Method and control device for controlling a vehicle trailer

Abstract

A method for controlling a vehicle trailer (10) of a vehicle combination (100) comprising a towing vehicle (20) and the vehicle trailer (10), comprising the following steps performed while the vehicle combination (100) is stationary (S): reading an operating specification for operating the vehicle combination (100) from stationary (S), reading a force acting on a trailer coupling (12) of the vehicle trailer (10) while stationary (S), which has a force component acting longitudinally on the trailer coupling (12), determining a force setpoint for the force acting on the trailer coupling (12) while stationary (S), and controlling a drive train (14) of the vehicle trailer (10) to provide a torque in the drive train (14) based on the read-in force and depending on the read-in operating specification, wherein the torque is provided in the drive train (14) in such a manner.that the force acting on the trailer coupling (12) adjusts to the specified target force value. Furthermore, a control device (110) for carrying out the procedure and a vehicle trailer (10) with such a control device.

Description

Technical area

[0001] The present invention relates to a method for controlling a vehicle trailer of a vehicle combination. The present invention also relates to a control device for controlling a drive train of a vehicle trailer. The present invention further relates to a vehicle trailer having a drive train for driving the vehicle trailer and such a control device. State of the art

[0002] Vehicle trailers are known from the prior art that have a drive train for driving the vehicle trailer. Such powered vehicle trailers can provide supporting tractive force during travel of a vehicle combination in order to reduce the tractive force required by a towing vehicle of the vehicle combination while the vehicle combination is in motion. However, with the vehicle trailer of the vehicle combination, an increased tractive force requirement may be present on the towing vehicle even when the vehicle combination is stationary or when the vehicle combination starts moving, which the towing vehicle cannot meet for efficient or safe operation of the vehicle combination. Description of the invention

[0003] The present invention relates in one aspect to a method for controlling a vehicle trailer of a vehicle combination. The vehicle combination comprises a towing vehicle and the vehicle trailer. The towing vehicle can be a self-propelled towing vehicle, for example the towing vehicle can be a self-propelled motor vehicle or a self-propelled commercial vehicle. The towing vehicle can be an electrically powered towing vehicle. The vehicle trailer can be a self-propelled vehicle trailer. The vehicle trailer can be an electrically powered vehicle trailer. The towing vehicle and the vehicle trailer can thus each be powered separately. If the towing vehicle is a motor vehicle, the towing vehicle can be a vehicle which, for example, falls into at least one vehicle class of a subcompact car, a small car and a compact class car.

[0004] The method comprises, as a step carried out when the vehicle combination is at a standstill, reading in an operating specification for operating the vehicle combination from a standstill. The vehicle combination can be at a standstill on an inclined or uneven roadway. The vehicle combination can be operated while at a standstill, wherein the towing vehicle can hold the vehicle combination at a standstill by actuating a braking system of the towing vehicle. The towing vehicle can thus provide a holding force that holds the vehicle combination at a standstill. The operating specification can be a starting specification that can specify that the vehicle combination should start from a standstill. The operating specification can be read in via a user interface that can be actuated by a driver of the vehicle combination to provide the operating specification.The user interface can be located on a mobile device, which the driver can use to specify the operating instructions. Alternatively, the user interface can also be located on the towing vehicle, for example, on an on-board computer. The operating instructions can be read wirelessly, for example, via a Wi-Fi radio signal.

[0005] The method comprises, as a further step carried out while the vehicle combination is stationary, reading in a force acting on a trailer coupling of the vehicle trailer while the vehicle combination is stationary. The force can be a tensile force. The method can comprise, as a further step carried out while the vehicle combination is stationary, detecting the force using a force sensor arranged on the trailer coupling. The vehicle trailer can have the trailer coupling and the force sensor. The force sensor can be an at least one-dimensional force sensor, for example a three-dimensional force sensor, which is configured to detect a force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer. The detected force can be read in the reading step.

