Hand torque control method, control system and steer-by-wire system

Abstract

The present disclosure relates to a hand torque control method, a control system and a steer-by-wire system. The hand torque control method comprises: obtaining a steering wheel rotation angle; controlling a motor to drive a transmission assembly to drive a wheel to steer according to the steering wheel rotation angle; obtaining position information of the transmission assembly; determining a hand torque of the steering wheel; wherein the hand torque comprises a first hand torque and a second hand torque, the first hand torque is determined if the position information does not reach a set limit position range, the second hand torque is determined if the position information reaches the limit position range; the first hand torque increases with the increase of the steering wheel rotation angle at least one first change rate, the second hand torque increases with the increase of the steering wheel rotation angle at least one second change rate, and the second change rate is greater than the first change rate; and applying the hand torque to the steering wheel. In this way, the steering feeling can be improved and the driving experience can be improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of vehicle steering system, in particular to a hand torque control method, a control system and a steer-by-wire system. BACKGROUND

[0002] With the development of electronic appliances and steering system technology, steer-by-wire technology has gradually matured. In the steer-by-wire technology, the hand torque of the steering wheel is completely realized by a hand feel simulation motor. Therefore, the steering wheel input and the wheel angle can be completely decoupled. The transmission ratio of the steering system can be calibrated as needed, that is, the variable transmission ratio function can be realized. Correspondingly, the hand torque when the steering wheel is close to the limit angle needs to match the change of the transmission ratio of the steering system.

[0003] For different working conditions, configuring different hand torque when the steering wheel is close to the limit angle, improving the steering feel and enhancing the driving experience have become new challenges. SUMMARY

[0004] The purpose of the present disclosure is to provide a hand torque control method, a control system and a steer-by-wire system, which can improve the steering feel and enhance the driving experience.

[0005] One aspect of an embodiment of the present disclosure provides a hand torque control method for a steering wheel of a steer-by-wire system, the steer-by-wire system comprising a steering execution device, the steering execution device comprising a motor, a wheel and a transmission assembly connecting the motor and the wheel; the hand torque control method comprising:

[0006] obtaining a steering wheel angle;

[0007] controlling the motor to drive the transmission assembly to drive the wheel to steer according to the steering wheel angle;

[0008] obtaining position information of the transmission assembly;

[0009] determining a hand torque of the steering wheel; wherein the hand torque comprises a first hand torque and a second hand torque, if the position information does not reach a set limit position range, the first hand torque is determined; if the position information reaches the limit position range, the second hand torque is determined; the first hand torque increases with the increase of the steering wheel angle at least at a first change rate, and the second hand torque increases with the increase of the steering wheel angle at least at a second change rate, the second change rate being greater than the first change rate; and

[0010] applying the hand torque to the steering wheel.

[0011] In one embodiment, the obtaining the position information of the transmission assembly comprises:

[0012] obtaining actual position information of the transmission assembly detected by a sensor;

[0013] the determining the hand torque of the steering wheel comprises:

[0014] if the actual position information does not reach a set limit position range, determining the first hand torque;

[0015] if the actual position information reaches the limit position range, determining the second hand torque.

[0016] In one embodiment, the obtaining the position information of the transmission assembly comprises:

[0017] determining analog position information of the transmission assembly according to vehicle speed and steering wheel rotation angle;

[0018] the determining the hand torque of the steering wheel comprises:

[0019] if the analog position information does not reach a set limit position range, determining the first hand torque;

[0020] if the analog position information reaches the limit position range, determining the second hand torque.

[0021] In one embodiment, the determining the analog position information of the transmission assembly according to vehicle speed and steering wheel rotation angle comprises:

[0022] determining the analog position information of the transmission assembly according to steering transmission ratio, the vehicle speed and the steering wheel rotation angle.

[0023] In one embodiment, the obtaining the position information of the transmission assembly comprises:

[0024] obtaining actual position information of the transmission assembly detected by a sensor;

[0025] the determining the second hand torque comprises:

[0026] determining a difference between the actual position information and the analog position information;

[0027] compensating the second hand torque according to the difference.

[0028] In one embodiment, the determining the second hand torque comprises:

[0029] obtaining vehicle speed;

[0030] determining the second hand torque according to the vehicle speed.

[0031] In one of the embodiments, the determining the second hand torque comprises:

[0032] Obtaining a steering wheel speed;

[0033] Determining the second hand torque according to the steering wheel speed.

[0034] In one of the embodiments, the determining the second hand torque according to the steering wheel speed comprises:

[0035] Determining a gain factor according to the steering wheel speed;

[0036] Multiplying the gain factor with the second hand torque as a new second hand torque.

