Steering control methods and vehicle steering systems

Abstract

This disclosure provides a steering control method and a vehicle steering system, relating to the field of vehicle steering. The steering control method includes: acquiring the vehicle's forward speed u. i According to the forward speed u i Determine the current driving condition of the vehicle, which includes low-speed, medium-speed, and high-speed conditions; if the vehicle is in a low-speed condition, set the transmission ratio i of the vehicle's steering system. a Equal to the first target value; if the vehicle is in a medium-speed operating condition, the transmission ratio i of the vehicle steering system a Determined by formula (1); if the vehicle is in high-speed operation, the transmission ratio i of the vehicle steering system is... a The formula (1) is used to determine the steering performance. This disclosure achieves the requirements of flexible steering at low speeds and stable steering at medium and high speeds. At high speeds, it reduces the yaw rate gain and lateral acceleration gain, ensuring good emergency avoidance capabilities of the vehicle at high speeds while maintaining steering stability.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of vehicle steering, and in particular to a steering control method and a vehicle steering system. BACKGROUND

[0002] Traditional automobile steering systems usually adopt fixed transmission ratio for torque and angle transmission. Under the fixed transmission ratio, although a small transmission ratio scheme can improve the steering sensitivity of the automobile at low speed, it will also reduce the stability at high speed; a large transmission ratio scheme is on the contrary, which can improve the stability at high speed, but reduces the steering sensitivity at low speed. The traditional steering system has poor control ability for the steering angle of the automobile at low speed and high speed, and the driving experience and safety are difficult to guarantee.

[0003] To this end, the related technology has an active steering system with variable transmission ratio characteristics: at low speed, the transmission ratio is small, and a small steering angle of the driver can complete a large change in the direction of the vehicle body, such as turning around, thereby improving the steering sensitivity of the automobile; at high speed, the transmission ratio is large, and a small steering wheel angle input will not cause a large change in the driving direction of the automobile, thereby enabling the automobile to have good emergency avoidance capability, while maintaining the steering stability and driving safety performance of the automobile.

[0004] However, the variable transmission ratio design is mostly fixed yaw rate gain or fixed lateral acceleration gain, without considering the problem that the driver's perception sensitivity is different at high speed and low speed, which affects the steering performance of the automobile. SUMMARY

[0005] The present disclosure provides a steering control method and a vehicle steering system, which can solve the problem that the variable transmission ratio design does not consider the different perception sensitivities of the driver at high speed and low speed, which affects the steering performance of the automobile.

[0006] The technical solution is as follows:

[0007] In one aspect, a steering control method is provided, which includes:

[0008] obtaining a forward speed u i of a vehicle;

[0009] determining a driving condition in which the vehicle currently locates according to the forward speed u i , the driving condition including a low-speed condition, a medium-speed condition and a high-speed condition;

[0010] if the vehicle is in the low-speed condition, setting a transmission ratio i a of a vehicle steering system equal to a first target value;

[0011] if the vehicle is in the medium-speed condition, the transmission ratio ia is determined by formula (1) :

[0012]

[0013] If the vehicle is in the high-speed working condition, the transmission ratio i of the vehicle steering system a is determined by formula (2) :

[0014]

[0015] In formula (1) and (2), K is a stability factor, L is the wheelbase of the vehicle, G ω is the yaw rate gain, and G a is the lateral acceleration gain.

[0016] In some embodiments, the driving working condition in which the vehicle currently is determined according to the forward speed u i includes a low-speed working condition, a medium-speed working condition and a high-speed working condition, and includes:

[0017] If u i < u1, it is determined that the vehicle currently is in the low-speed working condition;

[0018] If u1≤ u i ≤ u2, it is determined that the vehicle currently is in the medium-speed working condition;

[0019] If u i > u2, it is determined that the vehicle currently is in the high-speed working condition.

[0020] In some embodiments, u1 = 18 km / h and u2 = 85 km / h.

[0021] In some embodiments, the yaw rate gain G ω in formula (1) is determined by formula (3) :

[0022]

[0023] In formula (3), G ω2 is the yaw rate gain when u i = u2, and G ω1 is the yaw rate gain when u i = u1.

