Active return control method and device, electric power steering system and vehicle

Abstract

The invention relates to an active return control method and device, an electric power steering system and a vehicle, and the method comprises the steps that the steering angle of a steering wheel is obtained; according to the steering wheel turning angle, active return required torque is obtained through calculation by means of a cascade control algorithm; and controlling a motor to output a corresponding torque according to the active return demand torque so as to return the steering wheel.

Description

Technical Field

[0001] The present disclosure relates to the technical field of vehicle electric power steering, and more specifically, to an active return control method, device, electric power steering system and vehicle. Background Art

[0002] With the development of vehicle technology, vehicles are equipped with Electric Power Steering (EPS). For vehicles with electric power steering, the self-centering performance of the steering system is an important indicator for evaluating the vehicle's driving performance. The active self-centering performance of the steering system is related to the active self-centering control strategy of the steering system.

[0003] The active self-centering control strategy provided by the prior art requires many parameters to be calibrated, the self-centering process is not smooth and uniform, and the stability is poor.

[0004] Therefore, it is necessary to provide an active return control method for an electric power steering system. Summary of the invention

[0005] An object of the present invention is to provide a new technical solution for an active self-centering control method.

[0006] According to a first aspect of the present invention, there is provided an active return control method, comprising:

[0007] Get the steering wheel angle;

[0008] According to the steering wheel angle, the active return torque is calculated by using a cascade control algorithm;

[0009] According to the active return-to-center required torque, the motor is controlled to output a corresponding torque to return the steering wheel to the center position.

[0010] Optionally, the active return-to-center required torque is calculated using a cascade control algorithm according to the steering wheel angle, including:

[0011] According to the steering wheel angle, the target return angular velocity value is calculated using the outer loop PI controller in the cascade control algorithm;

[0012] The active return-to-centering required torque is calculated based on the target return-to-centering angular velocity value and the inner-loop PI controller in the cascade control algorithm.

[0013] Optionally, the active return-to-centering required torque is calculated according to the target return-to-centering angular velocity value and the inner loop PI controller in the cascade control algorithm, including:

[0014] Get the actual return angular velocity value;

[0015] The active self-centering required torque is calculated according to the target self-centering angular velocity value and the actual self-centering angular velocity value by using the inner loop PI controller.

[0016] Optionally, the method further includes:

[0017] Determining a return angular velocity value error according to the target return angular velocity value and the actual return angular velocity value;

[0018] According to the return angular velocity error, the error change rate of the return angular velocity value is calculated;

[0019] According to the return angular velocity error and the change rate of the return angular velocity value error, the corresponding relationship between the input and output of the variable universe fuzzy controller is used to obtain the change of the proportional coefficient of the inner loop PI controller and the change of the integral coefficient of the inner loop PI controller;

[0020] The proportional coefficient and the integral coefficient of the inner loop PI controller are determined according to the proportional coefficient change of the inner loop PI controller, the integral coefficient change of the inner loop PI controller and the proportional coefficient and the integral coefficient pre-stored in the inner loop PI controller.

[0021] Optionally, the method further includes:

[0022] Get the mechanical return angular velocity value when the vehicle enters active return control;

[0023] According to the target return angular velocity value and the mechanical return angular velocity value, an adjusted target return angular velocity value is determined; wherein,

[0024] The active return angular velocity value and the actual return angular velocity value are calculated by using an inner loop PI controller of the cascade control system to obtain the active return required torque, including:

[0025] According to the adjusted target return angular velocity value and the actual return angular velocity value, the active return required torque is calculated by using the inner loop PI controller of the cascade control system.

[0026] Optionally, determining an adjusted target return angular velocity value according to the target return angular velocity value and the mechanical return angular velocity value includes:

[0027] Obtaining a first return angular velocity difference according to the target return angular velocity value and the mechanical return angular velocity value;

[0028] performing rate limiting processing on the first return-to-positive angular velocity difference to obtain a second return-to-positive angular velocity difference;

[0029] The adjusted target return angular velocity value is obtained according to the second return angular velocity difference and the mechanical return angular velocity value.

[0030] Optionally, the method further comprises: determining a return-to-center condition of the vehicle; wherein the return-to-center condition is one of an active return-to-center condition and a driver-controlled return-to-center condition;

[0031] The operations involved in the active return-to-center control method are performed only when the return-to-center condition of the vehicle is an active return-to-center condition.

[0032] Optionally, determining the return-to-center working condition of the vehicle includes:

[0033] Obtaining a first steering wheel torque, a steering wheel angle, and a vehicle speed;

[0034] A return-to-center condition of the vehicle is determined according to the first steering wheel torque, the steering wheel angle, and the speed of the vehicle.

[0035] Optionally, determining the return-to-center condition of the vehicle according to the first steering wheel torque, the steering wheel angle, and the speed of the vehicle includes:

[0036] determining whether the absolute value of the first steering wheel torque is less than or equal to a preset torque threshold, and whether the duration for which the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold exceeds a preset duration, determining whether the absolute value of the steering wheel angle is greater than or equal to a first preset angle threshold, and determining whether the vehicle speed is greater than or equal to a first preset vehicle speed threshold;

[0037] When the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold, and the duration for which the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold exceeds the preset duration, the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, and the vehicle speed is greater than or equal to the first preset speed threshold, the vehicle's return-to-center condition is determined to be an active return-to-center condition.

[0038] Optionally, the method further includes:

[0039] Control the motor output test torque of the electric power steering system;

[0040] Obtaining a steering wheel torque within a preset time after the motor outputs a test torque;

[0041] Determining whether the absolute value of the steering wheel torque is less than or equal to a preset torque threshold;

[0042] Only when it is determined that the absolute value of the steering wheel torque is less than or equal to the preset torque threshold value, it is determined whether the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold value, and whether the vehicle speed is greater than or equal to the first preset speed threshold value.