[0037] In one of the embodiments, the determining the gain factor according to the steering wheel speed comprises:

[0038] If the gain factor is within the gain threshold interval, keeping the gain factor unchanged;

[0039] If the gain factor is outside the gain threshold interval, taking the gain threshold interval boundary value closest to the gain factor as a new gain factor.

[0040] In one of the embodiments, the determining the second hand torque comprises:

[0041] If the second hand torque is within a torque threshold interval, keeping the second hand torque unchanged;

[0042] If the second hand torque is outside the torque threshold interval, taking the torque threshold interval boundary value closest to the second hand torque as a new second hand torque.

[0043] Another aspect of the embodiments of the present disclosure provides a control system comprising one or more processors for implementing the hand torque control method in any of the above embodiments.

[0044] Still another aspect of the embodiments of the present disclosure provides a steer-by-wire system comprising a steering wheel, the control system in the above embodiments, and a steering execution device connected to the control system; the steering execution device comprises a motor, a wheel, and a transmission assembly connecting the motor and the wheel, the motor drives the transmission assembly to drive the wheel to steer.

[0045] The technical solutions provided by the embodiments of the present disclosure can have the following beneficial effects:

[0046] According to the position information of the transmission assembly, the turning angle information of the steering wheel is determined, and before the position information reaches the set limit position range, a gentle increasing hand torque is provided. When the position information reaches the set limit position range, a sharp increasing hand torque is provided, and the driver is provided with the feeling feedback of the steering wheel turning to the limit angle. In this way, the steering feeling can be improved, thereby improving the driving experience.

[0047] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0048] The accompanying drawings, which are included as part of this disclosure, serve to provide further understanding of the present disclosure, the illustrative embodiments of the present disclosure, and the explanations thereof, and do not constitute improper limitations on the present disclosure.

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required to be used in the embodiment description will be briefly introduced below. 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.

[0050] Figure 1 A flowchart of a hand torque control method in an embodiment is shown.

[0051] Figure 2 A mapping relationship diagram of the simulated position of the rack and the turning angle of the steering wheel in an embodiment is shown.

[0052] Figure 3 A mapping relationship diagram of the simulated position of the rack and the vehicle speed in an embodiment is shown.

[0053] Figure 4 A mapping relationship diagram of the hand torque and the simulated position of the rack in an embodiment is shown.

[0054] Figure 5 A mapping relationship diagram of the gain factor and the steering wheel speed in an embodiment is shown.

[0055] Figure 6 A structural schematic diagram of a steer-by-wire system in an embodiment is shown. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solutions and advantages of the present disclosure more clear, the present disclosure will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and do not limit the protection scope of the present disclosure.

[0057] Unless otherwise defined, all 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 belongs. The terminology used in the description of the disclosure herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure.

[0058] The steer-by-wire system of the present disclosure will be described in detail below with reference to the accompanying drawings. The features in the following embodiments and implementations can be combined with each other without conflict.

[0059] The present disclosure provides a hand torque control method for a steering wheel of a steer-by-wire system. The steer-by-wire system includes a steering execution device, which includes a motor, a wheel, and a transmission assembly connecting the motor and the wheel. The hand torque control method includes: obtaining a steering wheel rotation angle. According to the steering wheel rotation angle, the motor drives the transmission assembly to drive the wheel to steer. Position information of the transmission assembly is obtained. The hand torque of the steering wheel is determined, wherein the hand torque includes a first hand torque and a second hand torque. If the position information does not reach a set limit position range, the first hand torque is determined. If the position information reaches the limit position range, the second hand torque is determined. The first hand torque increases with the increase of the steering wheel rotation angle at least at a first change rate. The second hand torque increases with the increase of the steering wheel rotation angle at least at a second change rate. The second change rate is greater than the first change rate. The hand torque is applied to the steering wheel.

[0060] According to the position information of the transmission assembly, the rotation angle information of the steering wheel is determined. Before the position information reaches the set limit position range, a gentle increasing hand torque is provided. When the position information reaches the set limit position range, a sharply increasing hand torque is provided, which provides the driver with a feedback of the steering wheel turning to the limit angle. In this way, the steering feeling can be improved, thereby improving the driving experience.

[0061] Figure 1 A flowchart of the hand torque control method in an embodiment of the present disclosure is shown in FIG. 1. Referring to FIG. 1, in an embodiment of the present disclosure, a hand torque control method is provided, which includes the following steps: Figure 1

[0062] In step S11, the steering wheel rotation angle is obtained.