[0006] The force acting on the trailer's trailer coupling when the vehicle is stationary has a force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer. The force acting on the trailer coupling in the longitudinal direction of the vehicle trailer. The force acting on the trailer coupling when the vehicle is stationary can be a tractive force, whereby the force component acting on the trailer coupling can be a tractive force component. The tractive force can result from the weight of the vehicle trailer or from the resulting downhill force of the vehicle trailer when the vehicle combination is on an inclined road. The tractive force can therefore develop in proportion to the incline of a road on which the vehicle combination is located. The force acting on the trailer coupling when the vehicle is stationary can be a positive tractive force.The positive tractive force can act on the towing vehicle in the direction of the slope force when the vehicle combination is on an uphill slope. The force acting when stationary can be a negative tractive force or a compressive force. The negative tractive force can act on the towing vehicle in the direction of the slope force when the vehicle combination is on a downhill slope.

[0007] The method comprises, as a further step, determining a force setpoint for the force acting on the trailer coupling while the vehicle combination is stationary. The force setpoint can be a tractive force setpoint. The force setpoint can be a force setpoint that is to be set or regulated while the vehicle combination is stationary. The force setpoint can be substantially zero. A force setpoint that is substantially zero can be a force setpoint that has a positive or negative residual tractive force component that assists the tractive force when the vehicle combination starts moving in the starting direction.

[0008] The method comprises, as a further step carried out while the vehicle combination is stationary, controlling a drive train of the vehicle trailer to provide a torque in the drive train based on the read-in force and as a function of the read-in operating specification. The drive train can be an electric drive train. The torque can be provided to provide traction assistance. The drive train of the vehicle trailer can have at least one drive motor for driving at least one vehicle wheel of the vehicle trailer. In the controlling step, the drive motor can be controlled to provide a drive torque for driving the vehicle wheel in the drive train based on the read-in force and as a function of the read-in operating specification.The torque is provided in the drive train in such a way that the force acting on the trailer hitch adapts to the specific force target value.

[0009] According to one embodiment of the method, the drive train can be controlled in the controlling step such that a torque is generated at the vehicle wheel. If the vehicle combination is stationary on an inclined roadway, traction assistance can be provided for starting on the inclined roadway, whereby the torque generated at the vehicle wheel can counteract the downhill force of the vehicle trailer. When the vehicle combination starts moving, such traction assistance can provide a holding force for holding the vehicle trailer and reduce the traction requirement for the towing vehicle.

[0010] According to a further embodiment of the method, the force acting on the trailer coupling of the vehicle trailer when the vehicle is stationary can have a positive tractive force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer. If, according to this embodiment, the operating specification is a starting specification which specifies that the vehicle combination should start from a standstill in the opposite direction to the force acting on the positive tractive force component, the drive train can be controlled in the control step such that a positive torque is generated at the vehicle wheel. If the vehicle combination is stationary on an incline, tractive force assistance can be provided for starting off on the incline, in which the positive torque generated at the vehicle wheel can counteract the downhill force of the vehicle trailer.When the vehicle combination starts uphill, such traction assistance can provide a holding force to hold the vehicle trailer on the incline and reduce the traction requirement for the towing vehicle.

[0011] According to a further embodiment of the method, the force acting on the trailer coupling of the vehicle trailer when stationary can have a negative tractive force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer. If, according to this embodiment, the operating specification is a starting specification which specifies that the vehicle combination should start from a standstill in or opposite to the direction of force of the negative tractive force component, the drive train can be controlled in the control step such that a negative torque is generated at the vehicle wheel. If the vehicle combination is stationary on a downhill slope, tractive force assistance can be provided for starting on the downhill slope, in which the negative torque generated at the vehicle wheel can counteract the downhill force of the vehicle trailer.When starting the vehicle combination on a downhill or uphill slope, this type of traction assistance can provide holding force to hold the vehicle trailer on the slope and reduce the tractive force required by the towing vehicle. Starting downhill can involve starting in the forward direction of travel of the towing vehicle, while starting uphill can involve starting in the reverse direction of travel.

