Steering rack travel control for misalignment compensation

Abstract

A system performs a method for operating a vehicle. The system includes a first steering system for a first axle of the vehicle and a processor. The processor determines that the first shaft has misaligned wheels thereon, applies a non-zero steering wheel angle to a steering wheel of the vehicle to maintain straight movement of the vehicle having the misaligned wheels, measures a value of the non-zero steering wheel angle, determines a misaligned angle of the misaligned wheels based on the value of the non-zero steering wheel angle, and transmits the determined misaligned angle to the first shaft. A reduced range of travel of the first shaft is determined based on a first nominal range of travel of the first shaft and the misalignment angle, and the first steering system is activated to steer the vehicle by limiting movement of the first shaft using the reduced range of travel. The reduced range of travel allows misaligned wheels to move without contacting the vehicle.

Description

Technical Field

[0001] This disclosure relates to operating a vehicle with misaligned wheels, and more specifically, to a system and method for controlling the travel range of a steering rack on an axle of the vehicle to compensate for the misaligned wheels. Background Technology

[0002] Standard vehicle operation or steering assumes that the vehicle's wheels are correctly aligned. However, sometimes the wheels become misaligned. This misalignment can lead to steering difficulties and other problems. For example, during steering, a correctly aligned wheel may not contact the inner wall of the wheel well, while a misaligned wheel may. Therefore, it is desirable to provide a method for identifying misaligned wheels and compensating for steering range to prevent misaligned wheels from contacting the vehicle. Summary of the Invention

[0003] In one exemplary embodiment, a method of operating a vehicle is disclosed. A misaligned wheel is determined to be present on a first axle. A non-zero steering wheel angle is applied to the vehicle's steering wheel to maintain straight-line movement of the vehicle relative to its longitudinal axis, even with the misaligned wheel present. The value of the non-zero steering wheel angle maintaining straight-line movement of the vehicle is measured. A misalignment angle of the misaligned wheel is determined based on the value of the non-zero steering wheel angle. A reduced travel range of the first axle is determined based on a first nominal travel range of the first axle and the misalignment angle, wherein the reduced travel range allows the misaligned wheel to move without contacting the vehicle. The vehicle is steered by restricting the movement of the first axle using the reduced travel range.

[0004] In addition to one or more features described herein, the method further includes: using the first nominal travel range to restrict movement of the first axle when the misaligned wheel is not in contact with the vehicle at any location on the first axle within the first nominal travel range.

[0005] In addition to one or more features described herein, the method further includes: determining an extended travel range of a second axle of the vehicle based on the misalignment angle of the misaligned wheel on the first axle, and steering the vehicle by limiting the movement of the second axle using the extended travel range, wherein the extended travel range is greater than a second nominal travel range of the second axle.

[0006] In addition to one or more features described herein, using a reduced travel range to limit the movement of the first axle and using an extended travel range to limit the movement of the second axle allows the vehicle to achieve the desired turning radius.

[0007] In addition to one or more features described herein, one of the first axles is the front axle of the vehicle, and the second axle is the rear axle of the vehicle, and the first axle is the rear axle of the vehicle, and the second axle is the front axle.

[0008] In addition to one or more features described herein, applying a non-zero steering wheel angle to maintain straight-line vehicle movement also includes applying a steering wheel angle only at the front axle of the vehicle when the rear axle is in neutral.

[0009] In addition to one or more features described herein, the method also includes determining the misalignment angle based on a non-zero steering wheel angle that keeps the vehicle moving straight and a multiplicative constant that depends on whether the first axle is the front or rear axle.

[0010] In another exemplary embodiment, a system for operating a vehicle is disclosed. The system includes a first steering system for a first axle of the vehicle and a processor. The processor is configured to: determine that there is a misaligned wheel on the first axle; apply a non-zero steering wheel angle to the steering wheel of the vehicle to maintain straight movement of the vehicle relative to the longitudinal axis of the vehicle while the misaligned wheel is present; measure a value of the non-zero steering wheel angle that maintains straight movement of the vehicle; determine a misalignment angle of the misaligned wheel based on the value of the non-zero steering wheel angle; determine a reduced travel range of the first axle based on a first nominal travel range of the first axle and the misalignment angle, wherein the reduced travel range allows the misaligned wheel to move without contacting the vehicle; and activate the first steering system to steer the vehicle by limiting the movement of the first axle using the reduced travel range.

