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

Abstract

The present disclosure relates to an active return control method and device, an electric power steering system and a vehicle, wherein the method comprises: acquiring a steering wheel angle; calculating an active return demand torque by using a cascade control algorithm according to the steering wheel angle; 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] This disclosure relates to the field of electric power steering technology for vehicles, and more specifically, to an active return-to-center control method, device, electric power steering system, and vehicle. Background Technology

[0002] With the development of vehicle technology, vehicles are now equipped with electric power steering (EPS) systems. For vehicles using EPS, the steering system's return-to-center performance is an important indicator for evaluating vehicle driving performance. The active return-to-center performance of the steering system is related to its active return-to-center control strategy.

[0003] The active self-alignment control strategy provided by existing technology requires a large number of parameters to be calibrated, the self-alignment process is not smooth and uniform enough, and the stability is poor.

[0004] Therefore, there is a need to provide an active return-to-center control method for electric power steering systems. Summary of the Invention

[0005] One objective of this invention is to provide a new technical solution for an active homing control method.

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

[0007] Get the steering wheel angle;

[0008] Based on the steering wheel angle, the active return-to-center torque is calculated using a cascade control algorithm.

[0009] Based on the required torque for active return to center, the motor is controlled to output the corresponding torque to return the steering wheel to center.

[0010] Optionally, the step of calculating the active self-centering torque using a cascade control algorithm based on the steering wheel angle includes:

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

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

[0013] Optionally, the step of calculating the active return-to-center torque based on the target return-to-center angular velocity value and the inner loop PI controller in the cascade control algorithm includes:

[0014] Obtain the actual angular velocity value for return to center;

[0015] Based on the target return angular velocity value and the actual return angular velocity value, the active return torque requirement is calculated using the inner loop PI controller.

[0016] Optionally, the method further includes:

[0017] The error in the return angular velocity value is determined based on the target return angular velocity value and the actual return angular velocity value.

[0018] The rate of change of the error in the angular velocity of the return to center is calculated based on the error in the angular velocity of the return to center.

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

[0020] Based on the changes in the proportional coefficient and integral coefficient of the inner-loop PI controller, and the pre-stored proportional and integral coefficients of the inner-loop PI controller, determine the proportional coefficient and integral coefficient of the inner-loop PI controller.

[0021] Optionally, the method further includes:

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

[0023] Based on the target return angular velocity value and the mechanical return angular velocity value, the adjusted target return angular velocity value is determined; wherein,

[0024] The step of calculating the active return-to-center torque based on the target return-to-center angular velocity value and the actual return-to-center angular velocity value using the inner loop PI controller of the cascade control system includes:

[0025] Based on the adjusted target return angular velocity value and the actual return angular velocity value, the active return torque requirement is calculated using the inner loop PI controller of the cascade control system.

[0026] Optionally, determining the adjusted target return angular velocity value based on the target return angular velocity value and the mechanical return angular velocity value includes:

[0027] The first return angular velocity difference is obtained based on the target return angular velocity value and the mechanical return angular velocity value;

[0028] The first positive angular velocity difference is subjected to rate limiting processing to obtain the second positive angular velocity difference;

[0029] The adjusted target angular velocity value is obtained based on the difference between the second angular velocity and the mechanical angular velocity value.

[0030] Optionally, the method further includes: determining the vehicle's return-to-center condition; 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 only executed when the vehicle's return-to-center condition is active return-to-center.

[0032] Optionally, determining the vehicle's return-to-center condition includes:

[0033] Obtain the first steering wheel torque, steering wheel angle, and vehicle speed;

[0034] The vehicle's return-to-center condition is determined based on the first steering wheel torque, the steering wheel angle, and the vehicle speed.

[0035] Optionally, determining the vehicle's return-to-center condition based on the first steering wheel torque, steering wheel angle, and vehicle speed includes:

[0036] 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 a first preset angle threshold; and determine whether the vehicle speed is greater than or equal to a first preset speed threshold.