[0043] Optionally, the method further includes:

[0044] When it is determined that the vehicle is in an active return-to-center condition, the steering wheel angle and the vehicle speed are obtained;

[0045] The control mode of the vehicle active return control is determined according to the steering wheel angle and the vehicle speed; wherein the control modes of the vehicle active return control are an under-return control mode and an over-return control mode.

[0046] Optionally, the proportional coefficient and the integral coefficient of the controller involved in the under-return control mode are different from the proportional coefficient and the integral coefficient of the controller involved in the over-return control mode.

[0047] Optionally, determining the control mode of the vehicle active return control according to the steering wheel angle and the vehicle speed includes:

[0048] Determining whether the vehicle speed is less than or equal to a second preset vehicle speed threshold;

[0049] When the vehicle speed is less than or equal to the second preset vehicle speed threshold, determining that the control mode of the vehicle active return control is an under-return control mode;

[0050] In the case where the vehicle speed is greater than the second preset vehicle speed threshold, determining whether the vehicle speed is greater than or equal to a third preset vehicle speed threshold; wherein the second preset vehicle speed threshold is less than the third preset vehicle speed threshold;

[0051] When the vehicle speed is greater than or equal to the third preset vehicle speed threshold, determining that the control mode of the vehicle active return-to-center control is a return-to-center overshoot control mode;

[0052] When the vehicle speed is greater than the second preset vehicle speed threshold and less than the third preset vehicle speed threshold, determining whether the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold;

[0053] When the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold, determining that the control mode of the vehicle active return control is an under-return control mode;

[0054] When the absolute value of the steering wheel angle is greater than the second preset angle threshold, it is determined that the control mode of the vehicle active return control is a return-to-center overshoot control mode.

[0055] According to a second aspect of the present invention, there is provided an active return control device, comprising:

[0056] An acquisition module is used to obtain the steering wheel angle;

[0057] A calculation module, configured to calculate the active return torque required by the steering wheel according to the steering wheel angle by using a cascade control algorithm;

[0058] The control module is used to control the motor to output a corresponding torque according to the active return torque requirement so as to return the steering wheel to the center.

[0059] According to a third aspect of the present invention, there is provided an electronic device comprising a memory and a processor, wherein the memory stores a computer program for controlling the processor to operate so as to execute the active return control method according to any one of the first aspects of the present invention.

[0060] According to a fourth aspect of the present invention, there is provided an electric power steering system, comprising the active return control device as described in the second aspect or the electronic device as described in the third aspect.

[0061] According to a fifth aspect of the present invention, there is provided a vehicle comprising the electric power steering system as described in the fourth aspect.

[0062] The active self-centering control method provided by the present invention only utilizes the steering wheel angle and adopts a cascade control algorithm to calculate the active self-centering required torque. The method involves fewer parameters in the calculation, is independent of the vehicle speed, and has high control accuracy.

[0063] Features and advantages of the embodiments of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the embodiments of the specification.

[0065] Figure 1 4 is a processing flow chart of an active return control method according to an embodiment of the present invention.

[0066] Figure 2 It is a schematic diagram of a processing flow for determining a control mode of active positive return control according to an embodiment of the present invention.

[0067] Figure 3 1 is a schematic diagram of a processing flow for determining an active return torque requirement according to an embodiment of the present invention.

[0068] Figure 4 1 is a schematic diagram of a processing flow for determining an active return torque requirement according to an embodiment of the present invention.

[0069] Figure 51 is a principle block diagram of an active return control device according to an embodiment of the present invention.

[0070] Figure 6 Schematic diagram of the hardware structure of an active self-centering control device according to an embodiment of the present invention.

[0071] Figure 7 4 is a principle block diagram of an electric power steering system according to an embodiment of the present invention.

[0072] Figure 8 4 is a principle block diagram of an electric power steering system according to an embodiment of the present invention.

[0073] Fig. 9 is a schematic structural diagram of a vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION

[0074] Various exemplary embodiments of the present specification will now be described in detail with reference to the accompanying drawings.

[0075] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the embodiments of the present specification and its application or uses.

[0076] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0077] <Method Example>

[0078] In one embodiment of the present invention, an active return control method is provided. Figure 1 As shown, this embodiment may include the following steps S110 to S140.

[0079] Step S110, obtaining a steering wheel angle.

[0080] The steering wheel angle is collected by the steering angle sensor.

[0081] Step S120, according to the steering wheel angle, the active return torque required is calculated using a cascade control algorithm.

[0082] Step S130, according to the active return torque requirement, the motor is controlled to output a corresponding torque to return the steering wheel to the center.

[0083] The active self-centering control method provided by the embodiment of the present invention only utilizes the steering wheel angle and adopts a cascade control algorithm to calculate the active self-centering required torque. The method involves fewer parameters in the calculation, is independent of the vehicle speed, and has high control accuracy.

[0084] In one embodiment, step S120 includes steps S121 - S122 .

[0085] Step S121, according to the steering wheel angle, using the outer loop PI controller in the cascade control algorithm, calculates the target return angular velocity value.

[0086] Based on the following calculation formula, the target return angular velocity value ω1 is calculated:

[0087] ω1=K p1 ×(θ a -θ)+K i1 ×∫(θ a -θ)dt,

[0088] Among them, θ a is the desired target steering wheel return angle, set to 0, θ is the steering wheel angle, K p1 is the proportional coefficient of the outer loop PI controller, K i1 is the integral coefficient of the outer loop PI controller.

[0089] Step S122, calculating the active return-to-center required torque according to the target return-to-center angular velocity value and the inner loop PI controller in the cascade control algorithm.

[0090] In one embodiment, step S122 specifically includes: obtaining an actual return angular velocity value; and calculating the active return required torque using an inner loop PI controller according to the target return angular velocity value and the actual return angular velocity value.

[0091] The actual return angular velocity value is the steering wheel angular velocity calculated by taking the derivative of the steering wheel angle.

