to fig. 6A, 6B and 6C, which are schematic illustrations of the steering functionality of a towbarless aircraft trailer 100 providing Ackerman (Ackerman) steering for an aircraft 202, respectively.

Referring to FIG. 6A, which shows the aircraft 202 turning with its landing gear wheels 204 directly forward along the longitudinal axis 220 of the aircraft 202, note the following parameter definitions:

l-the distance between the axis of rotation 302 of the landing gear wheel 204 and the main gear line 304, here indicated by reference numerals 306 and 308, along the longitudinal axis 220 of the aircraft 202;

a is the longitudinal distance between a line 310 connecting the centers of the rear steerable wheels 108 and 110 of the trailer 100 and a line 312 connecting the centers of the front steerable wheels 104 and 106;

b — the distance between the centers of the wheels 108 and 110 of the trailer 100 and the distance between the centers of the wheels 104 and 106; and

c — the distance between the landing gears 306 and 308 along line 304.

Fig. 6B shows the landing gear wheels 204 of the aircraft 202 rotated through an angle a in response to the aircraft pilot turning the aircraft using the joystick 206 to rotate the support assembly 125 relative to the chassis 103 of the trailer 100. The controller 119 causes the trailer steerable wheels 104, 106, 108 and 110 to turn so as to steer the trailer 100 so that alpha becomes zero, as described with reference to fig. 3A to 3E. Controller 119 also controls the movement of trailer 100 to cause aircraft 202 to produce ackermann steering, as shown in fig. 6B, wherein the following parameters are based:

r + C/2 — the instantaneous turning radius of the aircraft 202;

α is the angle of rotation of the landing gear wheel 204 relative to the longitudinal axis 220 of the aircraft 202; and

β i is the steering angle of the wheels of the trailer 100 (i 104, 106, 108 and 110).

β i can be calculated as a function of α as follows:

·L/[R+C/2]＝tanα＞＞R＝L/tanα-C/2

·tan(β108)＝[L-A/2cosα-B/2sinα]/[L/tanα+A/2-B/2sinα]

·tan(β110)＝[L-A/2cosα+(A/2tanα+B/2)sinα]/[L/tanα+(A/2tanα+B/2)cosα]

·tan(β104)＝[L-A/2cosα+B/2sinα]/[L/tanα-A/2+B/2sinα]

·tan(β106)＝[L-A/2cosα-(A/2tanα+B/2)sinα]/[L/tanα-(A/2tanα+B/2)cosα]

fig. 6C shows the operation of the trailer 100 according to the trailer steering algorithm, such that the trailer 100 is oriented relative to the aircraft 202 such that a is zero. As described with reference to fig. 3A through 3E, the controller 119 orients the trailer 100 by turning the trailer steerable wheels 104, 106, 108, and 110 as described above so as to reduce the angle α detected by the turn sensor 145 to zero. The controller 119 is operable to orient the trailer 100 so that the instantaneous turning radius R + C/2 of the trailer towing the aircraft 202 is equal to the instantaneous turning radius R + C/2 of the aircraft 202 itself, so that in this example shown in figures 3A to 3E, the aircraft pilot can maneuver the aircraft in the same manner, whether it is being towed by the trailer 100 or is traveling under its own power.

Referring now to fig. 7A and 7B, which illustrate a portion of a towbarless aircraft trailer, fig. 7C illustrates a portion of a variable angle swash plate motor. Hydraulic drive system pressure (P)_S) The speed and force control loop outputs are the RPM of the diesel motor 160 and the desired control angle Φ of the variable angle swash plate pump 161 the speed control input (feedback) is a wheel odometer signal (θ'), and the force control input (feedback) is a force sensor signal (∑ F) and a hydraulic system pressure (P)_S) Motor torque-vehicle traction. The system pressure will be limited so that landing gear loading does not exceed limits, both at all times and in real time.

The diesel motor 160 controls the hydraulic variable displacement pump flow rate and the motor torque controls the pump pressure. The dynamic response of the motor is approximately modeled as a time constant τ_dFirst instruction system N_d(τ_dS + 1). N for the rotation speed of the hydraulic motor 162_dAnd (4) showing. Constant of hydraulic pump is K_pThe control angle of the variable angle swash plate pump is Φ, and may be controlled by a valve (not shown). Hydraulic motor 162 constant D_mWhich provides a tractive torque-force F_t. The brake viscous friction of the hydraulic system is B_hThe mass of the vehicle is M₂Which can be converted into an equivalent inertia J calculated with the motor₂. There is no spring effect in the system (continuous rotation).