[0037] 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 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 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 probe torque of the electric power steering system;

[0040] Within a preset time period after the motor outputs the test torque, the steering wheel torque is obtained;

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

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

[0043] Optionally, the method further includes:

[0044] Once the vehicle is confirmed to be in active self-centering mode, the steering wheel angle and vehicle speed are obtained.

[0045] Based on the steering wheel angle and 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 the under-centering control mode and the over-centering control mode.

[0046] Optionally, the proportional and integral coefficients of the controller involved in the insufficient homing control mode are different from those of the controller involved in the overshoot homing control mode.

[0047] Optionally, determining the control mode for the vehicle's active self-centering control based on the steering wheel angle and the vehicle speed includes:

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

[0049] If 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 the insufficient return-to-center control mode.

[0050] If the vehicle speed is greater than the second preset speed threshold, determine whether the vehicle speed 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.

[0051] When the vehicle speed is greater than or equal to the third preset vehicle speed threshold, the control mode of the vehicle active return-to-center control is determined to be the return-to-center overshoot control mode.

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

[0053] If 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 the insufficient return-to-center control mode.

[0054] If 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 the return-to-center overshoot control mode.

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

[0056] The acquisition module is used to acquire the steering wheel angle;

[0057] The calculation module is used to calculate the active return torque based on the steering wheel angle 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-to-center torque requirement, so as to return the steering wheel to center.

[0059] According to a third aspect of the present invention, an electronic device is provided, comprising a memory and a processor, the memory storing a computer program for controlling the processor to operate in order to perform the active homing control method according to any one of the first aspects of the present invention.

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

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

[0062] The active self-centering control method provided by this invention uses only the steering wheel angle and a cascade control algorithm to calculate the active self-centering torque requirement. It involves few parameters in the calculation, is independent of the vehicle speed, and has high control precision.

[0063] The features and advantages of the embodiments of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

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

[0065] Figure 1 This is a flowchart of an active homing control method according to an embodiment of the present invention.

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

[0067] Figure 3 This is a schematic diagram of the process for determining the active return torque according to an embodiment of the present invention.

[0068] Figure 4 This is a schematic diagram of the process for determining the active return torque according to an embodiment of the present invention.

[0069] Figure 5This is a schematic diagram of an active self-alignment control device according to an embodiment of the present invention.

[0070] Figure 6 This is a schematic diagram of the hardware structure of an active self-alignment control device according to an embodiment of the present invention.

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

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

[0073] Figure 9 This is a structural schematic diagram of a vehicle according to an embodiment of the present invention. Detailed Implementation

[0074] Various exemplary embodiments of this 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 and is in no way intended to limit the embodiments of this specification or their application or use.

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

[0077] <Method Implementation>

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

[0079] Step S110: Obtain the steering wheel angle.

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

[0081] Step S120: Based on the steering wheel angle, the active return torque is calculated using a cascade control algorithm.

[0082] Step S130: Based on the active return-to-center torque requirement, control the motor to output the corresponding torque so that the steering wheel returns to center.

[0083] The active self-centering control method provided in this embodiment of the invention uses only the steering wheel angle and a cascade control algorithm to calculate the active self-centering torque requirement. It involves few parameters in the calculation, is independent of the vehicle speed, and has high control accuracy.

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

[0085] Step S121: Based on the steering wheel angle, the target return-to-center angular velocity value is calculated using the outer loop PI controller in the cascade control algorithm.

[0086] Based on the following formula, the target's angular velocity ω1 is calculated.

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

[0088] Where, θ a The desired steering wheel straightening angle is set to 0, θ is the steering wheel angle, and K p1 K is the proportional gain of the outer loop PI controller. i1 The integral coefficient of the outer loop PI controller.

[0089] Step S122: Calculate the active return-to-center torque based on 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 the actual return angular velocity value; and calculating the active return torque demand using an inner loop PI controller based on the target return angular velocity value and the actual return angular velocity value.

[0091] The actual return-to-center angular velocity is the steering wheel angular velocity calculated by differentiating the steering wheel angle.

