Power assist motor control method, system, device and storage medium

Abstract

The present invention discloses a power-assist motor control method, system, device and storage medium. The method comprises: obtaining the vehicle speed, steering column angle and steering column rotation speed of the vehicle, and calculating the target protection torque based on the vehicle speed, steering column angle and steering column rotation speed, wherein the target protection torque changes with the vehicle speed, and then when the rack of the steering gear is in the terminal protection area and moves toward the terminal position, the original power-assist motor torque is adjusted according to the target protection torque to obtain the expected torque of the power-assist motor, and the power assist of the power-assist motor to the steering column is controlled according to the expected torque; the present invention not only considers the steering column angle and rotation speed during terminal protection, but also considers the influence of the vehicle speed, and limits the rack movement by the vehicle speed, steering column angle and steering column rotation speed, thereby alleviating the terminal collision impact under different vehicle speeds, and ensuring that the vehicle has a good rack terminal protection effect under various vehicle speed conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle steering system control, and in particular to a power assist motor control method, system, device and storage medium. Background Art

[0002] The vehicle steering system is an important part of the vehicle chassis, mainly including the steering wheel, steering column, steering gear and steering wheel, etc. The driver transmits the torque of the steering wheel to the steering gear through the steering column, thereby driving the steering gear to steer the vehicle. When the driver controls the steering of the vehicle through the steering wheel, when the steering wheel (steering column) is turned to the extreme position, the rack of the steering gear moves to the end position and collides with the end position, causing damage to the mechanical parts and the collision impact will affect the driver's feel. Therefore, it is necessary to limit the steering when the rack reaches the end position to protect it.

[0003] The existing rack end protection method generally sets an end protection area for the rack, which is the area from the starting position to the end position. When the rack moves to the end protection area, the steering wheel rotation resistance is increased by reducing the power torque of the power motor, thereby slowing down or stopping the movement speed of the rack toward the end position, and finally reducing the rack collision force. However, by reducing the power in the end protection area, the impact of the rack collision can only be slightly reduced, and it is impossible to effectively prevent the end collision impact in response to different working conditions, resulting in poor end protection effect. Summary of the invention

[0004] The present invention provides a power assist motor control method, system, device and storage medium to solve the problem that the traditional terminal protection method cannot cope with different working conditions and effectively prevent terminal collision impact, resulting in poor terminal protection effect.

[0005] A method for controlling a power assist motor is provided, comprising:

[0006] The vehicle speed, steering column angle and steering column speed are obtained, and a target protection torque is calculated based on the vehicle speed, steering column angle and steering column speed, where the target protection torque changes with the vehicle speed;

[0007] When the rack of the steering gear is in the end protection area and moves toward the end position, the original assist torque of the assist motor is adjusted according to the target protection torque to obtain the desired torque of the assist motor, and the assist of the assist motor to the steering column is controlled according to the desired torque.

[0008] Optionally, the target protection torque is calculated based on the vehicle speed, the steering column angle and the steering column rotation speed, including:

[0009] determining a reference speed according to the steering column angle, the reference speed decreasing as the rack moves toward the end position;

[0010] determining a speed difference between a steering column speed and a reference speed;

[0011] The damping force is calculated according to the speed difference and the vehicle speed to obtain the damping torque, and the target protection torque is determined according to the damping torque.

[0012] Optionally, the damping force is calculated according to the rotation speed difference and the vehicle speed to obtain the damping torque, including:

[0013] The maximum damping torque is determined according to the vehicle speed, and the damping coefficient is determined according to the speed difference;

[0014] The product of the maximum damping torque and the protection factor is taken as the damping torque.

[0015] Optionally, the maximum damping torque is determined according to the vehicle speed, including:

[0016] Acquire maximum damping torque data, where the maximum damping torque data is the maximum damping torque value allowed at different vehicle speeds obtained by pre-calibration based on actual vehicle test data;

[0017] The maximum damping torque value corresponding to the vehicle speed is found in the maximum damping torque data and is used as the maximum damping torque.

