Vehicle equipped with a system for determining a vertical load

Abstract

A vehicle has a body that at least partially defines a passenger cabin and a first steering system that includes a first actuator configured to change a road wheel angle for a first pair of steerable wheels assigned to a first axle. The vehicle also has a controller communicating with the first steering system. The controller is configured to identify when a trailer is attached to the vehicle and to determine an unloaded first actuator current used by the first steering system. The controller is also configured to determine a loaded first actuator current used by the first steering system when the trailer is attached and to calculate a vertical load on the vehicle based on an unloaded load on the first axle, the unloaded first actuator current, and the loaded first actuator current for the first steering system.

Description

The present description concerns the operation of a vehicle with a trailer and, in particular, a system for determining the vertical load on the vehicle. Many vehicles are equipped with a tow hitch, enabling the connection of a trailer. This ability allows for the transport of items that would otherwise not fit inside the vehicle. The type of trailer, vehicle, and tow hitch determine the trailer's load capacity and how the load should be distributed. One way to determine the total weight the trailer and vehicle can bear is to calculate the vertical load (the "tongue weight") on the vehicle from the trailer. This can be determined using a mechanical method that integrates a scale into the tow hitch or by weighing the vehicle and trailer combination on a vehicle scale. DE 10 2023 128 602 B3 describes methods and systems for a vehicle towing a trailer. The method comprises: receiving sensor data from one or more vehicle sensors using a processor; estimating a steering torque value based on the sensor data using a processor; estimating a steering angle value based on the sensor data using the processor; determining a trailer drawbar angle value based on the steering torque value and the steering angle value using the processor; and generating a control signal for controlling the vehicle based on the trailer drawbar angle value using the processor. DE 10 2023 125 969 A1 describes a method for a vehicle. The method comprises: initiating a steering impulse by a processor according to a pattern while the vehicle is stationary; learning a load assigned to the front axle of the vehicle by the processor based on the steering impulse; transferring the load assigned to the front axle of the vehicle by the processor to a load assigned to the nose weight of a trailer; and generating a trailer nose weight value by the processor based on the load assigned to the nose weight of the trailer. US Patent 9,311,761 B1 describes a method for identifying a low-friction road surface from a inclined road surface for a vehicle. With the vehicle stationary, the ignition is switched on. A normal load for the vehicle is calculated. It is determined whether the vehicle is moving, and if so, a vehicle load is calculated using chassis and suspension information. Based on the calculated vehicle load and the calculated normal load, a road inclination angle is calculated. A normal inclination angle is determined and compared to the calculated road inclination angle to determine whether the vehicle is on a low-friction or inclined road surface. Furthermore, a method is described for determining whether a trailer is coupled to a vehicle. It can be considered a task to specify a vehicle with a system for determining the support load on the vehicle. The problem is solved by a vehicle according to the invention as claimed in claim 1. Furthermore, a method for determining a support load is described which can be carried out with the method according to the invention, and a non-volatile computer-readable storage medium is described which embodies programmed instructions which, when executed by a processor, are operational for carrying out the method, wherein the storage medium can be arranged in the vehicle according to the invention. A vehicle according to the invention is described. The vehicle has a body that at least partially defines a passenger cabin and a first steering system comprising a first actuator configured to change the road wheel angle for a first pair of steerable wheels associated with a first axle, the first pair of steerable wheels being configured to support the body. The vehicle also has a second pair of wheels configured to support the body and a controller communicating with the first steering system. The controller is configured to identify when a trailer is attached to the vehicle and to determine an unloaded first actuator current, which is used by the first steering system to change the road wheel angle for a first pair of steerable wheels on a road surface without the trailer attached.The controller is also configured to determine a loaded first actuator current used by the first steering system to change the road wheel angle for the first pair of steerable wheels on a given road surface when the trailer is attached. The controller is also configured to calculate a vertical load on the vehicle based on an unloaded load on the first axle, the unloaded first actuator current, and the loaded first actuator current for the first steering system. In one embodiment, the vehicle has a human-machine interface configured to provide a message based on the calculated support load. In one embodiment, the message includes an indicator that the support load is above a predetermined threshold. In one embodiment, the