[0092] Based on the following formula, the active self-alignment torque T is calculated. a ,

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

[0094] Where ω1 is the target angular velocity value, ω is the actual angular velocity value, and K p2 K is the proportional gain of the inner-loop PI controller. i2 K represents the integral coefficient of the inner-loop PI controller. p2 and K i2 This is a pre-stored value.

[0095] In one embodiment of the present invention, the method further includes: using a variable universe of discourse fuzzy control algorithm to obtain the correspondence between the input and output quantities of the variable universe of discourse fuzzy controller; wherein the input quantity is the homing angular velocity error and the rate of change of the homing angular velocity error, and the output quantity 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.

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

[0097] In traditional fuzzy controllers, the universe of discourse (UOD) is fixed once determined. However, changes in the input signal and the controlled object will cause changes in the input quantities. At this point, the initial UOD no longer meets the control requirements and needs to be reset. Variable UOD aims to enable dynamic changes to the initial UOD, improving the adaptive capability of fuzzy control. In this embodiment, a transfer function model with a variable UOD scaling factor is used to determine the UOD for each quantity, as shown below:

[0098]

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

[0100] In this embodiment, the initial universe of discourse for error e is [-200, 200]. When using the transfer function model with a variable universe of discourse scaling factor, the initial universe of discourse 200 is subtracted by a constant b, and then input into the transfer function model with the variable universe of discourse scaling factor for calculation. This yields a curve, where the horizontal axis represents e, and the vertical axis represents the universe of discourse for e; that is, different e correspond to different universes of discourse. To prevent the output from changing too drastically due to an excessively small universe of discourse when e is small, b should be added to the vertical axis value of the aforementioned universe of discourse curve to obtain the final universe of discourse curve. If the value of the universe of discourse curve corresponding to the error e is ev, then the range of the universe of discourse for the error e is [-ev, ev].

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

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

[0103] The corresponding outputs are calculated and recorded using a fuzzy control algorithm. This transforms the correspondence between the inputs and outputs of the variable universe fuzzy controller into an offline rule table. Specifically, Δkp and Δki can be obtained by looking up the table using e and ec in two dimensions, avoiding online computation of the fuzzy control algorithm.

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

[0105] In this embodiment, the change in the proportional coefficient of the inner-loop PI controller is added to the pre-stored proportional coefficient of the inner-loop PI controller to obtain the proportional coefficient of the inner-loop PI controller. The change in the integral coefficient of the inner-loop PI controller is added to the pre-stored integral coefficient of 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: acquiring the mechanical return-to-center angular velocity value when the vehicle enters active return-to-center control; determining an adjusted target return-to-center angular velocity value based on the target return-to-center angular velocity value and the mechanical return-to-center angular velocity value; and calculating the active return-to-center required torque using an inner-loop PI controller based on the adjusted target return-to-center angular velocity value and the actual return-to-center angular velocity value.

[0107] Specifically, based on the target angular velocity value and the mechanical angular velocity value, the first angular velocity difference is obtained; the first angular velocity difference is subjected to rate limiting processing to obtain the second angular velocity difference; based on the second angular velocity difference and the mechanical angular velocity value, the adjusted target angular velocity value is obtained.

[0108] The mechanical return-to-center angular velocity value when the vehicle enters active return-to-center control is the derivative of the steering wheel angle, and is the angular velocity value corresponding to the active return-to-center control when it is entered.

[0109] In this embodiment, to prevent the target angular velocity from increasing too rapidly, the rate of increase of the first angular velocity difference is limited to obtain a second angular velocity difference. This second angular velocity difference is then added to the mechanical angular velocity value to obtain the adjusted target angular velocity value. This smoothly connects the mechanical angular velocity value during active angular velocity return with the calculated target angular velocity, preventing sudden changes in angular velocity during active angular velocity return and ensuring a smooth and stable angular velocity return process.

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

[0111] In one embodiment, after the vehicle completes a steering maneuver, the steering wheel angle is acquired, and the steering wheel angular velocity is calculated by differentiating the steering wheel angle. It is determined whether the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity, and whether the duration of this opposition exceeds a preset duration. If 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 this opposition exceeds the preset duration, the vehicle is determined to be in a straightening condition.