[0012] According to a further embodiment of the method, the force acting on the trailer coupling of the vehicle trailer from a standstill during start-up can have a positive tractive force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer. If, according to this embodiment, the operating specification is a start-up specification which specifies that the vehicle combination should start off from a standstill in the opposite direction to the force acting on the positive tractive force component, the drive train can be controlled in the control step such that a positive torque is generated at the vehicle wheel. If there is slippage at the vehicle wheel of the towing vehicle, tractive force assistance can be provided for start-up, in which the positive torque generated at the vehicle wheel can reduce the tractive force requirement for the towing vehicle and the slip.When starting off on an uneven road surface or a road surface with low friction, for example on loose or icy ground, this makes it possible for the vehicle combination to start off from a standstill.

[0013] The method can be used to provide traction assistance for the towing vehicle while the vehicle combination is stationary, allowing the towing vehicle to start from a standstill under a reduced towing load. Furthermore, the method can be used to provide traction assistance during start-up by the vehicle trailer providing additional towing force for starting the vehicle combination. The method can thus reduce the towing load of the towing vehicle while stationary and when starting from a standstill. The operational reliability of the vehicle combination and its handling while stationary and when starting can thus be advantageously improved using the method.

[0014] According to a further embodiment of the method, this can comprise, as a further step carried out while the vehicle combination is stationary, reading in a brake signal provided by a braking system of the towing vehicle. The step of controlling the drive train can be carried out based on the read-in brake signal. The brake signal can be read in via a plug connection, for example a 13-pin trailer plug connection, via which the brake signal from the braking system is communicated. The vehicle combination can have the plug connection, which can connect the towing vehicle and the vehicle trailer for the exclusive communication of signals. The brake signal can signal that a service brake is being applied by a driver.The control step can be performed depending on the read-in brake signal, wherein the control step is performed when the read-in brake signal signals that the service brake is being applied by the driver. A holding force applied by the braking system when the vehicle combination is stationary can thus be reduced by the provided torque. According to a further embodiment, the steps of the method can be performed when the braking system provides a holding force. The steps of the method can be performed when the service brake of the towing vehicle is being applied by the driver.

[0015] According to a further embodiment of the method, the operating specification read in during the step of reading in the operating specification can comprise a direction of travel specification that specifies a starting direction of the vehicle combination for starting from a standstill. The direction of travel specification can be read in via the user interface. The direction of travel specification can comprise a forward direction of travel specification that indicates that the vehicle combination should start in the forward direction of travel of the towing vehicle. The direction of travel specification can comprise a reverse direction of travel specification that indicates that the vehicle combination should start in the reverse direction of travel of the towing vehicle. Alternatively or in addition to the direction of travel specification, the operating specification can comprise a longitudinal dynamics specification that specifies a longitudinal dynamics parameter of the vehicle combination for starting from a standstill.The longitudinal dynamics parameter can include a travel speed value for starting the vehicle combination. Alternatively or additionally, the longitudinal dynamics parameter can include an acceleration value for starting the vehicle combination. The step of controlling the drive train can be carried out in such a way as to depend on the specified direction of travel, whereby the sign of the torque can be selected depending on the specified direction of travel. The step of controlling the drive train can be carried out in such a way as to depend on the specified longitudinal dynamics, whereby the magnitude of the torque can be selected depending on the specified longitudinal dynamics. The torque can thus be variably adjusted in order to adapt the traction assistance to the direction of travel and the longitudinal dynamics of starting.

[0016] According to a further embodiment of the method, the force setpoint determined in the step of determining the force setpoint for the force acting on the trailer coupling can have a setpoint force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer, which is substantially equal to zero. The setpoint force component can have a positive or negative tractive force component, which has a tractive force-assisting effect when the vehicle combination starts moving in the starting direction. In the step of controlling the drive train, the torque can be provided in the drive train such that a force acting on the trailer coupling is established which is substantially equal to zero. A downhill force of the vehicle trailer can thus be compensated by the torque when the vehicle combination is stationary.Traction support can therefore be achieved at a standstill by compensating for the downhill force with the provided torque.

