Method for controlling yaw movement of vehicle

Abstract

The invention relates to a method for controlling a yaw movement of a vehicle (1). The vehicle (1) comprises a first set of motion support means (11) for controlling the movement of the first set of steerable wheels (10), and at least one second motion support means (21) for controlling the movement of the second set of wheels (20). Each motion support device of the first set of motion support devices (11) can generate a load by a respective individual wheel. The method comprises: obtaining an indication of a desired yaw motion to be applied by the vehicle (1); and determining whether a first set of steerable wheels (10) can obtain a desired yaw motion by: selecting a steering configuration of the first set of steerable wheels; and operating said first set of motion support devices (11) associated with said first set of steerable wheels (10) in order to apply a first yaw moment to the vehicle (1). When it is determined that the first set of steerable wheels (10) is unable to obtain a desired yaw movement without exceeding one or more predetermined limits, at least one second movement support device (21) associated with said second set of wheels (21) is operated to apply a second yaw moment to the vehicle (1).

Description

Technical Field

[0001] The invention relates to a method for controlling a yaw movement of a vehicle. The invention also relates to a control unit, a vehicle, a computer program and a computer program medium.

[0002] The present invention is applicable to heavy vehicles, such as trucks, buses and construction equipment. The present invention is also applicable to any other suitable vehicle, such as a car. Background Art

[0003] In the field of vehicles, in particular light, medium and heavy vehicles, usually referred to as trucks, various control functions for vehicles are constantly developing. Specifically, the control functions are aimed at improving the drivability of the vehicle, the comfort of the driver and the safety during operation.

[0004] One control function that is often always under improvement is the steering of a vehicle. In this particular area of ​​technology there is a constant development regarding autonomous steering systems, steer-by-wire systems, and the like. In particular, these types of steering systems continually grapple with the problem of controlling a vehicle to follow the curvature of a road as desired. For example, an autonomous steering system may base its steering on the curvature detected in front of the vehicle. A steer-by-wire system bases its steering on input from either a human operator or an autonomous function.

[0005] One problem is that for some steering operating systems, vehicle power consumption is relatively high. Another problem is that steering system failure increases the risk of traffic accidents, such as vehicle collisions due to the failure of the steering system to operate as expected. In order to improve power consumption and reduce the risk of accidents, WO2022 / 042818 A1 discusses a method for improving steering, in which the steering of the vehicle is performed by having a pair of independently steerable wheels, and the yaw motion of the vehicle is controlled by independently propelling the pair of steerable wheels, also known as propulsion steering.

[0006] However, on surfaces with a low coefficient of friction, such as ice or snow, or due to limited wheel angles available, the yaw motion may be limited. In these cases, the yaw moment may be limited. It is therefore necessary to limit the requested steering torque, thereby also limiting the yaw motion that can be generated.

[0007] Therefore, it is desirable to further improve vehicle steering operation to more efficiently control the yaw motion of the vehicle. Summary of the invention

[0008] The object of the present invention is to improve the vehicle steering operation of a vehicle.

[0009] According to a first aspect, the above object is achieved by a method according to claim 1. Therefore, a method for controlling the yaw motion of a vehicle is provided. The vehicle comprises a first set of steerable wheels and a second set of wheels. The vehicle comprises a first set of motion support devices for controlling the movement of the first set of steerable wheels, and at least one second motion support device for controlling the movement of the second set of wheels. Each motion support device of the first set of motion support devices directly or indirectly drives a corresponding individual wheel connected to the first set of steerable wheels, so that each motion support device of the first set of motion support devices can generate a load via the corresponding individual wheel. The method comprises: obtaining an indication of a desired yaw motion to be applied by the vehicle; determining whether the desired yaw motion is achievable by a first set of steerable wheels by: selecting a steering configuration of the first set of steerable wheels to produce a first yaw motion portion; and operating the first set of motion support devices associated with the first set of steerable wheels to apply a first yaw moment to the vehicle to produce a second yaw motion portion without exceeding one or more predetermined limits for the steering configuration and / or the first set of motion support devices associated with the first set of steerable wheels; and in response to determining that the first set of steerable wheels cannot achieve the desired yaw motion without exceeding one or more predetermined limits for the steering configuration and / or the first set of motion support devices associated with the first set of steerable wheels, operating at least one second motion support device associated with the second set of wheels to apply a second yaw moment to the vehicle.

[0010] In this way, when the first set of steerable wheels cannot achieve the desired yaw motion without exceeding one or more predetermined limits, at least one second motion support device can be operated to apply a second yaw moment to the vehicle. In other words, when the yaw motion resulting from the combination of steering and operating the first set of steerable wheels cannot achieve the desired yaw motion, the second set of wheels can be operated to further increase the yaw motion when needed. In this way, the second set of wheels can be used to temporarily increase the yaw motion capability when the vehicle is turning. As used herein, the term "operating at least one second motion support device associated with the second set of wheels to apply a second yaw moment to the vehicle" is intended to cover such a situation: at least one second motion support device can be operated together with, for example, the first set of steerable wheels to apply a second yaw moment to the vehicle; and such a situation: at least one second motion support device can be operated alone to apply a second yaw moment to the vehicle.

[0011] Optionally, operating the first set of motion support devices associated with the first set of steerable wheels to apply a first yaw moment to the vehicle comprises: each motion support device of the first set of motion support devices generates an individual load for its corresponding individual wheel of the first set of steerable wheels. In other words, the first set of steerable wheels may have different forces on each corresponding individual wheel to generate the first yaw moment and thus improve yaw motion control.

[0012] Optionally, generating individual loads for respective individual wheels of the first set of steerable wheels comprises applying respective loads in different directions to two different respective wheels of the first set of steerable wheels. When loads are applied in different directions to two different respective wheels, an increased yaw moment, and thus an increased yaw motion, may be achieved.

[0013] Optionally, generating individual loads for respective individual wheels of the first set of steerable wheels comprises braking and / or propelling at least one wheel of the first set of steerable wheels.

[0014] Optionally, the one or more predetermined constraints for the first set of motion support devices comprise, for each motion support device of the first set of motion support devices, a maximum individual load based on friction forces for its respective individual wheel of the first set of steerable wheels.

[0015] Optionally, the one or more predetermined limitations for the first set of movement support devices include a power and / or energy limitation for each movement support device in the first set of movement support devices.

[0016] Optionally, the one or more predetermined constraints for the steering configuration include a maximum steering angle that can be applied by each respective individual wheel of the first set of steerable wheels.

[0017] Optionally, the one or more predetermined constraints for the first set of motion supporting devices include a maximum torque for each individual wheel of the first set of steerable wheels.