controller is configured to calculate a loaded load on the first axis, and the message includes an indicator when the loaded load on the first axis exceeds a predetermined threshold for the first axis. In one embodiment, the control system is configured to calculate the support load on the vehicle based on a coefficient of friction between the first pair of steerable wheels and an actual road surface and a coefficient of friction between the first pair of steerable wheels and an unloaded road surface. In one embodiment, the first steering system comprises a front steer-by-wire steering system or a front electric power steering system, and the vehicle has a trailer coupling for attachment to the trailer, located adjacent to a rear bumper on the vehicle. In one embodiment, the first steering system has a rear steer-by-wire steering system and the vehicle has a trailer coupling for connecting to the trailer, which is located in a loading area of ​​the vehicle. In one embodiment, the vehicle has a second steering system comprising a second actuator configured to move a second pair of steerable wheels, assigned to a second axle, between a second plurality of road wheel angles. The second pair of steerable wheels is configured to support the vehicle body, and the control unit communicates with the second steering system. The control unit is configured to determine an unloaded second actuator current, which is used by the second steering system to change a road wheel angle for the second pair of steerable wheels on the road surface without the trailer attached.The control system is also configured to determine a loaded second actuator current used by the second steering system to change the road wheel angle for the second pair of steerable wheels on the current road surface when the trailer is attached, and to calculate the support load on the vehicle based on an unloaded load on the second axle, the second unloaded actuator current, and the second loaded actuator current. In one embodiment, the first steering system is a front steer-by-wire steering system and the second steering system is a rear steer-by-wire steering system. In one embodiment, the first steering system has a rear steer-by-wire system. In one embodiment, the controller is configured to calculate a loaded load on the first axis, and the message includes an indicator when the loaded load on the first axis exceeds a predetermined threshold for the first axis. In one embodiment, the controller is configured to calculate a loaded load on the second axis, and the message includes an indicator when the loaded load on the second axis exceeds a predetermined threshold for the second axis. A non-volatile, computer-readable storage medium is described that embodies programmed instructions which, when executed by a processor, are operational for carrying out a procedure. The procedure comprises identifying when a trailer is attached to a vehicle, determining an unloaded first actuator current used by a first steering system to change a road wheel angle for a first pair of steerable wheels on a road surface without the trailer attached, and determining a loaded first actuator current used by the first steering system to change the road wheel angle for the first pair of steerable wheels on a current road surface when the trailer is attached.The procedure also includes calculating a support load on the vehicle based on an unloaded load on a first axle, the unloaded first actuator current and the loaded first actuator current, and communicating a message based on the support load through a human-machine interface on the vehicle. The message indicates that the support load is above a predetermined threshold. The method involves calculating the support load on the vehicle based on a coefficient of friction between a first pair of steerable wheels on the vehicle and an actual road surface, and a coefficient of friction between the first pair of steerable wheels and an unloaded road surface. The method involves determining an unloaded second actuator current used by a second steering system to change the road wheel angle for a second pair of steerable wheels on the road surface without the trailer attached, and determining a loaded second actuator current used by the second steering system to change the road wheel angle for the second pair of steerable wheels on the same road surface when the trailer is attached. The method also involves calculating the vertical load on the vehicle based on an unloaded load on a second axle, the second unloaded actuator current, and the second loaded actuator current. The first steering system is a front steer-by-wire system and the second steering system is a rear steer-by-wire system. The first steering system features a rear steer-by-wire system. A method for determining the nose weight on a vehicle is described. The method includes identifying when a trailer is attached to the vehicle, determining an unloaded first actuator current used by a first steering system to change the road wheel angle for a first pair of steerable wheels on a road surface when the trailer is not attached, and determining a loaded first actuator current used by the first steering system to change the road wheel angle for the first pair of steerable wheels on a road surface when the trailer is attached. The method also includes calculating the nose weight on the vehicle based on an unloaded load on a first axle, the unloaded first actuator current, and the loaded first actuator current, and communicating a message based on the nose weight via a human-machine interface on the vehicle. The method includes determining an unloaded