[0063] The steering wheel rotation angle is the angle input of the driver turning the steering wheel. The position of the steering wheel when the vehicle is straight is taken as the starting 0° position. The clockwise turning of the steering wheel is set to make the steering wheel rotation angle increase positively, and the counterclockwise turning of the steering wheel is set to make the steering wheel rotation angle decrease negatively. The limit rotation angle of the clockwise turning of the steering wheel is the positive limit rotation angle, and the limit rotation angle of the counterclockwise turning of the steering wheel is the negative limit rotation angle.

[0064] ​Exemplarily, the rotation range of the steering wheel is 180° clockwise and 180° counterclockwise, and the rotation angle range of the steering wheel is -180° to 180°, wherein -180° is a negative limit rotation angle and 180° is a positive limit rotation angle.

[0065] In step S12, the motor drives the transmission assembly to drive the wheels to steer according to the rotation angle of the steering wheel.

[0066] The greater the rotation angle of the steering wheel, the greater the rotation angle of the wheels.

[0067] In step S13, the position information of the transmission assembly is obtained.

[0068] In some embodiments, the transmission assembly is a transmission gear and a rack meshing with each other, the motor drives the transmission gear to rotate, the transmission gear drives the rack to move, and the rack drives the wheels to rotate. In other embodiments, the transmission assembly is a transmission belt and a rack cooperating with each other, the motor drives the transmission belt to rotate, the transmission belt drives the rack to move, and the rack drives the wheels to rotate. In addition, the rack can also mesh with a pinion, and the pinion reacts the displacement of the rack through the rotation angle. The present disclosure does not limit the specific implementation of the transmission assembly.

[0069] In some embodiments, the position information of the transmission assembly is obtained as the rotation angle information of the transmission gear. In other embodiments, the position information of the transmission assembly is obtained as the displacement information of the transmission belt. In still other embodiments, the position information of the transmission assembly is obtained as the rotation angle information of the pinion. The present disclosure does not limit the selection of the specific transmission assembly. The position information can be the rotation angle information, the displacement information, and other related information reflecting the movement of the transmission assembly, and the present disclosure also does not limit the position information.

[0070] In the present embodiment, the position information of the transmission assembly is obtained as the position information of the rack. The rack is displaced with the rotation of the steering wheel. The position of the rack when the vehicle is straight is taken as the starting 0 position. When the steering wheel rotates clockwise, the rack moves positively. When the steering wheel rotates counterclockwise, the rack moves negatively. The limit position of the positive movement of the rack is a positive end point, and the limit position of the negative movement of the rack is a negative end point. It can be understood that when the steering wheel rotates to the positive limit rotation angle, the rack moves to the positive end point correspondingly. When the steering wheel rotates to the negative limit rotation angle, the rack moves to the negative end point correspondingly.

[0071] Exemplarily, the movement range of the rack is 20 cm positively and 20 cm negatively, and the position range of the rack is -20 cm to 20 cm, wherein -20 cm is the negative end point and 20 cm is the positive end point.

[0072] In the online steering system, the steering transmission ratio between the steering wheel and the wheels is variable. The position of the transmission assembly is not affected by the steering transmission ratio. For example, the negative end point and the positive end point of the rack remain unchanged relative to the vehicle. The present disclosure selects the position information of the transmission assembly to infer whether the steering wheel angle reaches the positive limit angle or the negative limit angle, or selects the position information of the transmission assembly to infer whether the steering wheel angle is close to the positive limit angle or the negative limit angle, thereby improving the accuracy of decision-making and ensuring the effect of online steering.

[0073] In some embodiments, obtaining the position information of the transmission assembly includes obtaining actual position information of the transmission assembly detected by a sensor.

[0074] In the present embodiment, obtaining the position information of the transmission assembly includes obtaining actual position information of the rack detected by a sensor. The actual position information of the rack can be the actual position of the rack after an actual displacement distance from the starting 0 position.

[0075] In other embodiments, obtaining the position information of the transmission assembly includes determining simulated position information of the transmission assembly according to the vehicle speed and the steering wheel angle.

[0076] When the vehicle is in a situation where the transmission assembly moves with a lag relative to the rotation of the steering wheel due to mechanical limits or environmental limits (for example, in a ditch, a rut, a curb, etc.) of the transmission assembly or system capability limits (for example, the motor can be in a degraded state, with reduced output capability, and the response of the steering execution device lags behind the rotation of the steering wheel), the actual position information of the transmission assembly and the steering wheel angle are not synchronized, and the hand torque determined according to the actual position information no longer meets the normal steering requirements.

[0077] The present disclosure simulates the position information of the transmission assembly according to the vehicle speed and the steering wheel angle. The simulated position information of the transmission assembly is synchronized with the steering wheel angle compared to the actual position information. The hand torque determined according to the simulated position information meets the real-time synchronous feedback requirements.