[0011] In addition to one or more features described herein, the processor is also configured to activate the first steering system to steer the first axle by limiting the movement of the first axle using the first nominal travel range when the misaligned wheel is not in contact with the vehicle at any location on the first axle within the first nominal travel range.

[0012] In addition to one or more features described herein, the processor is also configured to determine an extended travel range of the vehicle's second axle based on the misalignment angle of the misaligned wheel on the first axle, and to activate a second steering system to use the extended travel range to limit the movement of the second axle, wherein the extended travel range is greater than a second nominal travel range of the second axle.

[0013] In addition to one or more features described herein, the processor is also configured to use the reduced travel range to limit the movement of the first axle and to use the extended travel range to limit the movement of the second axle, thereby allowing the vehicle to achieve a desired turning radius.

[0014] In addition to one or more features described herein, one of the first axles is the front axle of the vehicle, and the second axle is the rear axle of the vehicle, and the first axle is the rear axle of the vehicle, and the second axle is the front axle.

[0015] In addition to one or more features described herein, applying a non-zero steering wheel angle to maintain straight-line vehicle movement also includes applying a steering wheel angle only at the front axle of the vehicle when the rear axle is in neutral.

[0016] In addition to one or more features described herein, the processor is also configured to determine the misalignment angle based on a non-zero steering wheel angle that keeps the vehicle moving straight and a multiplicative constant that depends on whether the first axle is the front or rear axle.

[0017] In yet another exemplary embodiment, a vehicle is disclosed. The vehicle includes a first steering system for a first axle of the vehicle, a second steering system for a second axle of the vehicle, and a processor. The processor is configured to: determine that the first axle has a misaligned wheel thereon; apply a non-zero steering wheel angle to the steering wheel of the vehicle to maintain straight-line movement of the vehicle relative to the longitudinal axis of the vehicle while having the misaligned wheel; measure a value of the non-zero steering wheel angle that maintains straight-line movement of the vehicle; determine a misalignment angle of the misaligned wheel based on the value of the non-zero steering wheel angle; determine a reduced travel range of the first axle based on a first nominal travel range of the first axle and the misalignment angle, wherein the reduced travel range allows the misaligned wheel to move without contacting the vehicle; determine an extended travel range of the second axle based on the misalignment angle of the misaligned wheel on the first axle, wherein the extended travel range is greater than a second nominal travel range of the second axle; and activate the first steering system to steer the vehicle. The second steering system is activated to steer the vehicle by limiting the movement of the first axle using the reduced travel range, and the second steering system is activated to steer the vehicle by limiting the movement of the second axle using the extended travel range.

[0018] In addition to one or more features described herein, the processor is also configured to activate the first steering system to steer the first axle by limiting its movement through the first nominal travel range when the misaligned wheel is not in contact with the vehicle at any location on the first axle within the first nominal travel range.

[0019] In addition to one or more features described herein, the processor is also configured to use the reduced travel range to limit the movement of the first axle and to use the extended travel range to limit the movement of the second axle, thereby allowing the vehicle to achieve a desired turning radius.

[0020] In addition to one or more features described herein, one of the first axles is the front axle of the vehicle, and the second axle is the rear axle of the vehicle, and the first axle is the rear axle of the vehicle, and the second axle is the front axle.

[0021] In addition to one or more features described herein, applying a non-zero steering wheel angle to maintain straight-line vehicle movement also includes applying a steering wheel angle only at the front axle of the vehicle when the rear axle is in neutral.

[0022] In addition to one or more features described herein, the processor is also configured to determine the misalignment angle based on a non-zero steering wheel angle that keeps the vehicle moving straight and a multiplicative constant that depends on whether the first axle is the front or rear axle.

[0023] The above-described features and advantages, as well as other features and advantages, of this disclosure will become apparent when taken in conjunction with the accompanying drawings and the following detailed description. Attached Figure Description

[0024] Other features, advantages, and details appear by way of example only in the following detailed description, which is described in detail with reference to the accompanying drawings, wherein:

[0025] Figure 1 A vehicle according to an exemplary embodiment is shown;

[0026] Figure 2 A schematic plan view of the vehicle in an illustrative embodiment is shown;

[0027] Figure 3 It is a diagram showing the range of angles of motion of the correctly aligned wheels of a vehicle;

[0028] Figure 4 This is a flowchart of a method for steering a vehicle when its wheels are misaligned;