[0018] Optionally, determining whether the desired yaw movement is achievable by the first set of steerable wheels comprises evaluating whether it is possible to identify a combination of the first yaw movement portion and the second yaw movement portion, which combination results in the desired yaw movement.

[0019] Optionally, evaluating whether it is possible to identify a combination of the first yaw movement portion and the second yaw movement portion, which combination results in the desired yaw movement, comprises selecting a corresponding steering angle for the first set of steerable wheels.

[0020] Optionally, evaluating whether it is possible to identify a combination of the first yaw motion portion and the second yaw motion portion, which combination results in the desired yaw motion, comprises selecting a respective load to be generated by each respective wheel of the first set of steerable wheels.

[0021] Optionally, obtaining the indication of the desired yaw motion of the vehicle comprises obtaining a steering angle of the vehicle. The steering angle may be a steering wheel angle.

[0022] Optionally, the method further comprises comparing the steering angle with a model of a reference vehicle and determining the desired yaw motion as the yaw motion applied by the reference vehicle in the model when the reference vehicle in the model steers at the obtained steering angle.

[0023] Optionally, obtaining the indication of a desired yaw motion of the vehicle comprises obtaining the desired yaw motion to be exerted by the vehicle.

[0024] Optionally, the first yaw motion is based in part on a wheel suspension scrub radius of each respective wheel of the first set of steerable wheels.

[0025] Optionally, the ground wiping radius of each corresponding wheel in the first group of steerable wheels is the distance between the position where the kingpin axis of the corresponding wheel intersects with the road surface and the center portion of the corresponding wheel.

[0026] Optionally, the second yaw motion is based in part on a torque applied to each respective wheel of the first set of steerable wheels.

[0027] Optionally, the at least one second motion support device comprises a respective second motion support device for each wheel of the second set of wheels for individually controlling the movement of each respective wheel of the second set of wheels.

[0028] Optionally, at least one second motion support device controls the movement of the second set of wheels by jointly controlling the movement of the second set of wheels.

[0029] Optionally, the second set of wheels consists of non-steerable wheels.

[0030] Optionally, the second yaw moment is at least partly a resultant yaw moment generated by operating the at least one second motion support device with respective individual steering angles of the first set of steerable wheels.

[0031] According to a second aspect, a control unit is provided to perform the method according to the first aspect. The control unit may be an electronic control unit.

[0032] According to a third aspect, a vehicle is provided, the vehicle comprising a control unit according to the second aspect.

[0033] Optionally, the vehicle comprises a first set of steerable wheels and a second set of wheels, the vehicle comprising a first set of motion support devices for controlling the movement of the first set of steerable wheels, and at least one second motion support device for controlling the movement of the second set of wheels, wherein each motion support device in the first set of motion support devices is directly or indirectly drive-connected to a corresponding individual wheel in the first set of steerable wheels, so that each motion support device in the first set of motion support devices is capable of generating a load through a corresponding wheel in the first set of steerable wheels.

[0034] Optionally, each respective wheel of the first set of steerable wheels is mounted to a respective kingpin bolt such that an axis distance along an angle of the respective kingpin bolt causes a rubbing radius where a centerline of the respective wheel intersects, and wherein a yaw motion generated when rotating at least one wheel of the first set of steerable wheels is based on the rubbing radius.

[0035] Optionally, the first set of motion support means comprises a respective electric motor for each respective wheel of the first set of steerable wheels.

[0036] Optionally, the first set of motion support means further comprises a respective brake for each respective wheel of the first set of steerable wheels.

[0037] Optionally, the vehicle is an autonomous vehicle.

[0038] According to a fourth aspect, there is provided a computer program comprising program code means for performing the method according to the first aspect when said program is run on a computer.

[0039] According to a fifth aspect, there is provided a computer program medium carrying a computer program comprising program code means for performing the method according to the first aspect when said program is run on a computer.

[0040] Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Embodiments of the invention cited as examples will be described in more detail hereinafter with reference to the accompanying drawings.

[0042] In the attached picture:

[0043] Figure 1 is a schematic overview of a vehicle according to an embodiment of the present invention.

[0044] Figure 2 is a schematic block diagram showing a comparison between the prior art and the embodiments herein.

[0045] Figure 3 is a flow chart of a method according to an embodiment of the present invention.

[0046] Figure 4 is a schematic block diagram illustrating an example scenario of a vehicle.

[0047] Figure 5 is a schematic block diagram illustrating an example scenario of a wheel in a vehicle.

[0048] Figure 6 is a schematic diagram illustrating example scrub radii for a kingpin bolt and a wheel.

[0049] Figure 7 is a schematic block diagram and combined flow chart illustrating example scenarios of embodiments of the present invention.

[0050] Figure 8 is a schematic block diagram and combined flow chart illustrating example scenarios of embodiments of the present invention.

[0051] Figure 9a to Figure 9b is a schematic block diagram showing a control unit. DETAILED DESCRIPTION

[0052] Figure 1 A schematic overview of a vehicle 1 is shown. Figure 1 Although shown as a truck in the figure, the embodiments herein may be applicable to any suitable vehicle, such as any of a car, a truck, a bus, etc.

[0053] The vehicle 1 comprises a first set of steerable wheels 10. Although Figure 1 The first set of steerable wheels 10 is depicted at the front of the vehicle 1 , but the first set of steerable wheels 10 may be located at any suitable part of the vehicle 1 . The vehicle 1 further comprises a first set of motion support devices 11 for controlling the movement of the first set of steerable wheels 10 .

[0054] Each of the first group of motion support devices 11 is directly or indirectly drive-connected to a corresponding individual wheel in the first group of steerable wheels 10, so that each of the first group of motion support devices 11 can generate a load through a corresponding wheel in the first group of steerable wheels 10. The corresponding individual wheels can also be steered individually. In other words, it may be possible to steer, brake and / or propel the first group of steerable wheels using different configurations, forces and / or directions. In order to generate individual loads on the corresponding individual wheels, the first group of motion support devices 11 may include an electric motor and any suitable brake, such as an electric brake, a service brake and / or a pneumatic brake.

[0055] Each respective wheel of the first set of steerable wheels 10 may be mounted to a respective kingpin bolt. The kingpin bolt may be attached to an axle associated with the first set of steerable wheels 10. The first set of steerable wheels 10 may be mounted to the respective kingpin bolts such that the axis distance extending along the angle of the respective kingpin bolts causes the center lines of the respective wheels to intersect at a rubbing radius. In this way, the yaw motion generated when turning at least one wheel of the first set of steerable wheels 10 may be based on the rubbing radius, i.e., the yaw motion is increased at a higher rubbing radius. This is because, for example, when a braking torque is applied, the respective wheel will rotate about an axis extending along the angle of the respective kingpin bolt, and thus induce an additional yaw moment on the vehicle 1 based on the rubbing radius.