To increase the speed and bandwidth of the force control loop (increase the response speed), a servo valve 164 is installed in the hydraulic system between the motor high and low pressure lines. The servo valve 164, a fast response valve, controls the speed and amount of energy dissipation (absorption). The controlled opening of the servo valve 164 actually "causes leakage" through the narrow passage 165, which narrow passage 165 decelerates the vehicle until it is completely stopped (no flow in the motor, all flow being discarded through the servo valve 164). At rapid pilot braking (0.4 g-0.5g deceleration), the energy absorbing system can be inverted and then the vehicle impact (40 tons) borne by the landing gear. However, even with a maximum possible deceleration of 0.5g, a force of 20 tons (e.g. 60 tons for B747 with a maximum allowable 0.15W) is generated at the landing gear of 40,000 × 0.5 g.

Fig. 7A shows the flow of hydraulic fluid 167 during non-braking. Such as may occur when the aircraft is accelerating or moving at a substantially constant speed. In this case, the servo valve 164 (of the control bypass 166) is closed to allow all hydraulic fluid to flow between the variable angle swash plate pump 161 and the hydraulic motor 162, thereby turning the trailer wheels.

Fig. 7B shows the flow of hydraulic fluid 167 during braking. Once the aircraft pilot brakes the aircraft, the servo valve 164 opens, causing hydraulic fluid 167 to leak through the bypass 166 into a narrow passage 165 that slows the vehicle.

Fig. 7C shows the angle of the variable angle swash plate controlling the vehicle speed. The diesel motor controls a variable angle swash plate pump 161. A smaller angle will lower the pressure of the hydraulic pump, thereby reducing fluid flow and slowing the wheel.

Figure 7D shows that an additional bypass 181 may be connected in parallel with the variable angle swash plate pump 161. The additional bypass comprises a servo valve 181 and is capable of opening in response to a pressure above a desired hydraulic fluid pressure or in response to an output of at least one force sensor indicative of pilot controlled braking of the aircraft. Which may be controlled by controller 119 and/or a hydraulic pressure sensing element (not shown).

Obviously, both bypasses can be opened upon detection of the aircraft braking, they can be opened in parallel or in series. One of the bypasses is opened when a braking force exceeding a first threshold is detected, and the other is opened when a braking force exceeding another threshold is detected.

For example, both bypasses may be opened when a braking force of about 0.5g or higher is detected, while only the additional bypass is opened when a braking force of not more than 0.2g is detected.

Fig. 8A is an input/output block diagram of a force control loop 171 and a speed control loop 172 that are part of controller 119. The output of the force control loop and speed control loop is the RPM of the diesel motor 160 (in N)_dRepresentation) and the control-angle (Φ) of the variable angle swash plate pump 161. The inputs (feedback) to force control circuit 171 may be a force sensor signal and a hydraulic system pressure (P). The input (feedback) to the speed control loop 172 may be a wheel odometer signal.

Fig. 8B shows an example of a multiple-input/multiple-output (MIMO) controller. The controller controls the speed and the force applied by the towbarless trailer. It receives a number of input variables, such as:

·W_destowbarless trailer desired speed V provided by diesel motor speed (RPM)_des；

·D_pHydraulic pump capacity (torque/flow T)_p＝D_p×P，Qp＝D_pwe) (ii) a And

·D_mhydraulic motor capacity (torque/flow T)_m＝D_m×P，Qm＝D_mwm)；

And multi-terminal output of a plurality of control variables, such as:

·V_ehvehicle speed (which is determined by the hydraulic motor speed W)_mControl);

·F_{traction apparatus}Vehicle traction (which is controlled by hydraulic motor pressure P); and

·W_{e motor}-diesel motor speed.

Figure 9 illustrates the various forces applied to an aircraft and a towbarless trailer.

Figure 10 shows the various control loops implemented by the controller of the towbarless aircraft trailer.

Fig. 11 is a flow chart of a method 2000 for towing an aircraft.