[0092] Based on the following calculation formula, the active return torque T is calculated. a ,

[0093] T a =K p2 ×(ω1-ω)+K i2 ×∫(ω1-ω)dt,

[0094] Among them, ω1 is the target return angular velocity value, ω is the actual return angular velocity value, K p2 is the proportional coefficient of the inner loop PI controller, K i2 K is the integral coefficient of the inner loop PI controller. p2 and K i2 It is a pre-stored value.

[0095] In one embodiment of the present invention, the method also includes: using a variable universe fuzzy control algorithm to obtain the corresponding relationship between the input and output of the variable universe fuzzy controller; wherein the input is the return angular velocity value error and the rate of change of the return angular velocity value error, and the output is the change in the proportional coefficient of the inner loop PI controller and the change in the integral coefficient of the inner loop PI controller.

[0096] Specifically, the basic domain of the return angular velocity value error e and the return angular velocity value error change rate ec is determined. In this embodiment, the initial domain of e is [-200, 200], the initial domain of ec is [-20000, 20000], the initial domain of the proportional coefficient change Δkp of the inner loop PI controller is [-0.5, 0.5], and the initial domain of the integral coefficient change Δki of the inner loop PI controller is [-3, 3].

[0097] In traditional fuzzy controllers, once the domain is determined, it cannot be changed. However, changes in the input signal and the controlled object will cause changes in the input quantity. At this time, the initial domain no longer meets the control requirements and needs to be reset. The variable domain is to enable the initial domain to change dynamically and improve the adaptive ability of fuzzy control. In this embodiment, a transfer function model of a variable domain expansion factor is used to determine the domain of each quantity, as shown below:

[0098]

[0099] Among them, a is an adaptive factor, which is calibrated according to actual needs.

[0100] In this embodiment, the initial domain of e is [-200, 200]. When using the transfer function model with a variable domain scaling factor, a constant b is subtracted from the initial domain 200 and then input into the transfer function model with a variable domain scaling factor for calculation. A curve can be obtained. The horizontal coordinate of the curve means e, and the vertical coordinate means the domain of e, that is, different e corresponds to different domains. In order to prevent the output from changing too drastically due to the domain being too small when e is small, b should be added to the vertical coordinate value of the above-mentioned domain curve to obtain the final domain curve. If the domain curve value corresponding to the error e is ev, the domain range of the error e at this time is [-ev, ev].

[0101] Determine the membership function. In this embodiment, in the middle range, the fuzzy subset membership function selects a triangular membership function. On both sides, the fuzzy subset membership function selects an S-type membership function to improve adaptability.

[0102] Establish a fuzzy rule table. Establish a fuzzy rule table based on the characteristics of the control system and debugging experience.

[0103] The corresponding output is calculated and recorded using the fuzzy control algorithm. In this way, the corresponding relationship between the input and output of the variable domain fuzzy controller can be converted into an offline rule table. That is, the corresponding Δkp and Δki can be obtained by looking up the two-dimensional table of e and ec, avoiding the online operation of the fuzzy control algorithm.

[0104] In one embodiment of the present invention, the method also includes: determining a return-to-right angular velocity value error based on a target return-to-right angular velocity value and an actual return-to-right angular velocity value; calculating a rate of change of the return-to-right angular velocity value error based on the return-to-right angular velocity value error; obtaining a change in a proportional coefficient of an inner-loop PI controller and a change in an integral coefficient of an inner-loop PI controller based on the return-to-right angular velocity value error and the rate of change of the return-to-right angular velocity value error and using a correspondence between an input and an output of a variable universe fuzzy controller; determining a proportional coefficient of an inner-loop PI controller and an integral coefficient of an inner-loop PI controller based on the change in the proportional coefficient of the inner-loop PI controller, the change in the integral coefficient of the inner-loop PI controller and the proportional coefficient and integral coefficient pre-stored in the inner-loop PI controller.

[0105] In this embodiment, the proportional coefficient change of the inner loop PI controller is added to the proportional coefficient pre-stored in the inner loop PI controller to obtain the proportional coefficient of the inner loop PI controller. The integral coefficient change of the inner loop PI controller is added to the integral coefficient pre-stored in the inner loop PI controller to obtain the integral coefficient of the inner loop PI controller.

[0106] In one embodiment of the present invention, the method further includes: obtaining a mechanical return angular velocity value when the vehicle enters active return control; determining an adjusted target return angular velocity value according to the target return angular velocity value and the mechanical return angular velocity value. According to the adjusted target return angular velocity value and the actual return angular velocity value, the inner loop PI controller is used to calculate the active return required torque.

[0107] Specifically, a first return-to-right angular velocity difference is obtained according to the target return-to-right angular velocity value and the mechanical return-to-right angular velocity value; the first return-to-right angular velocity difference is rate-limited to obtain a second return-to-right angular velocity difference; and an adjusted target return-to-right angular velocity value is obtained according to the second return-to-right angular velocity difference and the mechanical return-to-right angular velocity value.

[0108] The mechanical return angular velocity value when the vehicle enters active return control is the angular velocity value corresponding to the active return control when the vehicle enters the active return control, which is calculated by derivation of the steering wheel angle.

[0109] In this embodiment, in order to prevent the target return angular velocity from increasing too fast, the first return angular velocity difference is rate-limited to obtain a second return angular velocity difference, and the second return angular velocity difference is added to the mechanical return angular velocity value to obtain the adjusted target return angular velocity value. In this way, the mechanical return angular velocity value at the time of active return is smoothly connected with the calculated target return angular velocity, preventing the return angular velocity from changing suddenly during active return, and making the return process smooth and stable.

[0110] In one embodiment, the method further includes: determining a return-to-center condition of the vehicle; wherein the return-to-center condition is one of an active return-to-center condition and a driver-controlled return-to-center condition; and only when the return-to-center condition of the vehicle is an active return-to-center condition, operations involved in the active return-to-center control method are performed.

