Steering control method, device, and system, and vehicle

Abstract

A steering control method, device, and system, and a vehicle, which relate to the technical field of vehicle control and are used for achieving small-radius steering of a vehicle. The method comprises: on the basis of a vehicle speed and a steering wheel angle of a vehicle, determining that the vehicle has entered a low-speed steering scenario; and, on the basis of the steering wheel angle and a steering wheel hand force of the vehicle, controlling at least one axle of the vehicle to output a first differential torque, an outer wheel of the at least one axle outputting a positive torque, an inner wheel of the at least one axle outputting a negative torque, and the difference between the negative torque and the positive torque being equal to the first differential torque. By automatically controlling at least one axle of the vehicle to output a differential torque when the vehicle enters a low-speed steering scenario, small-radius steering or even an in-place U-turn of the vehicle can be achieved, and the turning angle of the vehicle is effectively reduced. In addition, the steering wheel angle and the steering wheel hand force are parameters related to the steering intent of the driver; and on the basis of these parameters, the vehicle is controlled to achieve differential torque steering, such that the actual steering of the vehicle meets the subjective demands of the driver, thereby improving the steering experience of the driver.

Description

Steering control method, device, system and vehicle

[0001] Cross-reference to related applications

[0002] This application claims priority to the Chinese patent application No. 202411234657.4, filed on September 4, 2024, and entitled "Steering control method, device, system and vehicle", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of vehicle control, and in particular to a steering control method, device, system and vehicle. BACKGROUND

[0004] With the development of automobile technology, people's requirements for vehicle intelligence are also getting higher and higher. The automobile steering system, as an important subsystem of the automobile chassis system, can be used to change the driving direction of the automobile, and its performance will directly affect the steering performance, stability of control, comfort of driving and safety of driving of the automobile, and has become one of the basic configurations of the automobile.

[0005] At present, the automobile steering system can be realized by the active rear wheel steering system. The active rear wheel steering system can reduce the turning radius and improve the flexibility of steering by setting a steering mechanical structure on the rear wheel of the automobile without tire wear. However, the active rear wheel steering system can only be applied to vehicles with a longer wheelbase, such as traditional luxury cars or large buses. Moreover, the steering mechanical structure of the rear wheel will limit the turning angle of the automobile, and the minimum turning angle can only be 10°-12°, and cannot achieve smaller radius steering or spot steering.

[0006] In summary, how to realize small radius steering of the vehicle still needs further research. SUMMARY

[0007] The present application provides a steering control method, device, system and vehicle to realize small radius steering of the vehicle.

[0008] In a first aspect, the present application provides a steering control method applicable to a vehicle, at least one axle of the vehicle can output a torque in different directions, the method comprising: determining that the vehicle enters a low-speed steering scene according to a vehicle speed and a steering wheel angle of the vehicle, and controlling the at least one axle of the vehicle to output a first differential torque according to the steering wheel angle and a steering wheel hand force of the vehicle. Wherein, the outer wheel of the at least one axle outputs a positive torque, the inner wheel of the at least one axle outputs a negative torque, and the difference between the negative torque and the positive torque is equal to the first differential torque.

[0009] Based on the above steering control method, by controlling at least one axis of the vehicle to output differential torque when the vehicle enters a low-speed steering scene, the small-radius steering or even the U-turn of the vehicle can be realized, and the turning angle of the vehicle is effectively reduced. In addition, the steering control method can be automatically enabled in a low-speed steering scene without the vehicle being in a parking scene, and the intelligent steering degree is high, the use scene is more widely applicable, and the applicable vehicle models are more, such as any type of vehicle with at least one axis with differential torque output function, including large vehicles, small vehicles, vehicles with long wheelbase, and vehicles with short wheelbase, etc. Therefore, the above steering control method not only realizes the small-radius steering of the vehicle, but also improves the versatility of the application scene and the applicability of the vehicle model.

[0010] Furthermore, the above steering control method combines the steering wheel angle and the steering wheel hand force to comprehensively control the differential torque of at least one axis of the vehicle, wherein the steering wheel angle is related to the turning radius in the low-speed steering scene, and the steering wheel hand force is related to the steering intention of the driver. Therefore, the above steering control method can correct the turning radius in the current steering scene in combination with the steering intention of the driver, so that the actual turning radius not only meets the needs of the current low-speed steering scene, but also meets the subjective needs of the driver, and improves the steering experience of the driver.

[0011] In a possible design, the vehicle enters the low-speed steering scene according to the vehicle speed and the steering wheel angle, specifically, the vehicle speed is less than or equal to a first vehicle speed, and the steering wheel angle is greater than or equal to a first steering angle. Wherein, the first vehicle speed and the first steering angle can be configured as the vehicle speed and the steering angle when the vehicle is about to turn in a scene with a small-radius turning requirement, for example, the first vehicle speed is 10 km / h, and the first steering angle is 400°.

[0012] Based on the above design, the above steering control strategy can be enabled when the vehicle is about to enter the turning state, to assist the vehicle to realize small-radius steering or U-turn.

[0013] In a possible design, the first differential torque of at least one axis of the vehicle is controlled according to the steering wheel angle and the steering wheel hand force of the vehicle, specifically, the ideal turning radius is determined according to the steering wheel angle, the ideal turning radius is corrected according to the steering wheel angle and the steering wheel hand force to obtain the target turning radius, and then the first differential torque of at least one axis of the vehicle is controlled according to the target turning radius.

[0014] Based on the above design, the turning radius is controlled from the angle of the steering center, which is equivalent to using an active rear wheel steering system, and the difference torque is controlled from the angle of the yaw rate, which is equivalent to using a distributed electric drive steering system. Based on this, the above steering control method first calculates the turning radius that can not wear the tire using the active rear wheel steering system, and then converts it to the distributed electric drive steering system for difference torque control. The two steering systems can be coordinated together while not wearing the tire, and the target turning radius can be followed by controlling the difference torque, which can achieve consistency of the control target, optimize the coordination logic between the two steering systems, and reduce the mutual interference problem when the two steering systems are coordinated.

[0015] In one example of the above design, the ideal turning radius is determined according to the steering wheel angle, which can be specifically: first, according to the steering wheel angle, the passive wheel angle is determined, which is in a positive proportional relationship with the steering wheel angle; then, according to the passive wheel angle, the ideal turning radius is determined based on the following formula: Wherein, R k is the ideal turning radius, c1 is the distance from the instantaneous steering center to the front axle in the direction of vehicle travel, δ f is the passive wheel angle, b is the distance from the vehicle center of mass to the rear axle, and c2 is the distance from the instantaneous steering center to the rear axle in the direction of vehicle travel.

[0016] Based on the above example, the kinematic model of the vehicle, ackermann steering geometry, can be used to calculate the ideal turning radius of the vehicle. The geometric calculation method is relatively simple, which can improve the efficiency of radius calculation and further improve the real-time performance of steering control.

[0017] In one example of the above design, the ideal turning radius is corrected according to the steering wheel angle and the steering wheel hand force to obtain the target turning radius, which can be specifically: according to the vehicle speed, the steering wheel angle and the steering wheel hand force, the steering correction coefficient is determined, and the ideal turning radius is corrected using the steering correction coefficient to obtain the target turning radius.

[0018] Based on the above example, the vehicle speed is related to the safe turning of the vehicle, and the steering wheel angle and the steering wheel hand force are related to the small radius steering intention of the driver. Therefore, based on the vehicle speed, the steering wheel angle and the steering wheel hand force, the ideal turning radius is corrected to meet the requirements of vehicle safe turning and driver's small radius steering intention.

[0019] In a further example, according to the steering correction coefficient, the ideal turning radius can be corrected based on the following formula to obtain the target turning radius: R ref = R K-D x G ain wherein R ref is a target turning radius, R K is an ideal turning radius, G ain is a steering correction coefficient, and D is a constant coefficient.

[0020] Based on the above example, the larger the steering correction coefficient, the smaller the target turning radius, the greater the strength of the small-radius turning, and the better the effect of reducing the turning radius.

[0021] In a further example, the steering correction coefficient has a first mapping relationship with the vehicle speed, the steering wheel angle, and the steering wheel hand force, in which: when the vehicle speed is in a first vehicle speed interval, the steering wheel angle is in a first steering angle interval, and the steering wheel hand force is in a first hand force interval, the steering correction coefficient is 1; when the vehicle speed is in a second vehicle speed interval, the steering wheel angle is in a second steering angle interval, and the steering wheel hand force is in a second hand force interval, the steering correction coefficient is 0; when the vehicle speed is in a third vehicle speed interval, the steering wheel angle is in a third steering angle interval, and the steering wheel hand force is in a third hand force interval, the steering correction coefficient is a third value, which is greater than 0 and less than 1. The third vehicle speed interval is greater than the first vehicle speed interval and less than the second vehicle speed interval, the third steering angle interval is greater than the second steering angle interval and less than the first steering angle interval, and the third hand force interval is greater than the second hand force interval and less than the first hand force interval.

[0022] Based on the above example, the steering correction coefficient is a mapping relationship related to the vehicle speed, the steering wheel angle, and the steering wheel hand force: the steering correction coefficient in the interval of high vehicle speed, small steering wheel angle, and light steering wheel hand force is reduced to the lowest, i.e., 0, and no steering assistance gain is currently generated; the steering correction coefficient in the interval of low vehicle speed, large steering wheel angle, and heavy steering wheel hand force is increased to the highest, i.e., 1, and the maximum steering assistance gain is currently generated; and the steering correction coefficient in the interval of medium vehicle speed, medium steering wheel angle, and medium steering wheel hand force is increased with the decrease of the vehicle speed, the increase of the steering angle, and the increase of the steering hand force. Based on the mapping relationship, the steering intention of the driver can be made explicit, and integrated into the final control target, so that the turning radius of the vehicle can change in real time with the change of the steering intention of the driver.

[0023] In one example of the above design, according to the target turning radius, the at least one axle of the vehicle outputs a first differential torque, which can be specifically: first, determining a target yaw rate corresponding to the target turning radius, then determining an additional yaw moment according to the actual yaw rate of the vehicle and the target yaw rate, and then controlling the at least one axle of the vehicle to output the first differential torque according to the additional yaw moment.

[0024] Based on the above example, the deviation between the actual yaw rate and the target yaw rate can be gradually reduced, so that the actual yaw rate gradually approaches the target yaw rate, and the vehicle has less fluctuation and better stability during the approaching process.

[0025] In a further example, the additional yaw moment can be determined based on the following equation according to the actual yaw rate and the target yaw rate of the vehicle: where ΔM z is the additional yaw moment, a is the distance from the vehicle's center of mass to the front axle, K1 is the front wheel cornering stiffness, b is the distance from the vehicle's center of mass to the rear axle, K2 is the rear wheel cornering stiffness, V x is the vehicle speed, ω ref is the target yaw rate, ω IMU is the actual yaw rate, and β IMU is the cornering angle of the vehicle's center of mass.

[0026] Based on the above example, the required additional yaw moment can be calculated based on the actual yaw rate, the target yaw rate, and the parameters related to the structure of the vehicle, and the vehicle can be controlled based on the additional yaw moment to follow the target turning radius and further reduce the actual turning radius of the vehicle.

[0027] In a possible design, at least one axle of the vehicle is an active axle, and in this case, after the control of the at least one axle of the vehicle outputs the first differential torque, if the driver's requested torque changes, the passive axle of the vehicle responds to the changed torque.

[0028] Based on the above design, the lateral and longitudinal motions of the vehicle can be decoupled, the active axle differential torque and the active axle steering are used to control the lateral yaw motion, and the passive axle torque is used to control the longitudinal acceleration and deceleration, so that the driver's requirements for acceleration and deceleration and the requirement for reducing the turning radius can be met at the same time.

[0029] In a possible design, at least one axle of the vehicle is an active axle, and the inner and outer wheels of the active axle use different motors, and the inner and outer wheels of the passive axle share the same motor or use different motors.

[0030] Based on the above design, the different motors of the inner and outer wheels of the active axle can be used to output different direction torques of the inner and outer wheels of the active axle, and the same motor or different motors of the passive axle can be used to output the same direction torques of the inner and outer wheels of the passive axle.

[0031] In a further possible design, before the control of the at least one axle of the vehicle outputs the first differential torque, if the passive wheel rotation angle is the maximum angle in the first direction, the active wheel rotation angle is controlled to be the maximum rotation angle in the second direction, and the first direction is opposite to the second direction.

[0032] Based on the above design, the opposite rotation angles of the active wheel and the passive wheel can be used to speed up the steering of the vehicle.

[0033] In a possible design, according to the vehicle speed and the steering wheel angle of the vehicle, before it is determined that the vehicle enters a low-speed steering scenario, if it is detected that the vehicle speed is less than or equal to a second vehicle speed and the steering wheel angle is greater than or equal to a second steering wheel angle, the user is determined to instruct to start the steering assistance function through human-computer interaction.

[0034] Based on the above design, the user can instruct to start or not to start the steering assistance function, and the subjective demand of the user can be met.

[0035] In a possible design, before the at least one axle of the vehicle is controlled to output the first differential torque, it can be further determined that the vehicle is in a forward gear, a reverse gear, or a neutral gear. That is, when the vehicle is in the forward gear, the reverse gear, or the neutral gear, differential torque control steering can be performed, and when the vehicle is in the parking gear, differential torque control steering is not performed.

[0036] Based on the above design, differential torque control steering can be performed only in a scenario in which small-radius steering is needed, so as to save computing resources.

[0037] In a possible design, after the at least one axle of the vehicle is controlled to output the first differential torque, if the vehicle speed is greater than a second vehicle speed and / or the vehicle is switched to the parking gear, the at least one axle of the vehicle is controlled to output a torque of the same direction.

[0038] Based on the above design, when the vehicle speed is increased to a certain vehicle speed, the small-radius steering control can be ended, so as to avoid high-speed steering and improve the safety of vehicle driving. In addition, after the vehicle is parked, the small-radius steering control can be ended, so as to save computing resources.

[0039] In a second aspect, the present application provides a steering control device, which has the function of implementing the method of the first aspect or any one of the designs of the first aspect, for example, the steering control device includes a module, a unit or a means for performing the operations involved in the method of the first aspect or any one of the designs or examples of the first aspect, which can be implemented by software, or by hardware, or by a combination of software and hardware.

[0040] In a third aspect, the present application provides a steering control apparatus, which comprises an interface circuit and one or more processors. The one or more processors are coupled with a memory. The memory is configured to store part or all of the computer programs or instructions necessary for implementing the functions involved in the method of the first aspect or any of the designs or examples of the first aspect. The one or more processors can execute the computer programs or instructions, which, when executed, cause the steering control apparatus to implement the method of the first aspect or any of the designs or examples of the first aspect. The interface circuit is configured to implement the communication function within the steering control apparatus and / or the communication function between the steering control apparatus and other devices or components.

[0041] In a possible design of the present application, the communication interface can be a transceiver, or an input / output interface. Optionally, the transceiver can be a transceiver circuit. Optionally, the input / output interface can be an input / output circuit.

[0042] In another possible design of the present application, when the steering control apparatus is a chip or a chip system, the communication interface can be an input / output interface, an interface circuit, an output circuit, an input circuit, a pin or related circuit on the chip or chip system. The processor can also be implemented as a processing circuit or a logic circuit.

[0043] The above steering control apparatus can be a controller in the vehicle, or a module (e.g., a processor, a chip or a chip system) in the controller, or a logic node, a logic module or software capable of implementing all or part of the functions of the controller.

[0044] In a fourth aspect, the present application provides a steering control system, which comprises a steering control apparatus and vehicle-mounted sensors. The vehicle-mounted sensors are connected to the steering control apparatus, and are configured to collect sensor information of the vehicle and send the sensor information to the steering control apparatus. The steering control apparatus is configured to execute the method of the first aspect or any of the designs of the first aspect according to the sensor information of the vehicle.