Method 2000 begins with stage 2010 where the aircraft is towed by a towbarless aircraft trailer, while a force exerted on the landing gear of the aircraft in at least a generally horizontal direction is detected by at least one force sensor and the bypass is kept closed; wherein the bypass is connected to a variable angle swash plate pump and to a hydraulic pump of a trailer wheel drive module connected to the trailer wheels.

Stage 2010 may be implemented by any of the towbarless airplane towing activities described above.

Stage 2015 after stage 2010, for detecting pilot-controlled airplane braking. Stage 2010 is triggered by one of the force sensors.

Stage 2020 follows stage 2015 for determining to open the bypass.

Stage 2030 follows stage 2020 for controlling, by the trailer controller, opening of the bypass to reduce a force exerted on the aircraft landing gear as a result of pilot controlled braking of the aircraft at least partially in response to an output of the at least one force sensor indicating that the pilot of the aircraft is controlling aircraft braking. Wherein during braking after the bypass is opened, at least a majority of the hydraulic fluid circulates between the hydraulic motor and the bypass to reduce the rotational speed of the idler wheel.

Stage 2030 can include one or a combination of the following:

opening a bypass, the opening of which is determined so as to reduce the flow of hydraulic fluid through the bypass with respect to the flow when the bypass is closed;

opening the bypass with a valve for a period of time much less than the braking period; and

opening the bypass with a valve for a period of time much less than the resonant period of the hydraulic motor.

Stage 2030 is followed by closing the bypass. The bypass is closed when the force exerted on the landing gear is less than a threshold value or when the predetermined braking period is over or both. The braking cycle ends when the aircraft is completely stopped or is traveling at a speed below a predetermined speed threshold.

Method 2000 includes a stage 2040 of providing one or more control loops. Stage 2040 may be performed in parallel with one of stages 2010, 2015, 2020, 2030, and 2035. Stage 2040 may include providing a speed control loop, a force control loop, a feedback and/or feed forward loop, and/or the like.

Stage 2040 may include determining, by the trailer controller, a control angle for the variable angle swash plate pump. For convenience, stage 2020 of deciding to open the bypass includes providing a control loop that can be triggered by the output of such a control loop.

Stage 2040 may include at least one or a combination of the following:

controlling the speed of the towbarless aircraft trailer, exerting a force on the aircraft landing gear by determining the control angle of the variable angle swash pump;

causing the variable angle swash plate pump to control the angle to change rapidly to prevent the force exerted on the aircraft landing gear from exceeding a force threshold;

causing the variable angle swashplate pump control angle to change slowly in response to the desired speed of the towbarless aircraft trailer; and

providing a feed forward method to determine the control angle of the variable angle swash plate pump.

Stage 2040 includes several sub-stages in which the change in speed of the aircraft (2042) is detected and a feed forward method is provided for the variable angle swash plate pump (2044) to cause the variable angle swash plate pump (2046) to control the angle change and slow the aircraft down.

Figure 12 shows an aircraft including an Electronic Flight Bag (EFB) 991 capable of communicating (wirelessly) with an EFB992 of a towbarless aircraft trailer. These EFBs can allow pilots to remotely control towbarless aircraft trailers.

EFB992 may communicate wirelessly with a remote command center, such as an airport tower. The wireless communication can allow for the provision of information to the airport tower, transmitting instructions to the towbarless aircraft trailer. Various communication protocols may be used such as Wi-Fi, Wi-Max, Bluetooth, etc.

Fig. 13 illustrates a towbarless airplane trailer that includes a first camera 881, which is directed toward the front of the towbarless airplane trailer and can help detect obstacles, and a second camera 882, which views the support assembly 125 and helps monitor the manner in which the towbarless airplane trailer supports the wheels.

The movement of the towbarless aircraft trailer may be responsive to the position and movement of one or more other towbarless aircraft trailers. If multiple towbarless aircraft trailers share the same route (or if their routes overlap), the towing of one towbarless aircraft trailer should be responsive to the towing method of the other towbarless aircraft trailer.