second actuator current used by a second steering system to change the road wheel angle for a second pair of steerable wheels on the road surface without the trailer attached, and determining a loaded second actuator current used by the second steering system to change the road wheel angle for the second pair of steerable wheels on the same road surface when the trailer is attached. The method also includes calculating the vertical load on the vehicle based on an unloaded load on a second axle, the second unloaded actuator current, and the second loaded actuator current. Figure 1 schematically illustrates a vehicle attached to a trailer. Figure 2 illustrates an exemplary method for determining a vertical load on the vehicle from Figure 1. With reference to Fig. 1, the vehicle 10 generally comprises a chassis 12, a body 14, and front and rear wheels 17. The body 14 is mounted on the chassis 12 and essentially encloses components of the vehicle 10, defining a passenger cabin. The body 14 and the chassis 12 can together form a frame. The wheels 17 are each rotatably coupled to the chassis 12 near a respective corner of the body 14. The vehicle wheels 17 are supported by a front axle 19F and a rear axle 19R. In various embodiments, the vehicle 10 can be an autonomous vehicle. The vehicle 10 is attached to a trailer 9 by a trailer coupling 11. The vehicle 10 is, for example, a vehicle that is automatically controlled to transport passengers from one place to another. As shown, the vehicle 10 generally comprises a drive system 20, a transmission system 22, a steering system 24, a braking system 26, a sensor system 28, an actuator system 30, at least one control system 34, and a communication system 36. The drive system 20 can, in various embodiments, include an electric machine, such as one or more traction motors to enable torque vectoring, and / or a fuel cell drive system. The vehicle 10 further comprises a battery (or battery pack) 21, which is electrically connected to the drive system 20. Accordingly, the battery pack 21 is configured to store electrical energy and to supply electrical energy to the drive system 20. Additionally, the drive system 20 may include an internal combustion engine. The transmission system 22 is configured to transmit power from the drive system 20 to the vehicle wheels 17 according to selectable speed ratios. According to various embodiments, the transmission system 22 may comprise a gear-ratio automatic transmission, a continuously variable transmission, or another suitable transmission. The braking system 26 is configured to provide braking torque to the vehicle wheels 17. The braking system 26 may, in various embodiments, comprise friction brakes, brake-by-wire, a regenerative braking system such as an electric machine, and / or other suitable braking systems.The steering system 24 influences the position of the vehicle wheels 17 by receiving rotational input torques from a driver via a steering wheel HW. The steering system 24 may include an electric actuator 32, which forms a section of either a steer-by-wire steering system or an electric power steering (EPS) steering system. The sensor system 28 comprises one or more sensors 40 (i.e., detection devices) that detect observable conditions of the external environment and / or the interior environment of the vehicle 10. The sensors 40 communicate with the controller 34 and may, but are not limited to, include one or more radar devices, one or more lidar (light detection and ranging) sensors, one or more ground penetrating radar (GPR) sensors, one or more global positioning system (GPS) devices, one or more cameras (e.g., optical cameras and / or thermal cameras, such as a rear camera and / or a front camera), a brake pedal position sensor, an accelerator pedal position sensor, a steering angle sensor, a speed sensor, a wheel speed sensor, ride height sensors, ultrasonic sensors, one or more inertial measurement units (IMUs), and / or other sensors. The actuator system 30 comprises one or more actuator devices 42 that control one or more vehicle features, such as, but not limited to, the drive system 20, the transmission system 22, the steering system 24, which includes front and rear steering components, and the braking system 26. In this description, the steering system 24 comprises a front steering system 25 for turning the front wheels 17 and a rear steering system 43, such as an Active Rear Steer (ARS) system, for steering the rear wheels 17 independently of the front wheels 17. Furthermore, in one example, the front steering system and the rear steering system are both drive-by-wire systems without a direct mechanical connection between the steering wheel and the wheels 17. In another example, the front steering system comprises an electric power steering system with a direct mechanical connection between the steering wheel HW and the front wheels 17.In both examples, the front and rear steering systems use an electric steering actuator 32 that receives an input current proportional to an input received via the steering wheel hardware. In various embodiments, the vehicle features may further include interior and / or exterior vehicle features, such as, but not limited to, doors, a trunk, and cabin features such as air conditioning, music, lighting, etc. (not numbered). For example, the actuator devices 42 include an accelerator pedal, a brake pedal, etc. The controller 34 comprises at least one processor 44 and a non-volatile computer-readable storage device or medium 46. The processor 44 can be a custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among several processors associated with