[0112] The steering wheel angular velocity is calculated by differentiating the steering wheel angle and then filtered using a least-squares algorithm. It should be noted that the phase delay of the filtered signal must meet preset requirements and cannot be too large, otherwise it will reduce the stability margin of the control system.

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

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

[0115] In one embodiment, a first steering wheel torque, a steering wheel angle, and the vehicle speed are acquired. Based on the first steering wheel torque, steering wheel angle, and vehicle speed, the vehicle's self-centering condition is determined. The active self-centering control method provided by this invention is executed only when the vehicle's self-centering condition is an active self-centering condition. The active self-centering control method provided by this invention is not executed when the vehicle's self-centering condition is a driver-controlled condition.

[0116] The steering wheel torque is acquired by a torque sensor. The steering wheel angle is acquired by a steering angle sensor. The vehicle speed is obtained through the vehicle's CAN network.

[0117] Specifically, it is determined whether the absolute value of the first steering wheel torque is less than or equal to a preset torque threshold, 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, 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.

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

[0119] If the absolute value of the first steering wheel torque is greater than a preset torque threshold, or if 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 does not exceed a preset duration, or if the absolute value of the steering wheel angle is less than a first preset angle threshold, or if the vehicle speed is less than a first preset speed threshold, then the vehicle's return-to-center condition is determined to be 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 this invention is not executed.

[0120] The preset torque threshold can be calibrated based on the driver's hand force when releasing the steering wheel and returning it to center. Specifically, the driver's hand force when releasing the steering wheel and returning it to center is collected at different vehicle speeds, and the mean E(Tr) and standard deviation δ(Tr) of the driver's hand force when releasing the steering wheel and returning it to center are calculated at different vehicle speeds. The preset torque threshold is E(Tr) + 2*δ(Tr). It should be noted that the hand force when releasing the steering wheel and returning it to center is the steering wheel torque value at that moment.

[0121] The preset duration can be set as needed, for example, 0.05 seconds. The first preset turning angle threshold can be set as needed. The first preset vehicle speed threshold can be set as needed.

[0122] In one embodiment of the present invention, the method further includes: controlling the motor of the electric power steering system to output a test torque; after the motor outputs the test torque, acquiring a second steering wheel 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 when it is determined 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 the preset duration, continuing to perform the operations of 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 speed threshold.

[0123] If the absolute value of the second steering wheel torque is greater than a preset torque threshold, or if the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold, and the duration during which the absolute value of the second steering wheel torque is less than or equal to the preset torque threshold does not exceed a preset duration, the active return-to-center control method provided by this invention will not be executed.

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

[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 embodiments, and will not be elaborated further here.

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

[0128] It should be noted that the application of the test torque provided in this embodiment can be performed after determining whether the absolute value of the first steering wheel torque is less than or equal to a preset torque threshold, and after determining 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, and before determining whether the absolute value of the steering wheel angle is greater than or equal to a first preset angle threshold, and before determining whether the vehicle speed is greater than or equal to a first preset speed threshold. Alternatively, the application of the test torque provided in this 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 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; it 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 self-centering condition, the steering wheel angle and the vehicle speed are acquired. Based on the steering wheel angle and the vehicle speed, a control mode for the active self-centering control is determined; wherein, the control mode for the active self-centering control is an under-centering control mode and a self-centering overshoot control mode.

[0130] The proportional and integral coefficients of the controller involved in the undershoot control mode are different from those involved in the overshoot control mode.

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

[0132] Specifically, it is determined whether the vehicle speed is less than or equal to a second preset speed threshold. If the vehicle speed is less than or equal to the second preset speed threshold, the control mode of the vehicle's active return-to-center control is determined to be an under-centering control mode. If the vehicle speed is greater than the second preset speed threshold, it is determined 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. If the vehicle speed is greater than or equal to the third preset speed threshold, the control mode of the vehicle's active return-to-center control is determined to be a return-to-center overshoot control mode. If 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 a second preset angle threshold. If 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's active return-to-center control is determined to be an under-centering control mode. If the absolute value of the steering wheel angle is greater than the second preset angle threshold, the control mode of the vehicle's active return-to-center control is determined to be a return-to-center overshoot control mode.