Assuming that two towbarless aircraft trailers are expected to tow their aircraft to the same takeoff runway, i.e. assuming that the towing process will end at approximately the same position (which is usually the start of the runway), it is assumed that there is a predetermined time difference between two adjacent takeoff. For example, if a first aircraft is expected to arrive at the start of a takeoff runway at a first point in time, then a second aircraft should not arrive (to the start of the takeoff runway) until after a predetermined time difference has elapsed. Typically, rather than determining a single time difference, a set of time differences is determined. These time differences are typically dependent on airport throughput and current air traffic load. A typical time difference may be, although need not be, one to three minutes.

In many cases, these time differences may be achieved by reducing the traction speed in such a way that the actual traction speed is lower than the maximum allowable traction speed. Maximum allowable traction speed is generally defined in a unit area and is responsive to variables such as road grade, weather conditions (e.g., snow, rain, high winds), road curvature, and other factors that affect maximum allowable traction speed.

Reducing the speed can reduce air pollution and also reduce the chance of braking for the pilot.

The desired speed may be calculated from a towbarless aircraft trailer, a central control body, or the like. For example, one towbarless aircraft trailer can calculate the desired velocity of one or more other towbarless aircraft trailers.

The relevant position and additional or alternative speed information of the plurality of towbarless aircraft trailers may be transferred from one towbarless aircraft trailer to another towbarless aircraft trailer, to a central control entity, etc. A towbarless airplane trailer may relay information related to one or more other towbarless airplane trailers, in addition or alternatively to a central control entity.

Fig. 14 shows three towbarless aircraft trailers 1601, 1602, 1603. Assume that all three towbarless aircraft trailers are expected to tow their aircraft to the same takeoff runway 1610, and that the towing will end up at approximately the same location, i.e., runway area 1612. The towbarless airplane trailers 1601, 1602, 1603 can exchange their speed and position information, which can additionally or alternatively be provided by a central control entity, such as a control system of an airport tower, such as the control system shown in fig. 4E.

The three towbarless aircraft trailers 1601, 1602, 1603 may detect each other's speed and/or position using radar or other detectors.

Assume that the towbarless aircraft trailer 1601 leads the towbarless aircraft trailer 1602, and that the towbarless aircraft trailer 1603 follows the towbarless aircraft trailer 1602. It is also assumed that the allowable time difference range is determined, for example, as Δ t₁To Δ t₂。

It is desirable for the towbarless aircraft trailer 1602 to be at a first point in time t₁To location 1612. The desired arrival time may be calculated or detected by any one of the towbarless airplane trailers 1601, 1602, 1603 or another entity (if the towbarless airplane trailer 1602 has arrived at the runway area 1612) and can be transmitted to the towbarless airplaneTrailers 1602 and 1603.

The towing scheme of the towbarless aircraft trailer 1602 may be designed such that it is at a second point in time t₂To runway area 1612, where t₂Is (t)₁+Δt₁) To (t)₁+Δt₂). The traction scheme includes a desired speed along the route of the guide location 1612. In any case, the desired speed should not exceed the allowable speed determined by road and air conditions. The towing scheme can be calculated by the central control body or the towbarless airplane trailer 1602, but can also be calculated by another towbarless airplane trailer.

The towing scheme of the towbarless aircraft trailer 1603 may be designed to be at a third point in time t₃To runway area 1612. t is t₃Is (t)₂+Δt₁) To (t)₂+Δt₂). The traction scheme includes a desired speed along the route of the guide location 1612. In any event, the desired speed should not exceed the allowable speed determined by road and air conditions. The towing scheme may be calculated by the central control entity, the towbarless airplane trailer 1603 or another towbarless airplane trailer.

Cruise control solutions may be provided by towbarless aircraft trailers.

The cruise control scheme allows the pilot to determine the actual speed of the towbarless aircraft trailer by maintaining the speed of the aircraft within a predetermined speed range for a predetermined period of time, for example to avoid the actual speed of the towbarless aircraft trailer falling below its desired speed.

This cruise control scheme allows the pilot to determine the actual speed of the towbarless aircraft trailer-from situations where the actual speed of the towbarless aircraft trailer is higher than its desired speed-by pilot-controlled acceleration or deceleration.

The operator may exit cruise control by pushing the brake out of the cruise control mechanism, allowing an attempt to match his actual speed to the desired speed.

FIG. 15 illustrates a method 1700 of towing an aircraft.