[0024] In some embodiments, G ω2 = 0.16 s -1 , and G ω1 = 0.33 s -1 .

[0025] In some embodiments, the lateral acceleration gain Ga is determined by formula (4):

[0026]

[0027] In formula (4), G a2 is the lateral acceleration gain when u i = u2, G a1 is the lateral acceleration gain when u i = u1.

[0028] In some embodiments, G a2 = 6.67, G a1 = 8.54.

[0029] In some embodiments, the steering control method further comprises:

[0030] If the vehicle is in the high-speed working condition, the transmission ratio i a of the vehicle steering system is determined by formula (5):

[0031]

[0032] In formula (5), G ω2 is the yaw rate gain when u i = u2, G a2 is the lateral acceleration gain when u i = u2.

[0033] In some embodiments, the first target value is equal to 8.

[0034] In another aspect, a vehicle steering system is provided, which adopts the steering control method described in the present disclosure.

[0035] The vehicle steering system comprises:

[0036] An information acquisition module, which is configured to acquire the forward speed u i of the vehicle.

[0037] A working condition judgment module, which is configured to determine the current driving working condition of the vehicle according to the forward speed u i input by the information acquisition module.

[0038] A calculation module, which is configured to calculate the transmission ratio i i of the vehicle steering system according to the forward speed u a input by the information acquisition module and the driving working condition determined by the working condition judgment module.

[0039] The technical scheme provided by the present disclosure has at least the following beneficial effects:

[0040] The steering control method of the present disclosure introduces the requirements of the driver on the yaw rate gain and the lateral acceleration gain at different vehicle speeds into the design of the steering transmission ratio, so that the driver can feel faster vehicle response at low speed, and the vehicle is more stable at high speed, reducing the driver's steering burden.

[0041] The yaw rate gain and the lateral acceleration gain adopt linear variation, so that the driver can more smoothly adapt to the change in vehicle handling performance caused by the variable transmission ratio, and improve the driver's steering experience.

[0042] The present disclosure realizes the requirements of flexible steering at low speed, stable steering at medium and high speed, reduces the yaw rate gain and the lateral acceleration gain at high speed, balances the steering stability, ensures good emergency avoidance ability of the vehicle at high speed, prevents the transmission ratio from being too large, and makes the vehicle take too long to change direction during driving. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical scheme in the embodiments of the present disclosure, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor.

[0044] Figure 1 is a flowchart of the steering control method provided by the embodiment of the present disclosure;

[0045] Figure 2 is a structural schematic diagram of the vehicle steering system provided by the embodiment of the present disclosure;

[0046] Figure 3 is a flowchart of the steering control method provided by another embodiment of the present disclosure;

[0047] Figure 4 is a flowchart of the steering control method provided by another embodiment of the present disclosure;

[0048] Figure 5 is a variation curve diagram of the steering transmission ratio provided by the embodiment of the present disclosure;

[0049] Figure 6 is a structural schematic diagram of the vehicle steering system provided by the embodiment of the present disclosure;

[0050] Figure 7 is a structural schematic diagram of the vehicle steering control device provided by the embodiment of the present disclosure.

[0051] The reference signs in the drawings are as follows:

[0052] 1. Steering wheel; 2. Steering shaft; 3. Road sensor motor; 4. Steering angle sensor; 5. Steering gear; 6. Electronic control module; 7. Steering torque sensor; 8. Vehicle speed sensor; 9. Front wheels;

[0053] 100. Information Acquisition Module; 200. Operating Condition Judgment Module; 300. Calculation Module;

[0054] 400, Processor; 500, Memory; 600, Communication Interface; 700, Bus. Detailed Implementation

[0055] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0056] Unless otherwise defined, all technical terms used in the embodiments of this disclosure have the same meaning as commonly understood by one of ordinary skill in the art.

[0057] Traditional steering systems typically assist the driver in steering the car through hydraulic or electric power steering. The steering wheel reaction force provides feedback to the driver on the movement and force of the wheels and tires, allowing the driver to promptly, conveniently, and accurately grasp the car's driving status and control it more effectively.

[0058] In traditional steering systems, the steering ratio is fixed, meaning the ratio of the driver's steering wheel input angle to the front wheel steering angle remains constant. However, an ideal steering ratio should change according to vehicle speed.