[0133] In one embodiment, a mapping table between vehicle speed and preset turning angle thresholds is pre-stored. When the vehicle speed is greater than a second preset speed threshold but less than a third preset speed threshold, the corresponding preset speed threshold is retrieved from the mapping table based on the vehicle speed and used as the second preset turning angle threshold.

[0134] In one embodiment, when executing the active return-to-center control method provided in any of the above embodiments, if 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 for which the direction of the steering wheel angle is the same as the direction of the steering wheel angular velocity exceeds a preset duration, the active return-to-center control is exited.

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

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

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

[0138] This is because when the driver intervenes with relatively little force during the active return-to-center control process, if the return-to-center angular velocity is too high, the active return-to-center control will disengage abruptly, causing steering wheel vibration. In this case, it is necessary to determine the unloading rate of the torque required for active return-to-center based on the driver's intervention force and the actual return-to-center angular velocity. The smaller the force and the larger the actual return-to-center angular velocity, the smaller the unloading rate.

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

[0140] See Figure 2 The control mode for active homing control is determined by steps S201 to S215.

[0141] Step S201: After the vehicle completes the steering action, the steering wheel angle is obtained, the derivative of the steering wheel angle is calculated, and the steering wheel angular velocity is obtained.

[0142] Step S202: Determine whether the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity, and whether the duration of the opposite direction of the steering wheel angle and 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 during which the direction of the steering wheel angle is opposite to the direction of the steering wheel angular velocity does not exceed a preset duration, then step S203 is executed to determine that the vehicle is not in the straightening condition and no further 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 of the steering wheel angle being opposite to the direction of the steering wheel angular velocity exceeds a preset duration, then step S204 is executed 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 of the absolute value of the first steering wheel torque being 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, then step S205 is executed to determine that the vehicle's return-to-center condition is the driver-controlled return-to-center condition, and no further operations are performed.

[0146] If the result of step S204 is that 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 a preset duration, then step S206 is executed to control the motor output of the electric power steering system to test torque.

[0147] Step S207: After the motor outputs the test torque, the second steering wheel torque is obtained.

[0148] Step S208: Determine 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, then step S205 is executed to determine that the vehicle's return-to-center condition is the driver-controlled return-to-center condition, and no further operations are performed.

[0150] If the result of step S208 is that the absolute value of the second steering wheel torque is less than or equal to a 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 exceeds a preset duration, then step S209 is executed to determine whether the absolute value of the steering wheel angle is greater than or equal to a 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, then step S205 is executed to determine that the vehicle's return-to-center condition is the driver-controlled return-to-center condition, and no further 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 steering angle threshold, then step S210 is executed to determine whether the vehicle speed is greater than or equal to the first preset vehicle speed threshold.

[0153] If the result of step S210 is that the vehicle speed is less than the first preset vehicle speed threshold, then step S205 is executed to determine that the vehicle's return-to-center condition is the driver-controlled return-to-center condition, and no further 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, then 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, then step S212 is executed to determine that the control mode of the vehicle active return control is the insufficient return control mode.

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

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

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

[0159] If 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, then step S212 is executed to determine that the control mode of the vehicle active return-to-center control is the insufficient return-to-center control mode.

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

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

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

[0163] See Figure 3 Determining the required torque for active return to center includes steps S301 to S313.

[0164] Step S301: Obtain the steering wheel angle θ.

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

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

[0167] Step S304, based on the target return angular velocity value ω1 and the mechanical return angular velocity value ω m The first positive angular velocity difference ω is obtained. c .

[0168] Step S305, calculate the first positive angular velocity difference ω c After applying a rate limiting process, the second positive angular velocity difference ω is obtained. d .

[0169] Step S306, based on the second positive angular velocity difference ω d and the mechanical return angular velocity value ω m The adjusted target angular velocity value ω is obtained. t .

[0170] Step S307: Obtain the actual angular velocity value ω for returning to center.