The method 1700 begins at any of stages 1707, 1708, and 1709.

Stage 1707 includes calculating a desired speed of the tow bar aircraft trailer. Stage 1707 may include at least the following:

calculating its desired speed based on the position of the towbarless aircraft trailer;

calculating a desired velocity of the towbarless aircraft trailer based on the position of the towbarless aircraft trailer and the position of at least one other towbarless aircraft trailer;

calculating a desired velocity of the towbarless aircraft trailer based on the position of the towbarless aircraft trailer and the position and velocity of at least one other towbarless aircraft trailer sharing at least one route with the towbarless aircraft trailer;

calculating a desired velocity of the towbarless aircraft trailer based on the position of the towbarless aircraft trailer and a desired time for the towbarless aircraft trailer to reach an end of the towing position; and

calculating the expected speed of the towbarless aircraft trailer based on the position of the towbarless aircraft trailer, the estimated time for another towbarless aircraft trailer to reach one end of the towing point, and the expected time for the towbarless aircraft trailer to arrive.

Stage 1708 includes transmitting the speed and position information to at least one other towbarless aircraft trailer. Stage 1708 can include transmitting speed and position information to a remote command center and receiving speed and position information of at least one other towbarless aircraft trailer from the remote command center.

Stage 1709 includes detecting a speed and position of at least one other towbarless aircraft trailer using a sensor, such as a radar or laser sensor.

Stage 1710 follows stages 1707, 1708 and 1709, which compare the actual speed of the towbarless aircraft trailer with the desired speed of the towbarless aircraft trailer. The actual speed may be detected and the desired speed may be received by or calculated by the towbarless aircraft trailer.

Stage 1720 follows stage 1710, where the towbarless aircraft trailer is caused to maintain an actual speed of the towbarless aircraft trailer if the actual speed is less than its desired speed, and if the actual speed of the towbarless aircraft trailer remains within a predetermined speed range for a predetermined period prior to the comparison. The predetermined speed range is a relatively narrow range.

Stage 1730 may also follow stage 1710 where the towbarless aircraft trailer is caused to maintain an actual speed of the towbarless aircraft trailer if the actual speed is greater than its desired speed and if the aircraft is detected to be at least one of pilot controlled braking and deceleration.

Stage 1740 may also follow stages 1720 and 1730 where the actual speed of the towbarless aircraft trailer is changed to match the desired speed of the towbarless aircraft trailer when pilot controlled braking is detected.

Method 1700 may include a stage 1790 in which positive tractive effort is provided by a towbarless aircraft trailer of an aircraft. This provision can only be transmitted or cannot be influenced by the additional forces exerted by the trailer.

Fig. 16 shows a timing chart between the desired speed and the actual speed.

By way of illustration, FIG. 16 includes speed values, force values, and RPM values. There are no limiting examples of speed, force and RPMs.

The timing diagram represents one example of the change in the desired speed of the towbarless trailer (which may also be referred to as the "desired speed"), the actual speed of the towbarless trailer (which may also be referred to as the "actual speed"), the brakes provided by the pilot, the force exerted on the landing gear of the aircraft (which is supported by the towbarless aircraft trailer), and the rotational speed of the towbarless aircraft trailer diesel motor (over time).

Table 1 shows the time t₀-t₁₈The values of (c).

TABLE 1

The traction process starts at t₁. At t₀And t₁Meanwhile, the pilot steps on the brake, and the towbarless airplane trailer is static.

t₁At the moment, the towbarless aircraft trailer starts moving, its actual speed increases until (t) is reached₃Time) 10 knots. t is t₄At time, the desired speed is increased to 20 knots, at time t₄And t₅In between, the speed of the towbarless aircraft trailer is increased until the desired speed is reached (time t)₅) And (5) 20 sections. At time t₅And t₆In between, the actual speed and the desired speed are equal to 20 knots, and the trailer maintains its speed. At time t₆And t₇In between, the pilot depresses the brake (due to the possible steering at the lower desired speed of 10 knots), and the actual speed of the towbarless aircraft trailer drops to 11 knots until time t₈Until now. At time t₈And t₁₀In between, the pilot depresses the brake, and although the desired speed is 20 knots, the actual speed decreases to zero (at time t)₉) And is maintained at that level until time t₁₀Until now. At time t₁₀And t₁₂In between, the trailer speed is increased to 10 knots. At time t₁₂And t₁₃In between, the pilot maintains the speed of the aircraft at approximately 10 knots, which results in a desired speed change of 10 knots. In other words, flyThe driver sets the cruising speed to 10 knots. The speed is maintained until within a short period of time (at time t)₁₄And t₁₅In between) the pilot depresses the brake and disengages the cruise control. Accordingly, the desired speed is reset to 20 knots at time t₁₅And t₁₆Until 20 knots are reached. At time t₁₇The pilot begins to brake, stopping the towbarless aircraft trailer.