[0111] In one embodiment, after the vehicle completes the steering action, the steering wheel angle is obtained, the steering wheel angle is derived, and the steering wheel angular velocity is calculated. It is determined whether the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity, and it is determined whether the duration of the direction of the steering wheel angle being opposite to the direction of the steering wheel angular velocity exceeds a preset time. When it is determined that the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity, and the duration of the direction of the steering wheel angle being opposite to the direction of the steering wheel angular velocity exceeds a preset time, it is determined that the vehicle is in a return-to-center condition.

[0112] The steering wheel angle is derived to calculate the steering wheel angular velocity, and the steering wheel angular velocity is filtered using the least squares algorithm to obtain the steering wheel angular velocity after filtering. It should be noted that the phase delay of the signal after filtering meets the preset requirements and cannot be too large, otherwise the stability margin of the control system will be reduced.

[0113] When the sign of the steering wheel angle is opposite to the sign of the steering wheel angular velocity, it is determined that the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity.

[0114] The preset duration can be set according to requirements, for example, 0.05s.

[0115] In one embodiment, a first steering wheel torque, a steering wheel angle, and a vehicle speed are obtained. According to the first steering wheel torque, the steering wheel angle, and the vehicle speed, a return-to-center condition of the vehicle is determined. When the return-to-center condition of the vehicle is an active return-to-center condition, the active return-to-center control method provided by the present invention is executed. When the return-to-center condition of the vehicle is a driver-controlled condition, the active return-to-center control method provided by the present invention is not executed.

[0116] The first steering wheel torque is collected by the torque sensor. The steering wheel angle is collected by the angle sensor. The vehicle speed is obtained through the vehicle CAN network.

[0117] Specifically, determine whether the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold, determine whether the duration for which the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold exceeds the preset duration, determine whether the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, and determine whether the vehicle speed is greater than or equal to the first preset speed threshold.

[0118] When the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold, and the duration for which the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold exceeds the preset duration, the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, and the vehicle speed is greater than or equal to the first preset speed threshold, the vehicle's return-to-center condition is determined to be an active return-to-center condition.

[0119] When the absolute value of the first steering wheel torque is greater than the preset torque threshold, or the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold, and the duration of the absolute value of the first steering wheel torque being less than or equal to the preset torque threshold does not exceed the preset duration, or the absolute value of the steering wheel angle is less than the first preset angle threshold, or the vehicle speed is less than the first preset speed threshold, it is determined that the vehicle's return-to-center condition is a driver-controlled return-to-center condition. When the vehicle's return-to-center condition is a driver-controlled condition, the active return-to-center control method provided by the present invention is not performed.

[0120] The preset torque threshold can be calibrated according to the hand force value when the driver lets go and straightens the car. Specifically, the hand force value when the driver lets go and straightens the car at different vehicle speeds is collected, and the mean value E(Tr) and standard deviation δ(Tr) of the hand force value when the driver lets go and straightens the car at different vehicle speeds are calculated. The preset torque threshold is E(Tr)+2*δ(Tr). It should be noted that the hand force value when the driver lets go and straightens the car is the steering wheel torque value when the driver lets go and straightens the car.

[0121] The preset time length can be set as required, for example, 0.05s. The first preset turning angle threshold can be set as required. The first preset vehicle speed threshold can be set as required.

[0122] In one embodiment of the present invention, the method also includes: controlling the motor of the electric power steering system to output a test torque; obtaining a second steering wheel torque after the motor outputs the test torque; determining whether the absolute value of the second steering wheel torque is less than or equal to a preset torque threshold, and determining whether the duration for which the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold exceeds a preset duration; only after determining that the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold and whether the duration for which the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold exceeds a preset duration, proceed to determine whether the absolute value of the steering wheel angle is greater than or equal to a first preset angle threshold and whether the vehicle speed is greater than or equal to a first preset speed threshold.

[0123] When the absolute value of the second steering wheel torque is greater than the preset torque threshold, or the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold, and the duration for which the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold does not exceed the preset duration, the active return control method provided by the present invention is not executed.

[0124] The trial torque applied in this embodiment is a linear torque. The direction of the trial torque is consistent with the direction in which the vehicle returns to the center. During the application of the trial torque, if the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold, that is, the trial torque has not been overcome by the driver, it can be considered that the driver is in a hands-off return condition. If the second steering wheel torque is greater than the preset torque threshold, that is, the trial torque is overcome by the driver, it can be considered that the vehicle is in a driver-controlled return condition, and the active return control method provided by the present invention is no longer executed. Since the applied trial torque is small and increases linearly, it has little impact on the driver and will not conflict with the driver's driving intention.

[0125] The second steering wheel torque is collected by a torque sensor.

[0126] The preset torque threshold can be determined according to the method provided in the above embodiment, and will not be elaborated here.

[0127] The preset duration can be set according to requirements, for example, 0.05s.

[0128] It should be noted that the application of the test torque provided in the present embodiment can be performed after determining whether the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold, and determining whether the duration of the absolute value of the first steering wheel torque being less than or equal to the preset torque threshold exceeds the preset duration, and before determining whether the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, and determining whether the vehicle speed is greater than or equal to the first preset speed threshold. Alternatively, the application of the test torque provided in the present embodiment no longer requires determining whether the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold, and determining whether the duration of the absolute value of the first steering wheel torque being less than or equal to the preset torque threshold exceeds the preset duration, and only requires determining whether the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, and determining whether the vehicle speed is greater than or equal to the first preset speed threshold.

[0129] In one embodiment of the present invention, when it is determined that the vehicle is in an active return-to-center condition, the steering wheel angle and the vehicle speed are obtained. According to the steering wheel angle and the vehicle speed, the control mode of the vehicle active return-to-center control is determined; wherein the control mode of the vehicle active return-to-center control is an under-return-to-center control mode and an over-return-to-center control mode.

[0130] The proportional coefficient and the integral coefficient of the controller involved in the under-correction control mode are different from the proportional coefficient and the integral coefficient of the controller involved in the over-correction control mode.

[0131] The steering wheel angle is collected by the angle sensor. The vehicle speed is obtained through the vehicle CAN network.