[0078] In the present embodiment, obtaining the position information of the transmission assembly includes determining simulated position information of the rack according to the vehicle speed and the steering wheel angle. The simulated position information of the rack can be the simulated position of the rack after a simulated displacement distance from the starting 0 position.

[0079] Figure 2 For the mapping relationship diagram of the simulated position of the rack and the steering wheel angle in an embodiment of the present disclosure, refer to FIG. 1. Figure 2 As shown in FIG. 1, the simulated position of the rack increases with the increase of the steering wheel angle, but the change rate of the increase decreases with the increase of the steering wheel angle due to the limitation of system capability.

[0080] Figure 3 For the mapping relationship between the rack's simulated position and the vehicle speed in an embodiment of the present disclosure, refer to FIG. 2A, which shows that, at a certain steering wheel angle, the rack's simulated position decreases with the increase of the vehicle speed, and the decreasing rate decreases with the increase of the vehicle speed, considering the driving stability of the vehicle. Figure 3

[0081] The relationship among the steering wheel angle, the vehicle speed and the rack's simulated position is a three-dimensional mapping relationship, that is, when the steering wheel angle and the vehicle speed are determined, the rack's simulated position can be determined.

[0082] Further, the simulated position information of the transmission assembly is determined according to the vehicle speed and the steering wheel angle, including determining the simulated position information of the rack according to the steering transmission ratio, the vehicle speed and the steering wheel angle.

[0083] The steering wheel angle input corresponds to different wheel angle outputs at different steering transmission ratios. For example, at a 1:1 transmission ratio, the steering wheel rotates 45°, and the wheel rotates 45° correspondingly. At a 1:2 transmission ratio, the steering wheel rotates 45°, and the wheel rotates 90° correspondingly.

[0084] In the embodiment, the simulated position information of the transmission assembly is determined according to the vehicle speed and the steering wheel angle, including determining the simulated position information of the rack according to the steering transmission ratio, the vehicle speed and the steering wheel angle.

[0085] The mapping relationship between the rack's simulated position and the steering wheel angle and the mapping relationship between the rack's simulated position and the vehicle speed are different at different steering transmission ratios. The mapping relationship between the rack's simulated position and the steering wheel angle and the mapping relationship between the rack's simulated position and the vehicle speed are selected according to the steering transmission ratio. Then, the simulated position information of the rack is determined according to the steering wheel angle, the vehicle speed, the mapping relationship between the rack's simulated position and the steering wheel angle and the mapping relationship between the rack's simulated position and the vehicle speed.

[0086] In step S14, the hand torque of the steering wheel is determined; wherein the hand torque includes a first hand torque and a second hand torque, the first hand torque is determined if the position information does not reach the set limit position range, the second hand torque is determined if the position information reaches the limit position range; the first hand torque increases with the increase of the steering wheel angle at least at a first change rate; the second hand torque increases with the increase of the steering wheel angle at least at a second change rate; the second change rate is greater than the first change rate.

[0087] ​The limit position range of the transmission assembly corresponds to a limit steering wheel angle range of the steering wheel angle. Generally, the limit position range of the transmission assembly includes a negative limit position range at a negative end point and a positive limit position range at a positive end point. The limit steering wheel angle range includes a negative limit steering wheel angle range at a negative limit steering wheel angle and a positive limit steering wheel angle range at a positive limit steering wheel angle. The negative limit position range corresponds to the negative limit steering wheel angle range, and the positive limit position range corresponds to the positive limit steering wheel angle range. The present disclosure does not limit the size of the limit position range and the size of the limit steering wheel angle range. The limit position range includes a limit position and an interval close to the limit position, which can be set in advance, or set according to experience and actual needs. The limit position range can be set as a fixed value, or set as a proportion of the total movement range of the transmission assembly, for example, one-twentieth of the total movement range.

[0088] Exemplarily, the total movement range of the rack is (-20 cm, 20 cm), the negative limit position range of the rack is (-20 cm, -18 cm), and the positive limit position range is (18 cm, 20 cm). The negative limit steering wheel angle range of the steering wheel angle is (-180°, -165°), and the positive limit steering wheel angle range is (165°, 180°). When the steering wheel angle is within (-180°, -165°), the position of the rack is within (-20 cm, -18 cm). When the steering wheel angle is within (165°, 180°), the position of the rack is within (18 cm, 20 cm).

[0089] The hand torque includes a first hand torque and a second hand torque. If the position information does not reach the set limit position range, the determined hand torque of the steering wheel is the first hand torque. If the position information reaches the set limit position range, the determined hand torque of the steering wheel is the second hand torque.