[0045] In a possible design of the present application, the vehicle-mounted sensors can include one or more of the following sensors: a wheel speed sensor, a steering wheel angle sensor, a steering wheel torque sensor, an inertial detection unit, a pedal position sensor.

[0046] In a possible design, the at least one axle of the vehicle is a driven axle, and the steering control system further includes an inner wheel motor of the driven axle and an outer wheel motor of the driven axle, the inner wheel motor being connected to an inner wheel of the driven axle of the vehicle, and the outer wheel motor being connected to an outer wheel of the driven axle of the vehicle. Based on this, when the steering control device controls the at least one axle of the vehicle to output the first differential torque, the steering control device can send a first control signal to the inner wheel motor of the driven axle, and send a second control signal to the outer wheel motor of the driven axle. The inner wheel motor outputs a negative torque according to the first control signal, and the outer wheel motor outputs a positive torque according to the first control signal, and the difference between the positive torque and the negative torque is the first differential torque.

[0047] In a further possible design, the steering control system further includes a passive wheel motor, the passive wheel motor being connected to an inner wheel of a passive axle of the vehicle and an outer wheel of the passive axle. The steering control device is further configured to: if it is detected that the torque requested by the driver changes, send a third control signal to the passive wheel motor, the third control signal including a torque change amount; and the passive wheel motor is configured to: output a third torque according to the third control signal, and the difference between the third torque and a historical torque of the passive wheel motor is equal to the torque change amount.

[0048] In a fifth aspect, the present application provides a vehicle, which includes the steering control device in the second aspect or any possible design of the second aspect, or includes the steering control device in the third aspect or any possible design of the third aspect, or includes the steering control system in the fourth aspect or any possible design of the fourth aspect.

[0049] In a sixth aspect, the present application provides a computer readable storage medium, which stores computer readable instructions, and when a computer reads and executes the computer readable instructions, the computer executes the method in the first aspect or any possible design of the first aspect.

[0050] In a seventh aspect, the present application provides a computer program product, and when a computer reads and executes the computer program product, the computer executes the method in the first aspect or any possible design of the first aspect.

[0051] In an eighth aspect, the present application provides a chip, which is used to read a computer program stored in a memory, and execute the method in the first aspect or any possible design of the first aspect. Optionally, the chip can include a processor, which is coupled to the memory and used to read the computer program stored in the memory, and implement the method in the first aspect or any possible design of the first aspect. Optionally, the chip can further include a memory, a communication interface, a power supply module, and the like. The memory is used to store the computer program; the communication interface is used to receive and send data; and the power supply module is used to supply power to the processor.

[0052] In a ninth aspect, the present application provides a chip system, which comprises a processor for supporting the computer to implement the method in the first aspect or any one of the designs in the first aspect. In a possible design, the chip system further comprises a memory for storing the programs and data necessary for the computer. The chip system can be composed of a chip, or can include the chip and other discrete devices.

[0053] The technical effects achieved by the second aspect to the ninth aspect can be referred to the description of the beneficial effects of the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0054] FIG. 1a exemplarily shows a turning radius in a forward driving process of a vehicle according to the present application;

[0055] FIG. 1b exemplarily shows a turning radius in a backward driving process of a vehicle according to the present application;

[0056] FIG. 2a exemplarily shows a possible application scenario according to the present application;

[0057] FIG. 2b exemplarily shows another possible application scenario according to the present application;

[0058] FIG. 2c exemplarily shows still another possible application scenario according to the present application;

[0059] FIG. 3a exemplarily shows an architecture of a steering control system according to the present application;

[0060] FIG. 3b exemplarily shows a connection relationship between a motor and a wheel according to the present application;

[0061] FIG. 4 exemplarily shows a flow of a steering control method according to the present application;

[0062] FIG. 5 exemplarily shows an implementation form of a first difference torque output by a driving shaft according to the present application;

[0063] FIG. 6 exemplarily shows a flow of a method for calculating the first difference torque according to the present application;

[0064] FIG. 7 exemplarily shows an implementation flow of a steering assistance function according to the present application;

[0065] FIG. 8a exemplarily shows an interface of human-computer interaction according to the present application;

[0066] FIG. 8b exemplarily shows another interface of human-computer interaction according to the present application;

[0067] FIG. 9 exemplarily shows a steering control trajectory corresponding to an application scenario according to the present application;

[0068] Figure 10 illustrates a schematic diagram of a steering control trajectory corresponding to an application scenario two provided in this application;

[0069] Figure 11 illustrates a schematic diagram of the structure of a steering control device provided in this application;

[0070] Figure 12 illustrates a schematic diagram of another steering control device provided in this application;

[0071] Figure 13 illustrates a schematic diagram of another steering control device provided in this application. Detailed Implementation

[0072] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0073] The following provides explanations for some of the terms used in this application. It should be noted that these explanations are for the convenience of those skilled in the art and do not constitute a limitation on the scope of protection claimed in this application.

[0074] I. Differential Torsion Direction

[0075] Differential torque steering refers to creating a yaw tendency in a vehicle by controlling the torque levels of the inner and outer wheels to differ, thereby improving steering agility. The inner and outer wheels can share a single motor or have their own independent motors. When they have independent motors, differential torque is generated by controlling the two motors to output different torques to the two wheels.

[0076] II. Turning radius

[0077] The turning radius can be understood as the distance from the outermost wheel of a vehicle to the steering center. The steering center refers to the instantaneous center where all parts and particles of the vehicle rotate around the same point with different radii of rotation; it is also called the instantaneous steering center.

[0078] For example, assuming the view is from the bottom of the vehicle (see Figure 1a), if the vehicle turns right while moving forward, the outermost wheel is the left rear wheel Z. 22 The turning radius is the Z-axis of the left rear wheel. 22 The distance h to the instantaneous turning center O 22 If turning left, the outermost wheel is the right rear wheel (Z). 21 The turning radius is the Z-axis of the right rear wheel. 21 The distance h to the instantaneous turning center O 21 Conversely, referring to Figure 1b, if turning left during the vehicle's reversing process, the outermost wheel is the right front wheel Z. 11 The turning radius is the Z-axis of the left front wheel. 11Distance h to the instantaneous turning center O 11 If turning right, the outermost wheel is the left front wheel Z 12 The turning radius is the right front wheel Z 12 Distance h to the instantaneous turning center O 12 .

[0079] Three, steering wheel hand force

[0080] The steering wheel hand force, also known as steering force, refers to the force exerted by the driver on the steering wheel to change the direction of the vehicle.

[0081] The foregoing introduces some terms involved in the present application. The following introduces possible application scenarios of the present application.

[0082] Please refer to FIG. 2a, FIG. 2b and FIG. 2c, which exemplarily show three possible application scenarios of the present application, in which the steering control method is applied to a vehicle. In combination with FIG. 2a to FIG. 2c, when the vehicle enters a low-speed turning scenario, such as the side-out warehouse starting scenario shown in FIG. 2a, or the narrow road U-turn scenario shown in FIG. 2b, or the off-road soil road low-speed cornering scenario shown in FIG. 2c, and other scenarios, such as the ice and snow road low-speed cornering scenario, etc., the vehicle can control the inner and outer wheels of at least one axle of the vehicle to generate differential torque according to the steering control method provided by the present application, while realizing small-radius turning or U-turn, giving the driver a sense that the turning radius of the vehicle can be changed by manipulating the steering wheel, to improve the driver's steering experience. When the vehicle is in a non-low-speed turning scenario, such as a straight-ahead scenario, or a scenario where the vehicle is turning but the speed is relatively high, or a scenario where the vehicle is at a relatively low speed but is not turning, etc., the vehicle can control the wheel torque according to the original control logic, and some devices related to the steering control method can not work or be in a dormant state waiting for invocation, thereby saving vehicle energy to some extent.

[0083] For example, the above vehicle can be various types of vehicles, such as pure electric vehicles (pure EV / battery EV), hybrid electric vehicles (HEV), range extended electric vehicles (REEV), plug-in hybrid electric vehicles (PHEV), other new energy vehicles (NEV), or fuel vehicles, etc. These vehicles can be applied to the fields of intelligent driving, assisted driving or connected cars, etc.

[0084] It should be understood that the above application scenarios are only examples, and the steering control method provided by the present application can also be applied to other possible scenarios, and is not limited to the above examples. For example, the steering control method can also be applied to other vehicles, such as ships, airplanes, drones, trains, subways, high-speed rails, or transport vehicles, etc., to assist the driver to realize or automatically realize the steering of the vehicle. For another example, the steering control method can also be applied to robots as auxiliary power for robot steering, to realize the flexibility of robot steering, and the robot can include but is not limited to home robots, navigation robots, autonomous food delivery robots, medical robots, or industrial robots, etc. For another example, the steering control method can also be applied to smart life scenarios, such as being integrated on an automatic following trolley case, or being integrated on a smart dining chair, or being integrated on a smart scooter, etc. Here, they are not listed one by one.

[0085] It should be noted that the application scenarios described in the present application are for more clearly illustrating the technical solutions of the present application, and do not constitute a limitation on the technical solutions provided by the present application.

[0086] As described in the background, the active rear wheel steering system can reduce the turning radius through the rear wheel steering mechanical structure, but cannot achieve ultra-small radius steering. Therefore, in order to achieve ultra-small radius steering, the industry has proposed a distributed electric drive steering system.

[0087] In the existing distributed electric drive steering system, each wheel of the vehicle is assigned a separate motor, and each motor can output torque to the corresponding wheel. When implementing small radius steering, the distributed electric drive steering system controls the wheels of the four motors to generate differential torque, such as the left front wheel and the left rear wheel generating differential torque, and the right front wheel and the right rear wheel also generating differential torque. These two parts of differential torque make the vehicle generate a yaw moment, which can make the vehicle achieve ultra-small radius steering or even in-place steering through tire grinding. The distributed electric drive steering system has the advantages of high control freedom, strong redundancy, fast response speed, and high response accuracy, and has gradually become a trend of high-performance vehicle drive configuration.

[0088] Although the existing distributed electric drive steering system can achieve ultra-small radius steering or in-place steering of the vehicle, it can only be applied to four-motor distributed drive vehicles, and can only be used in special vehicle modes. For example, it can only be used in a parking mode (such as the side out of the garage before starting as shown in FIG. 2a), but cannot be used in a non-parking mode (such as the narrow road U-turn scenario shown in FIG. 2b, the off-road soil road low-speed cornering scenario shown in FIG. 2c, etc.). Therefore, the use scenario of the existing distributed electric drive steering system is relatively single and limited. Moreover, since the front and rear wheels will generate differential torque, the vehicle tires will be worn during steering, especially when steering on paved roads, the tire wear is more serious.

[0089] Based on the above, the distributed electric drive steering system can achieve tire wear steering through wheel differential torque to reduce the turning radius, and the rear wheel steering system can reduce the turning radius without tire wear, so if the two steering systems are coordinated, theoretically, the turning radius can be further reduced with minimal tire wear, thereby achieving more extreme steering assistance. However, it is difficult to coordinate the distributed electric drive steering system and the active rear wheel steering system, mainly in the following two points:

[0090] Problem one, the active rear wheel steering system and the distributed electric drive steering system belong to different actuators, the active rear wheel steering system mainly controls the motion steering center of the vehicle (i.e. the turning radius, also known as the steering geometric center), and the distributed electric drive steering system mainly controls the vehicle yaw moment, the control targets of the two steering systems are different, and it is difficult to achieve coordinated control;

[0091] Problem two, if the active rear wheel steering system and the distributed electric drive steering system are coordinated together, the two steering systems will simultaneously adjust the vehicle dynamics and respectively feedback control based on the actual motion state of the vehicle, so the adjustment of the vehicle dynamics by one of the steering systems will inevitably interfere with the feedback information of the other steering system, resulting in inaccurate feedback control of the other steering system. That is, the two steering systems will produce coupling interference when coordinated, which may reduce the control accuracy of the steering control system, and may not be better than the steering effect of using only one of the steering systems.

[0092] In view of this, the present application provides a steering control method, which can appropriately coordinate the yaw moment control in the distributed electric drive steering system and the steering geometry control in the active rear wheel steering system to achieve consistency of the control target, while avoiding mutual interference caused by coupling of the two, and ensuring that the final steering control effect meets the expectation.

[0093] The steering control method in the present application can be applied to a steering control system, which can be integrated into a vehicle, which can be a vehicle with at least one axle having the function of outputting different direction torque.

[0094] Taking the vehicle as an example, please refer to FIG. 3a, which shows a schematic diagram of the architecture of a steering control system provided by the present application. In the architecture, the steering control system 300 can include a steering control device 310, a motor 320 and a vehicle sensor 330, the steering control device 310 is connected with the motor 320 and the vehicle sensor 330 respectively, and the motor 320 is also connected with the vehicle wheel 100. Each device will be described in detail below.

[0095] The steering control device 310 can be a device specially used to implement the steering control function, or a device that implements the steering control function while also implementing other functions. For example, in one example, the steering control device 310 can be a control unit in the vehicle, such as a vehicle control unit (VCU), a vehicle dynamics control (VDC), or a mobile data center (MDC), or can also be a domain controller, such as an intelligent driving domain controller or a chassis domain controller, etc. In this example, the steering control function can be implemented using the control unit that already exists in the vehicle, thereby improving the utilization rate of the in-vehicle devices.

[0096] Alternatively, in another example, to reduce the working pressure of the in-vehicle control unit, the steering control device 310 can also be an additional control unit specially used for steering, such as a separate digital signal processing (DSP) chip. The DSP chip is provided with all devices that complete the digital signal processing capability, including but not limited to: power amplifiers, analog-to-digital converters (ADCs), digital-to-analog converters (DACs), processing units, etc. The DSP chip is independent of the vehicle and can be connected to relevant components of the vehicle, such as the motor 320 and the vehicle-mounted sensors 330, to jointly implement the steering control of the vehicle. Alternatively, in another example, the steering control device 310 can also jointly implement the control unit that is independently provided and the control unit in the vehicle, i.e., part of the functions of the steering control device 310 are implemented by the independently provided control unit, and the other part of the functions are implemented by the control unit in the vehicle. Alternatively, other examples can also be included, which are not listed one by one here.

[0097] The motor 320 can be a hub motor or a wheel motor. The vehicle has at least one axle with the motor 320 connected to the wheels on the at least one axle. The at least one axle can be a driving axle or a driven axle, or both. When the at least one axle is only a driving axle or only a driven axle, the wheels on the other axle can be connected by a mechanical structure, such as a rear wheel steering mechanical structure in a main rear wheel steering system, or other mechanical structures, without limitation. When the at least one axle includes both a driving axle and a driven axle, one motor 320 can be provided to connect to the four wheels on the two driving axles. Alternatively, one motor 320 can be provided on each driving axle, and each motor 320 on a driving axle connects to the two wheels on the driving axle. Alternatively, two motors 320 can be provided on each driving axle, and each motor 320 connects to one wheel. Alternatively, one motor 320 can be provided on one driving axle and two motors 320 can be provided on the other driving axle. And so on.

[0098] For example, referring to FIG. 3b, which shows a connection relationship between a motor and a wheel provided by the application, the figure can be understood as a structure obtained by looking at the vehicle chassis from the bottom of the vehicle. In this example, it is assumed that the driving axle is the rear axle and the driven axle is the front axle. Two motors, i.e., the motor 3221 and the motor 3222, can be provided on the driving axle, the motor 3221 connects to the left rear wheel 121, and the motor 3222 connects to the right rear wheel 122. The motor 3221 controls the output torque of the left rear wheel 121, and the motor 3222 controls the output torque of the right rear wheel 122. One motor, i.e., the motor 321, can be provided on the driven axle, and the motor 321 connects to both the left front wheel 111 and the right front wheel 112. In other words, the left front wheel 111 and the right front wheel 112 share the same motor 321, and the motor 321 distributes the torque of the driven axle to the left front wheel 111 and the right front wheel 112, so that the sum of the output torque of the left front wheel 111 and the output torque of the right front wheel 112 is equal to the torque of the driven axle.