[0059] Over the years, vehicle steering systems have evolved into mechanical steering, hydraulic steering, electronic servo steering, electric power steering, steer-by-wire, and active steering. Among them, active steering systems, with their variable transmission ratio characteristics, can give the steering system different steering characteristics under different working conditions, making them more suitable for actual needs and improving steering quality.

[0060] The gear ratio should be set so that after the driver inputs a steering wheel angle, the gain of the vehicle's steady-state yaw rate on the steering wheel angle should not change with the vehicle speed and steering wheel angle. In this way, there is a one-to-one correspondence between the steering wheel angle and the front wheel angle of the car at different vehicle speeds and lateral accelerations, which can greatly reduce the burden of driver compensation operations.

[0061] Therefore, this disclosure provides a steering control method that incorporates the driver's requirements for yaw rate gain and lateral acceleration gain at different vehicle speeds into the steering gear ratio design, thereby achieving the vehicle's requirements for agile steering at low speeds and stable steering at medium and high speeds.

[0062] The steering control method disclosed herein is applicable to vehicles that rely on variable gear ratio steering systems, such as electric vehicles, fuel vehicles, and new energy vehicles. These variable gear ratio steering systems include, but are not limited to, mechanical variable gear steering systems and electronic variable gear steering systems.

[0063] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0064] Figure 1 This is a schematic flowchart of the steering control method provided in the embodiments of this disclosure.

[0065] On the one hand, combined with Figure 1 As shown, this embodiment provides a steering control method, which includes:

[0066] Step S1, obtain the vehicle's forward speed u i ;

[0067] Step S2, based on the forward speed u i Determine the current driving conditions of the vehicle, which include low-speed, medium-speed, and high-speed conditions;

[0068] Step S3: If the vehicle is operating at low speed, set the transmission ratio i of the vehicle steering system. a Equal to the first target value;

[0069] Step S4, if the vehicle is in a medium-speed operating condition, the transmission ratio i of the vehicle steering system a Determined by formula (1):

[0070]

[0071] Step S5, if the vehicle is in high-speed operation, the transmission ratio i of the vehicle steering system a Determined by formula (2):

[0072]

[0073] In formulas (1) and (2), K is the stability factor, L is the wheelbase of the vehicle, and G... ω For the yaw rate gain, G a This is the lateral acceleration gain.

[0074] The stability factor K is related to the vehicle's structure, such as the position of the vehicle's center of gravity and the wheelbase. The lower the vehicle's center of gravity, the greater the stability factor K.

[0075] The wheelbase L of a vehicle is the distance between two perpendicular lines drawn through the midpoints of two adjacent wheels on the same side of the vehicle and perpendicular to the vehicle's longitudinal plane of symmetry. Simply put, it's the distance from the center of the front axle to the center of the rear axle. Wheelbase affects curb weight, overall vehicle length, minimum turning radius, driveshaft length, and longitudinal clearance radius. A wheelbase that is too short can worsen braking or handling stability, increase longitudinal angular vibration of the vehicle body, and negatively impact ride comfort.

[0076] The steering control method in this embodiment incorporates the driver's requirements for yaw rate gain and lateral acceleration gain at different vehicle speeds into the steering gear ratio design. At low speeds, the driver can feel a faster vehicle response, and at high speeds, the vehicle is more stable, reducing the driver's operating burden.

[0077] Yaw rate refers to the deflection of a car around its vertical axis, and the magnitude of this deflection represents the car's stability. If the yaw rate reaches a certain threshold, it indicates that the car is experiencing dangerous conditions such as skidding or fishtailing. It primarily reflects the overall tilt state of the vehicle body, and can be used in conjunction with signals from the steering angle sensor and the four wheel speed sensors to independently control the braking of each wheel, thereby ensuring the vehicle's handling stability.

[0078] Lateral acceleration is caused by the centrifugal force generated when a vehicle turns. The frictional force provided by the front wheels to resist this centrifugal force has both force and direction, thus producing lateral acceleration.