[0056] The vehicle 1 includes a second set of wheels 20. Although Figure 1 The second set of wheels 20 is depicted as being located at the rear of the vehicle 1, but the second set of wheels 20 may be located at any suitable portion of the vehicle 1. The vehicle 1 includes at least one second motion support device 21 for controlling the movement of the second set of wheels 20. The second set of wheels 20 may be steerable independently or in combination. In some embodiments, the second set of wheels 20 consists of non-steerable wheels.

[0057] In some embodiments, the at least one second motion support device 21 includes a respective second motion support device for each wheel in the second set of wheels 20 for individually controlling the movement of each respective wheel in the second set of wheels 20. In these embodiments, the second set of wheels 20 may be independently controlled similar to the first set of steerable wheels 10. In some of these embodiments, each wheel of the second set of wheels 20 may have an individual load controlled by a respective second motion support device. In some embodiments, the at least one second motion support device 21 jointly controls the movement of the second set of wheels 20. In these embodiments, the second set of wheels 20 may have the same corresponding load and / or corresponding steering.

[0058] The at least one second motion support device 21 may include one or more electric motors and any suitable brakes for jointly or independently braking the second set of wheels, such as electric brakes, service brakes and / or pneumatic brakes.

[0059] In some embodiments, each respective wheel in the second set of steerable wheels 20 can be mounted to a respective kingpin bolt. The kingpin bolt can be attached to an axle associated with the second set of wheels 20, such as a rear axle. The second set of wheels 20 can be mounted to the respective kingpin bolts such that the axis distance along the angle of the respective kingpin bolts causes the centerline of the respective wheels to intersect the scrubbing radius. In this way, the yaw motion generated when turning at least one wheel in the second set of wheels 20 can be based on the scrubbing radius.

[0060] In some embodiments herein, the vehicle 1 is autonomous. In some embodiments, the steering angle of the first set of steerable wheels 10 is automatically determined. In some embodiments herein, the vehicle 1 and the first set of steerable wheels 10 are manually steered. In some embodiments herein, the vehicle 1 is steered using any suitable mechanism and / or is assisted by any suitable mechanism, such as steer-by-wire.

[0061] The embodiments herein may be executed by a control unit 70. The control unit 70 may be included in the vehicle 1, but may also be included in any other suitable location that is communicatively connected with the vehicle 1.

[0062] Figure 2 A comparison of conventional steering and steering performed according to the embodiments of the present invention is shown. Conventional steering is performed by a vehicle 200, wherein a first set of front wheels 201 can be steered and operated in conjunction to generate a corresponding load on each front wheel. Similarly, a second set of rear wheels 202 can be operated in conjunction to generate a corresponding load on each rear wheel. In general, a yaw moment is generated around a center point 203 of the vehicle 200. The center point used herein may mean the center of mass around which a yaw moment is generated for turning the vehicle. Because conventional steering is limited in how each wheel is controlled; therefore, the yaw motion that can be obtained may be limited.

[0063] exist Figure 2 In the example scenario of , the vehicle 1 may be a four-wheel drive battery electric truck. The use of four in-wheel motors allows for more flexible maneuvering of the vehicle 1, for example, the electric motors in the first set of motion support devices 11 and the at least one second motion support device 21 can be used quickly to change the load on the respective wheels. Figure 2 In the example scenario of FIG. 1 , a separate first load 210a, 210b, 211a, 211b is generated on the first set of steerable wheels 10, wherein the load 211a is in the opposite direction to the load 211b, thereby achieving a significant yaw moment compared to when the loads 211a, 211b are in the same direction. In addition, corresponding loads 212a, 212b, 213a, 213b are generated on the second set of wheels 20. In this way, a resulting yaw motion around the center point 220 is achieved, which is increased compared to the yaw motion around the center point 203 of the vehicle 200.

[0064] Although the resulting yaw motion is increased compared to the yaw motion around the center point 203 of the vehicle 200, the achievable yaw moment is limited to the achievable moment generated on the first set of steerable wheels 10. In order to understand whether the vehicle 1 can obtain the desired yaw motion, it may be necessary to determine the limit of the yaw moment generated on the first set of steerable wheels 10. The limit of the yaw moment can be determined by the steering angle of the first set of steerable wheels and the corresponding individual loads 210a, 210b, 211a, 211b and the function of the rubbing radius of each corresponding wheel. When the desired yaw motion cannot be obtained, it is necessary to increase the yaw motion, and therefore the embodiments of the present invention may involve increasing and / or adjusting the loads 212a, 212b and / or steering angles of the second set of wheels 20, which thereby causes yaw acceleration. In other words, one wheel in the second set of wheels 20 can be pushed more than another wheel in the second set of wheels 20. In some scenarios, at least one wheel in the second set of wheels 20 can be braked to generate a yaw moment.

[0065] Figure 3 A method for controlling a yaw motion of a vehicle 1 is shown. The vehicle 1 comprises a first set of steerable wheels 10 and a second set of wheels 20. The vehicle 1 comprises a first set of motion support devices 11 for controlling the movement of the first set of steerable wheels 10, and at least one second motion support device 21 for controlling the movement of the second set of wheels 20. Each motion support device of the first set of motion support devices 11 directly or indirectly drives a corresponding individual wheel connected to the first set of steerable wheels 10, so that each motion support device of the first set of motion support devices 11 can generate a load through the corresponding individual wheel. The method can be performed, for example, by a control unit 70. The method can include one or more of the following actions, which can be performed in any suitable order.

[0066] Action 301 The method comprises obtaining an indication of a desired yaw motion to be exerted by the vehicle 1 .

[0067] In some embodiments, obtaining the indication of the desired yaw motion of the vehicle 1 comprises obtaining a steering angle of the vehicle 1. The steering angle may be obtained by manual driver generation. The steering angle may be a steering wheel angle.

[0068] In some embodiments, obtaining an indication of a desired yaw motion of vehicle 1 includes obtaining a steering angle of vehicle 1, comparing the steering angle to a model of a reference vehicle, and determining the desired yaw motion as the yaw motion applied by a reference vehicle in the model when the reference vehicle in the model turns at the obtained steering angle.

[0069] For example, a model of a reference vehicle may be trained using sensor data of the reference vehicle to generate a model of the reference vehicle using a machine learning approach.

[0070] In other words, the yaw motion is the yaw motion that would be produced in the reference vehicle if the reference vehicle were to turn at the steering angle. In this way, a yaw motion can be produced in the vehicle 1 that mimics the yaw motion of the reference vehicle. This improves the stability of the yaw motion, as it will behave and be predictable like the reference vehicle when turning, while still allowing the use of fast response motors, i.e. electric motors in each of the first set of motion support devices 11 and / or the at least one second motion support device 21, which can handle high frequency motion requests.