[0132] Specifically, it is determined whether the speed of the vehicle is less than or equal to the second preset speed threshold. When the speed of the vehicle is less than or equal to the second preset speed threshold, it is determined that the control mode of the vehicle's active return control is the under-return control mode. When the speed of the vehicle is greater than the second preset speed threshold, it is determined whether the speed of the vehicle is greater than or equal to the third preset speed threshold; wherein the second preset speed threshold is less than the third preset speed threshold. When the speed of the vehicle is greater than or equal to the third preset speed threshold, it is determined that the control mode of the vehicle's active return control is the return overshoot control mode. When the speed of the vehicle is greater than the second preset speed threshold and less than the third preset speed threshold, it is determined whether the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold. When the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold, it is determined that the control mode of the vehicle's active return control is the under-return control mode. When the absolute value of the steering wheel angle is greater than the second preset angle threshold, it is determined that the control mode of the vehicle's active return control is the return overshoot control mode.

[0133] In one embodiment, a correspondence table between vehicle speed and preset turning angle threshold is stored in advance. When the vehicle speed is greater than the second preset vehicle speed threshold and less than the third preset vehicle speed threshold, the corresponding preset vehicle speed threshold is searched from the correspondence table according to the vehicle speed to serve as the second preset turning angle threshold.

[0134] In one embodiment, when executing the active return-to-center control method provided by any of the above embodiments, when it is determined that the direction of the steering wheel angle is the same as the direction of the steering wheel angular velocity, and the duration that the direction of the steering wheel angle is the same as the direction of the steering wheel angular velocity exceeds a preset time length, the active return-to-center control exits.

[0135] In one embodiment, when executing the active return-to-center control method provided in any of the above embodiments, when it is determined that the absolute value of the steering wheel angle is less than a first preset angle threshold, the active return-to-center control is exited.

[0136] In one embodiment, when executing the active return-to-center control method provided in any of the above embodiments, when the absolute value of the steering wheel torque is greater than a preset torque threshold, the active return-to-center control is exited.

[0137] In one embodiment, when the active return control is exited, the unloading rate of the active return required torque is determined according to the driver's hand force value and the actual return angular velocity value, and the active return required torque is unloaded according to the unloading rate.

[0138] This is because when the driver intervenes in the active return control process with a small hand force, if the return angular velocity is large, the active return control will directly exit, which will cause the steering wheel to vibrate. At this time, it is necessary to determine the unloading rate of the active return torque based on the hand force value when the driver intervenes and the actual return angular velocity value. The smaller the hand force value, the larger the actual return angular velocity value, and the smaller the unloading rate.

[0139] Figure 2 It is a schematic diagram of a processing flow for determining a control mode of active positive return control according to an embodiment of the present invention.

[0140] See also Figure 2 , determining the control mode of active return control includes steps S201 to S215.

[0141] Step S201, after the vehicle completes the steering action, the steering wheel angle is obtained, the steering wheel angle is derived, and the steering wheel angular velocity is calculated.

[0142] Step S202, determining whether the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity, and whether the duration that the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity exceeds a preset duration.

[0143] If the result of step S202 is that the direction of the steering wheel angle is the same as the direction of the steering wheel angular velocity, and / or the duration that the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity does not exceed a preset duration, step S203 is executed to determine that the vehicle is not in the return-to-center condition, and no subsequent operations are performed.

[0144] If the result of step S202 is that the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity, and the duration that the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity exceeds a preset duration, step S204 is executed to determine whether the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold, and whether the duration that the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold exceeds a preset duration.

[0145] If the result of step S204 is that the absolute value of the first steering wheel torque is greater than the preset torque threshold, and / or the duration for which the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold does not exceed the preset duration, step S205 is executed to determine that the vehicle's return-to-center condition is a driver-controlled return-to-center condition, and no subsequent operations are performed.

[0146] If the result of step S204 is to determine that the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold, and the duration for which the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold exceeds the preset duration, step S206 is executed to control the motor output of the electric power steering system to output a test torque.

[0147] Step S207, obtaining a second steering wheel torque after the motor outputs a test torque.

[0148] Step S208, determining whether the absolute value of the second steering wheel torque is less than or equal to a preset torque threshold, and whether the duration for which the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold exceeds a preset duration.

[0149] If the result of step S208 is that the absolute value of the second steering wheel torque is greater than the preset torque threshold, and / or the duration for which the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold does not exceed the preset duration, step S205 is executed to determine that the vehicle's return-to-center condition is a driver-controlled return-to-center condition, and no subsequent operations are performed.

[0150] If the result of step S208 is to determine that the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold, and the duration that the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold exceeds the preset duration, step S209 is executed to determine whether the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold.

[0151] If the result of step S209 is that the absolute value of the steering wheel angle is less than the first preset angle threshold, step S205 is executed to determine that the vehicle's return-to-center condition is a driver-controlled return-to-center condition, and no subsequent operations are performed.

[0152] If the result of step S209 is that the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, step S210 is executed to determine whether the vehicle speed is greater than or equal to the first preset speed threshold.

[0153] If the result of step S210 is that the vehicle speed is less than the first preset vehicle speed threshold, step S205 is executed to determine that the vehicle's return-to-center condition is a driver-controlled return-to-center condition, and no subsequent operations are performed.

[0154] If the result of step S210 is that the vehicle speed is greater than or equal to the first preset vehicle speed threshold, step S211 is executed to determine whether the vehicle speed is less than or equal to the second preset vehicle speed threshold.

[0155] If the result of step S211 is that the vehicle speed is less than or equal to the second preset vehicle speed threshold, step S212 is executed to determine that the control mode of the vehicle active return control is the under-return control mode.

[0156] If the result of step S211 is that the vehicle speed is greater than the second preset vehicle speed threshold, step S213 is executed to determine whether the vehicle speed is greater than or equal to the third preset vehicle speed threshold.

[0157] When the result of step S213 is that the vehicle speed is greater than or equal to the third preset vehicle speed threshold, step S214 is executed to determine that the control mode of the vehicle active return control is the return overshoot control mode.