[0099] It should be noted that FIG. 3b is an example in which the motor 321, the motor 3221, and the motor 3222 are all hub motors, but in other examples, the motor 321, the motor 3221, and the motor 3222 can all be wheel motors, or a combination of hub motors and wheel motors, such as the motor 321 being a hub motor and the motor 3221 and the motor 3222 being wheel motors, and so on, which are not limited by the application.

[0100] The vehicle-mounted sensors 330 can include one or more sensors disposed in the vehicle, such as a wheel speed sensor 331, a steering wheel angle sensor 332, a steering wheel torque sensor 333, an inertial measuring unit (IMU) 334, and a pedal position sensor 335.

[0101] The wheel speed sensor 331 is disposed on the wheel 100, such as on the hub of each wheel or at the location of the front wheel brake disc, to collect the rotational speed information of the wheel on which it is disposed. The rotational speed information can be used to calculate the wheel speed, such as the number of revolutions per minute (r / min) of the wheel. Further, the wheel speed information can also be used to calculate the vehicle speed, such as the distance traveled by the vehicle per hour (km / h) in the forward or reverse direction.

[0102] The steering wheel angle sensor 332 can be disposed in the steering column below the steering wheel to collect the steering information of the steering wheel. The steering information can be used to calculate the steering angle of the steering wheel, such as the number of degrees (°) that the steering wheel has turned relative to the free state at the current time.

[0103] The steering wheel torque sensor 333 can also be disposed in the steering column below the steering wheel to collect the torque information on the steering wheel. The torque information can be used to calculate the steering force applied by the driver on the steering wheel, also known as the hand force, in units of Newton (N).

[0104] The inertial measuring unit 334 is disposed near the center point of the vehicle coordinate system, such as in the airbag. The inertial measuring unit 334 typically includes three single-axis accelerometers and three single-axis gyroscopes, with the three single-axis corresponding to the three axes of the vehicle coordinate system, such as the X-axis, Y-axis, and Z-axis shown in FIGS. 3a and 3b. The X-axis corresponds to the driving direction of the vehicle, also known as the longitudinal direction, the Y-axis corresponds to the pitch direction of the vehicle, also known as the lateral direction, and the Z-axis corresponds to the yaw direction of the vehicle, also known as the vertical direction. The three single-axis accelerometers can be used to collect acceleration information of the vehicle in the three-axis direction of the vehicle coordinate system. The acceleration information in the three-axis direction can be used to calculate the acceleration of the vehicle in the three-axis direction, i.e., the longitudinal acceleration, the lateral acceleration, and the vertical acceleration. Among them, the longitudinal acceleration refers to the acceleration generated when the vehicle accelerates or decelerates along the driving direction, the lateral acceleration refers to the lateral acceleration generated when the vehicle turns, and the vertical acceleration refers to the upward and downward acceleration generated when the vehicle goes uphill or downhill. The three single-axis gyroscopes can be used to collect angular velocity information of the vehicle relative to the three axes of the navigation coordinate system. The angular velocity information can be used to calculate the three angular velocities of the vehicle, i.e., the roll angle (Roll) speed, the pitch angle (Pitch) speed, and the yaw angle (Yaw) speed.

[0105] The pedal position sensor 335 is arranged on the pedal and is configured to collect the stroke information of the pedal, which can be used to calculate the depth of the pedal being stepped on. The pedal includes an accelerator pedal (also referred to as a throttle) and a brake pedal (also referred to as a brake), and correspondingly, the pedal position sensor 335 includes a position sensor of the accelerator pedal and a position sensor of the brake pedal. The stroke information collected by the position sensor of the accelerator pedal is used to calculate the depth of the accelerator pedal being stepped on. The deeper the accelerator pedal is stepped on, the larger the opening degree of the throttle of the vehicle will be, the more air will enter the engine of the vehicle, the fuel supply system of the engine will increase the fuel injection amount, the engine speed will rise, and the vehicle will accelerate. Similarly, the stroke information collected by the position sensor of the brake pedal is used to calculate the depth of the brake pedal being stepped on. The deeper the brake pedal is stepped on, the greater the pressure applied by the brake system to the wheels 100 will be, and the better the deceleration effect of the vehicle will be.

[0106] It can be understood that the above sensors can also be replaced by other sensors that can directly collect or indirectly calculate the same information. For example, in another example, the steering wheel torque sensor 333 can also be replaced by a steering wheel pressure sensor. The steering wheel pressure sensor can collect pressure information on the steering wheel, which can be used to directly calculate the steering force applied by the driver on the steering wheel. In another example, the wheel speed sensor 331 can also be replaced by a vehicle speed sensor. The vehicle speed sensor can collect vehicle speed information, which can be used to directly calculate the vehicle speed and, according to the corresponding relationship between the vehicle speed and the wheel speed, can also be used to calculate the wheel speed. In another example, the steering wheel angle sensor 332 can also be replaced by a steering wheel position sensor. The steering wheel position sensor can collect position information of the steering wheel, which can be used to calculate the steering travel. Different steering travels correspond to different steering angles one by one.

[0107] In addition, the information collected by the above sensors can include information directly collected by the sensors, or other information calculated or derived from the information directly collected by the sensors. For example, the information collected by the wheel speed sensor can be understood as wheel speed information, but the wheel speed information is actually intermediate data calculated from the information collected by the wheel speed sensor, and the vehicle speed information can also be calculated from the wheel speed information. That is to say, in addition to the information collected by the sensors, any information derived or calculated from the information collected by the sensors is also within the scope of the information collected by the sensors, which is not limited herein.

[0108] In addition, although not shown in FIG. 3a, the vehicle can also have other vehicle-mounted sensors, such as a vehicle-mounted camera and a vehicle-mounted radar. In addition, the vehicle can also have other non-sensor components, such as a communication module, an entertainment module, and an intelligent driving module, which are not described herein.

[0109] Based on the above contents shown in FIG. 3a and FIG. 3b and other contents described above, FIG. 4 exemplarily shows a possible flow diagram of a steering control method provided by the embodiments of the present application, which can be executed by a vehicle, further, can be executed by a steering control device in the vehicle, such as the steering control device 310 in FIG. 3a. As shown in FIG. 4, the method comprises steps 401 and 402, which will be introduced below in combination with the accompanying drawings.

[0110] In step 401, it is determined that the vehicle enters a low-speed steering scene according to the vehicle speed and the steering wheel angle.

[0111] Optionally, when the vehicle speed is less than or equal to the first vehicle speed, and the steering wheel angle is greater than or equal to the first steering wheel angle, it can be considered that the vehicle enters the low-speed steering scene. The first vehicle speed and the first steering wheel angle are used to indicate that the vehicle is about to turn in a scene with a small-radius turning demand. The first vehicle speed is related to the vehicle speed when the vehicle is about to turn in a scene with a small-radius turning demand, and the first steering wheel angle is related to the steering wheel angle when the vehicle is about to turn in a scene with a small-radius turning demand. The first vehicle speed and the first steering wheel angle can be configured according to the vehicle speed and the steering wheel angle when the vehicle is about to turn in each scene with a small-radius turning demand, which is statistically pre-configured, or can be configured by a person skilled in the art according to experience, which is not limited.

[0112] For example, in one example, considering that when the vehicle is about to turn in a scene with a small-radius turning demand, the vehicle speed is usually configured as first gear, and the steering wheel angle is usually turned to a very large value, therefore, the first vehicle speed can be configured as the vehicle speed corresponding to first gear or the vehicle speed nearby, such as 10 km / h, and the first steering wheel angle can be configured as a relatively large value, such as 350°, or 360°, or 370°, or 380°, or 390°, or 400°, etc., if the maximum steering wheel angle is 460°. Assuming that the first vehicle speed is configured as 10 km / h, and the first steering wheel angle is configured as 350°, when the vehicle speed is as low as 10 km / h or below, and the steering wheel angle is turned to 350° or above, it can be considered that the vehicle enters the low-speed turning scene, and the following step 402 is executed.

[0113] Optionally, the vehicle speed can be understood as an actual vehicle speed of the vehicle. The actual vehicle speed can be directly calculated according to information collected by a vehicle speed sensor, or can be indirectly calculated according to information collected by a wheel speed sensor. For example, taking the latter as an example, in combination with FIG. 3a, the steering control device 310 can periodically acquire information collected by the wheel speed sensor 331 and information collected by the inertial measurement unit 334. In each period, the longitudinal acceleration of the vehicle is calculated according to the information collected by the inertial measurement unit 334, the wheel speeds of the four wheels of the vehicle are calculated according to the information collected by the wheel speed sensor 331, and the wheel center speed is calculated based on the wheel speeds of the four wheels. Then, the vehicle speed is calculated according to the wheel center speed and the longitudinal acceleration. Optionally, in the process of calculating the vehicle speed, the influence of other factors can also be considered, for example, if the vehicle is in a slipping state, a slip ratio coefficient is also needed to correct the vehicle speed to improve the accuracy of indirectly calculating the vehicle speed.

[0114] It can be understood that if the vehicle speed is indirectly calculated according to the information collected by the wheel speed sensor, the vehicle speed corresponds to a theoretical vehicle speed, or also called a reference vehicle speed, which refers to the running speed of the vehicle's center of gravity after converting the wheel speeds of the four wheels of the vehicle. In the case of accurate calculation and comparison, the reference vehicle speed is not much different from the actual vehicle speed, and thus can also be used to represent the actual vehicle speed.

[0115] Optionally, the steering wheel angle can be directly calculated according to information collected by a steering wheel angle sensor, or can be indirectly calculated according to information collected by a steering wheel position sensor. For example, taking the former as an example, in combination with FIG. 3a, the steering control device 310 can acquire information collected by the steering wheel angle sensor 332 in the same period as described above, and calculate the steering wheel angle of the vehicle according to the information. In this way, in the same period, the steering control device 310 can acquire both the steering wheel angle of the vehicle and the vehicle speed, thereby providing support for the steering control device 310 to determine whether the vehicle enters the low-speed steering scene.

[0116] Step 402, controlling at least one axle of the vehicle to output a first differential torque according to the steering wheel angle and the steering wheel hand force of the vehicle, wherein the outer wheel of the at least one axle outputs a positive torque, the inner wheel of the at least one axle outputs a negative torque, and the difference between the positive torque and the negative torque is equal to the first differential torque.

[0117] Here, at least one axle of the vehicle supports outputting torques in different directions. In other words, the left wheel and the right wheel of each axle in the at least one axle can output torques in different directions, for example, the left wheel outputs a positive torque while the right wheel outputs a negative torque, or the left wheel outputs a negative torque while the right wheel outputs a positive torque. Of course, the left wheel can also output a positive torque while the right wheel outputs a positive torque, and the left wheel can also output a negative torque while the right wheel outputs a negative torque.

[0118] Optionally, the at least one axle can be a driven axle, which can be a front axle or a rear axle. There are many ways to support the driven axle to output different directions of torque, such as connecting the two wheels on the driven axle through a mechanical structure to output different directions of torque, or distributing different directions of torque to the two wheels on the driven axle through the same motor, or providing independent motors for the two wheels on the driven axle to drive the two wheels to output different directions of torque, etc., without limitation.

[0119] For example, in the last implementation, please refer to FIG. 5, which shows an implementation form of a driven axle outputting a first differential torque provided by the present application. This figure is an example of the above-mentioned motor layout shown in FIG. 3b, which can be considered as a view from the bottom of the vehicle chassis. In this example, the driven axle is the rear axle. If the vehicle turns right, the left rear wheel 121 is the outer wheel and the right rear wheel 122 is the inner wheel. The motor 3221 controls the left rear wheel 121 to output a positive torque, and the motor 3222 controls the right rear wheel 122 to output a negative torque. The torque distribution during forward driving when turning right is shown in (A) of FIG. 5, and the torque distribution during reverse driving when turning right is shown in (B) of FIG. 5. Conversely, if the vehicle turns left, the right rear wheel 122 is the outer wheel and the left rear wheel 121 is the inner wheel. The motor 3221 controls the left rear wheel 121 to output a negative torque, and the motor 3222 controls the right rear wheel 122 to output a positive torque. The torque distribution during forward driving when turning left is shown in (C) of FIG. 5, and the torque distribution during reverse driving when turning left is shown in (D) of FIG. 5.

[0120] The positive torque output by the outer wheel minus the negative torque output by the inner wheel equals the first difference torque. The first difference torque is calculated according to the steering wheel angle and the steering wheel force of the vehicle, and there are many possible calculation methods. For example, in one calculation method, different measurement environments can be configured in advance, and the inner-outer wheel difference torque that can make the vehicle steering effect better under each measurement environment can be determined, and a corresponding relationship between each measurement environment and the inner-outer wheel difference torque is established, wherein each measurement environment corresponds to a combination of a steering wheel angle and a steering wheel force. In this way, after obtaining the steering wheel angle and the steering wheel force of the vehicle each time, the measurement environment corresponding to the three information can be determined first, and then the corresponding relationship is directly queried to find the inner-outer wheel difference torque corresponding to the measurement environment, which is used as the first difference torque. For another example, in another calculation method, the steering wheel angle change and the steering wheel force change can be calculated according to the steering wheel angle and the steering wheel force obtained this time and the historical steering wheel angle and the historical steering wheel force, and then the first difference torque can be determined by querying the preset corresponding relationship according to the three changes. For another example, in another possible calculation method, the ideal difference torque can be calculated based on the steering wheel angle first, and then the ideal difference torque is corrected using the steering wheel angle and the steering wheel force to obtain the first difference torque. There are many possible calculation methods, which are not listed one by one here.

[0121] For ease of understanding, in one specific example, please refer to FIG. 6, which shows a flowchart of a method for calculating the first difference torque provided by the present application. The method takes controlling the output of the first difference torque by the driving shaft as an example, and mainly includes the following steps 601-603:

[0122] Step 601: Determine the ideal turning radius according to the steering wheel angle of the vehicle.

[0123] Here, the steering wheel angle can be directly calculated according to the information collected by the steering wheel angle sensor, or can be indirectly calculated according to the information collected by the steering wheel position sensor, which is not limited.

[0124] Optionally, the ideal turning radius can be determined according to the steering wheel angle of the vehicle, which can be specifically: the required driving wheel angle is calculated according to the steering wheel angle first, and then the ideal turning radius is determined according to the steering wheel angle and the required driving wheel angle. Further, the driven wheel angle can be calculated according to the steering wheel angle first, and then the required driving wheel angle is calculated according to the driven wheel angle and the vehicle speed, and then the ideal turning radius is determined according to the required driving wheel angle and the steering wheel angle.

[0125] For example, in combination with Fig. 3b and Fig. 5, assuming that the driving axle is the rear axle and the driven axle is the front axle, the driving wheel is the rear wheel and the driven wheel is the front wheel, since the front axle is connected with the steering rod below the steering wheel, the front wheel angle is related to the steering wheel angle, for example, can be equal to the product of the steering wheel angle and the transmission coefficient. The transmission coefficient is related to the transmission mechanism between the front axle and the steering rod, and the transmission coefficient is fixed after the transmission mechanism is set, which can be configured in the steering control device 310 when the vehicle is manufactured. Based on this, the steering control device 310 can also obtain the locally stored transmission coefficient after obtaining the steering wheel angle, and then calculate the product of the transmission coefficient and the steering wheel angle as the front wheel angle, that is, the driven wheel angle.