[0090] If the position information does not reach the set limit position range, the first hand torque can linearly increase at a first change rate as the steering wheel angle increases, or the first hand torque can increase in segments at a plurality of first change rates as the steering wheel angle increases, or the first hand torque can approach a curve type increase as the steering wheel angle increases.

[0091] If the position information reaches the limit position range, the second hand torque can linearly increase at a second change rate as the steering wheel angle increases, or the second hand torque can increase in segments at a plurality of second change rates as the steering wheel angle increases, or the second hand torque can approach a curve type increase as the steering wheel angle increases.

[0092] The second change rate is greater than the first change rate, indicating that the second hand torque increases by a greater value than the first hand torque when the steering wheel rotates by any same angle. For example, when the steering wheel rotates from 0° to 2°, the first hand torque increases from 0 Nm to 0.2 Nm. When the steering wheel rotates from 165° to 167°, the first hand torque increases from 10 Nm to 10.5 Nm.

[0093] When the position information includes the actual position information of the transmission assembly, if the position information does not reach the set limit position range, the first hand torque is determined to increase at the at least one first change rate as the steering wheel rotation angle increases; if the position information reaches the limit position range, the second hand torque is determined to increase at the at least one second change rate as the steering wheel rotation angle increases; the second change rate is greater than the first change rate, including:

[0094] If the actual position information does not reach the set limit position range, the first hand torque is determined to increase at the at least one first change rate as the steering wheel rotation angle increases; if the actual position information reaches the limit position range, the second hand torque is determined to increase at the at least one second change rate as the steering wheel rotation angle increases; the second change rate is greater than the first change rate.

[0095] When the position information includes the actual position information of the transmission assembly, if the position information does not reach the set limit position range, the first hand torque is determined to increase at the at least one first change rate as the steering wheel rotation angle increases; if the position information reaches the limit position range, the second hand torque is determined to increase at the at least one second change rate as the steering wheel rotation angle increases; the second change rate is greater than the first change rate, including:

[0096] If the actual position information does not reach the set limit position range, the first hand torque is determined to increase at the at least one first change rate as the steering wheel rotation angle increases; if the actual position information reaches the limit position range, the second hand torque is determined to increase at the at least one second change rate as the steering wheel rotation angle increases; the second change rate is greater than the first change rate.

[0097] Optionally, in some embodiments, the second hand torque is determined, including: obtaining position information of the transmission assembly; and determining the second hand torque according to the position information of the transmission assembly.

[0098] Specifically, in some embodiments, the second hand torque is determined according to the position information of the transmission assembly, including determining the second hand torque according to the actual position information of the transmission assembly. In this embodiment, the second hand torque is determined according to the actual position information of the transmission assembly, including determining the second hand torque according to the actual position information of the rack.

[0099] In some embodiments, the second hand torque is determined according to the position information of the transmission assembly, including determining the second hand torque according to the simulated position information of the transmission assembly. In this embodiment, the second hand torque is determined according to the simulated position information of the transmission assembly, including determining the second hand torque according to the simulated position information of the rack.

[0100] Figure 4 For the mapping relationship diagram of the hand torque and the simulated position of the rack in an embodiment of the present disclosure, refer to FIG. 1. Figure 4 As shown in FIG. 1, if the position information does not reach the set limit position range, the first hand torque slowly increases with the increase of the steering wheel rotation angle at least at a first change rate. In this embodiment, if the position information does not reach the set limit position range, the first hand torque slowly linearly increases with the increase of the steering wheel rotation angle at a smaller first change rate. If the position information reaches the set limit position range, the second hand torque slowly increases with the increase of the steering wheel rotation angle at least at a second change rate. In this embodiment, if the position information reaches the set limit position range, the second hand torque sharply linearly increases with the increase of the steering wheel rotation angle at a larger second change rate.

[0101] Optionally, in some embodiments, the second hand torque is determined including: determining the difference between the actual position information and the simulated position information; and compensating the second hand torque according to the difference.

[0102] By comparing the actual position information and the simulated position information, the position of the transmission assembly is further confirmed, so as to ensure the accuracy of the judgment and improve the reliability of the system.

[0103] The compensation of the second hand torque according to the difference can be that a mapping relationship between the difference and the second hand torque is pre-set, and the second hand torque is determined according to the mapping relationship and the difference. The compensation of the second hand torque according to the difference can also be that the second hand torque is calculated and determined according to an algorithm model in the related art, and the difference is brought into the algorithm model for real-time calculation. The present disclosure does not limit the specific implementation method of the compensation of the second hand torque according to the difference.

[0104] Optionally, in some embodiments, the second hand torque is determined including: obtaining the vehicle speed; and determining the second hand torque according to the vehicle speed.