[0017] According to a further embodiment of the method, the step of determining the force setpoint can be carried out based on at least one of the read-in operating specifications and an inclination of the roadway on which the vehicle combination is located. Alternatively or additionally, the force setpoint can be determined based on a predetermined tractive force target value of the towing vehicle. The sign of the force setpoint can be determined depending on the operating specification. Alternatively or additionally, the magnitude of the force setpoint can be determined depending on the operating specification. Further alternatively or additionally, the magnitude of the force setpoint can be determined depending on the tractive force target value. The vehicle trailer can have an inclination sensor with which the inclination can be detected. The inclination sensor can be arranged on the trailer coupling, wherein the force sensor and the inclination sensor can form a sensor system.The inclination sensor can be configured as an at least one-dimensional acceleration sensor, for example, as a three-dimensional acceleration sensor. The inclination sensor can be configured to detect an inclination of a roadway on which the vehicle trailer is located, in the longitudinal direction of the vehicle trailer. In a further step of the method, the inclination can be read in. From the read-in inclination, it can be deduced whether the vehicle combination is on an uphill or downhill slope. The force target value can be determined depending on whether the vehicle combination is on the uphill or downhill slope.

[0018] According to a further embodiment of the method, this can comprise, as a further step carried out while the vehicle combination is stationary before the vehicle combination starts moving, an evaluation of a braking signal provided by the towing vehicle. In the evaluation step, it can be determined that, based on the braking signal, a service brake of the towing vehicle is not being actuated or is no longer being actuated. The service brake can no longer be actuated in order to prepare for the towing vehicle to start moving. According to this embodiment, the method can comprise, as a further step carried out while the vehicle combination is stationary before the vehicle combination starts moving, a control of the drive train of the vehicle trailer to provide a torque in the drive train based on the read-in force and as a function of the evaluated braking signal.The torque can be provided such that the force acting on the trailer coupling adapts to a predetermined force setpoint for the force acting on the trailer coupling before starting off. The torque can be provided such that the force acting on the trailer coupling is adapted, for example, increased or decreased, using a ramp function to the predetermined force setpoint for the force acting on the trailer coupling before starting off. The predetermined force setpoint can have a force acting direction on the trailer coupling that is opposite to the force acting direction of the read-in force on the trailer coupling.

[0019] According to one embodiment of the method, the force acting on the trailer coupling of the vehicle trailer when stationary can have a positive tractive force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer. If, according to this embodiment, the operating specification is a starting specification which specifies that the vehicle combination should start from a standstill in the opposite direction to the force acting on the positive tractive force component, the drive train can be controlled in the control step carried out before the vehicle combination starts moving in such a way that a positive torque is generated at the vehicle wheel. If the vehicle combination is stationary on an incline, tractive force assistance can be provided for starting off on the incline, in which the positive torque generated at the vehicle wheel can counteract the downhill force of the vehicle trailer.When the vehicle combination starts uphill, this type of traction assistance can provide the traction needed to move the towing vehicle uphill, further reducing the traction requirement for the towing vehicle. The predetermined traction setpoint can be a negative traction setpoint.

[0020] According to one embodiment of the method, the force acting on the trailer coupling of the vehicle trailer when stationary can have a negative tractive force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer. If, according to this embodiment, the operating specification is a starting specification which specifies that the vehicle combination should start from a standstill in or opposite to the direction of action of the negative tractive force component, the drive train can be controlled in the control step carried out before the vehicle combination starts moving such that a negative torque is generated at the vehicle wheel. If the vehicle combination is stationary on a downhill slope, tractive force assistance can be provided for starting off on the downhill slope, in which the negative torque generated at the vehicle wheel can counteract the downhill force of the vehicle trailer.When the vehicle combination starts moving downhill, such traction assistance can provide a holding force to hold the vehicle trailer on the gradient and reduce the traction requirement for the towing vehicle. When the vehicle combination starts moving uphill, such traction assistance can provide a traction force to move the towing vehicle in reverse on the gradient and further reduce the traction requirement for the towing vehicle. The predetermined force setpoint can be a positive traction setpoint.