[0126] Further, the rear wheel angle is inversely proportional to the front wheel angle at low vehicle speed, and the steering control device 310 can calculate the required rear wheel angle, that is, the driving wheel angle, after calculating the front wheel angle in the above manner by substituting the vehicle speed and the front wheel angle into the inverse proportional relationship. The inverse proportional relationship is set according to the structure design of the front and rear axles of the vehicle and is configured in the steering control device 310 in advance. The inverse proportional relationship is used to make the rotation direction of the rear wheel angle opposite to that of the front wheel angle, while maintaining the stability of the cooperation of the rear wheel angle and the front wheel angle. The specific calculation formula can be seen in the following formula (1.1):

[0127] δ r = k x (V x - V0) x δ f ……(1.1)

[0128] Wherein, δ r is the rear wheel angle, δ f is the front wheel angle, V x is the vehicle speed, and k and V0 are constant coefficients greater than 0. When V x is less than V0, the direction of the rear wheel angle is opposite to that of the front wheel angle.

[0129] For example, in a specific example, during low-speed steering, in order to achieve a smaller turning radius, the steering wheel angle is usually punched to a relatively large value, such as 360° or nearby, and if the transmission coefficient is 1 / 9, the front wheel angle is the product of the steering wheel angle and the transmission coefficient, that is, 40°. Substituting the front wheel angle 40° into the above formula (1.1) to calculate the rear wheel angle is -10°, then: if the vehicle is currently steering to the right, the front wheel angle can be punched to 40° to the right and the rear wheel angle can be punched to 10° to the left; otherwise, if the vehicle is currently steering to the left, the front wheel angle can be punched to 40° to the left and the rear wheel angle can be punched to 10° to the right.

[0130] Further, after the passive wheel turning angle and the active wheel turning angle are calculated, the ideal turning radius can be determined according to the kinematic model of the vehicle. For example, since the current scenario is a low-speed scenario, the vehicle steering conforms to the ackermann steering geometry. The ackermann steering geometry considers that the centers of the turning paths of the four wheels of the vehicle intersect at a transient turning center on the extension line of the rear axle, and based on the transient turning center, the ideal turning radius can satisfy the following formula (1.2):

[0131] wherein R k is the ideal turning radius, b is the distance from the vehicle center of mass to the rear axle, c1 is the distance from the projection of the transient turning center on the vehicle running direction (i.e., the x-axis of the vehicle coordinate system) to the front axle, and c2 is the distance from the projection of the transient turning center on the vehicle running direction to the rear axle.

[0132] wherein the distances c1 and c2 of the transient turning center on the vehicle running direction to the front axle and to the rear axle are related to the rear wheel turning angle, the front wheel turning angle, and the wheelbase of the vehicle. Assuming that the rear wheel turning angle is δ r , the front wheel turning angle is δ f , and the wheelbase of the vehicle is L, the distances c1 and c2 of the transient turning center to the front axle and to the rear axle satisfy the following formula (1.3):

[0133] For example, assuming that through the preceding calculation steps, the front wheel turning angle δ f is calculated to be 40°, the rear wheel turning angle δ r is calculated to be 10°, and the wheelbase L of the vehicle is 3 m, then these values are substituted into the above formula (1.3) to calculate:

[0134] Assuming that the distance b from the vehicle center of mass to the rear axle is 1.5 m, then the value of c1 is 2.48 m, the value of c2 is 0.52 m, the value of b is 1.5 m, and the value of δ f is 40°, which are substituted into the above formula (1.2) to calculate:

[0135] Therefore, the ideal turning radius is about 3.11 m.

[0136] In step 602, the ideal turning radius is corrected according to the steering wheel turning angle and the steering wheel hand force of the vehicle to obtain a target turning radius.

[0137] It can be understood that the ideal turning radius is obtained according to the vehicle speed and the steering wheel turning angle, and is related to the motion turning center, and therefore, the ideal turning radius can be considered as the minimum turning radius that can be achieved by using the calculation method of the active rear wheel steering system. According to the foregoing introduction of the active rear wheel steering system, it can be known that the minimum turning radius can only achieve a steering angle of 10° to 12°, and therefore, the ideal turning radius can only achieve a steering angle of 10° to 12°, which may not meet the actual steering requirements of the driver (for example, in some narrow road turning or U-turn scenarios, the driver needs to turn a small angle, and the ideal turning radius is relatively large), and therefore, the ideal turning radius needs to be corrected to obtain a target turning radius that meets the requirements of the driver.

[0138] In a possible correction manner, the ideal turning radius can be corrected in combination with a parameter related to the steering intention of the driver. The parameter related to the steering intention of the driver includes but is not limited to the steering wheel turning angle and / or the steering wheel hand force. Taking the steering wheel turning angle and the steering wheel hand force as an example, when the steering wheel turning angle is larger and the steering wheel hand force is larger, it represents that the intention of the driver to turn a small angle is stronger, and the target turning radius expected by the driver is smaller, and therefore, the target turning radius can be obtained by reducing the ideal turning radius. Conversely, when the steering wheel turning angle is smaller and the steering wheel hand force is smaller, it represents that the intention of the driver to turn a small angle is weaker, and the target turning radius expected by the driver is larger, and therefore, the target turning radius can be obtained by not reducing the ideal turning radius or reducing the ideal turning radius to a smaller extent, that is, the target turning radius can be equal to or close to the ideal turning radius.

[0139] Optionally, in addition to the parameter related to the steering intention of the driver, other parameters can be further combined to correct the ideal turning radius. The other parameters can be, for example, parameters related to driving safety, such as the vehicle speed. When the vehicle speed is higher, the risk of turning a small angle is greater, and vehicle rollover is easy to occur, and therefore, the target turning radius cannot be too small, and in this case, the target turning radius can be equal to or close to the ideal turning radius. Conversely, when the vehicle speed is lower, even if the vehicle turns a small angle, rollover does not occur, and therefore, the target turning radius can be set to be smaller, and therefore, the target turning radius can be obtained by reducing the ideal turning radius.

[0140] Based on the above analysis, the following correction rule can be set: the ideal turning radius is taken as the bottom radius (i.e. the maximum turning radius), and a steering correction coefficient (also referred to as a steering auxiliary gain coefficient) is set, which is related to the vehicle speed, steering wheel angle and steering wheel hand force of the vehicle, and is used to correct the ideal turning radius to obtain the target turning radius. The steering correction coefficient used to correct the ideal turning radius to obtain the target turning radius can be corrected according to the following formula (2.1), for example:

[0141] R ref = R K -D x G ain ……(2.1)

[0142] wherein R ref is the target turning radius, R K is the ideal turning radius, G ain is the steering correction coefficient, and D x G ain is the correction amount of the turning radius, which is linearly related to the steering correction coefficient G ain .

[0143] wherein D is a constant coefficient, which can be designed by the person skilled in the art according to the actual vehicle structure, and the value of D needs to ensure that the target turning radius R ref is greater than 0 and less than or equal to the ideal turning radius R K . For example, in one example, the value of D is positive, which can be set to 1, or 2, or 1.2, or 1.5, or 1.8, etc. Of course, this is the case when the value of the steering correction coefficient G ain is positive. In other cases, the steering correction coefficient G ain may also be negative, in which case the value of D is negative, and the sum of the ideal turning radius R K and the product of the steering correction coefficient G ain and the constant coefficient D is taken as the target turning radius R ref , etc., without limitation.

[0144] Taking the positive value of D as an example, according to the above formula (2.1), the greater the value of the steering correction coefficient G ain , the smaller the target turning radius R ref , and the smaller the value of the steering correction coefficient G ain , the greater the target turning radius R ref . However, the target turning radius R ref cannot be too large or too small without limitation, so the steering correction coefficient G ainAn upper limit value and a lower limit value are set. Assuming that the upper limit value is a first value and the lower limit value is a second value, and the first value is greater than the second value, in one specific example, the steering correction coefficient G ain may be calculated in the following way:

[0145] The vehicle speed, steering wheel angle and steering wheel hand force of the vehicle are obtained. If the vehicle speed is in a first vehicle speed interval, the steering wheel angle is in a first steering wheel angle interval, and the steering wheel hand force is in a first steering wheel hand force interval, the value of the steering correction coefficient G ain is determined to be a first value. If the vehicle speed is in a second vehicle speed interval, the steering wheel angle is in a second steering wheel angle interval, and the steering wheel hand force is in a second steering wheel hand force interval, the value of the steering correction coefficient G ain is determined to be a second value. If the vehicle speed is in a third vehicle speed interval, the steering wheel angle is in a third steering wheel angle interval, and the steering wheel hand force is in a third steering wheel hand force interval, the value of the steering correction coefficient G ain is determined to be a third value, which is greater than the second value and less than the first value. The third vehicle speed interval is greater than the first vehicle speed interval and less than the second vehicle speed interval, the third steering wheel angle interval is greater than the second steering wheel angle interval and less than the third steering wheel angle interval, and the third steering wheel hand force interval is greater than the second steering wheel hand force interval and less than the third steering wheel hand force interval.

[0146] That is, a first mapping relationship between each vehicle speed interval, each steering wheel angle interval, each steering wheel hand force interval and the value of the steering correction coefficient G ain may be configured in advance. After obtaining the vehicle speed, steering wheel angle and steering wheel hand force of the vehicle, the first mapping relationship is queried to find the vehicle speed interval to which the vehicle speed belongs, the steering wheel angle interval to which the steering wheel angle belongs, and the steering wheel hand force interval to which the steering wheel hand force belongs, and the value of the steering correction coefficient G ain corresponding to these intervals can be queried. The first mapping relationship can be presented in the form of a table, or in other forms such as a formula, a database, an image, etc., without limitation.

[0147] Taking a table as an example, please refer to Table 1 below, which shows a possible presentation form of a first mapping relationship:

[0148] Table 1

[0149] In the above Table 1, the first value is 1, the second value is 0, and the third value is between 0 and 1. Combining Table 1 and the above formula (2.1):

[0150] The first speed interval is configured as [0, 2km / h], the first steering angle interval is configured as [400°, 460°], and the first hand force interval is configured as [100N, 150N], so when the vehicle speed is less than or equal to 2km / h, the steering wheel steering angle is greater than or equal to 400°, and the steering wheel hand force is greater than or equal to 100N, the steering correction coefficient is 1, and the steering correction coefficient G ain reaches the upper limit value, the target turning radius R ref is the minimum;

[0151] The second speed interval is configured as (10km / h, 20km / h], the second steering angle interval is configured as [300°, 350°), and the second hand force interval is configured as [50N, 80N), so when the vehicle speed is greater than 10km / h, the steering wheel steering angle is less than 320°, and the steering wheel hand force is less than 80N, the steering correction coefficient is 0, and the steering correction coefficient G ain reaches the lower limit value, the target turning radius R ref is the maximum;

[0152] The interval (2km / h, 10km / h] between the first speed interval [0, 2km / h] and the second speed interval (10km / h, 20km / h] is a third speed interval, which is divided into multiple sub-speed intervals, i.e., a first sub-speed interval (8km / h, 10km / h], a second sub-speed interval (6km / h, 8km / h], a third sub-speed interval (4km / h, 6km / h], and a fourth sub-speed interval (2km / h, 4km / h]; similarly, the interval [350°, 400°) between the first steering angle interval [400°, 460°] and the second steering angle interval [300°, 350°) is a third steering angle interval, which is divided into multiple sub-steering angle intervals, i.e., a first sub-steering angle interval [350°, 362°), a second sub-steering angle interval [362°, 375°), a third sub-steering angle interval [375°, 387°), and a fourth sub-steering angle interval [387°, 400°); the interval [80N, 100N) between the first hand force interval [100N, 150N] and the second hand force interval [50N, 80N) is a third hand force interval, which is divided into multiple sub-hand force intervals, i.e., a first sub-hand force interval [80N, 85N), a second sub-hand force interval [85N, 90N), a third sub-hand force interval [90N, 95N), and a fourth sub-hand force interval [95N, 100N). The multiple sub-speed intervals, the multiple sub-steering angle intervals, and the multiple sub-hand force intervals correspond to different values of the steering correction coefficient G ain , the smaller the speed of the sub-speed interval, the larger the steering angle of the sub-steering angle interval, and the larger the hand force of the sub-hand force interval, the larger the value of the steering correction coefficient G ain , but they are all between 0 and 1.

[0153] For example, assuming the calculated ideal turning radius is approximately 3.11m and the set coefficient D is 1.5, then: when the vehicle speed is above 10km / h, the steering wheel angle is turned below 350°, and the user applies less than 80N of force to the steering wheel, the steering correction coefficient G... ain The value of is 0, and the target turning radius R ref Equal to the ideal turning radius R K That is, 3.11m, which is the ideal turning radius R calculated based on the active rear-wheel steering system. K Vehicle steering control, ideal turning radius R K No correction was made; therefore, the steering correction factor G was not used. ain Steering assist function is not activated; when the vehicle speed decreases to 10km / h, the steering wheel angle is turned to 350°, and the user applies a force of 80N to the steering wheel, the steering correction coefficient G... ain The value of is increased to 0.2, and the correction amount for the turning radius is 0.2 × 1.5m, which is 0.3m. Therefore, the target turning radius R ref The current steering correction factor is 2.81m. ain To reduce the vehicle's turning radius, but not to the limit, the steering assist function is partially activated; when the vehicle speed further decreases to 2 km / h or below, the steering wheel angle is turned to 400° or more, and the user applies a force of 100N to the steering wheel, the steering correction coefficient G... ain The value of is increased to 1, the correction amount for the turning radius is 1 × 1.5m, that is, 1.5m, and the target turning radius R ref The target turning radius is 1.61m. ref When the minimum value is reached, the steering assist function is fully activated.

[0154] In the first mapping relationship shown in Table 1 above, the third vehicle speed range, the third turning angle range, and the third hand force range are divided into multiple sub-ranges, and each sub-range is configured with a steering correction coefficient G. ain Therefore, by finding the sub-interval containing the current vehicle speed, current steering wheel angle, and current steering wheel force, the corresponding steering correction coefficient G can be directly obtained. ain The value of is determined based on this first mapping relationship. Within the same sub-interval, each vehicle speed, each steering wheel angle, and each steering wheel force will be assigned the same steering correction coefficient G. ain Therefore, even if there are slight fluctuations in vehicle speed, the force applied to the steering wheel by the user, and the steering wheel angle, as long as the fluctuation amount does not exceed the range of the sub-interval, the target turning radius will not change, thus the vehicle can turn stably and the user's steering experience is better.

[0155] But the above table 1 is only a possible implementation of the first mapping relationship, which can also have other implementations. For example, in another possible implementation, the third speed interval, the third steering angle interval and the third hand force interval can also be configured in the form of a formula, when the vehicle speed belongs to the third speed interval, the steering wheel steering angle belongs to the third steering angle interval, and the steering wheel hand force belongs to the third hand force interval, the vehicle speed, the steering wheel steering angle and the steering wheel hand force are directly substituted into the formula, and the corresponding steering correction coefficient G ain The value can be calculated. Using the first mapping relationship, as long as the vehicle speed, the steering wheel steering angle and the steering wheel hand force change, the value of the corresponding steering correction coefficient G ain The target turning radius will also change, so the target turning radius will change in real time with the user's steering force, steering angle and vehicle speed. Or, it can also be other implementations, which are not listed here.

[0156] Based on the above steps, by monitoring the operation parameters related to the driver (or also including the parameters related to the driving safety), the driver's small radius steering intention can be identified, and the corresponding steering correction coefficient can be calculated according to the driver's small radius steering intention, and then the corresponding target steering radius is generated. The steering correction coefficient is a first mapping relationship related to vehicle speed, steering wheel steering angle, steering wheel hand force: the steering correction coefficient in the interval of high vehicle speed, small steering wheel steering angle, light steering wheel hand force is reduced to the lowest, i.e. 0, and the current steering assistance gain is not generated; the steering correction coefficient in the interval of low vehicle speed, large steering wheel steering angle, heavy steering wheel hand force is increased to the highest, i.e. 1, and the current maximum steering assistance gain is generated; the steering correction coefficient in the interval of medium vehicle speed, medium steering wheel steering angle, medium steering wheel hand force increases with the decrease of vehicle speed, the increase of steering angle and the increase of steering hand force. Based on the first mapping relationship, the driver's steering intention can be made explicit, and the final control target can be integrated, so that the turning radius of the vehicle can change with the change of the driver's steering intention, giving the driver a feeling that the vehicle's turning radius can be controlled by manually operating the steering wheel.