[0079] Yaw rate and lateral acceleration are both important steering characteristics of a car. The ideal gear ratio of the steering system can be obtained by ensuring that both yaw rate and lateral acceleration gains are consistent. However, determining the gear ratio solely through yaw rate and lateral acceleration gains only guarantees that one of these gains remains constant. In this embodiment, the yaw rate and lateral acceleration gains are linearly varied, allowing the driver to more smoothly adapt to changes in vehicle handling performance caused by variable gear ratios, thus improving the driver's handling experience.

[0080] This embodiment achieves the requirements of flexible steering at low speeds and stable steering at medium and high speeds. At high speeds, it reduces the yaw rate gain and lateral acceleration gain, taking into account steering stability while ensuring that the vehicle has good emergency avoidance capabilities at high speeds, and preventing excessively large transmission ratios that would cause excessively long turning times during vehicle operation.

[0081] Among some possible implementations, refer to Figure 2As shown, the vehicle steering system includes a steering wheel 1, a steering shaft 2, a road sensor motor 3, a steering angle sensor 4, a steering gear 5, an electronic control module 6, a steering torque sensor 7, and a vehicle speed sensor 8.

[0082] The steering wheel 1 is connected to the road sensor motor 3, the angle sensor 4, the steering torque sensor 7, and the steering gear 5 via the steering shaft 2. The front wheel 9 is connected to the steering gear 5. The electronic control module 6 is electrically connected to the angle sensor 4, the vehicle speed sensor 8, the steering torque sensor 7, and the steering gear 5.

[0083] The vehicle speed sensor 8 can obtain the vehicle's forward speed u. i and the forward speed u i The input is sent to the electronic control module 6, which uses the steering control method of this disclosure to determine the required steering ratio under the current working condition and controls the steering gear 5 to adjust the steering ratio between the steering wheel 1 and the front wheel 9.

[0084] During this process, the road sensor motor 3, the angle sensor 4, and the steering torque sensor 7 are connected to the electronic control module 6 for communication. The electronic control module 6 controls the road sensor motor 3 based on the feedback data from the angle sensor 4 and the steering torque sensor 7.

[0085] In some possible implementations, the vehicle's forward speed u i The speed is measured by a vehicle speed sensor 8, which may be installed, for example, inside the drive axle housing or transmission housing, or on other rotating parts. Alternatively, it may be an optical sensor mounted externally to the vehicle, relying on an external reference to measure the vehicle's forward speed.

[0086] Figure 3 This is a schematic flowchart of a steering control method provided in another embodiment of this disclosure.

[0087] Combination Figure 3 As shown, in some embodiments, based on the forward speed u i Determine the vehicle's current driving condition, which includes low-speed, medium-speed, and high-speed conditions.

[0088] Step S21, if u i If <u1, then the vehicle is currently operating at low speed.

[0089] Step S22, if u1≤u i If u2 ≤, then the vehicle is currently operating at medium speed.

[0090] Step S23, if u i If the value is greater than u2, then the vehicle is currently operating at high speed.

[0091] Based on the vehicle's forward speed ui It can achieve precise control over the vehicle's operating conditions, thereby enabling differentiated steering ratio control for different operating conditions and improving the driver's driving experience at different speeds.

[0092] In some embodiments, u1 = 18 km / h and u2 = 85 km / h. When the values ​​of u1 and u2 meet the above requirements, the vehicle operating conditions determined accordingly are more in line with the driver's perception range. That is, when the vehicle speed is below 18 km / h or above 85 km / h, the driver's perception has a more obvious difference from other speed ranges.

[0093] In some embodiments, the yaw rate gain G in formula (1) ω Determined by formula (3):

[0094]

[0095] In formula (3), G ω2 For u i = yaw rate gain at u2, G ω1 For u i =u1 yaw rate gain.

[0096] The yaw rate gain G under the current driving conditions is determined by formula (3). ω It can achieve linear changes in yaw rate gain, allowing the driver to adapt more smoothly to changes in vehicle handling performance caused by the variable transmission ratio, thus improving the driver's handling experience.

[0097] In some embodiments, where G ω2 =0.16s -1 G ω1 =0.33s -1 G ω2 G is the yaw rate gain corresponding to the upper limit of the medium-speed operating condition. ω1 This is the gain of the yaw rate corresponding to the lower limit of the medium speed condition. When the two gain values ​​meet the above requirements, they can better reflect the yaw rate of the vehicle under the current driving conditions, fully consider the influence of the yaw rate on the steering ratio, and ensure the calculation accuracy of the steering ratio.