[0158] When the result of step S213 is that the vehicle speed is less than the third preset vehicle speed threshold, step S215 is executed to determine whether the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold.

[0159] When the result of step S215 is that the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold, step S212 is executed to determine that the control mode of the vehicle active return control is the under-return control mode.

[0160] When the result of step S215 is that the absolute value of the steering wheel angle is greater than the second preset angle threshold, step S214 is executed to determine that the control mode of the vehicle active return control is the return overshoot control mode.

[0161] It should be noted that the preset durations involved in the above embodiments may be the same duration value or different duration values, and may be set according to the specific requirements of each embodiment.

[0162] Figure 3 and Figure 4 1 is a schematic diagram of a processing flow for determining an active return torque requirement according to an embodiment of the present invention.

[0163] See also Figure 3 , determining the active return required torque includes steps S301 to S313.

[0164] Step S301, obtaining a steering wheel angle θ.

[0165] Step S302: According to the steering wheel angle θ, the target return angular velocity value ω1 is calculated using the outer loop PI controller of the cascade control system.

[0166] Step S303, obtaining the mechanical return angular velocity value ω when the vehicle enters active return control m .

[0167] Step S304: according to the target return angular velocity value ω1 and the mechanical return angular velocity value ω m , get the first positive angular velocity difference ω c .

[0168] Step S305: Return the first angular velocity difference ω c Perform rate limiting processing to obtain the second positive angular velocity difference ω d .

[0169] Step S306: according to the second positive angular velocity difference ω d and mechanical return angular velocity value ω m , and get the adjusted target return angular velocity value ω t .

[0170] Step S307, obtaining the actual return angular velocity value ω.

[0171] Step S308: Return the angular velocity value ω according to the adjusted target t And the actual return angular velocity value ω, determine the return angular velocity value error e.

[0172] Step S309, calculating the return angular velocity value error change rate ec according to the return angular velocity value error e.

[0173] Step S310, calculating the error change rate ec of the angular velocity value according to the angular velocity value error e.

[0174] Step S311, according to the return angular velocity value error e and the return angular velocity value error change rate ec, using the corresponding relationship between the input and output of the variable universe fuzzy controller, obtain the proportional coefficient change Δkp of the inner loop PI controller and the integral coefficient change Δki of the inner loop PI controller.

[0175] Step S312, determining the proportional coefficient kp2 and the integral coefficient ki2 of the inner loop PI controller according to the proportional coefficient change Δkp of the inner loop PI controller, the integral coefficient change Δki of the inner loop PI controller and the proportional coefficient and integral coefficient pre-stored in the inner loop PI controller.

[0176] Step S313: Return the angular velocity value ω according to the adjusted target t The active self-aligning required torque Ta is calculated using the inner loop PI controller of the cascade control system and the actual self-aligning angular velocity value ω.

[0177] <Device Example>

[0178] An embodiment of the present invention provides an active return control device. Figure 5 The active return control device 500 includes an acquisition module 510 , a calculation module 520 and a control module 530 .

[0179] The acquisition module 510 is used to acquire the steering wheel angle. The calculation module 520 is used to calculate the active return torque according to the steering wheel angle using the cascade control algorithm. The control module 530 is used to control the motor to output the corresponding torque according to the active return torque to return the steering wheel to the center.

[0180] In one embodiment, the calculation module 520 is also used to calculate the target return angular velocity value according to the steering wheel angle using the outer loop PI controller in the cascade control algorithm; and calculate the active return required torque according to the target return angular velocity value and the inner loop PI controller in the cascade control algorithm.

[0181] In one embodiment, the calculation module 520 is further used to obtain an actual return angular velocity value; and according to the target return angular velocity value and the actual return angular velocity value, the inner loop PI controller is used to calculate the active return required torque.

[0182] In one embodiment, the active return control device further includes a variable universe fuzzy control module. The variable universe fuzzy control module is used to obtain the corresponding relationship between the input and output of the variable universe fuzzy controller using the variable universe fuzzy control algorithm; wherein the input is the return angular velocity value error and the rate of change of the return angular velocity value error, and the output is the change of the proportional coefficient of the inner loop PI controller and the change of the integral coefficient of the inner loop PI controller.

[0183] In one embodiment, the active return control device further includes an inner loop PI controller coefficient calculation module. The inner loop PI controller coefficient calculation module is used to determine the return angular velocity value error according to the target return angular velocity value and the actual return angular velocity value; calculate the return angular velocity value error change rate according to the return angular velocity value error; according to the return angular velocity value error and the return angular velocity value error change rate, using the corresponding relationship between the input and output of the variable universe fuzzy controller, obtain the proportional coefficient change of the inner loop PI controller and the integral coefficient change of the inner loop PI controller; according to the proportional coefficient change of the inner loop PI controller, the integral coefficient change of the inner loop PI controller and the proportional coefficient and integral coefficient pre-stored in the inner loop PI controller, determine the proportional coefficient of the inner loop PI controller and the integral coefficient of the inner loop PI controller.

[0184] In one embodiment, the calculation module 520 is further used to obtain the mechanical return angular velocity value when the vehicle enters the active return control; and determine the adjusted target return angular velocity value according to the target return angular velocity value and the mechanical return angular velocity value.

[0185] In one embodiment, the calculation module 520 is also used to obtain a first return-to-center angular velocity difference based on the target return-to-center angular velocity value and the mechanical return-to-center angular velocity value; perform rate limiting processing on the first return-to-center angular velocity difference to obtain a second return-to-center angular velocity difference; and obtain an adjusted target return-to-center angular velocity value based on the second return-to-center angular velocity difference and the mechanical return-to-center angular velocity value.

[0186] In this embodiment, the calculation module 520 is further used to calculate the active self-centering required torque using the inner loop PI controller according to the adjusted target self-centering angular velocity value and the actual self-centering angular velocity value.

[0187] In one embodiment, the active return control device further comprises a return condition determination module. The return condition determination module is used to determine the return condition of the vehicle; wherein the return condition is one of an active return condition and a driver-controlled return condition.

