Control system for steering system of vehicle

Abstract

A control system (104) for a steering system (101) of a vehicle (100), the control system comprising one or more controllers, the control system configured to: receive (600) a vehicle speed signal indicative of a current vehicle speed; receiving (602) a steering input signal output corresponding to a desired steering angle of the steered wheel; determining (604) when the current vehicle speed reaches zero from the received vehicle speed signal; and outputting (606) a control signal to control a steering angle of the steered wheel (103, 106) such that the steered wheel is controlled to turn toward a forward straight-going condition, if the current vehicle speed remains zero and the time since the current vehicle speed reaches zero is within the time period T.

Description

Technical Field

[0001] The present invention relates to a control system for a steering system of a vehicle; a steering system; a vehicle; and a method of controlling a steering system of a vehicle. Background Art

[0002] Some vehicle steering systems are electronically controlled so that there is no mechanical link between the steering request and the steering output. Such systems are referred to as "steer-by-wire" systems. An exemplary form of steer-by-wire is in a rear-wheel steering vehicle. Such steering systems are known to provide different benefits to the vehicle at different vehicle speeds. At higher vehicle speeds, the rear wheels may be steered in phase with the front wheels, thereby improving vehicle stability. At lower vehicle speeds, the rear wheels may be steered out of phase with the front wheels, thereby providing improved maneuverability.

[0003] Turning the wheels when stationary (known as dry steering) can produce undesirable results, such as excessive tire wear and / or increased loads in the steering actuator. In addition, dry steering may not be possible if the friction between the wheel and the surface it rides on is too high and / or the vehicle mass is large.

[0004] One approach is to prevent the wheels from turning below a predetermined threshold speed. The disadvantage of this approach is that the vehicle loses the maneuverability advantage provided by the rear wheel steering (RWS) system at low speeds. Summary of the invention

[0005] It is an object of the present invention to address one or more of the disadvantages associated with the prior art.

[0006] Aspects of the present invention relate to a control system for a steering system of a vehicle; a steering system; a vehicle; and a method of controlling a steering system of a vehicle.

[0007] According to one aspect of the present invention, a control system for a steering system of a vehicle is provided, the control system comprising one or more controllers, the control system being configured to: receive a vehicle speed signal indicating a current vehicle speed; receive a steering input signal output corresponding to a desired steering angle of a steering wheel; determine when the current vehicle speed reaches zero based on the received vehicle speed signal; and, when the current vehicle speed remains zero and the time since the current vehicle speed reaches zero is within a time period T, output a control signal to control the steering angle of the steering wheel so that the steering wheel is controlled to turn toward a forward straight ahead condition.

[0008] The present invention provides a control system that is operable to return a steering wheel of a vehicle toward a straight ahead condition when the vehicle speed is within a time period T in which the vehicle speed has reached zero. The control system additionally receives a steering input signal corresponding to a desired steering angle of the driver. During the time period T, the steering wheel may be steered toward the desired steering angle as long as the desired angle causes the steering wheel to be oriented toward the straight ahead condition. In the event that the desired steering angle deviates from the straight ahead condition, the control system may ignore the received steering input signal output.

[0009] One or more controllers may collectively include: at least one electronic processor configured to access at least one electronic memory device and execute instructions thereon to determine when the current vehicle speed reaches zero; and an electrical output configured to output a control signal to a steering actuator of the steering system.

[0010] The control system can be configured to: when the current vehicle speed remains zero, the time since the current vehicle speed reaches zero is within a time period T and the required steering angle is closer to the forward straight-ahead condition than the current steering angle, output a control signal to control the steering angle of the steering wheel so that the steering wheel is controlled to turn toward the required steering angle. Therefore, as long as the time period condition is met and the required angle is closer to the forward straight-ahead condition than the current wheel position, the control system can try and turn toward the required angle. Note that in the case where the required steering angle exceeds the forward straight-ahead condition, the control system can be configured to turn the steering wheel toward the required steering angle, but stop turning the control signal when the wheel reaches the forward straight-ahead condition. In the case where the required steering angle is further away from the forward straight-ahead condition than the current steering angle, the control system can be configured to simply maintain the current wheel position. When the end of the time period T is reached, the control system can be configured to keep the steering wheel at any position it has reached. The forward straight-ahead condition referred to herein is understood to mean the position where the steering wheel faces the forward straight-ahead condition, thus guiding the vehicle to continue the current direction / course in normal use.