[0157] But it should be understood that the above steps are only introduced by taking the example of the steering correction coefficient being related to the three factors of vehicle speed, steering wheel angle and steering wheel hand force at the same time, but in actual scenarios, the steering correction coefficient can also be related to only one or two factors, such as only related to the steering wheel angle, or only related to the steering wheel angle and the steering wheel hand force, or only related to the steering wheel angle and the vehicle speed, etc. In these cases, the steering correction coefficient can be calculated only by referring to the relevant one or two factors. For example, in the automatic driving scenario, the driver will not manually operate the steering wheel, therefore, there is no steering wheel hand force, in this case, the steering correction coefficient can be determined only by referring to the steering wheel angle and the vehicle speed, such as if the steering wheel angle is in the first steering angle interval and the vehicle speed is in the first vehicle speed interval, the steering correction coefficient is 1, if the steering wheel angle is in the third steering angle interval and the vehicle speed is in the third vehicle speed interval, the steering correction coefficient is 0, if the steering wheel angle is in the second steering angle interval and the vehicle speed is in the second vehicle speed interval, the steering correction coefficient is between 0 and 1, and is inversely proportional to the vehicle speed and proportional to the steering wheel angle. The specific implementation can refer to the above content, which will not be repeated here.

[0158] Step 603, controlling the driving shaft to output the first difference torque according to the target turning radius.

[0159] Optionally, after the target turning radius is calculated according to the above method, the steering control device 310 can calculate the first difference torque by the following steps one to three, and control the driving shaft to output the first difference torque:

[0160] Step one, the steering control device 310 calculates the corresponding target yaw rate according to the target turning radius.

[0161] For example, the target yaw rate can be calculated according to the following formula (3.1):

[0162] Wherein, ω ref is the target yaw rate, V x is the vehicle speed, and R ref is the target turning radius.

[0163] Based on this, assuming that the vehicle speed V x is 1 m / s, and the target turning radius R ref calculated in the above step 602 is 1.61 m, then these two parameters are substituted into the above formula (3.1), the target yaw rate ω ref can be calculated to be about 0.62 rad / s.

[0164] Step two, the steering control device 310 determines the required additional yaw moment according to the target yaw rate and the actual yaw rate.

[0165] Here, the actual yaw rate can be directly calculated from the information collected by the inertial measurement unit 334.

[0166] Optionally, based on the target yaw rate ω ref Assuming the actual yaw rate is ω IMU Then the target's yaw rate ω ref and actual yaw rate ω IMU The error between them is: Err ω =ω ref -ω IMU According to this error amount Err ω The required additional yaw moment can be calculated based on the following formula (3.2).

[0167] For example, in a specific case, the calculation method for the additional yaw moment can refer to the following formula (3.2):

[0168] Where, ΔM z To add yaw moment, 'a' is the distance from the vehicle's center of gravity to the front axle, K1 is the front wheel lateral stiffness, 'b' is the distance from the vehicle's center of gravity to the rear axle, K2 is the rear wheel lateral stiffness, and V... x For vehicle speed, β IMU The sideslip angle is the angle between the vehicle's center of gravity and its center of gravity.

[0169] For example, assuming the target's yaw rate is 0.62 rad / s, the actual yaw rate ω measured by the inertial measurement unit 334... IMU If the speed is 0.4 rad / s, then the error Err ω The value is 0.62 rad / s - 0.4 rad / s, which is 0.22 rad / s. Assume the distance *a* from the vehicle's center of gravity to the front axle and the distance *b* to the rear axle are both 1.5 m, and the vehicle speed is V. x 2m / s 2 The sideslip angle β of the vehicle's center of gravity IMU If the lateral stiffness is 0, the front wheel lateral stiffness K1 is 50000, and the rear wheel lateral stiffness K2 is 70000, then substituting the error of 0.22 rad / s and these parameters into the above formula (3.2), the additional yaw moment can be calculated.

[0170] Step 3: The steering control device 310 controls the drive shaft to output the first differential torque based on the additional yaw moment.

[0171] Here, based on the additional yaw moment ΔM calculated in step two above... z The steering control device 310 can control the output of the first differential torque of the vehicle's drive shaft. For example, it can control the inner wheel on the drive shaft to output negative torque and the outer wheel to output positive torque. The difference between the positive torque and the negative torque is equal to the first differential torque.

[0172] Optionally, in order to realize the stability of vehicle turning, the steering control device 310 can also gradually increase the first differential torque on the active shaft through a closed-loop control principle (such as a proportional-integral-derivative (PID) control algorithm or a similar control algorithm). For example, the steering control device 310 sends a torque request to the active shaft motor, which carries an additional yaw moment AM z . The active shaft motor responds to the torque request of the steering control device 310 in real time, outputs the first differential torque to the inner and outer wheels of the active shaft, and feeds back the actual torque of the current motor. According to the actual torque of the current motor, if the actual turning radius is found to be greater than the target turning radius, the steering control device 310 increases the additional yaw moment AM z carried in the torque request, and if the actual turning radius is found to be less than the target turning radius, the additional yaw moment carried in the torque request is reduced or negatively directed. In this way, the deviation between the actual yaw angular velocity and the target yaw angular velocity can be gradually reduced, so that the actual yaw angular velocity gradually approaches the target yaw angular velocity, and the fluctuation of the vehicle during the approaching process is small, and the stability of the vehicle turning is good. Moreover, the actual turning radius can also be repaired on some special road surfaces, such as in the working condition where the vehicle spin-out tendency increases on low adhesion road surfaces, causing the actual turning radius to decrease significantly. In this case, a reverse additional yaw moment can be generated to maintain the target turning radius and effectively follow the target turning radius.

[0173] Optionally, while the closed-loop control controls the first differential torque output by the active shaft, the passive shaft can not have a differential torque. To achieve this function, as shown in FIG. 5 above, independent motors can be configured on the left and right sides of the active shaft to separately control the inner and outer wheels of the active shaft and achieve the effect of outputting torque in different directions by the inner and outer wheels. The left and right sides of the passive shaft can have independent motors, or one motor, or no motor, but be connected through a mechanical structure, which is not limited in particular.

[0174] Further, optionally, the total torque of the whole vehicle also needs to be consistent with the torque requested by the driver, based on this, after calculating the first difference torque, the steering control device 310 also needs to obtain the torque requested by the driver, and according to the torque requested by the driver and the first difference torque, the torque is distributed to the driving shaft and the driven shaft, wherein the torque distributed on the driving shaft is used to make the inner and outer wheels have the first difference torque, and the sum of the torque distributed on the driving shaft and the torque distributed on the driven shaft is equal to the torque requested by the driver. For example, in the scene shown in (A) of FIG. 5, in the scene of one motor in the front wheel and two motors in the rear wheel, if the torque requested by the driver is 1000 Nm, and the first difference torque obtained by the closed-loop control method is 3000 Nm, then the steering control device 310 can control the right rear motor 3222 to provide -1500 Nm to the right rear wheel 122, and the left rear motor 3221 to provide +1500 Nm to the left rear wheel 121, and at the same time, control the front shaft motor 321 to provide +1000 Nm. In this way, the total torque of the torque +1000 Nm provided by the front shaft motor 321, the torque -1500 Nm provided by the right rear motor 3222, and the torque +1500 Nm provided by the left rear motor 3221 is 1000 Nm, which is consistent with the torque requested by the driver 1000 Nm.

[0175] Wherein, the torque requested by the driver can be directly calculated according to the information collected by the pedal position sensor 335. For example, when the driver has acceleration demand, he will step on the accelerator deeply, and the accelerator position sensor will send the depth information of the accelerator to the steering control device 310. The steering control device 310 calculates the current depth of the accelerator according to the depth information of the accelerator, and then queries the corresponding relationship between the preset torque and the depth corresponding to the accelerator to obtain the torque corresponding to the current depth of the accelerator. The torque is the torque requested by the driver. The deceleration process is similar, but the position sensor of the brake is used. The steering control device 310 calculates the depth of the brake according to the depth information collected by the brake position sensor, and then queries the corresponding relationship between the preset torque and the depth corresponding to the brake to obtain the torque corresponding to the current depth of the brake. The torque is the torque requested by the driver.

[0176] In some scenarios, according to the torque requested by the driver, the torque can also be distributed to the driving shaft and the driven shaft according to the optimal control principle. Based on the optimal distribution principle, in addition to referring to the number of driving motors on the front and rear shafts and the limit value of the driving capacity of each driving motor in the distribution process, the weight coefficient related to the wheel slip rate is also calculated to reduce the slip wheel torque distribution. In the case of priority to meet the consistency of the sum of the driving shaft torque and the driven shaft torque with the torque requested by the driver, the reasonable distribution of the total torque to each driving motor can be realized. Wherein, the specific implementation of the optimal control principle is related to the actual scene and the configuration mode of the person skilled in the art, which is not described in detail here.

[0177] In some scenarios, after the torque is distributed to the active shaft and the passive shaft based on the driver's requested torque and the first differential torque, the driver can also generate a new torque demand during the process of the vehicle steering according to the distributed torque, such as the driver continues to step on the accelerator or brake, or releases the accelerator or brake, which generates a new acceleration or deceleration demand, in which case the torque corresponding to the newly generated acceleration or deceleration demand can be responded by the passive shaft. For example, in combination with the above-mentioned FIG. 5, assuming that the passive shaft only has one passive shaft motor 321, the steering control device 310 can control the passive shaft motor 321 to increase or decrease the torque according to the new torque demand generated by the driver this time, in combination with the actual torque size of the left and right motors 3221 and 3222 of the active shaft, to play the role of more subtraction and less addition. In this way, even if the differential torque demand in the process of distributed differential torque steering and the driver's acceleration and deceleration demand are different, the passive shaft can respond to the difference, so that the active shaft still maintains the original differential torque demand, without affecting the small radius steering function of the active shaft, while keeping the sum of the passive shaft torque and the active shaft torque always matching the latest torque requested by the driver, so that the total torque of the vehicle meets the driver's acceleration and deceleration demand. The implementation scheme can decouple the lateral and longitudinal motion of the vehicle, control the lateral and yaw motion by using the differential torque of the active shaft and the steering, and control the longitudinal acceleration and deceleration by using the torque of the passive shaft, which can simultaneously meet the driver's acceleration and deceleration and reduce the steering radius demand.

[0178] In other scenarios, the driver's newly generated torque demand can be responded to by both the drive axle motor and the driven axle motor, or by the driven axle motor alone. For example, when the newly generated torque demand is less than or equal to a first threshold, it can be responded to by the driven axle motor alone; when it is greater than the first threshold, it can be responded to by the drive axle motor alone, or by both the drive axle motor and the driven axle motor together. For example, referring to Figure 5(A) above, assuming the front axle motor 321 provides a torque of +1000 Nm, the right rear motor 3222 provides a torque of -1500 Nm, and the left rear motor 3221 provides a torque of +1500 Nm, then: if the driver's newly generated torque demand is +400 Nm, if this torque demand is responded to by the front axle motor 321 alone, the torque provided by the front axle motor will become +1400 Nm. This torque is not much different from the torque provided by each rear axle motor, therefore, it is reasonable for the driver's newly generated torque demand to be responded to by the front axle motor 321 alone; however, if the driver's newly generated torque demand is +2000 Nm, if this torque demand is responded to by the front axle motor 321 alone... If the torque demanded by the front axle motor is met, the torque provided by the front axle motor will become +3000Nm. This torque differs significantly from the torque provided by each rear axle motor, which may cause vehicle instability during steering. Therefore, it is unreasonable for the front axle motor 321 to respond to this torque demand alone. Instead, both the front and rear axle motors can respond together. For example, the front axle motor can respond with 1000Nm, the left rear motor 3221 with 500Nm, and the right rear motor 3222 with 500Nm. In this case, the torque provided by the front axle motor becomes 2000Nm, the torque provided by the right rear motor 3222 becomes -1000Nm, and the torque provided by the left rear motor 3221 becomes +2000Nm. The torques of each motor are not significantly different, which is more reasonable.

[0179] In addition to controlling the torque of the drive and driven axles, the steering angles of the drive and driven wheels also need to be controlled when steering the vehicle. The driven wheel angle is determined by the steering wheel angle, while the drive wheel angle can be adjusted according to actual needs. For example, when the steering correction coefficient is at its maximum value, the driver's small-radius steering intention is greatest. Due to the very low vehicle speed, the steering wheel angle is very large, and the vehicle currently supports minimum radius steering. Therefore, the drive wheel angle can be configured to the maximum angle in the opposite direction. Here, "in the opposite direction" refers to the angle relative to the driven wheels. For example, if the drive wheels are the rear wheels and the driven wheels are the front wheels, then when the front wheels are at their maximum right turn angle, the rear wheels can be configured to their maximum left turn angle, and vice versa. In this way, when the driver's small-radius steering intention is greatest, by making the steering angles of the left and right wheels opposite and achieving the maximum angle difference, the fastest steering can be achieved, improving steering efficiency.

[0180] By using the above steering control method, the vehicle steering can be realized in combination with the turning radius and the differential torque, wherein the turning radius is controlled from the perspective of the steering center, which is equivalent to using the active rear wheel steering system, and the differential torque is controlled from the perspective of the yaw rate, which is equivalent to using the distributed electric drive steering system. Therefore, the above steering control method is equivalent to first calculating the turning radius that can not wear the tire by using the active rear wheel steering system, and then converting it to the differential torque control in the distributed electric drive steering system. In this way, the two steering systems can be coordinated together while not wearing the tire, the consistency of the control target is realized, and the aforementioned problem one existing in coordinating the two steering systems can be solved. In addition, the above steering control method ultimately realizes the follow-up of the target turning radius by closed-loop control of the differential torque. Therefore, the coordination logic between the two steering systems can be optimized while further reducing the turning radius, the coupling interference generated when the two steering systems are coordinated can be reduced, and the aforementioned problem two existing in coordinating the two steering systems can be solved.

[0181] The above describes the specific implementation of the steering control method in detail. The entire process of the steering control method from activation to exit will be described below. In the description, considering that the steering control method above will use the steering correction coefficient to correct the ideal turning radius when some conditions are met (low vehicle speed, large steering wheel angle, high steering wheel hand force), a steering assistance function is defined, which has four states: a closed state, an open state, a standby state, and an activated state. The closed state refers to a state in which the steering assistance function is not opened, the open state refers to a state in which the steering assistance function is opened, the standby state refers to a state in which the vehicle currently meets the set standby condition after the steering assistance function is opened, and the activated state refers to a state in which the user is truly assisted in steering.

[0182] Based on the four states of the steering assistance function, please refer to FIG. 7, which shows an implementation process schematic diagram of a steering assistance function provided by the present application. The method can be executed by a steering control device, such as the steering control device 310 in FIG. 3a. Taking the initial state of the steering assistance function as the closed state as an example, the method mainly includes the following steps:

[0183] Step 701, acquiring the vehicle speed and the steering wheel angle of the vehicle.

[0184] Optionally, the steering control device can acquire the vehicle speed and the steering wheel angle of the vehicle according to a first period. For example, the information collected by the speed sensor (or the information collected by the wheel speed sensor) and the information collected by the steering wheel angle sensor are acquired every 5 min, the vehicle speed is calculated according to the information collected by the speed sensor, the steering wheel angle is calculated according to the information collected by the steering wheel angle sensor, and then the following step 702 is executed according to the calculated vehicle speed and steering wheel angle.

[0185] In step 702, it is determined whether the vehicle speed and the steering wheel angle meet the first set condition. If yes, step 703 is performed. If no, step 701 is performed.

[0186] Optionally, the first set condition is that the vehicle speed is less than or equal to a second vehicle speed, and the steering wheel angle is greater than or equal to a second angle.