[0071] In some embodiments, obtaining an indication of a desired yaw motion of vehicle 1 includes obtaining a desired yaw motion to be applied by vehicle 1. For example, when vehicle 1 is an autonomous vehicle, vehicle 1 may have calculated the yaw motion necessary to turn in the most efficient manner.

[0072] Action 302

[0073] The method comprises determining whether a desired yaw motion is achievable by a first set of steerable wheels 10. Determining whether the desired yaw motion is achievable by the first set of steerable wheels 10 is performed by selecting a steering configuration of the first set of steerable wheels so as to produce a first yaw motion portion, and operating the first set of motion support devices 11 associated with the first set of steerable wheels 10 to apply a first yaw moment to the vehicle 1 so as to produce a second yaw motion portion without exceeding one or more predetermined limits for the steering configuration and / or the first set of motion support devices 11 associated with the first set of steerable wheels 10.

[0074] In other words, determining whether the desired yaw motion is achievable by the first set of steerable wheels 10 is performed using the respective steering angles of the first set of steerable wheels and their respective individual loads. The interaction of the respective angles and their respective individual loads may be used to determine the first yaw moment, i.e., the first yaw motion portion and the second yaw motion portion may be dependent on and based on the rubbing radius of each respective wheel of the first set of steerable wheels.

[0075] In some embodiments, operating the first set of motion support devices 11 associated with the first set of steerable wheels 10 to apply a first yaw moment to the vehicle 1 includes: each motion support device in the first set of motion support devices 11 generates an individual load for its corresponding individual wheel in the first set of steerable wheels 10.

[0076] In some embodiments, generating individual loads for respective individual wheels in the first set of steerable wheels 10 includes applying respective loads in different directions to two different respective wheels in the first set of steerable wheels 11 .

[0077] In this way, the first set of motion support devices 11 can generate exactly the necessary loads in each direction to optimally achieve a desired and / or maximum yaw moment on the vehicle 1 .

[0078] In some embodiments, generating individual loads of respective individual wheels of the first set of steerable wheels 10 includes braking and / or propelling at least one wheel of the first set of steerable wheels 11 .

[0079] In some embodiments, the one or more predetermined limits for the first set of motion support devices 11 include: for each motion support device in the first set of motion support devices 11, a maximum individual load based on the friction force for its corresponding individual wheel in the first set of steerable wheels 10. In other words, the yaw motion may be limited based on the possible load given the available friction.

[0080] In some embodiments, the one or more predetermined limitations for the first set of motion support devices 11 include power and / or energy limitations for each motion support device in the first set of motion support devices 11. In other words, the yaw motion may be limited based on a power and / or energy limitation, such as how much power an electric motor can use.

[0081] In some embodiments, the one or more predetermined constraints for the steering configuration include a maximum steering angle that can be applied by each respective individual wheel in the first set of steerable wheels 10. In other words, yaw motion can be limited based on the maximum steering angle of each respective individual wheel.

[0082] For some embodiments, some steering angles may not be achieved due to limitations (e.g., one or more predetermined limitations). Some steering angle requests may, for example, be too large (e.g., above a threshold) and / or too sudden (e.g., below a time threshold), which may result in large jerkiness on the front axle and / or the first set of steerable wheels 10. This may be due to heavy braking of one of the first set of steerable wheels 10 while simultaneously propelling another wheel, which may result in the vehicle 1 spinning. In some embodiments, the one or more predetermined limitations may include a limitation to remain below a lateral acceleration threshold, for example, a lateral acceleration below 3.5 m / s^2.

[0083] In some embodiments, the one or more predetermined limitations for the first set of motion support devices 11 include a maximum torque for each individual wheel in the first set of steerable wheels 10. In other words, yaw motion may be limited based on the maximum torque available to each respective individual wheel.

[0084] In some embodiments, determining whether the desired yaw motion is achievable by the first set of steerable wheels 10 includes determining whether the combination of the first yaw motion portion and the second yaw motion portion results in a maximized yaw motion of the vehicle 1 and / or the yaw motion of the vehicle 1 is within a threshold of the desired yaw motion. In other words, the combined effect of the first yaw motion portion and the second yaw motion portion needs to be determined in order to accurately determine the resulting yaw moment.

[0085] In some embodiments, determining whether the desired yaw motion is achievable by the first set of steerable wheels 10 includes evaluating whether it is possible to identify a combination of the first yaw motion portion and the second yaw motion portion that results in the desired yaw motion. The evaluation may involve an optimization problem. The evaluation may include establishing an optimal yaw motion based on a condition, for example, establishing a maximum yaw motion and / or establishing a yaw motion within a threshold of the desired yaw motion.

[0086] In some embodiments, evaluating whether it is possible to identify a combination of the first yaw motion portion and the second yaw motion portion, which combination results in the desired yaw motion, includes selecting a corresponding steering angle for the first set of steerable wheels 10. In other words, the corresponding steering angle is statically set, so that only the corresponding load of the first set of steerable wheels 10 needs to be determined for evaluation.

[0087] In some embodiments, evaluating whether it is possible to identify a combination of the first yaw motion portion and the second yaw motion portion that results in the desired yaw motion includes selecting a respective load to be generated by each respective wheel of the first set of steerable wheels 10. In other words, the respective loads for the first set of steerable wheels 10 are statically set so that only the respective steering angles need to be determined for evaluation.

[0088] In some embodiments, the first yaw motion is based in part on a wheel suspension scrubbing radius of each respective wheel in the first set of steerable wheels 10. In some of these embodiments, the scrubbing radius of each respective wheel in the first set of steerable wheels 10 is the distance between a location where a kingpin axis of the respective wheel intersects the road surface and a center portion of the respective wheel.

[0089] The second yaw motion portion may be based on a torque, such as a differential torque, applied to each respective wheel of the first set of steerable wheels 10. The first yaw motion portion may be based on a steering of the first set of steerable wheels 10, such as relative to a respective wiping radius. In some embodiments, at least one wiping radius needs to be positive.

[0090] Action 303

[0091] The method further includes, in response to determining that the first set of steerable wheels 10 cannot achieve a desired yaw motion without exceeding one or more predetermined limitations for the steering configuration and / or the first set of motion support devices 11 associated with the first set of steerable wheels 10 , operating at least one second motion support device 21 associated with the second set of wheels 21 , thereby applying a second yaw moment to the vehicle 1 .

[0092] In other words, when it is determined that the desired yaw motion cannot be obtained, the load from the second set of wheels can be used to increase the yaw moment of the vehicle 1. This means that in other words the second yaw moment can be seen as an additional yaw moment for the vehicle 1 when the first yaw moment is insufficient.