[0011] The steering system may be a rear wheel steering system.

[0012] The time period T may be a predetermined time value stored in a memory of one or more controllers. In addition, the time period T comprises a tunable time value. Thus, this allows the vehicle control system to be operable so that the time period during which the steering wheel is returned toward the forward straight condition may vary, for example, in response to a terrain setting, in response to the environment in which the vehicle is located, user preferences, etc. In the case where the vehicle comprises an electric vehicle, then the time period T may be tuned according to the state of charge of the vehicle, for example, for a higher state of charge, the time period may be longer, and for a lower state of charge, the length of the time period T may be gradually reduced.

[0013] Conveniently, in one embodiment, the time period T may include a time period of 0s to 2s starting from when the current vehicle speed reaches zero.

[0014] At the end of the time period T, the control system may be configured to stop outputting the control signal and to maintain the steering angle at its value at time = T. For large steering wheel displacements, when the current vehicle speed reaches zero, this may mean that the steering wheel may not return to the forward straight condition at the end of the time period T. In other words, when the angular displacement of the wheel is large at the end of the time period T, the steering wheel may not return to the aforementioned forward straight condition.

[0015] The control system may be further configured to: receive a driving mode signal indicating a driving mode of the vehicle (commonly referred to as "driver mode"); and not output a control signal based on the driving mode signal. When the vehicle is in certain driving modes, such as a "limp home" mode, the control system may be configured so that no output control signal for controlling the steering angle of the steering wheel is output.

[0016] According to another aspect of the present invention, there is provided a steering system, comprising the control system of the above aspect of the present invention. The steering system may include a steering actuator receiving a control signal output from the control system.

[0017] The invention extends to a vehicle comprising a control system steering system of the above aspect of the invention.The vehicle may be a rear wheel steered or all wheel steered vehicle.

[0018] According to another aspect of the present invention, a method for controlling a steering system of a vehicle is provided, the method comprising: receiving a vehicle speed signal indicating a current vehicle speed; receiving a steering input signal output corresponding to a desired steering angle of a steering wheel; determining when the current vehicle speed reaches zero based on the received vehicle speed signal; and, when the current vehicle speed remains zero and the time since the current vehicle speed reaches zero is within a time period T, controlling the steering angle of the steering wheel so that the steering wheel is controlled to turn toward a forward straight ahead condition.

[0019] The invention extends to a non-transitory computer readable medium comprising computer readable instructions which, when executed by a processor, cause the performance of the method of the above aspects of the invention.

[0020] Within the scope of the present application, it is explicitly contemplated that the various aspects, embodiments, examples and alternatives, in particular the individual features thereof, set forth in the preceding paragraphs, claims and / or the following description and drawings, can be used independently or in any combination. Features described in conjunction with one embodiment are applicable to all embodiments, unless such features are incompatible. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0022] Figure 1 shows a top view of a vehicle embodying the present invention;

[0023] Figure 2 shows a top view of another vehicle embodying the present invention;

[0024] Figure 3 Shown is the implementation Figure 1 and Figure 2 A block diagram of a vehicle steering system;

[0025] Figure 4 shows a plan view of a vehicle traveling at a relatively high speed;

[0026] Figure 5 shows a plan view of a vehicle traveling at a relatively low speed;

[0027] Figure 6 A method according to an embodiment of the present invention is shown;

[0028] Figure 7 Shown in more detail Figure 6 method. DETAILED DESCRIPTION

[0029] exist Figure 1 A vehicle 100 embodying the present invention is shown in a top view of FIG. The vehicle 100 is an automobile configured for use on and off-road on various types of terrain. In the present embodiment, the vehicle 100 is a four-wheel drive vehicle, but it should be understood that many of the features of the vehicle 100 described below are also applicable to front-wheel or rear-wheel drive vehicles.