[0098] In some embodiments, the lateral acceleration gain G in formula (1) a Determined by formula (4):

[0099]

[0100] In formula (4), G a2 For u iLateral acceleration gain G at u2 = u2 a1 For u i Lateral acceleration gain when =u1.

[0101] The lateral acceleration gain G under the current driving condition is determined by formula (4). a It can achieve linear changes in lateral acceleration gain, allowing the driver to adapt more smoothly to changes in vehicle handling performance caused by the variable transmission ratio, thus improving the driver's handling experience.

[0102] In some embodiments, where G a2 =6.67, G a1 =8.54. G a2 G represents the lateral acceleration gain corresponding to the upper limit of the medium-speed operating condition. a1 The lateral acceleration gain is the value corresponding to the lower limit of the vehicle speed under medium-speed conditions. When the two gain values ​​meet the above requirements, they can better reflect the lateral acceleration of the vehicle under the current driving conditions, fully consider the influence of lateral acceleration on the steering ratio, and ensure the accuracy of the steering ratio calculation.

[0103] Figure 4 This is a schematic flowchart of a steering control method provided in another embodiment of this disclosure.

[0104] Combination Figure 4 As shown, in some embodiments, the steering control method of this disclosure further includes:

[0105] Step S6, if the vehicle is in high-speed operation, the transmission ratio i of the vehicle steering system a It can also be determined using formula (5):

[0106]

[0107] In formula (5), G ω2 For u i = yaw rate gain at u2, G a2 For u i Lateral acceleration gain when u = 2.

[0108] In step S5 of this embodiment, a fixed value G is used. ω2 G a2 Calculate the gear ratio i of the vehicle steering system a While this improves computational efficiency and reduces computational difficulty, it also sacrifices some computational accuracy. Therefore, in some embodiments, step S6 can be used to accurately calculate the yaw rate and lateral acceleration corresponding to the vehicle speed under medium-speed conditions, thereby determining the transmission ratio i of the vehicle steering system. a More precise, providing a more refined and smoother driving experience.

[0109] In some embodiments, the first target value is equal to 8. That is, at the vehicle's forward speed u... i When the vehicle is operating at low speeds (below 10 km / h), the transmission ratio i of the vehicle's steering system... a This is a fixed value, reducing the computational burden on the vehicle.

[0110] refer to Figure 5 As shown, in the steering control method of this embodiment, when the vehicle is in a low-speed condition, steering control is performed with a fixed transmission ratio. When the vehicle is in a medium-speed or high-speed condition, steering control is performed with a variable transmission ratio. This achieves the requirement that the vehicle can steer flexibly at low speeds and stably at medium and high speeds. At high speeds, the yaw rate gain and lateral acceleration gain are reduced, which takes into account steering stability while ensuring that the vehicle has good emergency avoidance capabilities at high speeds and prevents the transmission ratio from being too large, which would result in excessively long change-of-direction time during vehicle operation.

[0111] On the other hand, this embodiment provides a vehicle steering system that employs the steering control method disclosed herein.

[0112] The vehicle steering system of this embodiment adopts the steering control method disclosed herein and has all the technical effects of this disclosure.

[0113] Combination Figure 6 As shown, in some embodiments, the vehicle steering system includes: an information acquisition module 100, which is used to acquire the vehicle's forward speed u. i The working condition judgment module 200 is used to determine the forward speed u input by the information acquisition module 100. i Determine the current driving condition of the vehicle; Calculation module 300, which calculates the forward speed u input by information acquisition module 100. i The driving conditions determined by the operating condition judgment module 200 are used to calculate and determine the transmission ratio i of the vehicle steering system. a .

[0114] The vehicle steering system provided in this embodiment can meet the requirements of flexible steering at low speeds and stable steering at medium and high speeds, while ensuring good emergency avoidance capabilities at high speeds.

[0115] On the other hand, this embodiment provides a vehicle steering control device, including a processor 400 and a memory 500 for storing executable instructions of the processor 400, the processor 400 being configured to execute the steering control method provided in this disclosure.