The timing diagram also shows that these accelerations and decelerations can result in changes in the forces exerted on the landing gear by the towbarless aircraft trailer. Peak value at time t₃、t₅Time t₈And t₉Time t₁₂And time t₁₆Is detected.

Figure 17 illustrates a method of controlling a towbarless aircraft trailer.

Method 1900 begins at stage 1910 with the towbarless aircraft trailer obtaining location information for at least one other towbarless aircraft trailer desiring to share at least a portion of a towing route with the towbarless aircraft trailer.

Stage 1920 follows stage 1910, wherein a desired velocity of the towbarless aircraft trailer is calculated based on the velocity and position of the towbarless aircraft trailer and the velocity and position information.

Either of stages 1930 and 1940 may follow stage 1920.

Stage 1930 includes providing the towbarless aircraft trailer with a desired speed. Stage 1940 follows stage 1930 in which the actual speed of the towbarless aircraft trailer is determined in response to the desired speed.

Stage 1950 follows stage 1940, wherein the aircraft is towed by a towbarless aircraft trailer in response to the desired speed.

The method 1900 may include providing a cruise control scheme and additionally or alternatively determining a desired speed based on at least one other towbarless aircraft trailer speed and/or position.

Stage 1920 can include at least one of:

calculating a desired velocity of the towbarless aircraft trailer based on the position of the towbarless aircraft trailer and a desired time for the towbarless aircraft trailer to reach one end of the towing position; and

calculating the expected speed of the towbarless aircraft trailer based on the position of the towbarless aircraft trailer, the estimated time for at least one other towbarless aircraft trailer to reach an end of the towing point, and the expected time for the towbarless aircraft trailer to reach the end of the towing position.

Method 1900 may also include one or more of the following stages:

stage 1990, in which the speed and position information is transmitted to at least one other towbarless aircraft trailer;

phase 1992, where the speed and location information is transmitted to a remote command center;

a stage 1993 in which the speed and position information of at least one other towbarless aircraft trailer is received from the remote command centre; and

stage 1994, wherein the velocity and position information of at least one other towbarless aircraft trailer is detected using sensors such as radar, laser sensors, etc.

The controller 119 of the towbarless aircraft trailer 100 may participate in the implementation of any of the methods 1700-1900.

For example, the controller 119 may be configured to implement one or a combination of the following:

comparing the actual speed of the towbarless aircraft trailer with its desired speed;

controlling at least one tow-wheel pilot to maintain the towbarless aircraft trailer at an actual speed if the actual speed of the towbarless aircraft trailer is less than its desired speed, if the actual speed of the towbarless aircraft trailer remains within a predetermined range (e.g. a narrow predetermined range) for a predetermined period of time prior to the comparison;

controlling at least one tow-wheel pilot to maintain the towbarless aircraft trailer at an actual speed if the actual speed of the towbarless aircraft trailer is greater than its desired speed, if at least one of pilot-controlled braking and aircraft deceleration is detected;

controlling at least one tow-wheel pilot to change the actual speed of the tow-bar aircraft trailer to match its desired speed if aircraft pilot control braking is detected;

calculating a desired speed of the towbarless aircraft trailer;

calculating its desired speed based on the position of the towbarless aircraft trailer and the position of at least one other towbarless aircraft trailer;

calculating the expected speed of the towbarless aircraft trailer based on the position of the towbarless aircraft trailer, the expected estimated time for another towbarless aircraft trailer to reach one end of the towing point, and the expected time for the towbarless aircraft trailer to reach that end of the towing position.