[0030] Figure 1 Also schematically shown is a steering system 101 configured to effectuate steering of the vehicle 100. The system 101 comprises an actuator 102 configured to cause steering of rear road wheels 103 of the vehicle 100, and a control system 104 comprising control means in the form of a controller 105 for controlling the operation of the actuator 102.

[0031] In this embodiment, the front road wheels 106 of the vehicle 100 are steered by means of a mechanism 107 comprising a steering wheel 108, which is connected to a pinion 109 via a steering column 110. The pinion 109 engages a rack 111 which is connected to a steering knuckle 112 via a tie rod 113.

[0032] The rear wheel 103 can be steered by a mechanism 114 operated by an actuator 102. In this embodiment, the actuator 102 is configured to drive a second pinion 115 associated with a second rack 116, which provides force to a steering knuckle 117 of the rear wheel 103 via a tie rod 118.

[0033] The steering input or position sensor 119 is configured to sense the orientation of the steering wheel 108 and provide a signal to the controller 105 indicating the orientation of the steering wheel 108 and, therefore, also the orientation of the front road wheels 106. The controller 105 is configured to provide an output signal to the actuator 102 based on the signal received from the steering input sensor 119 to cause the steering of the rear wheels 103. However, the output signal provided to the actuator 102 also depends on other signals received by the controller 105, as will be described in detail below. Note that the steering input signal output from the position sensor corresponds to the driver-requested steering angle of the steering wheels (103, 106) of the vehicle 100.

[0034] exist Figure 2 An alternative vehicle 100 embodying the present invention is shown in , wherein a system 101 implements “steer-by-wire” for all wheels 103 , 106 of the vehicle 100 . Figure 2 The vehicle 100 has Figure 1 Many features common to the vehicles of the present invention have been provided with the same reference numerals. Figure 1 of vehicles 100, Figure 2 The vehicle 100 includes a steering system 101, which includes a pinion 109 and a rack 112 configured to operate a steering knuckle 112 via a tie rod 113 to steer the front wheels 106. The first actuator 102 is configured to drive a second pinion 115 associated with a second rack 116, which provides a force to a steering knuckle 117 of the rear wheel 103 via a tie rod 118.

[0035] However, in Figure 2 In the embodiment of the present invention, the pinion 109 for driving the front wheels 106 is driven by the second actuator 202. The steering wheel 108 is mounted on the rotatable shaft 201, but it is not mechanically connected to the pinion 109. Instead, in addition to providing a signal to the actuator 102 to cause the steering of the rear wheels 103, the controller 105 is also configured to provide a signal to the second actuator 202 to cause the steering of the front wheels 106 based on the signal it receives from the steering input sensor 119 located on the shaft 201 of the steering wheel 108.

[0036] In an alternative embodiment, the vehicle 100 has Figure 2 The front wheels have steer-by-wire like those of the SUV, but the rear wheels 103 are not steerable.

[0037] Figure 1 Steering Systems 101 and Figure 2 The steering system is composed of Figure 3 The block diagram shown is used to illustrate. Figure 3 Also shown are some exemplary vehicle systems that may communicate with the steering system 101. The control system 104 includes a controller 105 that itself includes an electronic processor 301 and an electronic memory device 302 that stores instructions 303 executable by the processor 301 to cause the processor 301 to perform the method described below and output a signal to the first steering actuator 102 to cause the steering of the rear wheels 103. Figure 2 In the case of the vehicle 100, the processor 301 also provides a signal to the second steering actuator 202 for steering the front wheels 106. Figure 3 Only one controller, processor and memory device are shown, but it should be understood that the control system 104 may include several controllers 105, and each controller 105 may include several processors 301 and / or several electronic memory devices 302, so that the processing described below can be distributed over several processors.

[0038] In addition to receiving signals from the steering input sensor 119, the control system 104 also receives signals indicative of the speed of rotation of each road wheel 103, 106 from the wheel speed sensing arrangement 304. The wheel speed sensing arrangement 304 may comprise wheel speed sensors, each of which is arranged to measure the speed of rotation of a respective one of the wheels 103, 106 and to provide a value of the speed of rotation directly to the controller 105. Alternatively, the wheel speed sensors may form part of another system, such as an anti-lock braking system (not shown) comprising a control unit configured to receive signals from the wheel speed sensors and to provide wheel speed values ​​to the controller 105.