[0029] Figure 5 It is a diagram of a vehicle in a straight-ahead driving configuration, with three correctly aligned wheels and one misaligned wheel on the front axle;

[0030] Figure 6 This is a diagram of the vehicle during testing to determine the misalignment angle of the misaligned wheel on the front axle;

[0031] Figure 7 The diagram shows the result of wheels not being aligned on the front axle during steering;

[0032] Figure 8 This is a diagram showing a vehicle using steering maneuvers with a reduced forward travel range;

[0033] Figure 9 This is a diagram showing a vehicle using steering maneuvers with a reduced forward travel range and an extended rear travel range;

[0034] Figure 10 This is a schematic diagram of a vehicle in a straight-ahead driving configuration, with three correctly aligned wheels and one misaligned wheel on the rear axle;

[0035] Figure 11 This is a diagram of the vehicle during testing to determine the misalignment angle of the misaligned wheel on the rear axle;

[0036] Figure 12 The illustration shows the result of the rear wheels being misaligned on the rear axle during a turn;

[0037] Figure 13 This is a diagram showing a vehicle using steering maneuvers with a reduced rear travel range; and

[0038] Figure 14 This is a diagram showing a vehicle using steering maneuvers with a reduced rear travel range and an expanded front travel range. Detailed Implementation

[0039] The following description is exemplary in nature only and is not intended to limit this disclosure, its application, or use. It should be understood that throughout the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0040] According to an exemplary embodiment, Figure 1 Vehicle 100 is shown. Vehicle 100 can be a car, truck, van, bus, motorcycle, boat, or any other type of vehicle. According to one embodiment, vehicle 100 includes an internal combustion engine fueled by gasoline, diesel, etc. According to another embodiment, vehicle 100 is a hybrid electric vehicle that is partially or fully powered by electricity. According to another embodiment, vehicle 100 is an electric vehicle powered by electricity. According to one or more embodiments, vehicle 100 is an autonomous or semi-autonomous vehicle. An autonomous vehicle is a vehicle with automatic driving capabilities. A semi-autonomous vehicle is a vehicle that has some autonomous features (e.g., self-parking, lane keeping, etc.) but lacks fully autonomous control.

[0041] The vehicle includes vehicle sensors 102 for detecting various parameters of the vehicle and a controller 104 for determining whether the front or rear wheels are misaligned based on data received from the vehicle sensors and for performing compensatory actions to mitigate the effects of the misalignment. As described herein, the term "misalignment" refers to the incorrect positioning of one or more wheels of a vehicle relative to the other wheels of the vehicle. Proper wheel alignment ensures that the vehicle travels straight and correctly, maximizes wheel life, and ensures optimal handling and ride quality / comfort.

[0042] Controller 104 may include processing circuitry, which may include application-specific integrated circuits (ASICs), electronic circuitry, a processor (shared, dedicated, or grouped) and memory executing one or more software or firmware programs, combinational logic circuitry, and / or other suitable components providing the described functionality. Controller 104 may include a non-transitory computer-readable medium storing instructions that, when processed by one or more processors of controller 104, implement a method for controlling the road wheel angle of misaligned wheels to prevent contact with vehicles, according to one or more embodiments detailed herein.

[0043] The controller 104 operates the misalignment detection engine 110, which can monitor alignment observer excitation criteria (e.g., lateral acceleration equal to zero in the case of a non-zero steering wheel angle), calculate the expected vehicle heading, estimate the alignment error, apply a statistical filter (e.g., a moving average), and detect misalignment (e.g., whether misalignment exists and whether such misalignment is frontal or rearward).

[0044] Figure 2 A schematic plan view 200 of a vehicle 100 in an illustrative embodiment is shown. The vehicle 100 includes a left front wheel 202, a right front wheel 204, a left rear wheel 206, and a right rear wheel 208. The left front wheel 202 and the right front wheel 204 are connected by a front steering system on a front axle 210. The left rear wheel 206 and the right rear wheel 208 are connected by a rear steering system on a rear axle 218. In various embodiments, the front steering system may be a first steering system, and the rear steering system may be a second steering system. In other embodiments, the rear steering system is the first steering system, and the front steering system is the second steering system. The front axle 210 may include a front steering rack 212 that moves in a right-to-left direction from the vehicle 100 to rotate the left front wheel 202 and the right front wheel 204 relative to the vehicle's centerline (i.e., longitudinal axis) through the road wheel angle (RWA). The forward travel range 214 indicates the nominal travel range of the front steering rack 212, which is related to the nominal angle range of the front wheels, wherein the limit of the forward travel range corresponds to the angle limit of the nominal angle range. Electric power steering (EPS 216) is coupled to the front axle 210 and controls the movement of the front axle 210 and / or the front steering rack 212, thereby controlling the road wheel angles of the left front wheel 202 and the right front wheel 204.