[0187] For example, assuming that the first period is 5 min, the second vehicle speed is 20 km / h, and the second angle is 300°, in combination with steps 701 and 702, the steering control device 310 can calculate the vehicle speed and the steering wheel angle every 5 min when the steering assist function is in the off state. If the vehicle speed is reduced to 20 km / h and the steering wheel angle is increased to 300°, it indicates that the driver is currently turning the steering wheel, and the vehicle is most likely to turn. Therefore, it can be determined whether to turn on the steering assist function through step 703. Conversely, if the vehicle speed is continuously higher than or equal to 20 km / h and the steering wheel angle is continuously below 300°, it indicates that the vehicle is less likely to turn. It can return to step 701, that is, wait until the end of the current first period, and then start the vehicle speed and steering wheel angle judgment operation in the next first period until the first set condition is met.

[0188] In step 703, it is determined whether the user indicates to turn on the steering assist function through human-computer interaction.

[0189] Here, the human-computer interaction has many possible implementation manners, such as voice interaction, interface interaction, gesture interaction, application (APP) interaction, key interaction, brain wave interaction, etc., and the specific implementation manner is not limited.

[0190] Taking voice interaction as an example, the steering control device can control the audio in the vehicle cabin to issue a voice content of “Do you want to turn on the steering assist function” or the like, and control the microphone in the vehicle cabin to collect the voice reply of the driver. If the driver replies with a voice content of “turn on” or “yes” or “confirm” or the like, it is determined that the user indicates to turn on the steering assist function, and the steering control device can perform step 704. If the driver replies with a voice content of “do not turn on” or “no” or the like, it is determined that the user indicates not to turn on the steering assist function. In this case, the steering control device can return to step 701, that is, wait until the end of the current first period, and then start the vehicle speed and steering wheel angle judgment operation in the next first period. Alternatively, the steering assist function can be directly exited (i.e., step 708), and the analysis is restarted according to step 701 when the vehicle is powered on next time.

[0191] For example, the steering control device can also be connected to the vehicle screen. After determining that the vehicle speed and the steering wheel turning angle meet the first set condition, the steering control device can control the vehicle screen to display a first pop-up. As an example, the first pop-up has the form shown in FIG. 8a. The first pop-up contains the text content “whether to turn on the steering assistance function” or the like, and two buttons “yes” and “no”. If the user clicks the “yes” button, it is determined that the user indicates to turn on the steering assistance function, and the following step 704 is performed. If the user clicks the “no” button, it is determined that the user indicates not to turn on the steering assistance function, and the process returns to step 701, or directly exits the steering assistance function.

[0192] It can be understood that before the user indicates to turn on the steering assistance function, the steering assistance function is in an off state.

[0193] It should be noted that the above steps 701 to 703 are to set the triggering condition (the first set condition), and after the triggering condition is met, the user is interacted with to determine whether to turn on the steering assistance function. However, this is only one possible starting mode, and other starting modes are also possible. For example, in another possible starting mode, the control for turning on the steering assistance function can be pre-configured on the vehicle screen, such as the “steering assistance control” button shown in FIG. 8b. The user directly clicks the “steering assistance control” button on the vehicle screen to directly turn on the steering assistance function. For another example, a set gesture for turning on the steering assistance function can be pre-configured. When the in-vehicle camera captures that the user has made the set gesture, the steering control function is directly triggered. For another example, the steering assistance function can be automatically turned on after determining that the vehicle speed and the steering wheel turning angle meet the first set condition, without the need for user confirmation. There are many possible starting modes, which are not listed here.

[0194] Step 704: Determine whether the gear of the vehicle meets the second set condition. If yes, perform step 705. If no, perform step 708.

[0195] Optionally, the second set condition is that the gear of the vehicle is not the parking gear (P gear). In other words, the gear of the vehicle is one of the forward gear (D gear), the reverse gear (R gear), or the neutral gear.

[0196] Optionally, after the steering control function is turned on, the steering control device can acquire the gear information of the vehicle, and determine the current gear of the vehicle according to the gear information. If the current gear is a non-parking gear, it means that the vehicle is currently in forward or reverse, and the previous low speed and large steering wheel angle state is probably to turn in the forward process or turn in the reverse process, rather than parking. Therefore, the steering control device can enter the standby state of the steering assistance function, and execute the following step 705 in the standby state to determine when to start assisting the user to steer in real time. Conversely, if the current gear is a parking gear, it means that the vehicle is currently to be parked, and the previous low speed and large steering wheel angle is also because of the reason to park, rather than to turn. Therefore, the steering control device can execute the following step 708 to turn off the steering assistance function, in other words, make the steering assistance function return to the off state, until the next time the vehicle is restarted, and the first set condition is met, and then the steering assistance function will enter the on state again.

[0197] For example, taking 5 minutes as the first period, the steering control device determines whether to turn on the steering assistance function every 5 minutes. Once the steering assistance function is turned on, the gear state of the vehicle is acquired. If the gear state is a non-parking gear, the standby state of the steering assistance function is entered. Conversely, the steering assistance function is exited.

[0198] Step 705: Determine whether the vehicle speed and steering wheel angle meet the third set condition. If yes, execute step 706. If no, execute step 707.

[0199] Optionally, the third set condition is that the vehicle speed is less than or equal to the first vehicle speed, and the steering wheel angle is greater than or equal to the first steering angle. The first vehicle speed is lower than the second vehicle speed, and the first steering angle is greater than the second steering angle. For example, the second vehicle speed is 20 km / h, and the second steering angle is 300°. The first vehicle speed can be 10 km / h, and the first steering angle can be 350°. Alternatively, the first vehicle speed can be 9 km / h, and the first steering angle can be 360°. Alternatively, the first vehicle speed can be 6 km / h, and the first steering angle can be 400°. And so on, without limitation.

[0200] Optionally, after entering the standby state of the steering assistance function, the steering control device can acquire the vehicle speed and steering wheel angle according to a second period. The second period is less than the first period. For example, the first period is 5 minutes, and the second period can be 1 minute, 2 minutes, 3 minutes, and so on, without limitation.

[0201] For example, taking the second period as 1 min, the first vehicle speed as 10 km / h, and the first turning angle as 350° as an example, after entering the standby state of the steering assist function, the steering control device can obtain the information collected by the vehicle speed sensor (or the information collected by the wheel speed sensor) and the information collected by the steering wheel angle sensor every 1 min, calculate the vehicle speed according to the information collected by the vehicle speed sensor, calculate the steering wheel angle according to the information collected by the steering wheel angle sensor, and then determine whether the calculated vehicle speed is less than or equal to 10 km / h and whether the steering wheel angle is greater than or equal to 350°. If the vehicle speed is less than or equal to 10 km / h and the steering wheel angle is greater than or equal to 350°, it is determined that the steering assist function enters the active state, and the steering control device performs the following step 706 to assist the user in steering. If the vehicle speed is greater than 10 km / h or the steering wheel angle is less than 350°, it is determined that the current vehicle state cannot activate the steering assist function, and therefore, after the current second period ends, the comparison operation of the vehicle speed and the steering wheel angle in the next second period is started, and this process is repeated until it is determined that the third set condition is met.

[0202] Step 706: controlling at least one axle of the vehicle to output a first difference torque according to the steering wheel angle and the steering wheel hand force.

[0203] Here, after the steering control device determines that the steering assist function enters the active state, it can assist the vehicle in steering according to the method in step 402 described above. For example, the steering control device obtains the steering wheel angle and the steering wheel hand force, or can also obtain the vehicle speed, determines the ideal turning radius according to the steering wheel angle, determines the steering correction coefficient according to the vehicle speed, the steering wheel angle, and the steering wheel hand force, corrects the ideal turning radius using the steering correction coefficient to obtain the target turning radius, and then controls the driving axle of the vehicle to output the first difference torque according to the target turning radius. For specific implementation process of assisting steering, please refer to the description of step 402 and FIG. 6 above, which will not be repeated here.

[0204] Step 707: determining whether the vehicle speed meets a fourth set condition. If yes, step 705 is performed; if no, step 708 is performed.

[0205] Optionally, the fourth set condition includes that the vehicle speed is less than or equal to a second vehicle speed. Optionally, the fourth set condition can also include that the gear position is not a parking gear. The fourth set condition can be regarded as a condition for determining whether to exit the steering assist function. When the vehicle speed is less than or equal to the second vehicle speed and the gear position is not the parking gear, the fourth set condition is met, and the steering assist function continues to be started. Conversely, when the vehicle speed is greater than the second vehicle speed, the current vehicle has accelerated, and it may be unsafe to continue to make small-radius turns, and therefore, the steering assist function needs to be exited. When the gear position is the parking gear, it means that the current vehicle has stopped, and the vehicle no longer needs to turn, and therefore, the steering assist function also needs to be exited.

[0206] For example, taking 20km / h as the second speed, in the standby state of the steering assist function, the steering control device can determine whether to exit the steering assist function once after determining not to activate the steering assist function each time. If it is found that the vehicle speed increases to 20km / h or above, and / or the vehicle is switched to the parking gear, it indicates that the current conditions for starting the steering assist function are no longer met, and therefore the steering control device can execute the following step 708 to turn off the steering assist function. Conversely, if the vehicle speed is still less than or equal to 20km / h, and the vehicle is still not in the parking gear, it indicates that the current conditions for starting the steering assist function are still met, and therefore the steering control device can wait until the end of the current second period, and then start the comparison operation of the steering wheel angle and the vehicle speed in the next second period, until the third set condition is met, and the steering assist function is activated.

[0207] Step 708, exit the steering assist function.

[0208] It can be understood that when the steering assist function is in the off state or standby state, the steering correction coefficient is 0, and when the steering assist function enters the activated state, the steering correction coefficient is a value between 0 and 1, including 1. That is to say, only in the activated state of the steering assist function, the steering correction coefficient is used to correct the ideal turning radius to meet the driver's small radius steering intention. In the off state and standby state, the steering correction coefficient is not used to correct the ideal turning radius, and in these states, large turns can be made to meet the driver's demand for large radius steering intention.

[0209] Optionally, after detecting the signal of the vehicle power-off, the steering control device can also save the current state of the steering assist function, and directly restore the state after the next vehicle power-on. For example, assuming that the activated state before power-off, then after the next power-on, the steering assist function directly restores to the activated state, and the steering control device directly assists the user to steer according to the above-mentioned manner in step 706, so as to drive out of the curve entered before power-off. For another example, if the standby state before power-off, then after the next power-on, the steering assist function restores to the standby state, and the steering control device executes the above-mentioned step 705, that is, acquires the vehicle speed and steering wheel angle, and directly activates the steering assist function after determining that the third set condition is met, and exits the steering assist function when the fourth set condition is met. For another example, if the off state before power-off, then after the next power-on, the steering assist function also restores to the off state, and after the next power-on, the steering control device starts from the above-mentioned step 701 to gradually determine whether to start the steering assist function, whether to enter the standby state, whether to activate the standby state, whether to exit the steering assist function, and so on.

[0210] Based on the above method, the vehicle can directly restore the state of the steering assist function before power-off after power-on, so that it is not necessary to execute each step from the closed state step by step, and a certain response time can be saved, and the response speed of the auxiliary steering is improved.

[0211] Based on the above-described steering control method, two specific application scenarios are given below to illustrate the auxiliary effect of the steering control method.

[0212] Application scenario one

[0213] In application scenario one, it is assumed that the rear axle of the vehicle is the driving axle, the front axle of the vehicle is the driven axle, the first vehicle speed is 10 km / h, the second vehicle speed is 20 km / h, the first steering angle is 350°, and the second steering angle is 300°.

[0214] Referring to FIG. 9, a schematic diagram of a steering control trajectory corresponding to application scenario one provided by the present application is shown. In application scenario one, the vehicle is driving on the inside lane of a crossroad or a narrow road in the countryside, and needs to make a U-turn. Since the road is narrow, there is currently a small-radius U-turn requirement, and the above steering control scheme needs to be used to assist the U-turn, which specifically includes the following steps:

[0215] Step one, before the vehicle makes a U-turn, the vehicle speed will decrease, and the steering wheel angle will increase. When the vehicle speed is 20 km / h or below, and the steering wheel angle is 300° or above, the steering assist function is turned on.

[0216] Step two, in the current scenario, the vehicle makes a U-turn to the left during forward driving, the vehicle is in the forward gear, and the steering assist function is in standby state.

[0217] Step three, when approaching the U-turn position, the vehicle speed continues to decrease, and the driver turns the steering wheel to the left to the maximum angle. When the vehicle speed is 10 km / h, and the steering wheel angle is 350°, the system determines that the driver currently has a small-radius steering intention, and the steering assist function is activated.

[0218] Step four, the front wheel angle becomes the maximum left angle according to the steering wheel angle, the rear wheel angle is controlled to the maximum right angle, and the vehicle calculates the first differential torque according to the current vehicle speed, the steering wheel angle, and the steering wheel hand force. The inside motor of the rear axle outputs a negative torque, and the outside motor of the rear axle outputs a positive torque. The differential torque output by the inside and outside motors of the rear axle is the first differential torque, which is used to control the reduction of the turning radius. The effect of reducing the turning radius is related to the strength of the first differential torque, which is controlled by the vehicle speed, the angle of the driver turning the steering wheel, and the hand force.

[0219] Step five, during the turning process, if the driver is detected to step on the accelerator pedal, the front axle motor is controlled to increase torque to respond to the acceleration demand, if the driver is detected to release the accelerator pedal, the front axle motor is controlled to reduce torque, if the driver is detected to step on the brake pedal, kinetic energy recovery is performed to respond to the deceleration demand;

[0220] Step six, after the vehicle completes the turning, the driver will return the steering wheel to the normal position, and the vehicle detects the driver's intention to return the steering wheel to the normal position, ends this time of steering assistance, controls the rear wheel angle to decrease, and controls the inner and outer motors of the rear axle to no longer provide differential torque, and the steering assistance function enters a standby state;

[0221] Step six, the driver steps on the accelerator pedal, and the vehicle speed increases, when the vehicle speed increases to 20 km / h, or the gear is switched to the parking gear, the steering assistance function is automatically turned off.

[0222] In the above application scenario one, when the vehicle turns at the intersection or the narrow road in the countryside, the working condition is determined based on the steering wheel angle and the vehicle speed, and the steering assistance function is activated if the condition is met, which assists the vehicle to realize small-radius turning. Wherein, the turning track before assistance is W1 in FIG. 9, and the turning track after assistance is W2 in FIG. 9. W1 is the track of the ideal turning radius calculated based on the maximum angle control principle of the active rear wheel steering system, W2 is the track of the target turning radius obtained by correcting the ideal turning radius combined with the vehicle speed and the driver's operation information on the steering wheel, and the target turning radius and the corresponding yaw angular velocity are followed by calculating through the torque control of the distributed electric drive, so that the actual turning radius of the vehicle tends to the target turning radius, and the best steering control effect is realized.

[0223] Application scenario two

[0224] In the application scenario two, it is assumed that the rear axle of the vehicle is the active axle, the front axle of the vehicle is the passive axle, the first vehicle speed is 10 km / h, the second vehicle speed is 20 km / h, and the first turning angle is 350°.