[0039] Figure 4 and Figure 5 1 and 2 show plan views of a vehicle 100 traveling at a relatively high speed and a relatively low speed, respectively. Figure 4 and Figure 5 In both cases, the front wheel 106 is turned about 15 degrees relative to the longitudinal axis 1001 of the vehicle 100 to turn the vehicle 100 to the left. Figure 4 , the current speed of the vehicle 100 as determined from the wheel speed sensing device 304 is above the threshold speed, and therefore the rear wheels 103 have been turned in phase with the front wheels 106. That is, because the front wheels 106 have been turned to the left, the rear wheels 103 are also turned to the left. As is well known, turning the rear wheels 103 in phase with the front wheels 106 provides increased stability for the vehicle 100, which is advantageous at high speeds.

[0040] exist Figure 4In the example, the rear wheel 103 is only turned to the left by about 1.5 degrees, which is one tenth of the angle turned by the front wheel 106. The proportion of the front wheel steering angle that the rear wheel 103 has been turned is referred to herein as the gain value. Therefore, in this example, the rear wheel steering has a gain value of +0.1 (=1.5 / 15).

[0041] exist Figure 5 , the current speed of the vehicle 100 is below the threshold speed, and therefore the rear wheels 103 have been turned out of phase with the front wheels 106. That is, because the front wheels 106 have been turned left, the rear wheels 103 have been turned right. The stability of the vehicle 100 is not an issue at low speeds, and it is well known that turning the rear wheels 103 out of phase with the front wheels 106 provides the vehicle 100 with increased agility.

[0042] The rear wheel 103 has been turned to the right by about 3 degrees, i.e. one fifth of the angle turned by the front wheel 106. Therefore, in this example, the rear wheel steering has a gain value of -0.2 (= -3 / 15), i.e., the absolute value of the gain value (0.2) is higher than the gain value for speeds above the threshold speed, but because the rear wheel 103 is turned out of phase with the front wheel 106, the gain value is negative.

[0043] Depending on the user's driving style or the type of terrain on which the vehicle 100 is traveling, a particular set of vehicle characteristics ("driving modes") may be most appropriate, for example, one particular accelerator pedal mapping may be more appropriate than others, and similarly, a particular transmission mapping and a particular set of stability control settings may be most appropriate. In order to enable the user to select the settings that are most appropriate for the selected driving style or particular terrain, the vehicle 100 also includes a user input device (UID) 311, which is configured to enable the user to indicate the selected driving mode to the vehicle control system 310. For example, when driving on asphalt roads, the user can select the standard mode (or normal mode), and the vehicle control system 310 controls the ECU 307, TCU 308 and SCU 309 to operate in a mode suitable for asphalt roads. Alternatively, the user can select another mode, such as a grass, gravel and snow mode for driving on terrain that provides a low friction coefficient, or a sand mode for driving on a deformable surface that provides a very low friction coefficient, such as sand, or a rock crawling mode for driving on a rough surface with high friction. In response to such user indication, the vehicle control system 310 controls the ECU 307, TCU 308 and SCU 309 to operate in a mode suitable for the indicated terrain type. The mode selected by using the user input device 311 is also provided to the controller 105 and can be used to determine the signal provided to the first steering actuator 102 and / or the second steering actuator 202.

[0044] The user input device 311 may comprise one or more switches, a touch screen device or other electrical or electronic device suitable for enabling a user to provide an indication of the mode they wish to select.

[0045] The vehicle control system 310 may include a terrain estimation system (TES) 306. Such systems are known and described in the applicant's UK patent GB2492655B and the US patent application published as US2014350789A1. The terrain estimation system 310 is configured to select a driving mode that is the most appropriate mode for the subsystems 307, 308, 309 based on measurements indicating the terrain on which the vehicle 100 is traveling, so that the vehicle control system 310 can automatically control the subsystems 307, 308, 309 to operate in the selected mode.