[0105] The determination of the second hand torque according to the vehicle speed can be that a mapping relationship between the vehicle speed and the second hand torque is pre-set, and the second hand torque is determined according to the mapping relationship and the vehicle speed. The determination of the second hand torque according to the vehicle speed can also be that the second hand torque is calculated and determined according to an algorithm model in the related art, and the vehicle speed is brought into the algorithm model for real-time calculation. The present disclosure does not limit the specific implementation method of the determination of the second hand torque according to the vehicle speed.

[0106] In some embodiments, the greater the vehicle speed, the relatively more gradual the increase in the second torque, satisfying the driving demand. That is, the second change rate decreases as the vehicle speed increases.

[0107] Optionally, in some embodiments, determining the second hand torque comprises: obtaining the steering wheel speed; and determining the second hand torque according to the steering wheel speed.

[0108] In particular, determining the second hand torque according to the steering wheel speed comprises: determining a gain factor according to the steering wheel speed; and multiplying the gain factor by the second hand torque to obtain a new second hand torque.

[0109] Figure 5 For the mapping relationship between the gain factor and the steering wheel speed in an embodiment of the present disclosure, refer to FIG. 1. Figure 5 As shown in FIG. 1, the gain factor increases as the steering wheel speed increases. The gain factor can increase linearly as the steering wheel speed increases. In particular, the gain factor can increase linearly at a constant change rate as the steering wheel speed increases, or can increase linearly in multiple segments at different change rates as the steering wheel speed increases.

[0110] In some embodiments, the second hand torque multiplied by the gain factor is a second hand torque determined according to one or more input information such as the position information of the transmission assembly, the difference between the actual position information and the simulation position information, and the vehicle speed. The gain factor determined according to the steering wheel speed is multiplied by the second hand torque to obtain a new second hand torque.

[0111] In other embodiments, the second hand torque multiplied by the gain factor is a hand torque value determined according to one or more input information such as the position information of the transmission assembly, the difference between the actual position information and the simulation position information, the vehicle speed, and the steering wheel speed. The first hand torque is superimposed on the hand torque value to determine a second hand torque. The gain factor determined according to the steering wheel speed is multiplied by the second hand torque to obtain a new second hand torque.

[0112] It should be noted that the gain factor can be positive or negative. For a gain factor with a negative value, the second hand torque is adjusted to decrease the hand torque of the steering wheel. For a gain factor with a positive value, the second hand torque is adjusted to increase the hand torque of the steering wheel.

[0113] Further, in some embodiments, determining the gain factor according to the steering wheel speed comprises:

[0114] If the gain factor is within the gain threshold interval, the gain factor remains unchanged;

[0115] If the gain factor is outside the gain threshold interval, the gain factor closest to the boundary value of the gain threshold interval is taken as a new gain factor.

[0116] In view of the fact that the gain factor is too large, the second hand torque will change greatly, affecting the driving safety. Therefore, in an embodiment of the present disclosure, the gain factor needs to be limited, and it is determined whether the gain factor is within a preset gain threshold interval. It should be noted that the gain factor in the present disclosure within the gain threshold interval means that the gain factor is greater than or equal to the lower limit of the preset gain threshold, and less than or equal to the upper limit of the preset gain threshold. The boundary value of the gain threshold interval refers to the lower limit of the gain threshold or the upper limit of the gain threshold. Specifically, the gain factor can be compared with the preset gain threshold interval. If the current gain factor is within the gain threshold interval, it means that adjusting the second hand torque using the gain factor will not cause the second hand torque to change too much, so that the driving accident will not occur. In addition, when the second hand torque is adjusted using the gain factor, the driver is easy to perceive the change of the hand torque. Therefore, in the above case, the calculated gain factor can be used to regulate the second hand torque. If the current gain factor is greater than the upper limit of the gain threshold, it means that the gain factor calculated according to the above iterative algorithm will cause the second hand torque to change too much, thereby having a safety hazard, so the upper limit of the gain threshold needs to be used to replace the gain factor. If the gain factor is less than the lower limit of the gain threshold, it means that the calculated gain factor will make the current second hand torque decrease too much, resulting in too small steering wheel hand force, thereby causing driving safety risk, so the lower limit of the gain threshold needs to be used to replace the gain factor. It can be understood that for different vehicle speeds, the gain threshold interval corresponding to the gain factor is different due to the different required gain factors. It should be noted that the gain factor is related to the vehicle speed, and the gain factor gradually decreases as the vehicle speed increases.

[0117] In some embodiments, the second hand torque is determined, comprising:

[0118] If the second hand torque is within the torque threshold interval, the second hand torque is kept unchanged;

[0119] If the second hand torque is outside the torque threshold interval, the boundary value of the torque threshold interval closest to the second hand torque is taken as the new second hand torque.