[0045] Similarly, the rear axle 218 may include a rear steering rack 220 that moves along the right-to-left direction of the vehicle 100 to rotate the left rear wheel 206 and right rear wheel 208 relative to the centerline by a road wheel angle. The rear travel range 222 indicates the nominal travel range of the rear steering rack 220, which is related to the nominal angle range of the rear wheels, wherein the limits of the rear travel range correspond to the angle limits of the nominal angle range. An active rear steering system (ARS 224) may be coupled to the rear axle 218 and control the movement of the rear axle and / or the rear steering rack 220, thereby controlling the road wheel angles of the left rear wheel 206 and right rear wheel 208.

[0046] Steering wheel 226 provides steering commands to controller 104, which controls EPS 216 and ARS 224 to control the movement of the front axle 210 and front steering wheels, and the rear axle 218 and rear steering wheels, respectively. Steering angle sensor (SAS 228) measures the rotation of steering wheel 226 and outputs steering wheel angle (SWA) to controller 104. Controller 104 uses SWA to determine the steering control commands for EPS 216 and ARS 224.

[0047] Each wheel can rotate within its corresponding wheel cavity. The left front wheel 202 is selected for illustrative purposes and rotates within the right front wheel cavity 230. The travel range corresponding to the steering rack (i.e., the forward travel range 214) corresponds to the RWA angle range 232 of the left front wheel 202. For a correctly aligned wheel, the wheel angle range 232 is selected such that the wheel does not contact the vehicle or the inner wall 234 of the wheel cavity or any other component of the vehicle during any possible steering maneuver. Wheel misalignment may cause the misaligned wheel to extend beyond this angle range and contact the vehicle. The method disclosed herein prevents wheel contact from occurring.

[0048] The nominal travel range of the front and rear axles, as well as their limits, can be software-defined values ​​and can be reprogrammed to any selected values. Therefore, the angle range of each wheel can be controlled by setting appropriate angle limits (i.e., the travel range of the corresponding axle).

[0049] For the purpose of explanation, Figure 3 Figure 300 shows the angular range of motion of a correctly aligned wheel. It shows a correctly aligned wheel 302 and an misaligned wheel 304. The misaligned wheel is off-center by an misalignment angle α. When the corresponding axle is centered, the correctly aligned wheel 302 is aligned straight forward as shown by center mark 306 (RWA = 0). The nominal angular range indicates the range of motion that the wheel is normally allowed to move and prevents the wheel from contacting the vehicle. The nominal angular range of the wheel is limited by the left nominal RWA limit and the right nominal RWA limit. The right nominal RWA limit 308 (RWA... nomRThis indicates the maximum permissible angle (to the right) for the corresponding axle of wheel 302 used for proper alignment. Left nominal limit 312 (RWA) nomL The indicator shows the maximum permissible steering wheel angle (to the left) for the corresponding axle of wheel 302 used for proper alignment. Right contact limit 310 (RWA) contactR The indicator shows the angle (to the right) at which the correctly aligned wheel 302 makes physical contact with the vehicle. Left contact limit 314 (RWA) Contact1 The angle (to the left) indicates the angle at which the correctly aligned wheel 302 makes physical contact with the vehicle.

[0050] The angle of contact between the misaligned wheel 304 and the vehicle is adjusted by the same misalignment angle α. Due to this adjustment, the adjusted contact limit 320 of the misaligned wheel 304 is shown as the nominal RWA limit 308 on the right (RWA). nomR Therefore, even when turning within the nominal range, contact can occur when turning right. The method disclosed herein performs adjustment to prevent such contact of the misaligned wheel 304.