[0046] The TES 306 receives signals from a terrain sensing device 312 that includes a variety of different sensors and devices for providing information indicating the type of terrain on which the vehicle 100 is traveling. The terrain sensing device 312 may include the aforementioned IMU 305, the wheel speed sensing device 304, the steering input sensor 119, and other sensors (not shown), such as an ambient temperature sensor, an atmospheric pressure sensor, an engine torque sensor, a brake pedal position sensor, an accelerator pedal position sensor, a ride height sensor, etc. The various outputs from the terrain sensing device 312 are used by the terrain estimation system 310 to derive a number of terrain indicators. For example, vehicle speed is derived from the wheel speed sensors, wheel acceleration is derived from the wheel speed sensors, longitudinal forces on the wheels are derived from the IMU 305, and torques when wheel slip occurs (if wheel slip occurs) are derived from the motion sensors of the IMU 305 to detect yaw, pitch, and roll. The terrain indicators are then processed to determine the probability that each of the different driving modes is appropriate, and thereby determine which mode is most appropriate for the operation of the subsystem. In its automatic mode, the terrain estimation system 310 continuously determines for each mode the probability that the mode is appropriate, and based on another mode having a higher probability of consistency than the currently selected control mode, the vehicle control system 310 commands the subsystems to operate according to that other mode.

[0047] The mode determined automatically by the terrain estimation system 306 or selected using the user input device 311 is also provided to the controller 105 and may be used to determine the signals provided to the first steering actuator 102 and / or the second steering actuator 202 .

[0048] As mentioned above about Figure 3 and Figure 4 As described, first steering actuator 102 is operable to provide torque sufficient to turn wheels 103 of vehicle 100 at both lower speeds and higher speeds.

[0049] As the vehicle 100 slows down, the wheels 103 may be returned to the straight ahead condition based on a determined time value for when the vehicle speed will reach zero. A control system 104 operating in this manner is described in the applicant's UK patent GB1809351.8.

[0050] In some driving conditions, such as rapid deceleration when the vehicle approaches an intersection, the wheels 103, 106 may not fully return to the forward straight condition when the vehicle speed reaches zero. In other driving conditions, when the vehicle speed reaches zero, the wheels may or may not have returned to the forward straight condition, and the driver may turn the steering wheel 108 so that the steering input signal output from the steering input sensor 119 is received by the control system 104.

[0051] According to an embodiment of the present invention, Figure 6 and Figure 7 As described, the control system is operable to output control signals to control the steering angle of the steerable wheels according to the logic flow and conditions set forth below.

[0052] Steering Figure 6 , shows a method of controlling a steering system 101 of a vehicle 100 according to an embodiment of the present invention.

[0053] In step 600, a vehicle speed signal is received from the wheel speed sensing device 304 by the controller 105 within the control system 104. The vehicle speed signal indicates the current speed of the vehicle 100.

[0054] In step 602, the controller 105 receives a steering input signal output from a steering input sensor 119 that senses the orientation of the steering wheel 108. The signal received from the sensor 119 indicates the orientation of the steering wheel 108, and therefore also indicates the orientation of the front road wheels 106. The position of the actuator 102 associated with the rear wheel 103 indicates the angle of the rear wheel 103, where an actuator position of 0 mm corresponds to a straight ahead condition.

[0055] Note that the signals received by the controller 105 in the above steps 600 and 602 are received consecutively, and the numbering of the individual steps does not indicate any order of the steps.

[0056] In step 604, the controller 105 determines when the current vehicle speed reaches zero, and then in step 606, when the current vehicle speed remains zero and the time since the current speed reaches zero is within the time period T, the control system 104 outputs a control signal to the actuator (102, 202) to control the steering angle of the steering wheel (103, 106) so that the steering wheel is controlled to rotate toward the forward straight driving condition.

[0057] The processing sequence within the controller 105 corresponding to the above steps 604 and 606 is shown in more detail in Figure 7 and is shown in more detail in

[0058] In step 700, the controller 105 performs a vehicle speed check based on the vehicle speed signal received from the wheel speed sensing device 304.