[0171] Step S308, based on the adjusted target angular velocity value ω t The error e of the return angular velocity value is determined by combining the actual return angular velocity value ω with the return angular velocity value.

[0172] Step S309: Calculate the rate of change of the angular velocity error e based on the error e of the angular velocity value.

[0173] Step S310: Calculate the rate of change of the angular velocity error e based on the error e of the angular velocity value.

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

[0175] Step S312: Determine the proportional coefficient kp2 and integral coefficient ki2 of the inner loop PI controller based on the change in the proportional coefficient Δkp of the inner loop PI controller, the change in the integral coefficient Δki of the inner loop PI controller, and the pre-stored proportional and integral coefficients of the inner loop PI controller.

[0176] Step S313, based on the adjusted target angular velocity value ω t The active return-to-center torque Ta is calculated using the inner loop PI controller of the cascade control system, based on the actual return-to-center angular velocity ω and the actual return-to-center angular velocity ω.

[0177] <Device Embodiment>

[0178] One embodiment of the present invention provides an active self-alignment control device. See also... Figure 5 The active return-to-center 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-to-center torque requirement based on the steering wheel angle using a cascade control algorithm. The control module 530 is used to control the motor to output the corresponding torque based on the active return-to-center torque requirement, so as to return the steering wheel to center.

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

[0181] In one embodiment, the calculation module 520 is further configured to obtain the actual return-to-center angular velocity value; and to calculate the active return-to-center required torque using the inner loop PI controller based on the target return-to-center angular velocity value and the actual return-to-center angular velocity value.

[0182] In one embodiment, the active homing control device further includes a variable universe of discourse (VOD) fuzzy control module. The VOD fuzzy control module is used to obtain the correspondence between the input and output quantities of the VOD fuzzy controller using a VOD fuzzy control algorithm; wherein the input quantities are the homing angular velocity error and the rate of change of the homing angular velocity error, and the output quantities are 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.

[0183] In one embodiment, the active homing 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 homing angular velocity error based on the target homing angular velocity value and the actual homing angular velocity value; calculate the rate of change of the homing angular velocity error based on the homing angular velocity error; obtain the change in the proportional coefficient and integral coefficient of the inner-loop PI controller based on the correspondence between the input and output quantities of the variable domain fuzzy controller, using the homing angular velocity error and the rate of change of the homing angular velocity error; and determine the proportional coefficient and integral coefficient of the inner-loop PI controller based on the change in the proportional coefficient, the change in the integral coefficient, and the pre-stored proportional and integral coefficients of the inner-loop PI controller.

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

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

[0186] In this embodiment, the calculation module 520 is also used to calculate the active return torque demand based on the adjusted target return angular velocity value and the actual return angular velocity value using the inner loop PI controller.

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

[0188] In one embodiment, the vehicle return-to-center condition determination module is used to acquire a first steering wheel torque, a steering wheel angle, and the vehicle speed; and to determine the vehicle's return-to-center condition 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 further configured 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 a first preset angle threshold, and determine whether the vehicle speed is greater than or equal to a first preset speed threshold; if 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, then the vehicle's return-to-center condition is determined to be an active return-to-center condition.

[0190] In one embodiment, the active return-to-center control device further includes a test torque output module. The test torque output module controls the motor of the electric power steering system to output a test torque; within a preset time period after the motor outputs the test torque, it acquires the steering wheel torque; determines whether the absolute value of the steering wheel torque is less than or equal to a preset torque threshold; and only if the absolute value of the steering wheel torque is determined to be less than or equal to the preset torque threshold, it then determines 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.

[0191] In one embodiment, the active self-centering control device further includes a self-centering control mode determination module. The self-centering control mode determination module is used to acquire the steering wheel angle and vehicle speed when the vehicle is determined to be in active self-centering mode; and to determine the control mode of the vehicle active self-centering control based on the steering wheel angle and vehicle speed; wherein the control mode of the vehicle active self-centering control is an under-centering control mode and a self-centering overshoot control mode.