[0051] In various embodiments, the methods disclosed herein determine the misalignment angle of a wheel on a first axle, which may be a front or rear axle (and a second axle may be the other of the front or rear axle). The first axle has a first nominal travel range, and the second axle has a second nominal travel range. The first nominal travel range may be reduced to a reduced travel range, and the second nominal travel range may be extended to an extended travel range. The vehicle can be steered using a limitation on the reduced travel range on the first axle to prevent the misaligned wheel from contacting the vehicle. If desired, the vehicle can be steered using a limitation on the extended travel range on the second axle. Using an adjusted steering range (i.e., the reduced travel range on the first axle and the extended travel range on the second axle) to define the angular movement range of the respective wheels helps the vehicle achieve a desired turning radius without allowing the misaligned wheel to contact the vehicle.

[0052] Figure 4 This is a flowchart 400 of a method for steering a vehicle when its wheels are misaligned. In block 402, the method is executed using sensors on the vehicle to detect the presence of a misaligned wheel. In block 404, a decision is made based on whether the misaligned wheel is on the front axle. If it is determined that the misaligned wheel is on the front axle, the method proceeds to block 410. Otherwise, the method proceeds to block 406. In block 406, a decision is made based on whether the misaligned wheel is on the rear axle. If the misaligned wheel is on the rear axle, the method proceeds to block 422. Otherwise, the method proceeds to block 408. In block 408, no action is taken relative to the misaligned wheel. Blocks 410-420 describe the actions taken for a misaligned wheel on the front axle. Blocks 422-434 describe the actions taken when the misaligned wheel is on the rear axle.

[0053] First, refer to boxes 410-420. In box 410, the vehicle is traveling in a straight line, and the steering wheel angle (SWA) β, which allows the vehicle to maintain straight-line movement, is measured. If the vehicle has ARS224, the ARS is held in neutral to allow the rear steering rack to be centered. If the vehicle does not have ARS224, the rear wheels are naturally in neutral. The SWA instruction is used to control steering of only the front wheels by holding ARS224 in neutral.

[0054] In box 412, calculate the front wheel misalignment angle (α) caused by the misaligned wheel. front The front wheel misalignment angle is calculated based on the steering wheel angle β used to force the vehicle to drive in a straight line. Front wheel misalignment angle (α) front It can be calculated as shown in equation (1):

[0055]

[0056] Where mc is a multiplicative constant used for the front steering system, which is always equal to 2, and the front steering ratio relates the steering wheel angle to the front road wheel angle. Box 414 is a decision box in which, when the current steering rack is at the end of the forward travel range 214, it is determined whether the front wheel angle is sufficient to make the misaligned wheel contact the vehicle or a vehicle component.

[0057] The maximum front RWA of the misaligned wheel is calculated by adding the misalignment angle α to the nominal angle RWA limit, as shown in equation (2):

[0058] Max_Front_RWA misalign =front RWA nom +α front Equation (2)

[0059] The maximum front RWA of the misaligned wheel can be compared with the front wheel contact limit to determine if action is needed. If no potential contact is determined (i.e., Max_Front_RWA), then... misalign <Front RWA contact If the method proceeds to box 408, it terminates without adjusting the travel range. It then returns to box 414 if it is determined that the misaligned wheel can contact the vehicle (i.e., Max_Front_PWA). misalign Front RWA contact If the method moves to box 416, then the range of movement needs to be adjusted.

[0060] In box 416, the forward travel range 214 is adjusted to reduce the likelihood of contact between misaligned wheels. The reduced forward travel range is calculated based on the nominal front angle range of the front wheels, as shown in equation (3):

[0061]

[0062] C-factor is the ratio of the displacement (in millimeters) of the front steering rack per revolution of the steering wheel.

[0063] A reduced forward travel range indicates that the front steering rack can move further to the left or right under reduced range conditions. Box 418 is a decision box where it is determined whether ARS 224 has the ability to provide additional rack travel or to change the travel limit at the rear axle 218. If ARS 224 does not have the ability to provide additional rear rack travel, the method proceeds to box 408, where the method terminates without further travel range adjustment. Returning to box 418, if ARS 224 has the ability to provide additional rear rack travel, the method proceeds to box 420.

[0064] In box 420, the rear axle's travel range is extended from its nominal rear travel range to produce an extended rear travel range. The extended rear travel range of the rear axle can be calculated as shown in equation (4):

[0065] extended rear axle limit=(Rear RWA nom +α front Equation (4) is an equation representing the travel ratio.

[0066] The travel ratio is the ratio between the rear steering rack travel (in millimeters) and the rear road wheel angle (in degrees).