[0059] In step 702, the controller 105 determines, based on the vehicle speed check in step 700, that the current vehicle speed has reached zero.

[0060] In step 704, the controller 105 monitors how long the current vehicle speed has been zero, and in step 706, the controller compares the desired steering angle of the steering wheels (103, 106) with the actual position of the steering wheels (e.g., as determined according to the actuator positions 102, 202 or according to the steering input sensor 119).

[0061] Then, the controller 105 checks at the decision point 708 whether the condition - current speed = zero and the time (t) that the speed is zero < time period T - is true.

[0062] If the condition t < T is not satisfied, then at step 710, the controller 105 controls the steering wheels to maintain their current positions (i.e., the control signal output by the control system 104 holds the steering wheels in their current positions).

[0063] If the condition t < T is satisfied, the controller 105 proceeds to another decision point 712, where the controller checks whether the desired steering angle of the steering wheels (103, 106) is closer to the straight - ahead position than the current steering angle position.

[0064] If the desired steering angle is further from the straight - ahead position than the current steering angle, then at step 714, the controller 105 controls the steering wheels to maintain their current positions (i.e., the control signal output by the control system 104 holds the steering wheels in their current positions).

[0065] If the desired steering angle is closer to the straight - ahead position than the current steering angle, then at step 716, the controller 105 controls to turn towards the straight - ahead condition (i.e., the control signal output by the control system 104 controls the steering wheels to turn towards the straight - ahead condition). This straight - ahead condition may correspond to an actuator position of 0 mm.

[0066] Note that the control signal output by the control system 104 and / or the controller 105 controls the actuators (102, 202) to turn the steering wheels.

[0067] The control system 104 will continue to monitor both the current vehicle speed and the time since the vehicle speed reached zero. In the event that either condition is no longer satisfied, the control system 104 and / or controller 105 will cease outputting control signals to the actuator (102, 202) configured to turn the steering wheel, and will output control signals to keep the steering wheel in position (e.g., if the time t exceeds the time period T), or may control the steering wheel in accordance with the selected driving mode (e.g., if the vehicle speed is no longer zero). The time period T may be stored in the memory 302 of the controller 105, and may be a tunable value that may be changed by the vehicle manufacturer, vehicle service entity, or even the driver.

[0068] In the case where the vehicle is an electric vehicle, then controlling the steering wheel to turn when the vehicle is stationary may depend on the vehicle's state of charge. For example, if the vehicle is fully charged or has a state of charge above a certain threshold, the time period T may be set to a relatively longer period than if the vehicle is in a low state of charge. The control system 104 may be configured to change the time period T upon receiving the vehicle's state of charge. In a preferred embodiment, the time period T may include a period from t=0s to t=2s starting when the vehicle speed reaches zero.

[0069] As described above, the driving mode automatically determined by the terrain estimation system 306 or selected using the user input device 311 may also be provided to the controller 105 and may be used to determine the signal provided to the first steering actuator 102 and / or the second steering actuator 202. In particular, in certain driving modes (e.g., some off-road driving modes), even if the above conditions regarding the driving mode are met, the controller 105 may be used to determine the signal provided to the first steering actuator 102 and / or the second steering actuator 202. Figure 7 Under the logical conditions described above, the control system 104 may not output a control signal.

[0070] Table 1 shows Figure 3 Table 2 presents a numerical summary of Figure 6 Table 3 presents a numerical summary of Figure 7 A numerical summary of the

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[0076] The electronic processor 301 or each electronic processor 301 may include any suitable electronic processor (e.g., a microprocessor, a microcontroller, an ASIC, etc.) configured to execute electronic instructions. The electronic memory device 302 or each electronic memory device 302 may include any suitable memory device and may store various data, information, thresholds, lookup tables or other data structures and / or instructions therein or thereon. In an embodiment, the memory device 302 has information and instructions for software, firmware, programs, algorithms, scripts, applications, etc. stored therein or thereon, which may control all or part of the methods described herein. The processor or each electronic processor 301 may access the memory device 302 and execute and / or use these or those instructions and information to perform or execute some or all of the functions and methods described herein.