[0116] Figure 7This is a schematic diagram of the vehicle steering control device provided in an embodiment of the present invention. This device can be a computer device. (Refer to...) Figure 7 The device may include one or more of the following components: processor 400, memory 500, communication interface 600, and bus 700.

[0117] The processor 400 includes one or more processing cores. The processor 400 executes various functional applications and information processing by running software programs and modules. The memory 500 and the communication interface 600 are connected to the processor 400 via a bus 700. The memory 500 can be used to store at least one instruction, which the processor 400 uses to execute to implement the steps in the above method embodiments.

[0118] Furthermore, the memory 500 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, including but not limited to: magnetic disks or optical disks, electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), static random access memory (SRAM), read-only memory (ROM), magnetic storage, flash memory, and programmable read-only memory (PROM).

[0119] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory 500 including instructions, which can be executed by a processor 400 of a steering ratio determination device to determine a steering ratio method. For example, the non-transitory computer-readable storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, or optical data storage device.

[0120] In the description of this specification, the references to the terms "certain embodiments", "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example", or "some examples" refer to specific features, structures, materials, or characteristics described in connection with the embodiments or examples that are included in at least one embodiment or example of this disclosure.

[0121] The above description is merely an embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A steering control method characterized by, The steering control method comprises: acquiring a forward speed u of the vehicle i ; According to the forward speed u i determining a driving condition in which the vehicle currently is, the driving condition including a low-speed condition, a medium-speed condition and a high-speed condition; if the vehicle is in the low speed operating mode, setting a transmission ratio i of a steering system of the vehicle a to a first target value; if the vehicle is in the medium speed operating mode, the transmission ratio i of the vehicle steering system a is determined by equation (1): if the vehicle is in the high speed operating condition, the transmission ratio i of the vehicle steering system a is determined by equation (2): In the formulas (1) and (2), K is a stability factor, L is the wheelbase of the vehicle, G ω is a yaw rate gain, G a is a lateral acceleration gain; the stability factor K is inversely proportional to the position of the center of gravity of the vehicle; The yaw angular velocity gain G in the formula (1) ω is determined by the formula (3): In Equation (3), G ω2 is the yaw rate gain for u i = u2, and G ω1 is the yaw rate gain for u i = u1. The lateral acceleration gain G in the formula (1) a is determined by the formula (4): In equation (4), G a2 is the lateral acceleration gain for u i < = u2. G a1 is the lateral acceleration gain for u i < = u1.

2. The steering control method according to claim 1, characterized by, According to the forward speed u i The current driving condition of the vehicle is determined, including low-speed, medium-speed, and high-speed driving conditions, including: If u i If u1, it is determined that the vehicle is currently in a low-speed working condition; If u1 i If u1 i If u1 i If u1 i If u1 i If u1 i If u1 If u i > u2, it is determined that the vehicle is currently in a high-speed operating condition.

3. The turning control method according to claim 2, characterized by, wherein, u1 = 18 km / h, u2 = 85 km / h.

4. The turning control method according to claim 1, characterized by, wherein, G ω2 = 0.16 s -1 , G ω1 = 0.33 s -1 .

5. The turning control method according to claim 1, characterized by, wherein, G a2 = 6.67, G a1 = 8.

54.

6. The steering control method according to claim 2, characterized by, The steering control method further comprises: if the vehicle is in the high speed operating mode, the transmission ratio i of the vehicle steering system a may also be determined by equation (5): In Equation (5), G ω2 is the yaw rate gain for u i a2 is the lateral acceleration gain for u i = u2.​ 7. The steering control method according to any one of claims 1-6, characterized by, The first target value is equal to 8.

8. A vehicle steering system characterized by, The vehicle steering system employs the steering control method of any one of claims 1-7; The vehicle steering system comprises: an information acquisition module for acquiring a forward speed u of the vehicle i ; A working condition judging module is configured to determine the driving working condition of the vehicle according to the forward speed u input by the information collecting module i determining the driving working condition of the vehicle currently in; a computing module for calculating a transmission ratio i of a vehicle steering system according to the forward speed u input by the information collecting module and the driving condition determined by the driving condition judging module i , and the driving condition determined by the driving condition judging module a .

Images