[0188] In one embodiment, the return-to-center condition determination module is used to obtain a first steering wheel torque, a steering wheel angle, and a vehicle speed; and determine the return-to-center condition of the vehicle based on the first steering wheel torque, the steering wheel angle, and the vehicle speed.

[0189] In one embodiment, the return-to-center condition determination module is also used to determine whether the absolute value of the first steering wheel torque is less than or equal to a preset torque threshold, and whether the duration for which the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold exceeds a preset duration, determine whether the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, and determine whether the vehicle speed is greater than or equal to the first preset speed threshold; when the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold, and the duration for which the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold exceeds a preset duration, the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, and the vehicle speed is greater than or equal to the first preset speed threshold, the return-to-center condition of the vehicle is determined to be an active return-to-center condition.

[0190] In one embodiment, the active return control device further includes a test torque output module. The test torque output module is used to control the motor of the electric power steering system to output a test torque; obtain the steering wheel torque within a preset time after the motor outputs the test torque; determine whether the absolute value of the steering wheel torque is less than or equal to the preset torque threshold; and only when it is determined that the absolute value of the steering wheel torque is less than or equal to the preset torque threshold, determine whether the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, and determine whether the vehicle speed is greater than or equal to the first preset speed threshold.

[0191] In one embodiment, the active return control device further includes a return control mode determination module. The return control mode determination module is used to obtain the steering wheel angle and the vehicle speed when determining that the vehicle is in the active return condition; and determine the control mode of the vehicle active return control according to the steering wheel angle and the vehicle speed; wherein the control mode of the vehicle active return control is the return under control mode and the return overshoot control mode.

[0192] In one embodiment, the proportional coefficient and the integral coefficient of the controller involved in the undershoot control mode are different from the proportional coefficient and the integral coefficient of the controller involved in the overshoot control mode.

[0193] In one embodiment, the return-to-center control mode determination module is also used to determine whether the vehicle speed is less than or equal to a second preset speed threshold, and whether the vehicle speed is greater than or equal to a third preset speed threshold; wherein the second preset speed threshold is less than the third preset speed threshold; when the vehicle speed is less than or equal to the second preset speed threshold, the control mode of the vehicle active return-to-center control is determined to be an under-return-to-center control mode; when the vehicle speed is greater than or equal to the third preset speed threshold, the control mode of the vehicle active return-to-center control is determined to be an over-return-to-center control mode; when the vehicle speed is greater than the second preset speed threshold and less than the third preset speed threshold, it is determined whether the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold; when the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold, the control mode of the vehicle active return-to-center control is determined to be an under-return-to-center control mode; when the absolute value of the steering wheel angle is greater than the second preset angle threshold, the control mode of the vehicle active return-to-center control is determined to be an over-return-to-center control mode.

[0194] An embodiment of the present invention provides an electronic device, such as Figure 6 The electronic device 600 includes a memory 620 and a processor 610. The memory 620 stores a computer program, and the computer program is used to control the processor 610 to operate so as to execute the active return control method in any of the above embodiments.

[0195] <System Embodiment>

[0196] An embodiment of the present invention provides an electric power steering system. The electric power steering system includes an active return control device as provided in the above embodiment or an electronic device as provided in the above embodiment. Figure 7 .

[0197] See also Figure 8 ,The electric power steering system also includes a motor, a steering angle sensor and a torque sensor.

[0198] The steering angle sensor is used to collect the steering wheel angle. The torque sensor is used to collect the steering wheel torque. The electric power steering system obtains the vehicle speed through the vehicle CAN network.

[0199] After the active return control device calculates the return control required torque, it controls the motor to output the corresponding torque to drive the steering column to rotate, thereby returning the steering wheel to the center.

[0200] <Vehicle Embodiment>

[0201] One embodiment of the present invention provides a vehicle, such as Fig. 9 The vehicle includes the electric power steering system provided by the above embodiment.

[0202] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. For the electric vehicle embodiment, its related parts can be referred to the partial description of the method embodiment.

[0203] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0204] The embodiments of the present specification may be systems, methods and / or computer program products. The computer program product may include a computer-readable storage medium carrying computer instructions for causing a processor to implement various aspects of the embodiments of the present specification.

[0205] A computer-readable storage medium may be a tangible device that can hold and store computer instructions used by a computer instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which computer instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0206] The computer instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer instructions from the network and forwards the computer instructions for storage in the computer-readable storage medium in each computing / processing device.

[0207] The flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to the multiple embodiments of this specification. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a computer instruction, and a part of a module, a program segment or a computer instruction contains one or more executable computer instructions for realizing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or the flowchart, and the combination of the boxes in the block diagram and / or the flowchart can be implemented by a dedicated hardware-based system that performs the specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions. It is well known to those skilled in the art that it is equivalent to implement it by hardware, implement it by software, and implement it by combining software and hardware.

[0208] The embodiments of the present specification have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. An active return control method, characterized in that: include: Get the steering wheel angle; According to the steering wheel angle, the active return torque is calculated by using a cascade control algorithm; According to the active return-to-center required torque, the motor is controlled to output a corresponding torque to return the steering wheel to the center position.

2. The method according to claim 1, characterized in that The active return-to-center required torque is calculated by using a cascade control algorithm according to the steering wheel angle, including: According to the steering wheel angle, the target return angular velocity value is calculated using the outer loop PI controller in the cascade control algorithm; The active return-to-centering required torque is calculated based on the target return-to-centering angular velocity value and the inner-loop PI controller in the cascade control algorithm.

3. The method according to claim 2, characterized in that The active return-to-centering required torque is calculated based on the target return-to-centering angular velocity value and the inner loop PI controller in the cascade control algorithm, including: Get the actual return angular velocity value; The active self-centering required torque is calculated according to the target self-centering angular velocity value and the actual self-centering angular velocity value by using the inner loop PI controller.