[0120] In order to ensure driving safety, the second hand torque needs to be limited, and it is determined whether the second hand torque is within a preset torque threshold interval. In the second hand torque within the torque threshold interval of the present disclosure, it means that the second hand torque is greater than or equal to the lower limit of the preset torque threshold, and less than or equal to the upper limit of the preset torque threshold. The boundary value of the torque threshold interval refers to the lower limit of the torque threshold or the upper limit of the torque threshold. Whether the second hand torque needs to be limited can be determined by comparing the second hand torque with the torque threshold interval. Specifically, when the second hand torque is greater than the upper limit of the torque threshold, it means that using the second hand torque to adjust the steering wheel will cause the torque to be too large, which will greatly affect the driving experience, so the second hand torque needs to be replaced by the upper limit of the torque threshold. When the second hand torque is less than the lower limit of the torque threshold, it means that using the second hand torque to operate the steering wheel will cause the torque to be too small, which will cause a great safety risk to the driver operating the vehicle, so the lower limit of the torque threshold needs to be used as the adjusted second hand torque. When the second hand torque is less than or equal to the upper limit of the torque threshold, and greater than or equal to the lower limit of the torque threshold, it means that using the second hand torque to adjust the steering wheel can make it rotate smoothly. By limiting the second hand torque, the hand torque of the steering wheel is effectively ensured to be in a safe state, and the driving safety of the driver is improved.

[0121] The method of limiting the second hand torque can be used as the final protection strategy after the second hand torque is determined according to the input information.

[0122] In step S15, the hand torque is applied to the steering wheel.

[0123] After the determined hand torque is obtained, the hand torque is applied to the steering wheel to simulate the real steering feeling.

[0124] Figure 6 The structure diagram of the steer-by-wire system in an embodiment of the present disclosure is shown. Referring to Figure 6 In another embodiment of the present disclosure, a control system 10 is provided, which includes one or more processors for implementing the hand torque control method in any of the above embodiments. Referring to Figure 6 In still another embodiment of the present disclosure, a steer-by-wire system 20 is provided, which includes a steering wheel 21, a control system 10, and a steering execution device 22 connected to the control system. The steering execution device 22 includes a motor 221, a wheel 223, and a transmission assembly 222 connecting the motor 221 and the wheel 223, the motor 221 drives the transmission assembly 222 to drive the wheel 223 to steer.

[0125] In the embodiment, the control system 10 comprises a hand feel simulator 11 and an actuator 12. The hand feel simulator 11 is connected with the steering wheel 21, and the actuator 12 is connected with the steering execution device 22. The hand feel simulator 11 and the actuator 12 are in communication connection. The hand feel simulator 11 sends a steering signal to the actuator 12. The hand feel simulator 11 can detect the torque of the steering wheel 21. The hand feel simulator 11 is used to receive and process the steering wheel angle, the actual position information of the transmission assembly, the vehicle speed from the brake system, the steering transmission ratio from the vehicle human-computer interaction system, and the steering wheel speed. Moreover, the hand feel simulator 11 can determine the simulated position information of the transmission assembly according to the vehicle speed, the steering wheel angle, and the steering transmission ratio. The hand feel simulator 11 determines the second hand torque according to the foregoing input information, and applies the second hand torque to the steering wheel 21.

[0126] Further, the control system 10 further comprises a sensor 13 for detecting the actual position information of the transmission assembly 222, for example, the actual position information of the rack. The steering wheel angle and the steering wheel speed can be obtained by processing the torque detected by the hand feel simulator 11 and the actual position information detected by the sensor 13.

[0127] In other embodiments, the control system 10 comprises a steer-by-wire processor, and a hand torque motor is arranged at the steering wheel 21. The steer-by-wire processor is electrically connected with the hand torque motor and the motor 221 respectively. The steer-by-wire processor sends a steering signal to the motor 221. The steer-by-wire processor receives and processes the input information such as the position information of the transmission assembly, the difference between the actual position information and the simulated position information, the vehicle speed, the steering wheel speed, and determines the hand torque according to one or more input information. Then the steer-by-wire processor controls the hand torque to output the second hand torque to the steering wheel 21.

[0128] In the description of the present disclosure, it should be understood that the terms “middle”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0129] In addition, the terms "first", "second", and the like, are used only for descriptive purposes, and do not denote or imply a relative importance or an implied direction of indicated technical features. Thus, a feature defined with "first", "second", and the like, can include at least one of the features, explicitly or implicitly. In the description of the disclosure, the meaning of "a plurality" is at least two, for example, two, three, and the like, unless otherwise explicitly and specifically limited.