[0093] In some embodiments, the at least one second motion support device 21 includes a respective second motion support device for each wheel in the second set of wheels 20 for individually controlling the movement of each respective wheel in the second set of wheels 20. In this way, operating the at least one second motion support device 21 associated with the second set of wheels 21 to apply a second yaw moment to the vehicle 1 may include different loads and / or directions on the second set of wheels 20, such as the second yaw moment being maximized and / or the combination of the second yaw moment with the first yaw moment discussed in action 202 being within a threshold of a desired yaw motion.

[0094] In some embodiments, the second yaw moment is at least partially a resultant yaw moment generated by operating the at least one second motion support device 21 with the respective individual steering angles of the first set of steerable wheels 10. In other words, the resultant yaw moment is a yaw moment that the at least one second motion support device 21 may propel or otherwise cause the vehicle 1 to achieve based on the respective individual steering angles of the first set of steerable wheels 10.

[0095] In some embodiments, at least one second motion support device 21 controls the movement of the second set of wheels 20 by jointly controlling the movement of the second set of wheels 20. In other words, the second set of wheels 20 may still generate a yaw motion that is only increased compared to the first yaw motion.

[0096] Figure 4 An example scenario of a vehicle 1 is shown. Figure 4 At least a part of a vehicle arrangement for controlling a yaw motion of the vehicle 1 is depicted in FIG.

[0097] Figure 4 First, the wheel and / or tire forces acting on vehicle 1 are shown. In the vehicle frame, Figure 4 The geometric parameters are shown in . Figure 4Each wheel in the first set of steerable wheels 10 and / or in the second set of wheels 20 may be equipped with a motor with gears and brakes, for example as part of the first set of motion support devices 11 and / or of at least one second motion support device 21 .

[0098] The first set of steerable wheels 10 can be steered at a first angle 401a δ1 and a second angle 401b δ2. The first set of steerable wheels 10 can be constrained by a plurality of loads arranged in different directions at corresponding angles, the plurality of loads comprising: loads 402a, F x,1 , load 402b, F x,2 , load 403a, F y,1 , and load 403b, F y,2 .

[0099] The second set of wheels 20 may be constrained by a plurality of loads arranged in different directions at corresponding angles, the plurality of loads comprising: loads 412a, F x,3 , load 412b, F x,4 , load 413a, F y,3 , and load 413b, F y,4 .

[0100] The first set of steerable wheels 10 may have a wheelbase of 420°. f , such as the front axle width of the vehicle 1. The second set of wheels 10 may have a track width of 421 T r , such as the width of the rear axle of the vehicle 1. The vehicle 1 may have a center point 430, such as a center of mass, where a yaw motion may be generated to turn. Distances 422, 423 L f , L r It may be the respective distance from the front axle and / or the rear axle to the center point 430 .

[0101] Figure 5 Shown with Figure 4 The same example scenario, for any one of the wheels in the set of steerable wheels 10, being controlled by one of the motion support devices in the first set of motion support devices 11. The corresponding wheel is shown in wheel frame 540. The corresponding wheel shown is subjected to load 541 F wx,i Constraints, such as loads corresponding to loads 402a, F x,1 and load 402b, F x,2 The corresponding wheel shown is also subjected to a load of 542 F wx,i Constraints, such as loads corresponding to loads 403a, F y,1 and load 403b, F y,2 Any one of .

[0102] The torque that can be applied to each wheel (e.g. Figure 4 and Figure 5 in) can be based on the following:

[0103] The dynamic wheel equation can be defined as:

[0104] The transformation between the wheel frame and the vehicle frame can be defined as:

[0105] In the example scenario, a small angle approximation is performed so that sin(δ i )=0 and cos(δ i )=1. The embodiments of this paper can use the steady-state equation of the wheel, so that the longitudinal wheel force can be defined as:

[0106] Steering torque

[0107] Embodiments herein may include a wheel suspension design on a steering axle (e.g., the front axle of vehicle 1). The steering torque may be generated by a moment arm, which is the rubbing radius of the tire. The rubbing radius depends on the wheel suspension and is Figure 6 Shown in.

[0108] Figure 6 An example steerable wheel 602 is shown. The steerable wheel 602 may be a wheel in the first set of steerable wheels 10. The steerable wheel 602 may have a tire with a centerline 604 extending along the middle of the steerable wheel 602 and / or the tire on the steerable wheel 602. The steerable wheel 602 may have its center point in contact with a surface (e.g., a road) along the centerline 604, also referred to as a center portion of the steerable wheel 602.

[0109] The steerable wheel 602 may be mounted to the kingpin bolt 603 such that an axis 601 extending along an angle 606 of the kingpin bolt 603 is a ground wiping radius from where the centerline 604 intersects.

[0110] In this way, a yaw motion is generated when turning the steerable wheel 602, and the yaw motion is generated based on the wiping radius, that is, an increased yaw motion for a higher wiping radius. This is because when, for example, a braking torque is applied to the steerable wheel 602, the steerable wheel 602 will rotate about the axis 601 and thereby cause an additional yaw moment on the vehicle 1 based on the wiping radius. In other words, an increase in the wiping radius means that for the same torque applied to the steerable wheel 602, the steering torque is greater. In this way, the steerable wheel 602 will turn more and therefore generate an increased yaw moment. Therefore, the wiping radius can limit and / or indicate how much the steerable wheel 602 can be turned and / or what kind of yaw motion the steerable wheel 602 can generate.

[0111] The steering torque from the differential longitudinal force on the front axle can be defined as:

[0112] Use the equations for steady-state tire forces and refer to Figure 4-Figure 5 , the steering torque can be defined as:

[0113] To control the steering angle of the vehicle 1 , a proportional-integral (PI) controller is used.

[0114] A simple implementation makes the PI controller suitable and the discrete formula at time step k can be defined as:

[0115] Yaw moment and steering moment coupling:

[0116] The yaw moment of vehicle 1 can be described by the following equation:

[0117] The distance from the center of mass to the location where the wheel force is applied can be expressed as:

[0118] In the steady state and small angle approximation, the yaw moment of vehicle 1 can be defined as:

[0119] Therefore, the yaw moment can be divided into three different parts: the direct yaw moment from the front axle, such as the second yaw moment part of actions 301-302 above; the direct yaw moment from the rear axle, such as the second yaw moment of actions 301-302 above; and the yaw moment due to the steering angle, such as the first yaw moment part of actions 301-302 above:

[0120] From the front axle differential torque ∆T w, fa The yaw moment can be defined as:

[0121] From the rear axle differential torque ∆T w, fa The yaw moment can be defined as:

[0122] The yaw moment from the steering angle can be defined as:

[0123] The steering torque can be expressed as the differential torque ∆T w, ra To express it, it can be defined as:

[0124] Therefore, the direct yaw moment resulting from the steering moment can be defined as:

[0125] In other words, the yaw moment (eg, the first yaw moment of actions 301-303) on the steerable wheels (eg, the first set of steerable wheels 10) of the embodiment of the present invention can be subjected to the yaw motion portion M. 转向 Compared with the direct yaw moment, M 转向 The resulting yaw motion can be delayed, for example, because M 转向 The steering spends adjustment time period to affect the yaw motion.