[0021] According to one embodiment of the method, the force acting on the trailer coupling of the vehicle trailer from a standstill during start-up can have a positive tractive force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer. If, according to this embodiment, the operating specification is a start-up specification which specifies that the vehicle combination should start off from a standstill in the opposite direction to the force acting on the positive tractive force component, the drive train can be controlled in the control step carried out before the vehicle combination starts off such that a positive torque is generated at the vehicle wheel. If there is slippage at the vehicle wheel of the towing vehicle, tractive force assistance can be provided for start-up, in which the positive torque generated at the vehicle wheel can reduce the tractive force requirement for the towing vehicle and the slip.When starting off on a road surface with low friction, the vehicle combination can be assisted from a standstill with this type of traction assistance.

[0022] According to a further embodiment of the method, this can comprise, as a further step carried out when the vehicle combination starts moving, a reading of an operating signal which is provided by the towing vehicle when the vehicle combination starts moving. The operating signal can be a starting signal which can be provided based on a starting request from the driver of the commercial vehicle. According to this embodiment, the method can comprise, as a further step carried out when the vehicle combination starts moving, a reading of a force acting on the trailer coupling of the vehicle trailer when the vehicle combination starts moving, which force has a force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer.According to this embodiment, the method can comprise, as a further step performed when the vehicle combination starts moving, controlling the drive train of the vehicle trailer to provide a torque in the drive train based on the force read in when the vehicle combination starts moving. The torque can be provided such that the force acting on the trailer coupling adapts to a predetermined force setpoint for the force acting on the trailer coupling when moving off. The predetermined force setpoint can have a force acting direction on the trailer coupling that is opposite to the force acting direction of the force read in when the vehicle combination is stationary. The predetermined force setpoint can be the predetermined force setpoint for the force acting on the trailer coupling before moving off.According to this embodiment of the method, a further step performed when the vehicle combination starts moving can include reading in a speed signal provided by the towing vehicle. The speed signal can be read in via the plug connection. The control step can then be performed when the read-in speed signal has a speed value that falls below a predetermined speed value. The predetermined speed value can be less than 10 km / h, for example, less than 6 km / h, for the driving speed of the vehicle combination. The force acting on the trailer coupling can therefore be adjusted to the predetermined force target value or regulated to this when stationary and when starting off.In the step of controlling the drive train, the torque can therefore be provided in the drive train in such a way that the force acting on the trailer coupling is controlled by adjusting the torque to the force setpoint.

[0023] According to a further embodiment of the method, this can comprise, as a further step carried out during travel of the vehicle combination, reading in a speed signal provided by the towing vehicle. The speed signal can be read in via the plug connection. According to this embodiment, the method can comprise, as a further step carried out during travel of the vehicle combination, reading in a force acting on the trailer coupling of the vehicle trailer while the vehicle combination is traveling, which force has a force component acting on the trailer coupling in the longitudinal direction of the vehicle trailer. According to this embodiment, the method can comprise, as a further step carried out during travel of the vehicle combination, controlling the drive train of the vehicle trailer to provide a traction-assisting torque in the drive train based on the read-in force.The control step can be performed when the read-in speed signal has a speed value that exceeds a predetermined speed value. The torque can be provided such that the force acting on the trailer coupling adapts to a predetermined force target value for the force acting on the trailer coupling during travel. The traction-assisting torque can be provided such that the force acting on the trailer coupling is adapted, for example, increased or decreased, using a ramp function to the predetermined force target value for the force acting on the trailer coupling during travel. The energy requirement for the towing vehicle can thus be further reduced with the traction assistance.

[0024] According to a further embodiment of the method, the step of controlling the drive train to terminate traction assistance by the provided torque can be terminated based on a read-in operating specification. Alternatively or additionally, the step of controlling the drive train to terminate traction assistance by the provided torque can be terminated automatically based on a read-in speed signal that exceeds a predetermined speed value. The read-in operating specification can be specified by the driver and read in via the user interface. The speed signal can be provided by the towing vehicle and read in via the plug connection.