the controller 34, a semiconductor-based microprocessor (in the form of a microchip or chipset), a microprocessor, a combination thereof, or generally, a device for executing instructions. The computer-readable storage device or medium 46 can, for example, include volatile and non-volatile storage in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM).KAM is a persistent or non-volatile memory that can be used to store various operating variables while the processor 44 is turned off. The computer-readable memory device or computer-readable storage medium 46 can be implemented using a number of other memory devices, such as PROMs (programmable read-only memory), EPROMs (electrical PROMs), EEPROMs (electrically erasable PROMs), flash memory, or other electrical, magnetic, optical, or combination storage devices capable of storing data, some of which are executable instructions used by the controller 34 in controlling the vehicle 10. The instructions can comprise one or more separate programs, each containing an ordered list of executable instructions for implementing logical functions. When executed by the processor 44, the instructions receive and process signals from the sensor system 28, perform logic, calculations, procedures, and / or algorithms to automatically control the components of the vehicle 10, and generate control signals to the actuator system 30 to automatically control the components of the vehicle 10 based on the logic, calculations, procedures, and / or algorithms. Although a single controller 34 is shown in Fig.As shown in Figure 1, embodiments of the vehicle 10 may have a number of controllers 34 which communicate via a suitable communication medium or a combination of communication media and which work together to process the sensor signals, perform logic, calculations, procedures and / or algorithms and generate control signals to automatically control features of the vehicle 10. The vehicle 10 has a human-machine interface (HMI) 23, which can be a center console screen or a driver information center. The HMI 23 interacts with a user to display information and receives confirmation, activation, abort commands, etc. The HMI 23 can be configured as an alarm, such as a speaker to provide sound, haptic feedback in a vehicle seat or other object, a visual display, or any other device suitable for providing a notification to the driver of the vehicle 10. The HMI 23 communicates electronically with the controller 34 and is configured to receive input from a user (e.g., the driver). Accordingly, the controller 34 is configured to receive input from the user via the HMI 23.The HMI 23 features a display configured to show information to the user (e.g., driver or passenger) and may have one or more speakers to provide an auditable notification to the driver. Fig. 2 illustrates an exemplary method 100 for determining the vertical load on the vehicle 10. The method 100 begins at block 102 (“Start”). From block 102, the method 100 proceeds to block 104. At block 104 (“V < Vmax and trailer?”), the method 100 determines whether the current speed V of the vehicle 10 and the trailer is less than a predetermined maximum speed Vmax. The method 100 also determines whether a trailer, such as the trailer 9 in Fig. 1, is attached to the vehicle 10 by the trailer coupling 11. In one example, the trailer coupling 11 has a coupling that is mounted adjacent to a rear bumper on the vehicle 10. In another example, the trailer coupling 11 has a trailer coupling mounted on the loading platform, so that the connection between the trailer coupling 11 and the vehicle 10 overlaps at least partially with the rear axle 19R on the vehicle 10 (Fig. 1).Exemplary trailer couplings mounted on the loading platform include a fifth wheel coupling arrangement, a gooseneck coupling arrangement or another similar coupling arrangement mounted in the loading platform of vehicle 10. In one example, the method 100 determines whether the trailer 9 is attached to the vehicle 10 by detecting when a trailer wiring harness is connected to a vehicle trailer wiring harness. In another example, the method 100 determines whether the trailer 9 is attached to the vehicle 10 by performing object detection using a camera 13 (Fig. 1) located adjacent to the rear of the vehicle 10. If the speed V of the vehicle 10 is greater than Vmax or if the trailer 9 is not attached to the vehicle 10, the method 100 returns to block 102 to continue monitoring the speed V of the vehicle 10 or to identify whether the trailer 9 is attached to the vehicle 10. If the speed V is less than Vmax and the trailer 9 is attached to the vehicle 10, the method 100 passes from block 104 to block 106. In block 106 (“Draft Load Calc.”), method 100 determines the vertical load on the vehicle 10 from the trailer 9. In the illustrated example shown in Fig. 1, the trailer 9 is attached to the vehicle 10 by the trailer coupling 11 adjacent to the bumper on the vehicle 10. However, as discussed in more detail above and below, this description also applies to trailer coupling assemblies mounted on the loading platform. Method 100 can then calculate the vertical load on the vehicle 10 based on the input information provided to block 106 by block 108 (“Input”). In one example, vehicle 10 has a front EPS system and a rear steer-by-wire steering system. The input information provided to perform the support load calculation at block 106 includes an unloaded front axle load Ff0, an unloaded rear axle load Fr0, an unloaded rear steering actuator current Ir0, a loaded rear steering actuator current Ir, an unloaded front EPS actuator current If0, a loaded front EPS