[0126] Figure 7 An example scenario is shown of how yaw and steering moments may be generated in embodiments herein.

[0127] In the example scenario, the steering torque M 转向711 can be signaled by the first PI controller 705, optionally sent through the limiter module 712, which is in turn generated by the first module 704 based on the reference steering angle 702 (e.g., generated by the model of the reference vehicle discussed in the above actions 301-303) and the current steering angle 703 of the vehicle 1. The reference steering angle 702 and the current steering angle 703 can be the steering wheel angle and / or the corresponding steering on the first set of steerable wheels 10, respectively. The reference steering angle 702 can be derived from a path follower, for example as part of the model of the reference vehicle. The current steering angle 703 can be an average of the steering angles of the wheels in the first set of wheels 10. In some embodiments, the current steering angle 703 and / or the reference steering angle 702 can be an indication of the desired yaw motion in action 301.

[0128] In an example scenario, when additional yaw acceleration is requested (e.g., to be generated by the second set of wheels 20), the yaw acceleration signal (YA) 701 is triggered (e.g., as part of action 303 described above), and thus additional yaw moment can be added through feed-forward control in the second module 706 and the third module 707.

[0129] The second module 706 and the third module 707 determine the yaw moment achieved based on the reference steering angle 702, the current steering angle 703 and / or the requested YA.

[0130] The second module 706 may include a switch, wherein when M 转向 When saturated, the reference steering angle 702 may be used to generate an incremental feed-forward action. When the YA signal is above a threshold and / or is set high by any suitable controller (e.g., an advanced controller), YA may be used to determine a yaw moment signal to a third module 707. The third module 707 may determine / calculate a resulting yaw moment.

[0131] In the example scenario, the yaw motion of the vehicle 1 is then determined by determining the yaw moment relative to the scrubbing radius in the fourth module 708. The fifth module 709 can then determine the yaw motion of the vehicle 1 based on the yaw moments determined by the third module 707 and the fourth module 708. The modules of the example scenario can be separate units and / or co-located units, for example in the same circuit.

[0132] Steering torque limitation

[0133] The maximum torque of a wheel (eg, any one of the first set of wheels 10) may depend on any one or more of the following parameters: - Estimated friction: - Estimated normal load: - Parameter ξ, which is, for example, 0-1, depending on how much friction may need to be reserved for lateral forces.

[0134] Therefore, the maximum torque that can be applied to the wheel can be defined by, for example, assuming steady-state wheel dynamics:

[0135] The motor map may be used to obtain motor limits of motors (e.g. motors of the first set of motion support devices 11 and / or at least one second motion support device 21 ), and the lookup table may be used to obtain brake limits (e.g. brakes of the first set of motion support devices 11 and / or at least one second motion support device 21 ).

[0136] The upper limit can be defined as:

[0137] The lower limit can be defined as:

[0138] The combined actuator and friction limit for the motor may be expressed such that if the friction limit is below the motor capability (eg the motor capability of the first set of motion support devices 11 and / or the at least one second motion support device 21 ), the motor may be limited accordingly.

[0139] The upper limit can be defined as:

[0140] The lower limit can be defined as:

[0141] The limits of the brakes (e.g. of the first set of motion support devices 11 and / or of the at least one second motion support device 21) may be set such that if a motor can be used, it is used first and the brakes may intervene only if the braking request is greater than what the motor can handle and there is sufficient friction. Thus, the lower limit may be defined as:

[0142] The wheel cap can be defined as:

[0143] The wheel lower limit can be defined as:

[0144] Finally, the upper and lower steering limits can be defined as:

[0145] Yaw rate control

[0146] The single track model of the vehicle 1 can be expressed by the equations of motion, where the forces on the first set of steerable wheels 10 and the second set of wheels 20 are attributed to the individual wheels on the corresponding axles:

[0147] The wheel / tire force can be defined as:

[0148] The state space equation can be defined as:

[0149] Using the steady-state equations, the curvature can be given by k = ω z / v x Definition, the reference yaw rate based on autonomous input or steer-by-wire input can be defined as:

[0150] In the case of insufficient steering gradient, K u Defined as:

[0151] The yaw rate can then be controlled as follows:

[0152] The steering moment can be expressed from the direct yaw moment as:

[0153] M 转向 This can be done in a number of different ways, for example as described in WO2022 / 042818 A1. 转向,k It may be limited that the direct yaw moment may be distributed to the rear axle, for example as in action 303 above.

[0154] Figure 8 It shows how two virtual forces M can be generated in the embodiment of this paper. 转向 and M z .

[0155] The reference signal 801 may be an input to the sixth module 802. The reference signal 801 may be a reference steering angle, e.g., a steering wheel angle of the vehicle 1. In some embodiments, the reference signal 801 may be an indication of the desired yaw motion in action 301. The sixth module 802 determines a reference yaw rate, e.g., relative to the speed of the vehicle 1, the corresponding distance from the front and / or rear axles to the center point of the vehicle 1, etc. The seventh module 803 generates a yaw moment signal to be transmitted to the second PI controller 805, the yaw moment signal being generated by the seventh module 803 based on the reference yaw rate 803 and the current yaw rate 804 of the vehicle 1. The second PI controller 805 may then generate a yaw motion signal, which is sent to the eighth module 812. In addition, the current steering angle 810 of the vehicle 1 (e.g., where the current steering angle 810 may be a steering wheel angle and / or a corresponding steering on the first set of steerable wheels 10) may be configured to be fed forward to the eighth module 812 via the ninth module 811. The eighth module 812 can generate a yaw motion signal M generated by the vehicle 1 based on the current feedforward steering angle 810 and the yaw motion signal of the PI controller 805. z 807. Based on the yaw motion signal of the PI controller 805, the tenth module 806 can determine the steering torque M 转向 808 , for example, which is optionally passed through a limiter module 809 .