[0067] Now proceed to boxes 422-434. In box 422 (i.e., rear wheel misalignment detected), determine whether the vehicle is equipped with ARS224. If the vehicle is not equipped with ARS224, the method proceeds to box 408, where the method ends without range adjustment. Otherwise (i.e., the vehicle is equipped with ARS224), the method proceeds to box 424. In box 424, the vehicle travels in a straight line, and the steering wheel angle (SWA) β that allows the vehicle to maintain straight-line movement is measured. The ARS224 system remains in neutral to allow the (correctly aligned) rear wheels to point straight forward. While the ARS224 remains in neutral (i.e., rear steering rack centered), the SWA controls steering of only the front wheels via EPS216.

[0068] In box 426, calculate the rear wheel misalignment angle (α) for the misaligned wheel. rearThe rear wheel misalignment angle is calculated based on the SWA(β) used to make the vehicle travel in a straight line. Once the SWA(β) used for straight travel with misaligned wheels on the rear axle is known, the rear misalignment (α) is calculated as shown in equation (5). rear ):

[0069]

[0070] Equation (5) is similar to Equation (1), where the multiplication constant is now equal to 1. The maximum rear RWA limit of the misaligned wheel is determined by the misalignment angle α. rear The value is given by adding it to the nominal rear axle limit, as shown in equation (2):

[0071] Max_Rear_RWA misalign =rear RWA nom +α rear Equation (6)

[0072] Box 428 is a decision box in which, when the rear steering rack is at the end of the rear travel range 222, it is determined whether the rear wheel misalignment angle is sufficient to cause the misaligned wheel to contact the vehicle or a vehicle component. The maximum rear misalignment angle can be compared with the rear wheel contact limit to determine whether the travel range needs to be adjusted.

[0073] If it is determined that there is no potential contact (i.e., Max_Rear_RWA) misalign <Rear RWA contact If the method proceeds to box 408, it terminates without adjusting the travel range. It then returns to box 428 if it is determined that the misaligned wheel can contact the vehicle (i.e., Max_Rear_RWA). misalign >RWA contact If the method moves to box 430, then the range of movement needs to be adjusted.

[0074] In box 430, the rear travel range is adjusted to reduce the possibility of misaligned wheel contact. The reduced rear steering rack travel limit for the rear axle 218 is determined.

[0075] The rear travel range of the rear axle can be reduced from the nominal rear travel range. The reduced rear travel range corrects the misalignment angle of the misaligned wheel, as shown in equation (3):

[0076] reduced real travel limit=(rear RWA nom -α rear Equation (7) is: )*(travel ratio)

[0077] The reduced rear travel limit indicates the furthest point the rear steering rack can move left or right under reduced range conditions. Box 432 is a decision box where it is determined whether EPS 216 has additional rack travel capability, or the ability to change the travel limit at front axle 210. If no additional front steering rack travel capability is available, the method proceeds to box 408, where the method terminates without further range adjustment. Returning to box 432, if additional rack travel capability is available at front axle 210, the method proceeds to box 434.

[0078] In box 434, extended ARS rack travel is enabled to extend the front axle travel limit. The front axle can then move through a range defined by the extended front axle travel limit, calculated as shown in equation (5):

[0079] Extended front limit=(Front RWA nom +α rear )*((β / 360)*(C_factor)) Equation (8)

[0080] When the movement of the rear axle 218 (and ARS 224) is restricted to a reduced range of travel to accommodate the misaligned rear wheels, it becomes difficult to achieve the vehicle's desired turning radius for sufficiently large steering. Therefore, an extended range of travel can then be applied to the front axle 210 to allow the desired turning radius to be achieved.

[0081] Figures 5-9 It is shown Figure 4 The diagrams in boxes 410-420 illustrate the steering method. Each diagram shows a plan view of the vehicle and the relative orientation of the vehicle's wheels (left front wheel 202, right front wheel 204, left rear wheel 206, and right rear wheel 208) and the steering wheel 226. The steering angle indicator 502 shows the relative angle of the steering wheel 226. Figure 5 Figure 500 shows a vehicle 100 in a straight-driving configuration with three correctly aligned wheels and one misaligned wheel (e.g., the right front wheel 204). The steering wheel angle is at zero (SWA = 0), as indicated by the steering angle indicator 502 pointing straight ahead.