[0025] In a further aspect, the present invention relates to a control device configured to control a drive train of a vehicle trailer, wherein the control device is configured to carry out the method according to the preceding aspect. In yet another aspect, the present invention relates to a vehicle trailer having a drive train for driving the vehicle trailer and a control device according to the preceding aspect for controlling the drive train. Each embodiment of one aspect can form a corresponding embodiment of another aspect; for example, the control device can have a corresponding device for carrying out at least one step of the method. Short description of the characters Fig. 1 shows a vehicle combination with a towing vehicle and a vehicle trailer, which has a control device for controlling a drive train of the vehicle trailer. Fig. 2 shows a flowchart with procedural steps for controlling the vehicle trailer of the vehicle combination. Detailed description of embodiments

[0026] Fig. 1 shows a vehicle combination 100 comprising a towing vehicle 20 and a vehicle trailer 10. The vehicle trailer 10 and the towing vehicle 20 are coupled via a trailer coupling 12 in the longitudinal direction of the vehicle combination 100. The trailer coupling 12 has a force sensor 13, which is configured to detect a tensile force component acting on the trailer coupling 12 in the longitudinal direction of the vehicle trailer 10. The vehicle combination 100 is located on a roadway (not shown in the figures), which is inclined according to one embodiment. The towing vehicle 20 has a braking system 22, which is configured to generate a holding force for holding the vehicle combination 100 when the vehicle combination 100 is stationary on the roadway.

[0027] The vehicle trailer 10 has vehicle wheels 18, which are driven by wheel drive motors 17. The vehicle trailer 10 has an electric drive train 14 for generating torque through the wheel drive motors 17 and for driving the vehicle wheels 18. For this purpose, the electric drive train 14 has an electrical energy source 15 and an inverter 19 for supplying energy to the wheel drive motors 17.

[0028] The vehicle trailer 10 also has a control device 110 configured to control the electric drive train 14 to provide torque through the wheel drive motors 17 to drive the vehicle wheels 18. The control device 110 is also configured to read the tractive force component acting on the trailer coupling 12. The control device 110 is also configured to read a braking signal from the braking system 22 of the towing vehicle 20 via a plug connection 11 connecting the towing vehicle 20 and the vehicle trailer 10.

[0029] Fig. 2 shows a flowchart with steps for carrying out a method for controlling the vehicle trailer 10 of the vehicle combination 100 in a chronological sequence according to one embodiment of the method. Steps of the method are first carried out while the vehicle combination 100 is at a standstill S. Subsequently, steps of the method are carried out while the vehicle combination 100 is starting A from the standstill S. Following this, steps of the method are carried out while the vehicle combination 100 is driving F after the starting A.

[0030] In a first step S1 carried out in the standstill S, a driving direction specification for starting A of the vehicle combination 100 from the standstill S is read in by the control device 110. The driving direction specification is given by a driver of the towing vehicle 20 via a Fig.1 and communicates wirelessly with the control device 110. In a further step S2, carried out in the standstill S, the tensile force component acting on the trailer coupling 12 of the vehicle trailer 10 in the standstill S is read in by the control device 110, wherein the tensile force component is detected by the force sensor 13 in the standstill S on the trailer coupling 12.

[0031] In a further step S3 performed at standstill S, a braking signal is read in by the control device 110, which is provided by the braking system 22 of the towing vehicle 20 and communicated to the control device 110 via the plug connection 11. In a further step S4 performed at standstill S, a force setpoint for the tractive force acting on the trailer coupling 12 at standstill S is determined. In a further step S5 performed at standstill S, the drive train 14 of the vehicle trailer 10 is controlled based on the read-in tractive force and as a function of the read-in travel direction specification and the read-in braking signal. The drive train 14 is controlled such that a torque is provided by the wheel drive motors 17 for the vehicle wheels 18 such that the tractive force acting on the trailer coupling 12 adapts to the determined force setpoint.To provide the torque, the drive train 14 is controlled depending on the specified direction of travel and whether the brake signal is present. The sign of the torque is adjusted depending on the specified direction of travel. According to one embodiment, the torque is adjusted such that a force acting on the trailer coupling 12 of the vehicle trailer 10 in the stationary position S is established, which force is essentially zero. In step S5, the torque of the wheel drive motors 17 is thus controlled or adjusted such that traction assistance is provided for the towing vehicle 20, which essentially compensates for the traction force acting on the trailer coupling 12.