[0156] Control Distribution

[0157] The formulation of the control assignment problem can generally be defined as:

[0158] Rigid body dynamics can be used to derive how the virtual force v enters the equation of motion through the control efficiency matrix B and the available actuators u. The equation of motion can be defined as:

[0159] For simplification, for example to make the calculation feasible, we can only consider the plane motion:

[0160] And the equation of motion can be defined as:

[0161] The virtual force can be defined as:

[0162] Assuming steady-state wheel dynamics and small angles, the mapping v = Bu can be defined as:

[0163] The procedure for controlling the distribution may include locking the distribution of the steering angle, for example such that:

[0164] It may also be possible to generate the M shown above 转向 and M z , and if added yaw acceleration is desired, set the YA signal. Set the weight of the virtual force to:

[0165] In some embodiments, since the steering distribution is locked, and due to the selected weights, an added feed-forward action can be generated from at least one second motion support device 21 (e.g. a rear motor). Since the dynamics of the motor are much faster than the steering dynamics, this enables a faster response. If a faster response is not desired, the current steering angle is fed forward. This will result in using the front motor to purely track the steering angle.

[0166] In some embodiments, if M 转向 If the steering angle is saturated, an additional yaw moment can be added to at least one second motion support device 21, such as a rear motor. This is because the steering distribution is locked and due to the selected weights. The steering angle can be indirectly controlled by a yaw rate controller.

[0167] Additionally, some embodiments include using a PI controller to generate Fx for a desired speed and generating: .

[0168] The lateral forces Fy may be generated optionally, for example just for completeness of the calculation. This is because they may be small and / or otherwise negligible. The steering actuator may still be present on the vehicle 1, for example as part of the first set of motion support devices 11 and / or at least one second motion support device 21, so that some distribution of the lateral forces Fy may be required, for example, to make the switch to manual / conventional steering smoother and more efficient. In some of these embodiments, it may be assumed that there is no sideslip, for example, only the first set of steerable wheels 10 may generate lateral forces.

[0169] In some embodiments herein, the allocation of the steering wheel may be allowed, which means that in the control allocation of the embodiments herein, δ f Not locked to the current steering angle. This will allow blending of propulsion steering and regular power steering.

[0170] In some embodiments herein, a linear quadratic regulator (LQR) controller with a reference gain and / or using an integral state may be used. In some of these embodiments, the model may include M 转向and the direct yaw moment of the rear axle (such as the second yaw moment of action 303 above).

[0171] In order to perform the method actions described herein, the control unit 70 may be configured to control the yaw motion of the vehicle 1. The control unit 70 may also be configured to perform any one or more of the above actions 301-303, or any of the other examples and / or embodiments herein. The control unit 70 may be included in any suitable location, such as, for example, the vehicle 1. The control unit 70 may include, for example Figure 9a and Figure 9b The device depicted in .

[0172] The control unit 70 may include an input and output interface 900 configured to communicate with any necessary components and / or entities in the embodiments of the present invention. The input and output interface 900 may include a wireless and / or wired receiver (not shown) and a wireless and / or wired transmitter (not shown). The control unit 70 may be arranged in any suitable position of the vehicle 1. The control unit 70 may use the input and output interface 900 to control and communicate with the sensor actuator (sensor actuators such as the first group of motion support devices 11 and / or at least one second motion support device 21, subsystems, and interfaces in the vehicle 1) by using any one or more of the following: a controller area network (CAN), an Ethernet cable, Wi-Fi, Bluetooth, and / or other network interfaces.

[0173] The control unit 70 may be configured to obtain an indication of a desired yaw motion to be exerted by the vehicle 1 , for example by an obtaining unit 901 in the control unit 70 .

[0174] The control unit 70 may be configured to determine, for example by a determination unit 902 in the control unit 70, whether the desired yaw motion can be obtained by the first group of steerable wheels 10 by: selecting a steering configuration of the first group of steerable wheels so as to generate a first yaw motion portion, and operating the first group of motion support devices 11 associated with the first group of steerable wheels 10 to apply a first yaw moment to the vehicle 1 so as to generate a second yaw motion portion without exceeding one or more predetermined limits for the steering configuration and / or the first group of motion support devices 11 associated with the first group of steerable wheels 10.

[0175] The control unit 70 may be configured to, for example, via a determination unit 902 in the control unit 70: in response to determining that the first group of steerable wheels 10 cannot obtain a desired yaw motion without exceeding one or more predetermined limitations for the steering configuration and / or the first group of motion support devices 11 associated with the first group of steerable wheels 10, operate at least one second motion support device 21 associated with the second group of wheels 21, thereby applying a second yaw moment to the vehicle 1.

[0176] The embodiments herein may be implemented by a processor or one or more processors (such as Figure 9a The computer program code may be implemented as a processor 960 of a processing circuit in the control unit 70 depicted in FIG. 1 ) together with a computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program medium, for example in the form of a data computer readable medium carrying the computer program code, which is used to perform the embodiments herein when loaded into the control unit 70. One such computer readable medium may be in the form of a memory stick. The computer program code may also be provided as pure program code on a server and downloaded to the control unit 70.

[0177] The control unit 70 may further comprise a memory 970 comprising one or more memory units. The memory 970 comprises instructions executable by a processor in the control unit 70. The memory 970 is arranged to store, for example, information, instructions, data, configurations, sensor data, positioning information, yaw control information and applications to perform the methods herein when executed in the control unit 70.

[0178] In some embodiments, the computer program 980 includes instructions that, when executed by a computer (eg, at least one processor 960), cause at least one processor of the control unit 70 to perform the actions 301 - 303 described above.

[0179] In some embodiments, the computer-readable storage medium 990 includes a corresponding computer program 980. The computer-readable storage medium 990 may include program code for performing any of the steps of the above actions 301-303 when the program product is run on a computer (eg, at least one processor 960).

[0180] Those skilled in the art will appreciate that the units in the control unit 70 described above may refer to a combination of analog and digital circuits, and / or one or more processors configured with, for example, software and / or firmware stored in the control unit 70, which are executed by the corresponding one or more processors (such as the processors described above). One or more of these processors and other digital hardware may be included in a single application specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed in several separate components, whether packaged separately or integrated into a system on a chip (SoC).

[0181] It should be understood that the present invention is not limited to the embodiments described above and shown in the accompanying drawings; on the contrary, those skilled in the art will recognize that many changes and modifications can be made within the scope of the appended claims. In addition, all of the above embodiments can be combined in any suitable manner.