[0225] Please refer to FIG. 10, which shows the schematic diagram of the steering control track corresponding to the application scenario two provided by the present application. In the application scenario two, the vehicle has a side-out requirement, and due to the narrow parking area, there is a small-radius turning requirement at present, which needs to be assisted by the above steering control scheme, which specifically includes the following steps:

[0226] Step one, when there is a side-out requirement, the driver clicks the control on the car machine screen as shown in FIG. 8b to start the steering assistance function;

[0227] Step two, in the current scenario, the vehicle is leaving the garage to the left, the driver turns the steering wheel to the left to the maximum angle, and lifts the brake, the vehicle is switched to neutral, the steering assist function enters standby state, and because the vehicle speed is very low, the steering wheel angle is turned to the maximum angle, so the vehicle speed is less than 10 km / h, the steering wheel angle is greater than 350°, the system determines that the driver currently has a small radius steering intention, and the steering assist function is activated;

[0228] Step three, the front wheel angle becomes the maximum left angle with the steering wheel angle, the vehicle controls the rear wheel angle to be the maximum reverse angle, that is, the rear wheel angle is the maximum right angle, the vehicle calculates the first differential torque according to the current vehicle speed, the steering wheel angle and the steering hand force, controls the inner motor of the rear axle to output a negative torque and the outer motor of the rear axle to output a positive torque, and the differential torque output by the inner and outer motors of the rear axle is the first differential torque, which is used to control the reduction of the turning radius, and the effect of the reduction of the turning radius is related to the strength of the first differential torque and is controlled by the vehicle speed, the angle of the steering wheel turned by the driver and the steering hand force;

[0229] Step four, the driver maintains the maximum steering angle and a certain steering hand force, steps on the accelerator or crawls to control the vehicle to complete the small radius side-out garage. During the garage-out process, the acceleration demand generated by the driver stepping on the accelerator or releasing the accelerator and the deceleration demand generated by the driver stepping on the brake or releasing the brake are responded by the vehicle control front axle torque, the rear axle torque remains the first differential torque, and the front and rear axle torques remain the same as the torque requested by the driver;

[0230] Step five, after the vehicle completes the garage-out, the vehicle detects the steering wheel return, controls the rear wheel angle to decrease, and controls the inner and outer motors of the rear axle to no longer provide differential torque. When the driver accelerates the vehicle to a speed exceeding 20 km / h or the gear is switched to the parking gear, the auxiliary steering function is automatically turned off.

[0231] In the above application scenario two, when the vehicle is leaving the garage to the side, the working condition is determined based on the steering wheel angle and the vehicle speed, the steering assist function is activated if the condition is met, and the vehicle is assisted to realize small radius steering. Wherein, the steering track before being assisted is W1 in FIG. 10, and the steering track after being assisted is W2 in FIG. 10. W1 is the track of the ideal turning radius calculated based on the maximum angle control principle of the active rear wheel steering system, W2 is the track of the target turning radius obtained by modifying the ideal turning radius combined with the vehicle speed and the operation information of the steering wheel by the driver, the target turning radius and the corresponding yaw angular velocity are followed by the torque control of the distributed electric drive, so that the actual turning radius of the vehicle tends to the target turning radius, and the best garage-out control effect is realized.

[0232] Based on the above-described steering control method, the application can also provide a steering control device, which can be used to execute the above steering control method, and the related features can be referred to the above embodiments, which will not be described here.

[0233] In a possible implementation, FIG. 11 shows a possible structural schematic diagram of a steering control apparatus provided in the present application. The steering control apparatus 1100 can include modules or units for implementing the corresponding embodiments of the above method. For example, in a possible design, the steering control apparatus 1100 includes a processing unit 1110 and a transceiver unit 1120.

[0234] The processing unit 1110 can also be referred to as a processor, a processing chip, a processing board, a processing unit, or a processing apparatus, and the transceiver unit 1120 can also be referred to as a communication unit, a transceiver, a transceiver, or a transceiver apparatus. Optionally, the processing unit 1110 is configured to perform the processing operations in the above steering control method, and the transceiver unit 1120 is configured to perform the sending operations and the receiving operations in the above steering control method. The devices in the transceiver unit 1120 for implementing the receiving function can be regarded as a receiving unit, and the devices in the transceiver unit 1120 for implementing the sending function can be regarded as a sending unit, that is, the transceiver unit 1120 includes a receiving unit and a sending unit.

[0235] The steering control apparatus 1100 can be a steering control apparatus or a module (for example, a circuit, a chip, or a chip system) in the steering control apparatus in the above embodiments, or can also be a logic node, a logic module, or software applied to or matched with the steering control apparatus or the module thereof, and capable of realizing all or part of the functions of the steering control apparatus.

[0236] For example, in one embodiment, the transceiver unit 1120 is configured to acquire the vehicle speed and the steering wheel angle, and the processing unit 1110 is configured to determine, according to the vehicle speed and the steering wheel angle, that the vehicle enters a low-speed steering scene, and then control at least one axle of the vehicle to output a first differential torque according to the steering wheel angle and the steering wheel hand force of the vehicle. Wherein the outer wheel of the at least one axle outputs a positive torque, the inner wheel of the at least one axle outputs a negative torque, and the difference between the positive torque and the negative torque is the first differential torque.

[0237] In a possible implementation, the processing unit 1110 determines, according to the vehicle speed and the steering wheel angle, that the vehicle enters a low-speed steering scene, which can specifically be: determining that the vehicle speed is less than or equal to a first vehicle speed, and the steering wheel angle is greater than or equal to a first steering wheel angle.

[0238] In a possible implementation, the processing unit 1110 controls at least one axle of the vehicle to output a first differential torque according to the steering wheel angle and the steering wheel hand force of the vehicle, which can specifically be: determining an ideal turning radius according to the steering wheel angle, correcting the ideal turning radius according to the steering wheel angle and the steering wheel hand force to obtain a target turning radius, and then controlling at least one axle of the vehicle to output the first differential torque according to the target turning radius.

[0239] In a further possible implementation form, the processing unit 1110 determines the ideal turning radius from the steering wheel angle, in particular by first determining a passive wheel angle from the steering wheel angle, the passive wheel angle being in a positive proportion to the steering wheel angle, and then determining the ideal turning radius from the passive wheel angle based on the following formula: wherein R k is the ideal turning radius, c1 is a distance of a projection of an instantaneous steering center onto the front axle in a driving direction of the vehicle, δ f is the passive wheel angle, b is a distance of a center of mass of the vehicle to the rear axle, and c2 is a distance of a projection of the instantaneous steering center onto the rear axle in the driving direction of the vehicle.

[0240] In a further possible implementation form, the processing unit 1110 corrects the ideal turning radius from the steering wheel angle and a steering wheel hand force to obtain a target turning radius, in particular by determining a steering correction coefficient from the vehicle speed, the steering wheel angle and the steering wheel hand force, and correcting the ideal turning radius using the steering correction coefficient to obtain the target turning radius.

[0241] In a further possible implementation form, the processing unit 1110 corrects the ideal turning radius based on the following formula to obtain the target turning radius: R ref = R K - D x G ain wherein R ref is the target turning radius, R K is the ideal turning radius, G ain is the steering correction coefficient, and D is a constant coefficient.

[0242] In a further possible implementation form, the steering correction coefficient has a first mapping relationship with the vehicle speed, the steering wheel angle and the steering wheel hand force, in the first mapping relationship: the vehicle speed is in a first vehicle speed interval, the steering wheel angle is in a first steering angle interval, the steering wheel hand force is in a first hand force interval, and the steering correction coefficient is 1; the vehicle speed is in a second vehicle speed interval, the steering wheel angle is in a second steering angle interval, the steering wheel hand force is in a second hand force interval, and the steering correction coefficient is 0; the vehicle speed is in a third vehicle speed interval, the steering wheel angle is in a third steering angle interval, the steering wheel hand force is in a third hand force interval, and the steering correction coefficient is a third value, the third value being greater than 0 and less than 1. The third vehicle speed interval is greater than the first vehicle speed interval and less than the second vehicle speed interval, the third steering angle interval is greater than the second steering angle interval and less than the first steering angle interval, and the third hand force interval is greater than the second hand force interval and less than the first hand force interval.

[0243] In a possible implementation, the processing unit 1110 controls at least one axle of the vehicle to output the first differential torque according to the target turning radius, specifically, the processing unit 1110 can first determine a target yaw rate corresponding to the target turning radius, and then determine an additional yaw moment according to an actual yaw rate of the vehicle and the target yaw rate, and then control at least one axle of the vehicle to output the first differential torque according to the additional yaw moment.

[0244] In a further possible implementation, the processing unit 1110 determines the additional yaw moment based on the following formula:

[0245] where ΔM z is the additional yaw moment, a is a distance from a center of mass of the vehicle to a front axle, K1 is a front wheel cornering stiffness, b is a distance from the center of mass of the vehicle to a rear axle, K2 is a rear wheel cornering stiffness, V x is a vehicle speed, ω ref is the target yaw rate, ω IMU is an actual yaw rate, and β IMU is a cornering angle of the center of mass of the vehicle.

[0246] In a possible implementation, the at least one axle of the vehicle is an active axle, and the processing unit 1110 controls a passive axle of the vehicle to respond to the changed torque if the processing unit 1110 detects that a torque requested by a driver changes after the processing unit 1110 controls the at least one axle of the vehicle to output the first differential torque.

[0247] In a possible implementation, the at least one axle of the vehicle is an active axle, and an inner wheel and an outer wheel of the active axle use different motors, or an inner wheel and an outer wheel of the passive axle share the same motor or use different motors.

[0248] In a further possible implementation, the processing unit 1110 controls a maximum turning angle of a driven wheel in a first direction if the processing unit 1110 detects that the maximum turning angle of the driven wheel in the first direction before the processing unit 1110 controls the at least one axle of the vehicle to output the first differential torque.

[0249] In a possible implementation, the processing unit 1110 determines that the user instructs to turn on the steering assistance function by performing human-computer interaction with the user through the transceiver 1120 if the processing unit 1110 detects that the vehicle speed is less than or equal to a second vehicle speed and the steering wheel angle is greater than or equal to a second steering wheel angle before the processing unit 1110 determines that the vehicle enters the low-speed steering scenario according to the vehicle speed and the steering wheel angle.

[0250] In a possible implementation, the processing unit 1110 needs to first determine that the vehicle is in a forward gear, a reverse gear, or a neutral gear before the processing unit 1110 controls the at least one axle of the vehicle to output the first differential torque according to the steering wheel angle and the steering wheel hand force of the vehicle.

[0251] In a possible implementation, the processing unit 1110 controls the at least one axle of the vehicle to output a torque in the same direction after the first difference torque is output.

[0252] It can be understood that the division of units in the above device is only a logical division of functions, one function can correspond to one functional unit, or two or more functions can be integrated into one functional unit. In actual implementation, all or part of the units can be integrated into one physical entity, or can be distributed in different physical entities. In addition, the above functional units can be implemented in the form of hardware, or in the form of software, or in the form of hardware combined with software. Whether a certain function is executed in the form of hardware or software depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for a specific application, but such implementation should not be considered beyond the scope of the present application.

[0253] In one example, the functional units in any of the above steering control devices can be one or more integrated circuits configured to implement the above methods, such as one or more application specific integrated circuits (ASICs), or one or more central processing units (CPUs), one or more microcontroller units (MCUs), one or more digital signal processors (DSPs), or one or more field programmable gate arrays (FPGAs), or a combination of at least two of these integrated circuit forms.

[0254] In another possible implementation, please refer to Fig. 12, which shows another possible structural schematic diagram of the steering control device. The steering control device 1200 shown in Fig. 12 comprises at least one processor 1210 and an interface circuit 1220, the at least one processor 1210 is coupled with a memory, which can be located in the steering control device 1200, integrated with the processor 1210, or located outside the steering control device 1200. For example, the steering control device 1200 can further comprise at least one memory 1230. The at least one memory 1230 stores the computer programs (or instructions) and / or data necessary for implementing any of the above embodiments; the at least one processor 1210 can execute the computer programs (or instructions) and / or data stored in the at least one memory 1230 to complete the steering control method in any of the above embodiments.

[0255] The steering control device 1200 can interact with other devices through the interface circuit 1220. For example, the interface circuit 1220 can be a transceiver, a circuit, a bus, a module, a pin, or other types of communication interfaces. When the steering control device 1200 is a chip-type device or a circuit, the interface circuit 1220 in the steering control device 1200 can also be an input-output circuit, which can input (or receive) information and output (or send) information; the processor can be an integrated processor or a microprocessor or an integrated circuit or a logic circuit, which can determine the output information according to the input information.

[0256] The coupling in the embodiments of the present application is an indirect coupling or communication connection between devices, units or modules, which can be electrical, mechanical or other forms, for information interaction between devices, units or modules. The processor 1210 can operate cooperatively with the memory 1230 and the interface circuit 1220. The specific connection medium between the processor 1210, the memory 1230 and the interface circuit 1220 is not limited in the embodiments of the present application.

[0257] Optionally, as shown in Fig. 12, the processor 1210, the interface circuit 1220 and the memory 1230 are connected with each other through a bus. The bus can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the convenience of representation, only one thick line is shown in Fig. 12, but it does not mean that there is only one bus or only one type of bus.

[0258] In the embodiments of the present application, the processor 1210 can be a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic, a discrete hardware component, and can implement or execute the disclosed methods, steps and logic block diagrams in the embodiments of the present application. The general purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as hardware processor execution or executed by a combination of hardware and software modules in the processor.

[0259] In the embodiments of the present application, the memory 1230 can be a non-volatile memory such as a hard disk drive (HDD) or a solid-state drive (SSD), and can also be a volatile memory such as a random-access memory (RAM). The memory 1230 can be any other medium capable of carrying or storing desired program codes in the form of instructions or data structures and capable of being accessed by a computer, but is not limited to this. The memory 1230 in the embodiments of the present application can also be a circuit or any other device capable of realizing a storage function, used for storing program instructions and / or data.

[0260] When the steering control device 1200 is used to implement the above-mentioned method embodiments, the interface circuit 1220 is used to implement the functions of the above-mentioned transceiver unit 1120, and the processor 1210 is used to implement the functions of the above-mentioned processing unit 1110, which will not be repeated here.

[0261] In yet another possible implementation, please refer to FIG. 13, which shows another possible structural schematic diagram of a steering control device. The steering control device shown in FIG. 13 includes a state observer 1310, a rear wheel steering system and model 1320, an extreme steering assistant 1330 and a distributed electric drive actuator 1340. Among them, the state observer 1310 includes a vehicle state estimation module 1311 and a driver input module 1312, and the extreme steering assistant 1330 includes a steering assistance intention recognition module 1331, a coordination module 1332 and a yaw target calculation module 1333. The state observer 1310 is connected to the rear wheel steering system and model 1320, the steering assistance intention recognition module 1331, the yaw target calculation module 1333 and the distributed electric drive actuator 1340 respectively, the coordination module 1332 is connected to the steering assistance intention recognition module 1331, the rear wheel steering system and model 1320 and the yaw target calculation module 1333 respectively, and the distributed electric drive actuator 1340 is connected to the yaw target calculation module 1333 and each motor in the vehicle, such as the in-wheel motor of the driving axle, the out-wheel motor of the driving axle and the passive axle motor.

[0262] In the state observer 1310, the vehicle state estimation module 1311 receives information collected from the wheel speed sensor and the inertial measurement unit, calculates the wheel speed of the vehicle according to the information collected by the wheel speed sensor, calculates the longitudinal acceleration and the yaw rate according to the information (vehicle body posture change information) collected by the inertial measurement unit, calculates the reference vehicle speed of the vehicle according to the wheel speed and the longitudinal acceleration of the vehicle, and sends the reference vehicle speed to the rear wheel steering system and model 1320 and the steering assist intention recognition module 1331 respectively, and sends the yaw rate to the yaw target calculation module 1333.

[0263] In the state observer 1310, the driver input module 1312 receives information collected from the steering wheel angle sensor, the steering wheel hand force sensor (or torque sensor, etc.), the position sensor of the accelerator pedal, and the position sensor of the brake pedal, determines the passive wheel angle according to the information (angle information, which can be the original steering wheel input angle or the converted wheel angle) collected by the steering wheel angle sensor, calculates the steering wheel hand force according to the information collected by the steering wheel hand force sensor, calculates the requested torque of the driver according to the information (acceleration intention information, which can be the position stroke of the accelerator pedal or the converted acceleration torque request) collected by the position sensor of the accelerator pedal and the information (braking intention information, which can be the brake push rod stroke, or the master cylinder pressure, or the converted braking request) collected by the position sensor of the brake pedal. The driver input module 1312 sends the passive wheel angle to the rear wheel steering system and model 1320, sends the steering wheel hand force and the steering wheel angle to the steering assist intention recognition module 1331, and sends the requested torque of the driver to the distributed electric drive actuator 1340.