[0130] In the disclosure, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the disclosure can be understood according to the specific circumstances.

[0131] In the disclosure, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0132] It should be noted that when an element is referred to as "fixed to", "provided to", "fixed to" or "installed to" another element, it can be directly on another element or there can be a middle element. When an element is considered to be "connected" to another element, it can be directly connected to another element or a middle element can exist at the same time. Further, when an element is considered to be "fixedly connected" to another element, the two can be fixed in a detachable manner, or fixed in a non-detachable manner, such as sleeving, clamping, integral forming, welding, etc., which can be realized in traditional technology, and will not be repeated here.

[0133] The technical features of the above embodiments can be combined in any way. In order to make the description simple, not all possible combinations of technical features in the above embodiments are described, but as long as the combination of technical features does not exist contradictory, it should be considered as the scope of the present disclosure.

[0134] The above embodiments only express several implementation manners of the present disclosure, which are described in a more specific and detailed manner, but cannot be understood as a limitation on the scope of the patent. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present disclosure, which are all within the protection scope of the present disclosure.

Claims

1. A steering wheel hand torque control method for a steer-by-wire steering system, the steer-by-wire steering system comprising a steering execution device, the steering execution device comprising a motor, a wheel, and a transmission assembly connecting the motor and the wheel; characterized in that, The method comprises: obtaining a steering wheel steering angle; controlling the motor to drive the transmission assembly to drive the wheels to steer according to the steering wheel steering angle; obtaining position information of the transmission assembly; determining a hand torque of the steering wheel, wherein the hand torque comprises a first hand torque and a second hand torque, the first hand torque is determined if the position information does not reach a set limit position range, the second hand torque is determined if the position information reaches the limit position range, the first hand torque increases with the steering wheel steering angle at least at a first change rate, the second hand torque increases with the steering wheel steering angle at least at a second change rate, and the second change rate is greater than the first change rate; and applying the hand torque to the steering wheel; The method of obtaining the position information of the transmission assembly comprises: determining analog position information of the transmission assembly according to vehicle speed and the steering wheel steering angle; obtaining actual position information of the transmission assembly detected by a sensor; The method of determining the hand torque of the steering wheel comprises: determining the first hand torque if the analog position information does not reach the set limit position range; determining the second hand torque if the analog position information reaches the limit position range; The method of determining the second hand torque comprises: determining a difference between the actual position information and the analog position information; and compensating the second hand torque according to the difference.

2. The hand torque control method of claim 1, wherein, The method of obtaining the position information of the transmission assembly comprises: obtaining actual position information of the transmission assembly detected by a sensor; The method of determining the hand torque of the steering wheel comprises: determining the first hand torque if the actual position information does not reach the set limit position range; determining the second hand torque if the actual position information reaches the limit position range.

3. The hand torque control method of claim 1, wherein, The method of determining the analog position information of the transmission assembly according to vehicle speed and the steering wheel steering angle comprises: determining the analog position information of the transmission assembly according to a steering transmission ratio, the vehicle speed and the steering wheel steering angle.

4. The hand torque control method of claim 1, wherein, The method of determining the second hand torque comprises: obtaining vehicle speed; determining the second hand torque according to the vehicle speed.

5. The hand torque control method of claim 1, wherein, The method of determining the second hand torque comprises: obtaining steering wheel speed; determining the second hand torque according to the steering wheel speed.

6. The hand torque control method of claim 5, wherein, The method of determining the second hand torque according to the steering wheel speed comprises: determining a gain factor according to the steering wheel speed; multiplying the gain factor by the second hand torque to obtain a new second hand torque.

7. The hand torque control method of claim 6, wherein, The method of determining the gain factor according to the steering wheel speed comprises: if the gain factor is within a gain threshold interval, keeping the gain factor unchanged; if the gain factor is outside the gain threshold interval, taking a gain threshold interval boundary value closest to the gain factor as a new gain factor.

8. The hand torque control method of claim 1, wherein, The method of determining the second hand torque comprises: if the second hand torque is within a torque threshold interval, keeping the second hand torque unchanged; if the second hand torque is outside the torque threshold interval, taking a torque threshold interval boundary value closest to the second hand torque as a new second hand torque.

9. A control system characterized by, The hand torque control method as claimed in any one of claims 1 to 8 is implemented by one or more processors.

10. A steer-by-wire system characterized by, The control system comprises: The control system as claimed in claim 9, and a steering execution device connected to the control system; The steering execution device comprises a motor, a wheel, and a transmission assembly connecting the motor and the wheel, the motor driving the transmission assembly to drive the wheel to steer.

Images