[0032] In a further step S6, which is carried out while the vehicle combination 100 is at a standstill S before the vehicle combination 100 starts moving A, the braking signal provided by the braking system 22 of the towing vehicle 20 is evaluated. If the result of step S6 is that a braking request from the driver of the towing vehicle 20 is no longer present, the drive train 14 is controlled in a further step S7, which is carried out while the vehicle combination 100 is at a standstill S, in such a way that the provided torque changes. The torque is provided in the drive train 14 in a changed manner such that the tractive force acting on the trailer coupling 12 adapts to a predetermined force setpoint value for the tractive force acting on the trailer coupling 12 before the start of moving A. The predetermined force setpoint value has a force acting direction on the trailer coupling 12 that is opposite to the force acting direction of the read-in force on the trailer coupling 12.For starting A of the vehicle combination 100, a positive traction support in the direction of travel of the vehicle combination 100 can be provided already when the vehicle combination 100 is at a standstill S for starting A of the vehicle combination 100.

[0033] In a further step S8 performed during the start-up A of the vehicle combination 100, a start-up signal is read in by the control device 110, which is provided by the towing vehicle 20 during the start-up A of the vehicle combination 100. The start-up signal is based on a start-up request from the driver of the towing vehicle 20. In a further step S9 performed during the start-up A of the vehicle combination 100, a tractive force acting on the trailer coupling 12 of the vehicle trailer 10 during the start-up A of the vehicle combination 100 is read in by the control device 110, which has a tractive force component acting on the trailer coupling 12 in the longitudinal direction of the vehicle trailer 10. In a further step S10 performed during the start-up A, the drive train 14 of the vehicle trailer 10 is controlled by the control device 110.The drive train 14 of the vehicle trailer 10 is controlled such that a torque is provided by the wheel drive motors 17, by means of which the tractive force acting on the trailer coupling 12 during start-up A is adapted to a predetermined force setpoint for the tractive force acting on the trailer coupling 12 during start-up A. The predetermined force setpoint has a force acting direction on the trailer coupling 12 that is opposite to the force acting direction of the force read in at the trailer coupling 12 when the vehicle combination 100 is at a standstill S. During start-up A, the provided torque thus provides a tractive force assistance that exceeds the tractive force assistance provided at a standstill S.

[0034] In a further step S11 performed during travel F of the vehicle combination 100, a speed signal is read in by the control device 110, which is communicated by the towing vehicle 20 via the plug connection 11. In a further step S12 performed during travel F, a tractive force acting on the trailer coupling 12 of the vehicle trailer 10 during travel F of the vehicle combination 100 is read in by the control device 110, which has a tractive force component acting on the trailer coupling 12 in the longitudinal direction of the vehicle trailer 10. In a further step S13 performed during travel F of the vehicle combination 100, the drive train 14 of the vehicle trailer 10 is controlled by the wheel drive motors 17 to provide a tractive force-assisting torque.The traction assist torque is generated such that a traction assist provided in driving F is reduced compared to the traction assist provided in starting A. Reference symbol 10 vehicle trailers 11 Plug connection 12 Trailer hitch 13 Force sensor 14 Powertrain 15 Energy source 17 Wheel drive motor 18 vehicle wheels 19 inverters 20 towing vehicle 22 Brake system 100 vehicle combinations 110 Control device 120 User interface A Starting F Driving S standstill S1 Read operating specification S2, S9, S12 Reading force S3 Read brake signal S4 Determine force setpoint S5, S7, S10, S13 Control drive train S6 Evaluate brake signal S8 Read operating signal S11 Reading speed signal