actuator current If, an unloaded driver steering torque Td0, a loaded driver steering torque Td, an unloaded front equivalent steering actuator current Ife0, and a loaded front equivalent steering actuator current Ife. In one example, the unloaded front equivalent steering actuator current Ife0 is calculated using equation 1 below, and the loaded front equivalent steering actuator current Ife is calculated using equation 2 below. Equations 1 and 2 above also use a pinion ratio β and a motor current constant KIf for the EPS actuator 32 in the front steering system 25. Using this information, method 100 calculates the vertical load Ft using the following equation 3. In equation 3 above, c is the distance from the rear axle 19R to the connection point between the trailer coupling 11 and the trailer 19, and 1 is the wheelbase of the vehicle 10, as shown in Fig. 1 above. In another example, vehicle 10 has a front steer-by-wire system for a pair of front steerable wheels 17 and a rear steer-by-wire system for a pair of rear steerable wheels 17. In this example, the input information for block 108 includes an unloaded front axle load Ff0, an unloaded rear axle load Fr0, an unloaded rear steering actuator current If0, an unloaded rear steering actuator current Ir0, a loaded front steering actuator current If, and a loaded rear steering actuator current If. With this input information, the vertical load Ft can be calculated using the following equation 4. One feature of using the steering systems for the vehicle 10 according to the above equations 3-4 is that the support load Ft can be calculated independently of a coefficient of friction between the road surface and the wheels 17. In yet another example, vehicle 10 has a single pair of steerable front wheels 17 and rear wheels 17 that do not generate varying road wheel angles for steering. The single pair of steerable wheels 17 in this example is controlled by a steer-by-wire steering system. Vehicle 10 in this example also has a trailer hitch adjacent to the rear bumper. In this example, the input information for block 108 includes an unloaded front axle load Ff0, an unloaded front steering actuator current If0, a loaded front steering actuator current If, an unloaded front equivalent steering actuator current Ife0, a loaded front equivalent steering actuator current Ife, an unloaded dry road surface coefficient of friction µ0, and a current road surface coefficient of friction µ.With this input information, the support load Ft can be calculated using the following equation 5. In another example, vehicle 10 has a single pair of steerable front wheels 17 and rear wheels 17 that do not generate varying road wheel angles for steering. The single pair of steerable wheels 17 is controlled by an EPS system. Vehicle 10 in this example also has a trailer hitch adjacent to the rear bumper. The input information for block 108 includes an unloaded front axle load Ff0, an unloaded front EPS actuator current If0, a loaded front EPS actuator current If, an unloaded front equivalent current Ife0, a loaded front equivalent current Ife, an unloaded dry road surface coefficient of friction µ0, and a current road surface coefficient of friction µ.In an example, the unloaded forward equivalent current Ife0 is calculated using Equation 1 above, and the loaded forward equivalent current Ife is calculated using Equation 2 above. With this input information, the nose weight Ft can be calculated using Equation 6 below. In yet another example, the vehicle 10 has a rear steering system, where the rear steering system is a steer-by-wire system used in conjunction with a pair of rear steerable wheels 17. In this example, the input information for block 108 includes an unloaded rear axle load Fr0, a loaded rear steering actuator current Ir, an unloaded rear steering actuator current Ir0, an unloaded coefficient of dry road surface friction µ0, and a current coefficient of road surface friction µ. With this input information, the support load Ft can be calculated using the following equation 7. With the support load Ft, which is calculated based on the steering configuration of the vehicle 10 and the available input information as discussed above, procedure 100 then proceeds to block 110. In block 110 (“Axle loads Calc.”), procedure 100 determines a front axle load Ffan of the front axle 19F using equation 8 and a rear axle load Fran of the rear axle 19R using equation 9. With the loads Ft, Fr, and Ff, procedure 100 proceeds to block 112. At Block 112 (“Below the threshold?”), Procedure 100 determines whether one or more of the vertical load Ft, the front axle load Ff, or the rear axle load Fr are below a corresponding predetermined threshold weight or load. In an example, the predetermined threshold for the rear axle load Ff is the highest, followed by the front axle load Ff, and then the vertical load Ft. If any of these are below their respective predetermined thresholds, Procedure 100 returns to Block 104 to continue monitoring the speed V of the vehicle 10 and to determine whether the trailer 9 has been identified. If one or more of these values ​​are above their respective predetermined thresholds, Procedure 100 proceeds to Block 114. At block 114 (“Warning?”), procedure 100 issues a warning for each value exceeding the corresponding predetermined threshold. Procedure 100 can deliver the warning as a message using HMI 23, accompanied by one or more audible, visual, or haptic feedback signals, as discussed above. Procedure 100 then returns to block 104 to continue monitoring the speed V of vehicle 10 and to identify whether trailer 9 is connected to vehicle 10.