[0264] The rear wheel steering system and model 1320 calculates the active wheel angle according to the reference vehicle speed from the vehicle state estimation module 1311 and the passive wheel angle from the driver input module 1312, and calculates the ideal turning radius according to the active wheel angle and the passive wheel angle, and sends the ideal turning radius to the coordination module 1332.

[0265] In the extreme steering assist 1330, the steering assist intention recognition module 1331 calculates a steering correction coefficient according to the reference vehicle speed from the vehicle state estimation module 1311, and the steering wheel hand force and steering wheel angle from the driver input module 1312, and sends the steering correction coefficient to the coordination module 1332. The coordination module 1332 uses the steering correction coefficient from the steering assist intention recognition module 1331 to correct the ideal turning radius from the rear wheel steering system and model 1320, obtains a target turning radius, and sends it to the yaw target calculation module 1333. The yaw target calculation module 1333 calculates an additional yaw moment according to the target turning radius from the coordination module 1332 and the yaw angular velocity from the vehicle state estimation module 1311, and sends the additional yaw moment to the distributed electric drive actuator 1340.

[0266] The distributed electric drive actuator 1340 generates the driving torque of the distributed electric motor according to the additional yaw moment from the yaw target calculation module 1333 and the driver's requested torque from the driver input module 1312, and distributes it to the active shaft inner wheel motor, the active shaft outer wheel motor and the passive shaft motor. Among them, the torque of the active shaft inner wheel motor is negative, the torque of the active shaft inner wheel motor is positive, the difference between the positive and negative torques is equal to the additional yaw moment, and the sum of the active shaft torque and the passive shaft torque is the driver's requested torque. The active shaft inner wheel motor, the active shaft outer wheel motor and the passive wheel motor respond to the torque request of the distributed electric drive actuator 1340 in real time, and feedback the actual torque of the current motor.

[0267] It can be understood that the state observer 1310, the rear wheel steering system and model 1320, and the extreme steering assist 1330 in FIG. 13 realize the functions of the processor 1210 in FIG. 12 or the processing unit 1110 in FIG. 11 above in combination, which will not be repeated here.

[0268] Based on the above description, the present application can also provide a steering control system, as shown in FIG. 3a, which includes a steering control device 310, which can be any of the aforementioned steering control devices, such as the steering control device 1100 shown in FIG. 11, or the steering control device 1200 shown in FIG. 12, without limitation.

[0269] In a possible implementation, the steering control system 300 can further include vehicle-mounted sensors 330, which include but are not limited to at least one of a wheel speed sensor 331, a steering wheel rotation angle sensor 332, a steering wheel torque sensor 333, a steering wheel position sensor (not shown in FIG. 3a), an inertial measurement unit 334, a position sensor of an accelerator pedal (not shown in FIG. 3a), a position sensor of a brake pedal (not shown in FIG. 3a), and the like. The steering control device 310 is connected to the vehicle-mounted sensors 330, and can acquire information collected by the vehicle-mounted sensors 330, and perform the steps of the steering control method in any of the above embodiments according to the information, such as the steps of the steering control method shown in FIG. 4, FIG. 6, or FIG. 7.

[0270] In a possible implementation, the steering control system 300 can further include a motor 320 connected between the steering control device 310 and the wheels. The steering control device 310 sends a control signal to the motor 320 when controlling the vehicle to implement small-radius steering, and the motor 320 controls at least one axle of the vehicle to output a differential torque according to the control signal.

[0271] For example, taking at least one axle as the driving axle, the motor 320 can include an inner wheel motor of the driving axle and an outer wheel motor of the driving axle, the inner wheel motor of the driving axle being connected to an inner wheel of the driving axle of the vehicle, and the outer wheel motor of the driving axle being connected to an outer wheel of the driving axle of the vehicle. Based on this, the steering control device 310 sends a control signal to the motor 320, specifically, a first control signal to the inner wheel motor of the driving axle and a second control signal to the outer wheel motor of the driving axle. The inner wheel motor of the driving axle outputs a negative torque according to the first control signal, and the outer wheel motor of the driving axle outputs a positive torque according to the first control signal, and the difference between the positive torque and the negative torque is a first differential torque.

[0272] In one example, the motor 320 can further include a passive wheel motor connected to an inner wheel of a passive axle and an outer wheel of the passive axle of the vehicle. The steering control device 310 can be further configured to send a third control signal to the passive wheel motor if a change in the torque requested by the driver is detected, the third control signal including a torque change amount. The passive wheel motor is configured to output a third torque according to the third control signal, and the difference between the third torque and a historical torque of the passive wheel motor is equal to the torque change amount.

[0273] It should be noted that the steering control system 300 can further include other structures or devices, such as a mechanical transmission system, a motor controller, an axle, and the like, which are not limited in the present application.

[0274] Based on the above description, the application can also provide a vehicle, which can include a steering control system or a steering control device. The steering control system can be any of the foregoing steering control systems, such as the steering control system 300 shown in FIG. 3a. The steering control device can be any of the foregoing steering control devices, such as the steering control device 1100 shown in FIG. 11 or the steering control device 1200 shown in FIG. 12.

[0275] In a possible design, the vehicle can further include a head unit screen connected to the steering control system or the steering control device. Before the steering control system or the steering control device controls the vehicle to implement small-radius steering, the steering control system or the steering control device can be further configured to: if it is detected that the vehicle speed is less than or equal to the second vehicle speed and the steering wheel angle is greater than or equal to the second angle, control the head unit screen to display a human-computer interaction interface, where the human-computer interaction interface is configured to prompt a user to select whether to start the steering assistance function.

[0276] Exemplarily, the vehicle can include, but is not limited to, a car, a truck, a bus, an entertainment vehicle, an amusement park vehicle, a construction vehicle, an electric vehicle, a golf cart, a train, a driverless vehicle, a smart vehicle, a digital car, and the like.

[0277] Based on the above-described steering control method, the application can also provide a computer-readable storage medium having a computer program or instructions stored thereon, where the instructions, when executed on a computer, implement the steering control method as described in any of the foregoing embodiments.

[0278] Based on the above-described steering control method, the application can also provide a computer program product, which includes a computer program, where the computer program, when executed on a computer, implements the steering control method as described in any of the foregoing embodiments.

[0279] In the present application, "at least one" means one or more, and "multiple" means two or more. "Including at least one" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b or c can mean a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple. In addition, in the present application, the words "exemplarily" or "optionally" are used to mean as an example, illustration or description. Any embodiment or design scheme described as "example" or "option" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Or it can be understood that the use of the words "example" or "option" is intended to present the concept in a specific way, and does not limit the present application.

[0280] It can be understood that various numbers involved in the present application are only for the convenience of distinguishing, and are not used to limit the scope of the embodiments of the present application. The size of the serial numbers of the above processes does not mean the order of execution, and the execution order of the processes should be determined according to their functions and inherent logic. The terms "first", "second", "third" and the like similar expressions are used to distinguish similar objects, and do not necessarily be used to describe a specific order or sequence. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, including a series of steps or units. The method, system, product or device is not necessarily limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

Claims

1. A steering control method characterized by, The method is suitable for a vehicle, at least one axle of the vehicle can output torque in different directions, and the method comprises: determining that the vehicle enters a low-speed steering scene according to a vehicle speed and a steering wheel steering angle of the vehicle; controlling at least one axle of the vehicle to output a first differential torque according to the steering wheel steering angle and a steering wheel steering force of the vehicle, an outer wheel of the at least one axle outputs positive torque, and an inner wheel of the at least one axle outputs negative torque, and a difference between the positive torque and the negative torque is equal to the first differential torque.

2. The method of claim 1, wherein, The determining that the vehicle enters a low-speed steering scene according to a vehicle speed and a steering wheel steering angle of the vehicle comprises: determining that the vehicle speed is less than or equal to a first vehicle speed and the steering wheel steering angle is greater than or equal to a first steering angle.

3. The method of claim 1 or 2, wherein, The controlling at least one axle of the vehicle to output a first differential torque according to a steering wheel steering angle and a steering wheel steering force of the vehicle comprises: determining an ideal turning radius according to the steering wheel steering angle; correcting the ideal turning radius to obtain a target turning radius according to the steering wheel steering angle and the steering wheel steering force; controlling at least one axle of the vehicle to output the first differential torque according to the target turning radius.

4. The method of claim 3, wherein, The determining an ideal turning radius according to a steering wheel steering angle comprises: determining a passive wheel steering angle according to the steering wheel steering angle, the passive wheel steering angle being in a positive proportional relationship with the steering wheel steering angle. Based on the passive wheel rotation angle, the ideal turning radius is determined based on the following formula: wherein R k is the ideal turning radius, c1 is the distance of the instantaneous center of turning projected onto the front axle in the direction of travel of the vehicle, δ f is the passive wheel turning angle, b is the distance of the center of mass of the vehicle to the rear axle, and c2 is the distance of the instantaneous center of turning projected onto the rear axle in the direction of travel of the vehicle.

5. The method of claim 3 or 4, wherein, The correcting the ideal turning radius to obtain a target turning radius according to a steering wheel steering angle and a steering wheel steering force comprises: determining a steering correction coefficient according to the vehicle speed, the steering wheel steering angle and the steering wheel steering force; correcting the ideal turning radius to obtain the target turning radius by using the steering correction coefficient.

6. The method of claim 5, wherein, According to the turning correction coefficient, the ideal turning radius is corrected based on the following formula to obtain the target turning radius: R ref = R K - D x G ain where R ref is the target turning radius, R K is the ideal turning radius, G ain is the steering correction coefficient, and D is a constant coefficient.

7. The method of claim 5 or 6, wherein, The steering correction coefficient has a first mapping relationship with the vehicle speed, the steering wheel steering angle and the steering wheel steering force, and in the first mapping relationship: when the vehicle speed is in a first vehicle speed interval, the steering wheel steering angle is in a first steering angle interval, and the steering wheel steering force is in a first steering force interval, the steering correction coefficient is 1; when the vehicle speed is in a second vehicle speed interval, the steering wheel steering angle is in a second steering angle interval, and the steering wheel steering force is in a second steering force interval, the steering correction coefficient is 0; when the vehicle speed is in a third vehicle speed interval, the steering wheel steering angle is in a third steering angle interval, and the steering wheel steering force is in a third steering force interval, the steering correction coefficient is a third value, the third value is greater than 0 and less than 1; wherein the third vehicle speed interval is greater than the first vehicle speed interval and less than the second vehicle speed interval, the third steering angle interval is greater than the second steering angle interval and less than the first steering angle interval, and the third steering force interval is greater than the second steering force interval and less than the first steering force interval.

8. The method of any one of claims 3 to 7, wherein, The controlling at least one axle of the vehicle to output the first differential torque according to a target turning radius comprises: determining a target yaw angular velocity corresponding to the target turning radius; determining an additional yaw moment according to an actual yaw angular velocity of the vehicle and the target yaw angular velocity; controlling at least one axle of the vehicle to output the first differential torque according to the additional yaw moment.

9. The method of claim 8, wherein, Based on the actual yaw angular velocity of the vehicle and the target yaw angular velocity, the additional yaw moment is determined based on the following formula: where ΔM z is the additional yaw moment, a is the distance from the vehicle center of mass to the front axle, K1 is the front wheel cornering stiffness, b is the distance from the vehicle center of mass to the rear axle, K2 is the rear wheel cornering stiffness, V x is the vehicle speed, ω ref is the target yaw rate, ω IMU is the actual yaw rate, β IMU is the cornering angle of the vehicle center of mass.

10. The method of any one of claims 1 to 9, wherein, The at least one axle of the vehicle is a driven axle, and after the controlling the at least one axle of the vehicle to output the first difference torque, the method further comprises: If the driver's requested torque changes, then controlling the passive axle of the vehicle to respond to the changed torque.

11. The method of any one of claims 1 to 10, wherein, The at least one axle of the vehicle is a driven axle, and the inner and outer wheels of the driven axle share the same motor or use different motors.

12. The method of claim 11, wherein, Before the controlling the at least one axle of the vehicle to output the first difference torque, the method further comprises: If the passive wheel rotation angle is a maximum angle in a first direction, then controlling the driven wheel rotation angle to be a maximum rotation angle in a second direction, the first direction being opposite to the second direction.

13. The method of any one of claims 1 to 12, wherein, Before the determining that the vehicle enters the low-speed steering scenario according to the vehicle speed and the steering wheel rotation angle, the method further comprises: If the vehicle speed is less than or equal to a second vehicle speed, and the steering wheel rotation angle is greater than or equal to a second rotation angle, then determining that the user indicates to turn on the steering assistance function through human-computer interaction.

14. The method of any one of claims 1 to 13, wherein, Before the controlling the at least one axle of the vehicle to output the first difference torque according to the steering wheel rotation angle and the steering wheel torque of the vehicle, the method further comprises: Determining that the vehicle is in a forward gear, a reverse gear, or a neutral gear.

15. The method of any one of claims 1 to 14, wherein, After the controlling the at least one axle of the vehicle to output the first difference torque, the method further comprises: If the vehicle speed is greater than the second vehicle speed, and / or, the vehicle switches to a parking gear, then controlling the at least one axle of the vehicle to output a torque in the same direction.

16. A steering control device characterized by comprising: A module or unit for executing the method of any one of claims 1 to 15.

17. A steering control device characterized by comprising: A processor and an interface circuit, the processor being configured to communicate with other devices through the interface circuit to implement the method of any one of claims 1 to 15.

18. A steering control system characterized by comprising: A steering control device and a vehicle-mounted sensor, the vehicle-mounted sensor being connected to the steering control device; The vehicle-mounted sensor is configured to collect sensor information of the vehicle and send the sensor information to the steering control device; The steering control device is configured to execute the method of any one of claims 1 to 15 according to the sensor information of the vehicle.

19. The system of claim 18, wherein, The vehicle-mounted sensor comprises one or more of the following sensors: A wheel speed sensor, a steering wheel rotation angle sensor, a steering wheel torque sensor, an inertial detection unit, and a pedal position sensor.

20. The system of claim 18 or 19, wherein, The at least one axle is a driven axle, and the steering control system further comprises a driven axle inner wheel motor and a driven axle outer wheel motor, the driven axle inner wheel motor being connected to the driven axle inner wheel of the vehicle, and the driven axle outer wheel motor being connected to the driven axle outer wheel of the vehicle; The steering control device is specifically configured to send a first control signal to the driven axle inner wheel motor and a second control signal to the driven axle outer wheel motor; The driven axle inner wheel motor is configured to output a negative torque according to the first control signal; The driven axle outer wheel motor is configured to output a positive torque according to the first control signal, and the difference between the positive torque and the negative torque is the first difference torque.

21. The system of claim 20, wherein, The steering control system further comprises a passive wheel motor, the passive wheel motor being connected to the driven axle inner wheel and the driven axle outer wheel of the vehicle; The steering control device is further configured to send a third control signal to the passive wheel motor if a change in the driver-requested torque is detected, the third control signal including a torque change amount; The passive wheel motor is configured to output a third torque according to the third control signal, a difference between the third torque and a historical torque of the passive wheel motor being equal to the torque change amount.

22. A vehicle characterized by The steering control device as claimed in claim 16 or 17, or the steering control system as claimed in any one of claims 18 to 21.

23. A computer-readable storage medium, characterized in that, The storage medium has stored therein a computer program or instructions which, when executed, implement the method of any one of claims 1 to 15.

24. A computer program product, characterised in that, The computer program product includes instructions which, when executed, implement the method of any one of claims 1 to 15.

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