Claims

[1] Method for controlling a vehicle trailer (10) of a vehicle combination (100), which has a towing vehicle (20) and the vehicle trailer (10), with the steps carried out when the vehicle combination (100) is at a standstill (S): reading in (S1) an operating specification for operating the vehicle combination (100) from the standstill (S), reading in (S2) a force acting on a trailer coupling (12) of the vehicle trailer (10) in the standstill (S), which force has a force component acting in the longitudinal direction of the vehicle trailer (10) on the trailer coupling (12), determining (S4) a force setpoint for the force acting on the trailer coupling (12) in the standstill (S), and controlling (S5) a drive train (14) of the vehicle trailer (10) to provide a torque in the drive train (14) based on the read-in force and as a function of the read-in Operating specification, wherein the torque is provided in the drive train (14) in such a way,that the force acting on the trailer coupling (12) adapts to the specific force target value., [2] Method according to claim 1, with the further step, carried out when the vehicle combination (100) is at a standstill (S), of reading in (S3) a brake signal which is provided by a brake system (22) of the towing vehicle (20), wherein the step of controlling (S5) the drive train (14) is carried out based on the read-in brake signal. [3] Method according to claim 1 or 2, wherein the operating specification read in in the step of reading in (S1) the operating specification comprises at least one of a direction of travel specification, which specifies a starting direction of the vehicle combination (100) for starting (A) of the vehicle combination (100) from a standstill (S), and a longitudinal dynamics specification, which specifies a longitudinal dynamics parameter of the vehicle combination (100) for starting (A) from a standstill (S). [4] Method according to one of the preceding claims, wherein the force setpoint determined in the step of determining (S4) the force setpoint for the force acting on the trailer coupling (12) has a setpoint force component acting on the trailer coupling (12) in the longitudinal direction of the vehicle trailer (10) which is substantially equal to zero. [5] Method according to one of the preceding claims, wherein the step of determining (S4) the force setpoint is carried out based on at least one of the read-in operating specifications and an inclination of the roadway (2) on which the vehicle combination (100) is located. [6] Method according to one of the preceding claims, with the further steps carried out when the vehicle combination (100) is at a standstill (S) before the vehicle combination (100) starts moving (A): evaluating (S6) a braking signal provided by the towing vehicle (20), controlling (S7) the drive train (14) of the vehicle trailer (10) to provide a torque in the drive train (14) based on the input force and as a function of the evaluated braking signal, wherein the torque is provided in such a way that the force acting on the trailer coupling (12) adapts to a predetermined force setpoint value for the force acting on the trailer coupling (12) before the start (A), wherein the predetermined force setpoint value has a force acting direction on the trailer coupling (12) which is opposite to the force acting direction of the input force on the trailer coupling (12). [7] Method according to one of the preceding claims, with the further steps carried out during a start (A) of the vehicle combination (100): reading in an operating signal (S8) which is provided by the towing vehicle (20) during the start (A) of the vehicle combination (100), reading in (S9) a force acting on the trailer coupling (12) of the vehicle trailer (10) during the start (A) of the vehicle combination (100), which force has a force component acting on the trailer coupling (12) in the longitudinal direction of the vehicle trailer (10), controlling (S10) the drive train (14) of the vehicle trailer (10) to provide a torque in the drive train (14) based on the force read in during the start (A) of the vehicle combination (100), wherein the torque is provided in such a way that the force acting on the trailer coupling (12) adapts to a predetermined force setpoint for the force applied during the start (A) adjusts to the force acting on the trailer coupling (12),wherein the predetermined force setpoint has a force acting direction on the trailer coupling (12) which is opposite to the force acting direction of the force read in at the trailer coupling (12) when the vehicle combination (100) is at a standstill (S). [8] Method according to one of the preceding claims, with the further steps carried out during travel (F) of the vehicle combination (100): reading in (S11) a speed signal which is provided by the towing vehicle (20), reading in (S12) a force acting on the trailer coupling (12) of the vehicle trailer (10) during travel (F) of the vehicle combination (100), which force has a force component acting on the trailer coupling (12) in the longitudinal direction of the vehicle trailer (10), controlling (S13) the drive train (14) of the vehicle trailer (10) to provide a traction-assisting torque in the drive train (14) based on the read-in force, wherein the torque is provided such that the force acting on the trailer coupling (12) adapts to a predetermined force setpoint for the force acting on the trailer coupling (12) during travel (F). [9] Control device (110) for controlling a drive train (14) of a vehicle trailer (10), wherein the control device (110) is configured to carry out the method according to one of the preceding claims. [10] Vehicle trailer (10) comprising a drive train (14) for driving the vehicle trailer (10) and a control device (110) according to claim 9 for controlling the drive train (14).

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