Claims

Vehicle (10), comprising: a body (14) that defines at least a part of a passenger cabin; a first steering system (24, 25) comprising a first actuator (32) configured to change a road wheel angle for a first pair of steerable wheels (17) associated with a first axle (19F), the first pair of steerable wheels (17) being configured to support the body (14); a second pair of wheels (17) configured to support the body (14); and a control unit (34) in communication with the first steering system (24, 25), wherein the control unit (34) is configured to: identify when a trailer (9) is attached to the vehicle (10); determine an unloaded first actuator current (If0) used by the first steering system (24, 25) to change a road wheel angle for a first pair of steerable wheels (17) on a road surface without the trailer (9) attached;to determine a loaded first actuator current (If) used by the first steering system (24, 25) to change the road wheel angle for the first pair of steerable wheels (17) on a current road surface when the trailer (9) is attached; and to calculate a vertical load (Ft) on the vehicle (10) based on an unloaded load (Ff0) on the first axle (19F), the unloaded first actuator current (If0) and the loaded first actuator current (If) for the first steering system (24, 25). Vehicle (10) according to claim 1, wherein the vehicle (10) has a human-machine interface (23) configured to provide a message based on the calculated support load (Ft). Vehicle (10) according to claim 2, wherein the message includes an indicator that the support load (Ft) is above a predetermined threshold. Vehicle (10) according to claim 2, wherein the control (34) is configured to calculate a loaded load (Ff) on the first axle (19F), and the message includes an indicator when the loaded load (Ff) on the first axle (19F) is above a predetermined threshold for the first axle (19F). Vehicle (10) according to claim 2, wherein the control (34) is configured to calculate the support load (Ft) on the vehicle (10) based on a coefficient of friction between the first pair of steerable wheels (17) and an actual road surface and a coefficient of friction between the first pair of steerable wheels (17) and an unloaded road surface. Vehicle (10) according to claim 5, wherein the first steering system (24, 25) comprises a front steer-by-wire steering system or a front electric power steering system and the vehicle (10) has a trailer coupling (11) for attachment to the trailer (9) located adjacent to a rear bumper on the vehicle (10). Vehicle (10) according to claim 5, wherein the first steering system (24, 25) has a rear steer-by-wire steering system and the vehicle (10) has a trailer coupling (11) for connecting to the trailer (9) which is located in a loading area of ​​the vehicle (10). Vehicle (10) according to claim 2, wherein the vehicle (10) comprises: a second steering system (24, 43) comprising a second actuator (32) configured to move a second pair of steerable wheels (17) associated with a second axle (19R) between a second plurality of road wheel angles, the second pair of steerable wheels (17) being configured to support the body (14); and the controller (34) communicating with the second steering system (24, 43) and configured to: determine an unloaded second actuator current (Ir0) used by the second steering system (24, 43) to change a road wheel angle for the second pair of steerable wheels (17) on the road surface without the trailer (9) being attached;to determine a loaded second actuator current (Ir) used by the second steering system (24, 43) to change the road wheel angle for the second pair of steerable wheels (17) on the current road surface when the trailer (9) is attached; and to calculate the vertical load (Ft) on the vehicle (10) based on an unloaded load (Fr0) on the second axle (19R), the second unloaded actuator current (Ir0), and the second loaded actuator current (Ir). Vehicle (10) according to claim 8, wherein the first steering system (24, 25) is a front steer-by-wire steering system and the second steering system (24, 43) is a rear steer-by-wire steering system. Vehicle (10) according to claim 8, wherein the first steering system (24, 25) has a rear steer-by-wire system.

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