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

[0193] In one embodiment, the vehicle return-to-center control mode determination module is further configured 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; if 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-centering control mode; if 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 a return-to-center overshoot control mode; if the vehicle speed is greater than the second preset speed threshold and less than the third preset speed threshold, the module determines whether the absolute value of the steering wheel angle is less than or equal to a second preset angle threshold; if 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-centering control mode; if 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 a return-to-center overshoot control mode.

[0194] One embodiment of the present invention provides an electronic device, such as Figure 6 As shown. The electronic device 600 includes a memory 620 and a processor 610. The memory 620 stores a computer program for controlling the processor 610 to operate and execute the active return-to-center control method in any of the above embodiments.

[0195] <System Implementation Example>

[0196] One embodiment of the present invention provides an electric power steering system. The electric power steering system includes an active return-to-center control device as provided in the above embodiments or an electronic device as provided in the above embodiments. See details. Figure 7 .

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

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

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

[0200] <Vehicle Example>

[0201] One embodiment of the present invention provides a vehicle, such as Figure 9 As shown. The vehicle includes the electric power steering system provided in the above embodiments.

[0202] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. For the electric vehicle embodiments, relevant parts can be found in the descriptions of the method embodiments.

[0203] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0204] Embodiments of this specification may be systems, methods, and / or computer program products. A computer program product may include a computer-readable storage medium having computer instructions stored thereon for causing a processor to implement various aspects of the embodiments of this specification.

[0205] Computer-readable storage media can be tangible devices capable of holding and storing computer instructions for use by computer instruction execution devices. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing computer instructions thereon, and any suitable combination thereof. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

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

[0207] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this specification. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of computer instructions, which contains one or more executable computer instructions for implementing a specified logical function. In some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions. It will be known to those skilled in the art that implementation in hardware, implementation in software, and implementation using a combination of software and hardware are equivalent.

[0208] Various embodiments of this specification have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An active self-alignment control method, characterized in that, include: Determining the vehicle's return-to-center condition, wherein the return-to-center condition is one of an active return-to-center condition and a driver-controlled return-to-center condition, includes: acquiring a first steering wheel torque, a steering wheel angle, and the vehicle speed; determining the vehicle's return-to-center condition based on the first steering wheel torque, the steering wheel angle, and the vehicle speed, specifically including: 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, and determining the direction... The vehicle speed is determined to be greater than or equal to a first preset speed threshold if the absolute value of the steering wheel angle is greater than or equal to a first preset speed threshold. If the absolute value of the first steering wheel torque is less than or equal to a 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 exceeds the preset duration, and 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. When the vehicle's return-to-center condition is active return-to-center, the steering wheel angle is obtained; Based on the steering wheel angle, the active return-to-center torque is calculated using a cascade control algorithm. Based on the required torque for active return to center, the motor is controlled to output the corresponding torque to return the steering wheel to center.

2. The method according to claim 1, characterized in that, The step of calculating the active self-centering torque using a cascade control algorithm based on the steering wheel angle includes: Based on the steering wheel angle, the target return-to-center angular velocity value is calculated using the outer loop PI controller in the cascade control algorithm; The active return-to-center torque is calculated based on the target return-to-center 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 step of calculating the active return-to-center torque based on the target return-to-center angular velocity value and the inner loop PI controller in the cascade control algorithm includes: Obtain the actual angular velocity value for return to center; Based on the target return angular velocity value and the actual return angular velocity value, the active return torque requirement is calculated using the inner loop PI controller.

4. The method according to claim 3, characterized in that, The method further includes: The error of the return angular velocity value is determined based on the target return angular velocity value and the actual return angular velocity value. Based on the error in the positive angular velocity value, the rate of change of the error in the positive angular velocity value is calculated; Based on the error of the homing angular velocity value and the rate of change of the error of the homing angular velocity value, the change of the proportional coefficient and the change of the integral coefficient of the inner loop PI controller are obtained by using the correspondence between the input and output of the variable universe fuzzy controller. Based on the changes in the proportional coefficient and integral coefficient of the inner-loop PI controller, and the pre-stored proportional and integral coefficients of the inner-loop PI controller, determine the proportional coefficient and integral coefficient of the inner-loop PI controller.