[0077] At least one memory device 302 may include a computer-readable storage medium (e.g., a non-transitory or non-volatile storage medium) that may include any mechanism for storing information in a form readable by a machine or electronic processor / computing device, including, but not limited to: magnetic storage media (e.g., floppy disks); optical storage media (e.g., CD-ROMs); magneto-optical storage media; read-only memory (ROM); random access memory (RAM); erasable programmable memory (e.g., EPROM and EEPROM); flash memory; or an electronic or other type of medium for storing such information / instructions.

[0078] An example controller 105 has been described that includes at least one electronic processor 301 configured to execute electronic instructions stored in at least one memory device 302, which when executed cause the electronic processor 301 to perform the method as described above. However, it is contemplated that the present invention is not limited to implementation by way of a programmable processing device, and at least some and in some embodiments all of the functionality and / or method steps of the present invention may equally be implemented by way of non-programmable hardware, such as by way of a non-programmable ASIC, Boolean logic circuitry, etc.

[0079] It should be understood that various changes and modifications can be made to the present invention without departing from the scope of the application.

Claims

1. A control system for a steering system of a vehicle, the control system comprising one or more controllers, the control system being configured to: receiving a vehicle speed signal indicative of a current vehicle speed; receiving a steering input signal output corresponding to a desired steering angle of a steering wheel; determining when the current vehicle speed reaches zero based on the received vehicle speed signal; as well as When the current vehicle speed remains zero and the time since the current vehicle speed reaches zero is within a time period T, a control signal is output to control the steering angle of the steering wheel so that the steering wheel is controlled to turn toward a forward straight driving condition.

2. The control system according to claim 1, wherein: The one or more controllers collectively include: at least one electronic processor configured to access at least one electronic memory device and execute instructions on the at least one electronic memory device to determine when the current vehicle speed reaches zero; and An electrical output is configured to output the control signal to a steering actuator of the steering system.

3. A control system according to any preceding claim, wherein: The control system is configured to output a control signal to control the steering angle of the steering wheel when the current vehicle speed remains zero, the time since the current vehicle speed reaches zero is within a time period T, and the desired steering angle is closer to the forward straight condition than the current steering angle, so that the steering wheel is controlled to rotate toward the desired steering angle.

4. A control system according to any preceding claim, wherein: The steering system is a rear wheel steering system.

5. A control system according to any preceding claim, wherein: The time period T is a predetermined time value stored in a memory of the one or more controllers.

6. A control system according to any preceding claim, wherein: The time period T comprises a tunable time value.

7. The control system according to claim 6, wherein: The vehicle comprises an electric vehicle, and the time period T is tuned according to a state of charge of the vehicle.

8. The control system according to any one of claims 1 to 5, wherein: The time period T includes a time period of 0 s to 2 s starting from when the current vehicle speed reaches zero.

9. A control system according to any preceding claim, wherein: After the time period T, the control system is configured to stop outputting the control signal and maintain the steering angle at its value at time=T.

10. A control system according to any preceding claim, wherein: The control system is configured to: receiving a driving mode signal indicating a driving mode of the vehicle; and The control signal is not outputted according to the driving mode signal.

11. A steering system comprising a control system according to any preceding claim and a steering actuator.

12. A vehicle comprising a control system according to any one of claims 1 to 10 or a steering system according to claim 11.

13. The vehicle according to claim 12, wherein: The vehicle is a rear-wheel steer or all-wheel steer vehicle.

14. A method for controlling a steering system of a vehicle, the method comprising: receiving a vehicle speed signal indicative of a current vehicle speed; receiving a steering input signal output corresponding to a desired steering angle of a steering wheel; determining when the current vehicle speed reaches zero based on the received vehicle speed signal; as well as While the current vehicle speed remains zero and the time since the current vehicle speed reaches zero is within a time period T, the steering angle of the steering wheel is controlled so that the steering wheel is controlled to turn toward a forward straight driving condition.

15. A non-transitory computer readable medium comprising computer readable instructions which, when executed by a processor, cause execution of the method of claim 14.

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