Claims

1. A method for controlling the yaw motion of a vehicle (1), the vehicle (1) comprising a first set of steerable wheels (10) and a second set of wheels (20), the vehicle (1) comprising a first set of motion support devices (11) for controlling the movement of the first set of steerable wheels (10), and at least one second motion support device (21) for controlling the movement of the second set of wheels (20), wherein each motion support device of the first set of motion support devices (11) directly or indirectly drives a corresponding individual wheel connected to the first set of steerable wheels (10), so that each motion support device of the first set of motion support devices (11) can generate a load via the corresponding individual wheel, the method comprising: - obtaining (301) an indication of a desired yaw motion to be applied by the vehicle (1), - determining (302) whether the first set of steerable wheels (10) can achieve the desired yaw motion by: selecting a steering configuration of the first set of steerable wheels to produce a first yaw motion portion, and operating the first set of motion support devices (11) associated with the first set of steerable wheels (10) to apply a first yaw moment to the vehicle (1) to produce a second yaw motion portion without exceeding one or more predetermined limits for the steering configuration and / or the first set of motion support devices (11) associated with the first set of steerable wheels (10); - in response to determining (302) that the first set of steerable wheels (10) is unable to achieve the desired yaw motion without exceeding the one or more predetermined limitations for the steering configuration and / or the first set of motion support devices (11) associated with the first set of steerable wheels (10), operating (303) the at least one second motion support device (21) associated with the second set of wheels (21) so as to apply a second yaw moment to the vehicle (1).

2. The method of claim 1, wherein operating the first set of motion support devices (11) associated with the first set of steerable wheels (10) to apply the first yaw moment to the vehicle (1) comprises: Each motion support device of the first set of motion support devices (11) generates an individual load for its corresponding individual wheel of the first set of steerable wheels (10).

3. The method of claim 2, wherein generating individual loads for respective individual wheels of the first set of steerable wheels (10) comprises applying respective loads in different directions to two different respective wheels of the first set of steerable wheels (11).

4. The method according to any one of claims 2 to 3, wherein generating individual loads of corresponding individual wheels of the first set of steerable wheels (10) comprises braking and / or propelling at least one wheel of the first set of steerable wheels (11).

5. The method according to any of the preceding claims, wherein the one or more predetermined limitations for the first group of movement support devices (11) comprise: For each motion support device of the first set of motion support devices (11), a maximum individual load based on the friction force for its corresponding individual wheel of the first set of steerable wheels (10).

6. The method according to any of the preceding claims, wherein the one or more predetermined limitations for the first group of movement support devices (11) comprise power and / or energy limitations for each movement support device in the first group of movement support devices (11).

7. A method according to any one of the preceding claims, wherein the one or more predetermined constraints for the steering configuration include a maximum steering angle that can be applied by each respective individual wheel of the first set of steerable wheels (10).

8. The method according to any of the preceding claims, wherein the one or more predetermined limitations for the first set of motion support devices (11) comprise a maximum torque of each individual wheel of the first set of steerable wheels (10).

9. The method according to any of the preceding claims, wherein determining (302) whether the first set of steerable wheels (10) can obtain the desired yaw motion comprises evaluating whether it is possible to identify a combination of the first yaw motion portion and the second yaw motion portion, which combination results in the desired yaw motion.

10. The method of claim 9, wherein evaluating whether it is possible to identify a combination of the first yaw motion portion and the second yaw motion portion, which combination results in the desired yaw motion, comprises selecting a corresponding steering angle for the first set of steerable wheels (10).

11. A method according to any one of claims 9 or 10, wherein evaluating whether it is possible to identify a combination of the first yaw motion portion and the second yaw motion portion comprises selecting a respective load to be generated by each respective wheel of the first set of steerable wheels (10), the combination resulting in the desired yaw motion.

12. The method according to any one of the preceding claims, wherein obtaining (301) the indication of the desired yaw motion of the vehicle (1) comprises obtaining a steering angle of the vehicle (1).

13. The method of claim 12 further comprising comparing the steering angle to a model of a reference vehicle and determining the desired yaw motion as the yaw motion applied by the reference vehicle in the model when the reference vehicle in the model steers at the obtained steering angle.

14. The method according to any one of claims 1 to 11, wherein obtaining (301) the indication of a desired yaw motion of the vehicle (1) comprises obtaining the desired yaw motion to be exerted by the vehicle (1).

15. The method according to any of the preceding claims, wherein the second yaw motion is based in part on a wheel suspension scrubbing radius of each respective wheel of the first set of steerable wheels (10).

16. The method according to claim 15, wherein the wiping radius of each corresponding wheel in the first set of steerable wheels (10) is the distance between the position where the kingpin axis of the corresponding wheel intersects the road surface and the center portion of the corresponding wheel.

17. The method according to any of the preceding claims, wherein the second yaw motion is based in part on a torque applied to each respective wheel of the first set of steerable wheels (10).

18. A method according to any of the preceding claims, wherein the at least one second motion support device (21) comprises a respective second motion support device for each wheel of the second set of wheels (20) for individually controlling the movement of each respective wheel of the second set of wheels (20).

19. Method according to any one of claims 1 to 17, wherein said at least one second motion support device (21) controls the movement of said second set of wheels (20) by jointly controlling the movement of said second set of wheels.

20. A method according to any preceding claim, wherein the second set of wheels consists of non-steerable wheels.

21. The method according to any of the preceding claims, wherein the second yaw moment is at least partly a resulting yaw moment generated by operating (303) the at least one second motion support device (21) with respective individual steering angles of the first set of steerable wheels (10).

22. A control unit (70) configured to perform the method according to any one of claims 1 to 21.

23. A vehicle (1) comprising a control unit (70) according to claim 22.

24. The vehicle (1) according to claim 23, wherein the vehicle (1) comprises a first set of steerable wheels (10) and a second set of wheels (20), the vehicle (1) comprising a first set of motion support devices (11) for controlling the movement of the first set of steerable wheels, and at least one second motion support device (21) for controlling the movement of the second set of wheels, wherein each motion support device in the first set of motion support devices (11) directly or indirectly drives a corresponding individual wheel connected to the first set of steerable wheels (10), so that each motion support device in the first set of motion support devices (11) is able to generate a load through a corresponding wheel in the first set of steerable wheels (10).

25. The vehicle (1) of claim 24, wherein each respective wheel of the first set of steerable wheels (10) is mounted to a respective kingpin bolt such that an axis distance along an angle of the respective kingpin bolt results in a ground-rubbing radius where center lines of the respective wheels intersect, and wherein a yaw motion generated when at least one wheel of the first set of steerable wheels (10) is rotated is based on the ground-rubbing radius.

26. The vehicle (1) according to any one of the preceding claims, wherein the first set of motion support means (11) comprises a respective electric motor for each respective wheel of the first set of steerable wheels (10).

27. The vehicle (1) according to claim 26, wherein the first set of motion supporting means (11) further comprises a respective brake for each respective wheel of the first set of steerable wheels (10).

28. The vehicle (1) according to any one of claims 23 to 27, wherein the vehicle (1) is an autonomous vehicle.

29. A computer program (980) comprising program code means for performing the steps of any one of claims 1 to 21 when said program is run on a computer.

30. A computer program medium (990) carrying a computer program, the computer program comprising program code means for performing the steps of any one of claims 1 to 21 when the program is run on a computer.

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