5. The method according to claim 3, characterized in that, The method further includes: Obtain the mechanical return angular velocity value when the vehicle enters active return control; Based on the target return angular velocity value and the mechanical return angular velocity value, the adjusted target return angular velocity value is determined; wherein, The step of calculating the active return-to-center torque using the inner-loop PI controller based on the target return-to-center angular velocity value and the actual return-to-center angular velocity value includes: Based on the adjusted target return angular velocity value and the actual return angular velocity value, the active return torque requirement is calculated using the inner loop PI controller.

6. The method according to claim 5, characterized in that, The step of determining the adjusted target return angular velocity value based on the target return angular velocity value and the mechanical return angular velocity value includes: The first return angular velocity difference is obtained based on the target return angular velocity value and the mechanical return angular velocity value; The first positive angular velocity difference is subjected to rate limiting processing to obtain the second positive angular velocity difference; The adjusted target angular velocity value is obtained based on the difference between the second angular velocity and the mechanical angular velocity value.

7. The method according to claim 1, characterized in that, The method further includes: Control the motor output probe torque of the electric power steering system; Within a preset time period after the motor outputs the test torque, the steering wheel torque is obtained; Determine whether the absolute value of the steering wheel torque is less than or equal to a preset torque threshold; Only when the absolute value of the steering wheel torque is determined to be less than or equal to the preset torque threshold, is it performed to determine whether the absolute value of the steering wheel angle is greater than or equal to the first preset angle threshold, and whether the vehicle speed is greater than or equal to the first preset speed threshold.

8. The method according to claim 1, characterized in that, The method further includes: Once the vehicle is confirmed to be in active self-centering mode, the steering wheel angle and vehicle speed are obtained. Based on the steering wheel angle and 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 the under-centering control mode and the over-centering control mode.

9. The method according to claim 8, characterized in that, The proportional and integral coefficients of the controller involved in the undershoot control mode are different from those of the controller involved in the overshoot control mode.

10. The method according to claim 8, characterized in that, The step of determining the control mode for the vehicle's active self-centering control based on the steering wheel angle and vehicle speed includes: Determine whether the vehicle speed is less than or equal to a second preset speed threshold. If 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 the insufficient return-to-center control mode. If the vehicle speed is greater than the second preset speed threshold, determine whether the vehicle speed 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 vehicle speed is greater than or equal to the third preset vehicle speed threshold, the control mode of the vehicle active return-to-center control is determined to be the return-to-center overshoot control mode. If the vehicle speed is greater than the second preset speed threshold and less than the third preset speed threshold, determine whether the absolute value of the steering wheel angle is less than or equal to the second preset angle threshold. If 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 the insufficient return-to-center control mode. If 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 the return-to-center overshoot control mode.

11. An active return-to-center control device, characterized in that, include: The vehicle return-to-center condition determination module is used to determine the vehicle's return-to-center condition. This return-to-center condition is one of active return-to-center or driver-controlled return-to-center, and includes: acquiring a first steering wheel torque, steering wheel angle, and vehicle speed; determining the vehicle's return-to-center condition based on the first steering wheel torque, the steering wheel angle, and the vehicle speed, specifically including: 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. The system determines 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. If the absolute value of the first steering wheel torque is less than or equal to a 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 exceeds a preset duration, and 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, then the vehicle's return-to-center condition is determined to be an active return-to-center condition. The acquisition module is used to acquire the steering wheel angle when the vehicle's return-to-center condition is active return-to-center. The calculation module is used to calculate the active return torque based on the steering wheel angle using a cascade control algorithm. The control module is used to control the motor to output a corresponding torque according to the active return-to-center torque requirement, so as to return the steering wheel to center.

12. An electronic device, characterized in that, include: A memory and a processor, the memory storing computer instructions that, when executed by the processor, implement the active homing control method according to any one of claims 1-10.

13. An electric power steering system, characterized in that, Includes the active return-to-center control device as described in claim 11 or the electronic device as described in claim 12.

14. A vehicle, characterized in that, Including the electric power steering system as described in claim 13.

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