[0082] Figure 6Figure 600 shows vehicle 100 during a test to determine the misalignment angle of the misaligned wheel. The steering wheel is turned (to the right) to move the front axle such that the front road wheel angle (front RWA) of the left front wheel 202 is equal to and opposite to the front road wheel angle formed by the right front wheel 204. In this configuration, the lateral forces caused by each of the left front wheel 202 and the right front wheel 204 are equal to and opposite to each other, thus canceling each other out. As a result, vehicle 100 travels in a straight line. The steering wheel angle SWA (i.e., angle β) of the vehicle traveling in a straight line is then recorded.

[0083] Figure 7 Figure 700 shows vehicle 100, illustrating the consequences of misaligned wheels during steering. Steering wheel 226 has been turned to the left to perform vehicle steering. The front axle is at its forward travel limit, and the rear axle is at its rear travel limit. Due to the misalignment, the right front wheel 204 extends beyond the contact limit and makes contact with the vehicle.

[0084] Figure 8 Figure 800 shows a vehicle using a reduced forward travel range for steering operations. The forward travel range 214 is reduced to a reduced forward travel range 802. In other words, the reduced forward travel range 802 is applied as a limitation during steering operations at the front axle. As shown, the front wheels turn at the limit of the reduced forward travel range 802, and the rear wheels are shown at the limit of the rear travel range 222 (i.e., the nominal rear travel range). The amount of compensation provided by the rear wheels (limited by the rear travel range 222) may or may not be sufficient to help achieve the desired steering radius for large steering.

[0085] Figure 9 Figure 900 shows a vehicle 100 using a reduced front travel range 802 and an extended rear travel range 902 during steering operations. The extended rear travel range 902 is applied during steering operations at the rear axle. The front axle is at the limit of the reduced front travel range 802, and the rear axle is at the limit of the extended rear travel range 902. The additional angular steering provided by the rear axle helps achieve the vehicle's desired turning radius for large turns without causing misaligned wheels to contact the vehicle.

[0086] Figure 10-1 5 shows an illustrative embodiment. Figure 4 The diagrams in boxes 422-434 illustrate the steering method. Each diagram shows a plan view of the vehicle 100 and the relative orientation of the vehicle's wheels (left front wheel 202, right front wheel 204, left rear wheel 206, and right rear wheel 208) and the steering wheel 226. The steering angle indicator 502 shows the relative angle of the steering wheel 226. Figure 10Figure 1000 shows a vehicle 100 in a straight-driving configuration with three correctly aligned wheels and one misaligned wheel (e.g., the right rear wheel 208). The steering wheel angle is at zero (SWA = 0), as indicated by the steering angle indicator 502 pointing straight ahead.

[0087] Figure 11 Figure 1100 shows vehicle 100 during a test to determine the misalignment angle of the misaligned wheels. The steering wheel is turned (to the right) to move the front axle so that the front road wheel angle (front RWA) of the front wheels compensates for the misaligned rear wheels, causing vehicle 100 to travel in a straight line. The steering wheel angle SWA (i.e., angle β) of the vehicle traveling in a straight line is then recorded.

[0088] Figure 12 Figure 1200 shows the vehicle 100, illustrating the result of misaligned rear wheels during steering. The steering wheel 226 has been turned to the right to perform vehicle steering. The rear steering rack 220 is at the limit of its rear travel range, and the front steering rack is at the limit of its front travel range. Due to the misalignment, the right rear wheel 208 extends beyond its nominal contact limit and thus contacts the vehicle.

[0089] Figure 13 Figure 1300 shows a vehicle using a reduced rear travel range 1302 for steering operations. The rear travel range 222 is reduced to the reduced rear travel range 1302. In other words, the reduced rear travel range 1302 is applied as a limitation during steering operations at the rear axle. As shown, the rear wheels rotate at the limit of the reduced rear travel range 1302. The front wheels are shown at the limit of the front travel range 214. The amount of compensation provided by the front wheels may or may not be sufficient to help achieve the desired steering radius for large steering.

[0090] Figure 14 Figure 1400 shows a vehicle 100 using a reduced rear travel range 1302 and an extended front travel range 1402 during steering operations. The extended front travel range 1402 is limited during steering operations at the front axle. The rear axle is at the limit of the reduced rear travel range 1302, and the front axle is at the limit of the extended front travel range 1402. The additional angular steering provided by the front axle helps the vehicle achieve the desired steering radius for large turns without allowing misaligned rear wheels to contact the vehicle.