According to another example, the controller 119 may be configured to perform at least one or a combination of the following operations:

receiving speed and position information of at least one other towbarless aircraft trailer which is expected to share a part of at least one towing route with the towbarless aircraft trailer;

calculating a desired velocity of the towbarless aircraft trailer based on the velocity and position of the towbarless aircraft trailer and the velocity and position information;

calculating the expected speed of the towbarless aircraft trailer based on the position of the towbarless aircraft trailer, the estimated time for at least one other towbarless aircraft trailer to reach an end of the towing point and the expected time for the towbarless aircraft trailer to reach the end of the towing position.

The towbarless aircraft trailer may include a receiver and a transmitter. Referring to the examples provided in fig. 4E, they may be included or integrated within the controller 119. The transmitter may be arranged to transmit speed and position information to at least one other towbarless aircraft trailer. The transmitter is capable of transmitting speed and position information to a remote command center (e.g., a control system within an airport tower), and the receiver is capable of receiving speed and position information from the remote command center regarding at least one other towbarless aircraft trailer.

The towbarless aircraft trailer may further comprise radar, laser sensors or the like for detecting the speed and position of at least one other towbarless aircraft trailer. The range of the radar, the laser sensor and the like can reach hundreds of meters, and the radar, the laser sensor and the like can work at high frequency (40GHz and above).

It will be obvious to those skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, it will be apparent to those skilled in the art from this disclosure that various combinations and subcombinations of the various features of the invention described above, as well as modifications thereof, may be practiced otherwise than as described in the prior art. Further, those skilled in the art will immediately recognize that the present invention is susceptible to many variations, changes and modifications, all without departing from the true scope of the invention.

Claims

1. A towbarless aircraft trailer for receiving landing gear of an aircraft to tow the aircraft at actual speed, the towbarless aircraft trailer comprising:

a chassis for receiving at least a portion of the landing gear thereon; and

a propulsion device for propelling the towbarless aircraft trailer in a trajectory direction;

wherein the towbarless aircraft trailer further comprises a controller configured to

-comparing the actual speed of the towbarless aircraft trailer when towing the aircraft with its predetermined desired speed;

-detecting aircraft pilot control braking and aircraft deceleration;

-if the actual speed is lower than the desired speed, instructing the propulsion device to change the actual speed of the towbarless aircraft trailer to match the desired speed; and

-reducing the desired speed to the actual speed and instructing the propulsion device to maintain the actual speed of the towbarless aircraft trailer in all cases:

detecting at least one of an aircraft pilot control brake and the aircraft deceleration;

the actual speed is lower than the desired speed; and

during a predetermined period prior to the comparison, the actual speed remains below the desired speed by a predetermined speed range due to the detected aircraft pilot controlling braking and deceleration.

2. The towbarless aircraft trailer of claim 1, wherein the controller is further configured to instruct the propulsion device to maintain an actual speed when:

the actual speed is higher than the desired speed; and

at least one of an aircraft pilot control brake and the aircraft deceleration is detected.

3. The towbarless airplane trailer of claim 1, wherein the controller is further configured to calculate a desired velocity.

4. The towbarless airplane trailer of claim 1, wherein the controller is further configured to calculate a desired tractive effort corresponding to a desired speed.

5. The towbarless airplane trailer of claim 1, wherein the controller is further configured to calculate a desired velocity based at least on the trailer position.

6. The towbarless airplane trailer of claim 1, wherein the controller is further configured to calculate the desired velocity based at least on the position of the trailer and the position of the at least one other trailer.

7. The towbarless airplane trailer of claim 1, wherein the controller is further configured to calculate the desired velocity based at least on a position of the trailer and a position and velocity of at least one other trailer with which the trailer shares the at least one path.

8. The towbarless airplane trailer of claim 1, wherein the controller is further configured to calculate a desired velocity based at least on the position of the trailer and its desired time to reach an end of the towing position.

9. The towbarless airplane trailer of claim 1, wherein the controller is further configured to calculate a desired velocity based on at least the position of the trailer, an estimated time for another trailer to reach an end of the tow point, and a desired time for the trailer to reach the end of the tow location.

10. The towbarless airplane trailer of claim 1, further comprising a detector configured to detect a speed and position of at least one other trailer using the sensor; the controller is configured to calculate a desired speed based on at least the speed and the position of the other trailer.