4. The method according to claim 3, characterized in that The method further comprises: Determining a return angular velocity value error according to the target return angular velocity value and the actual return angular velocity value; According to the return angular velocity value error, a change rate of the return angular velocity value error is calculated; According to the return angular velocity value error and the change rate of the return angular velocity value error, using the corresponding relationship between the input and output of the variable universe fuzzy controller, the change of the proportional coefficient of the inner loop PI controller and the change of the integral coefficient of the inner loop PI controller are obtained; The proportional coefficient and the integral coefficient of the inner loop PI controller are determined according to the proportional coefficient change of the inner loop PI controller, the integral coefficient change of the inner loop PI controller and the proportional coefficient and the integral coefficient pre-stored in the inner loop PI controller.

5. The method according to claim 3, characterized in that: The method further comprises: Get the mechanical return angular velocity value when the vehicle enters active return control; According to the target return angular velocity value and the mechanical return angular velocity value, an adjusted target return angular velocity value is determined; wherein, The active return angular velocity value and the actual return angular velocity value are calculated by using the inner loop PI controller to obtain the active return torque, including: The active return angular velocity requirement is calculated and obtained by using the inner loop PI controller according to the adjusted target return angular velocity value and the actual return angular velocity value.

6. The method according to claim 5, characterized in that The step of determining an adjusted target return angular velocity value according to the target return angular velocity value and the mechanical return angular velocity value comprises: Obtaining a first return angular velocity difference according to the target return angular velocity value and the mechanical return angular velocity value; performing rate limiting processing on the first return-to-positive angular velocity difference to obtain a second return-to-positive angular velocity difference; The adjusted target return angular velocity value is obtained according to the second return angular velocity difference and the mechanical return angular velocity value.

7. The method according to claim 1, characterized in that The method further comprises: Determining a return-to-center condition of the vehicle; wherein the return-to-center condition is one of an active return-to-center condition and a driver-controlled return-to-center condition; The operations involved in the active return-to-center control method are performed only when the return-to-center condition of the vehicle is an active return-to-center condition.

8. The method according to claim 7, characterized in that Determining the return-to-center working condition of the vehicle includes: Obtaining a first steering wheel torque, a steering wheel angle, and a vehicle speed; A return-to-center condition of the vehicle is determined according to the first steering wheel torque, the steering wheel angle, and the speed of the vehicle.

9. The method according to claim 8, characterized in that Determining the return-to-center working condition of the vehicle according to the first steering wheel torque, the steering wheel angle and the vehicle speed includes: determining whether the absolute value of the first steering wheel torque is less than or equal to a preset torque threshold, and whether the duration for which the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold exceeds a preset duration, determining whether the absolute value of the steering wheel angle is greater than or equal to a first preset angle threshold, and determining whether the vehicle speed is greater than or equal to a first preset vehicle speed threshold; When the absolute value of the first steering wheel torque is less than or equal to a preset torque threshold, and the duration for which the absolute value of the first steering wheel torque is less than or equal to the preset torque threshold exceeds the preset duration, the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, and the vehicle speed is greater than or equal to the first preset speed threshold, the vehicle's return-to-center condition is determined to be an active return-to-center condition.

10. The method according to claim 9, characterized in that The method further comprises: Control the motor output test torque of the electric power steering system; Obtaining a steering wheel torque within a preset time after the motor outputs a test torque; Determining whether the absolute value of the steering wheel torque is less than or equal to a preset torque threshold; Only when it is determined that the absolute value of the steering wheel torque is less than or equal to the preset torque threshold value, it is determined whether the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold value, and whether the vehicle speed is greater than or equal to the first preset speed threshold value.

11. The method according to claim 7, characterized in that The method further comprises: When it is determined that the vehicle is in an active return-to-center condition, the steering wheel angle and the vehicle speed are obtained; The control mode of the vehicle active return control is determined according to the steering wheel angle and the vehicle speed; wherein the control modes of the vehicle active return control are an under-return control mode and an over-return control mode.

12. The method according to claim 11, characterized in that The proportional coefficient and the integral coefficient of the controller involved in the under-return control mode are different from the proportional coefficient and the integral coefficient of the controller involved in the over-return control mode.

13. The method according to claim 11, characterized in that The step of determining the control mode of the vehicle active return control according to the steering wheel angle and the vehicle speed includes: Determining whether the vehicle speed is less than or equal to a second preset vehicle speed threshold; When the vehicle speed is less than or equal to the second preset vehicle speed threshold, determining that the control mode of the vehicle active return control is an under-return control mode; In the case where the vehicle speed is greater than the second preset vehicle speed threshold, determining whether the vehicle speed is greater than or equal to a third preset vehicle speed threshold; wherein the second preset vehicle speed threshold is less than the third preset vehicle speed threshold; When the vehicle speed is greater than or equal to the third preset vehicle speed threshold, determining that the control mode of the vehicle active return-to-center control is a return-to-center overshoot control mode; When the vehicle speed is greater than the second preset vehicle speed threshold and less than the third preset vehicle speed threshold, determining whether the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold; When the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold, determining that the control mode of the vehicle active return control is an under-return control mode; When the absolute value of the steering wheel angle is greater than the second preset angle threshold, it is determined that the control mode of the vehicle active return control is a return-to-center overshoot control mode.

14. An active return control device, characterized in that: include: An acquisition module is used to obtain a steering wheel angle; A calculation module, configured to calculate the active return torque required by the steering wheel according to the steering wheel angle by using a cascade control algorithm; The control module is used to control the motor to output a corresponding torque according to the active return torque requirement so as to return the steering wheel to the center.

15. An electronic device, characterized in that: include: A memory and a processor, wherein the memory stores computer instructions, and when the computer instructions are executed by the processor, the active return control method according to any one of claims 1 to 13 is implemented.

16. An electric power steering system, characterized in that: It comprises the active return control device according to claim 14 or the electronic device according to claim 15.

17. A vehicle, characterized in that: Comprising the electric power steering system as claimed in claim 16.

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