[0091] The terms “a” and “an” do not indicate a limitation of quantity, but rather that at least one of the referenced items is present. Unless the context clearly indicates otherwise, the term “or” means “and / or”. Throughout the specification, reference to “aspect” means that a particular element described in connection with that aspect (e.g., a feature, structure, step, or characteristic) is included in at least one aspect described herein and may or may not be present in other aspects. Furthermore, it should be understood that the described elements may be combined in any suitable manner in the aspects.

[0092] When an element, such as a layer, film, region, or substrate, is referred to as being “on” another element, it can be directly on the other element, or there may be intermediate elements present. Conversely, when an element is referred to as being “directly” on another element, there are no intermediate elements present.

[0093] Unless otherwise stated herein, all test standards are the most recent standards effective up to the filing date of this application, or, if priority is claimed, the most recent standards effective up to the filing date of the earliest priority application in which the test standards appear.

[0094] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0095] While the foregoing disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made and elements can be substituted with equivalents without departing from its scope. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this disclosure without departing from the basic scope of this disclosure. Therefore, it is intended that this disclosure be limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A method of operating a vehicle, comprising: It was determined that there was an misaligned wheel on the first axle; A non-zero steering wheel angle is applied to the steering wheel of the vehicle to maintain the vehicle moving straight relative to the vehicle's longitudinal axis even with the misaligned wheels. Measure the value of the non-zero steering wheel angle that keeps the vehicle moving straight; The misalignment angle of the misaligned wheel is determined based on the value of the non-zero steering wheel angle; A reduced travel range of the first axle is determined based on a first nominal travel range of the first axle and the misalignment angle, wherein the reduced travel range allows the misaligned wheel to move without contacting the vehicle; and The vehicle is steered by limiting the movement of the first axle using the reduced travel range.

2. The method according to claim 1, further comprising: When the misaligned wheel is not in contact with the vehicle at any position on the first axle within the first nominal travel range, the movement of the first axle is restricted using the first nominal travel range.

3. The method according to claim 1, further comprising: The extended travel range of the vehicle's second axle is determined based on the misalignment angle of the misaligned wheel on the first axle, and the vehicle is steered by limiting the movement of the second axle using the extended travel range, wherein the extended travel range is greater than the second nominal travel range of the second axle.

4. The method according to claim 3, wherein, Using the reduced travel range to limit the movement of the first axle and using the extended travel range to limit the movement of the second axle allows the vehicle to achieve the desired turning radius.

5. The method according to claim 3, wherein: (i) The first axle is the front axle of the vehicle, and the second axle is the rear axle of the vehicle; (ii) the first axle is the rear axle of the vehicle, and the second axle is the front axle.

6. A system for operating a vehicle, comprising: A first steering system for the first axle of the vehicle; Processor, the processor being configured to: It is determined that the first shaft has an misaligned wheel thereon; A non-zero steering wheel angle is applied to the steering wheel of the vehicle to maintain the vehicle moving straight relative to the vehicle's longitudinal axis even with the misaligned wheels. Measure the value of the non-zero steering wheel angle that maintains the straight-line movement of the vehicle; The misalignment angle of the misaligned wheel is determined based on the value of the non-zero steering wheel angle; A reduced travel range of the first axle is determined based on a first nominal travel range of the first axle and the misalignment angle, wherein the reduced travel range allows the misaligned wheel to move without contacting the vehicle; and The first steering system is activated to steer the vehicle by limiting the movement of the first axle using the reduced travel range.

7. The system according to claim 6, wherein, The processor is also configured to activate the first steering system to steer the first axle by using the first nominal travel range to limit the movement of the first axle when the misaligned wheel is not in contact with the vehicle at any position of the first axle within the first nominal travel range.

8. The system according to claim 6, wherein, The processor is also configured to determine an extended travel range of the vehicle's second axle based on the misalignment angle of the misaligned wheel on the first axle, and to activate a second steering system to use the extended travel range to limit the movement of the second axle, wherein the extended travel range is greater than a second nominal travel range of the second axle.

9. The system according to claim 8, wherein, The processor is also configured to use the reduced travel range to limit the movement of the first axle and the extended travel range to limit the movement of the second axle, so as to allow the vehicle to achieve a desired turning radius.

10. The system according to claim 8, wherein: (i) The first axle is the front axle of the vehicle, and the second axle is the rear axle of the vehicle; (ii) the first axle is the rear axle of the vehicle, and the second axle is the front axle.

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