[0018] Optionally, before calculating the damping force according to the rotation speed difference and the vehicle speed to obtain the damping torque, the method further includes:

[0019] Determine whether the speed difference is greater than a preset value;

[0020] If the speed difference is less than or equal to the preset value, the power assist mode of the power assist motor is determined to be the basic protection mode, so as to calculate the basic protection torque according to the vehicle speed and the steering column angle, and use the basic protection torque as the target protection torque;

[0021] If the speed difference is greater than the preset value, the assist mode of the assist motor is determined to be the speed damping mode, so as to calculate the damping torque according to the speed difference and the vehicle speed, and the target protection torque in the speed damping mode is greater than the target protection torque in the basic protection mode.

[0022] Optionally, determining the target protection torque according to the damping torque includes:

[0023] Obtain the basic protection torque calculated according to the vehicle speed and the steering column angle;

[0024] The sum of the damping moment and the foundation protection force is taken as the target protection moment.

[0025] Optionally, the basic protection torque is calculated according to the vehicle speed and the steering column angle, including:

[0026] The maximum basic protection torque is determined according to the vehicle speed, and the protection factor is determined according to the steering column angle;

[0027] The product of the maximum basic protection moment and the protection coefficient is taken as the basic protection moment.

[0028] Optionally, determining a protection factor according to a steering column angle includes:

[0029] Determine the total length of the end protection area, which includes the starting position and the end position of the protection;

[0030] Determine the shortest distance between the steering column angle position and the starting point position;

[0031] Divide the shortest distance by the total length of the protected area to obtain the protection factor.

[0032] Optionally, the original power-assisting torque of the power-assisting motor is adjusted according to the target protection torque to obtain the desired torque of the power-assisting motor, and the power-assisting motor is controlled according to the desired torque, including:

[0033] The desired torque is obtained by subtracting the target protection torque from the original power-assist torque, and the positive and negative signs of the target protection torque correspond to the direction of the steering column angle;

[0034] The target current of the power-assist motor is calculated according to the expected torque, and the target current is input into the motor controller of the power-assist motor so as to perform closed-loop control on the control current of the power-assist motor through the motor controller.

[0035] A power-assist motor control system is provided, comprising a power-assist motor control device and a power-assist motor, wherein the power-assist motor control device is used for:

[0036] The vehicle speed, steering column angle and steering column speed are obtained, and a target protection torque is calculated based on the vehicle speed, steering column angle and steering column speed, where the target protection torque changes with the vehicle speed;

[0037] When the rack of the steering gear is in the end protection area and moves toward the end position, the original assist torque of the assist motor is adjusted according to the target protection torque to obtain the desired torque of the assist motor, and the assist of the assist motor to the steering column is controlled according to the desired torque.

[0038] A power-assisting motor control device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the power-assisting motor control method are implemented.

[0039] A readable storage medium is provided, which stores a computer program, and when the computer program is executed by a processor, the steps of the above-mentioned power assist motor control method are implemented.

[0040] In one solution provided by the above-mentioned power-assist motor control method, system, device and storage medium, the vehicle speed, steering column angle and steering column speed are obtained, and the target protection torque is calculated based on the vehicle speed, steering column angle and steering column speed. The target protection torque changes with the vehicle speed. Then, when the rack of the steering gear is in the terminal protection area and moves to the terminal position, the original power-assist motor torque is adjusted according to the target protection torque to obtain the desired torque of the power-assist motor, and the power assist of the power-assist motor to the steering column is controlled according to the desired torque. The present invention not only considers the steering column angle and speed during terminal protection, but also considers the influence of vehicle speed. The target protection torque is calculated by the vehicle speed, steering column angle and steering column speed, so that the target protection torque changes with the vehicle speed, thereby adjusting the power assist of the power-assist motor to the steering column, achieving the purpose of limiting the rack movement based on the vehicle speed, steering column angle and steering column speed, thereby alleviating the terminal collision impact at different vehicle speeds, and ensuring that the vehicle has a good rack terminal protection effect under various vehicle speed conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0042] Figure 1 is a schematic structural diagram of a power assist motor control system in one embodiment of the present invention;

[0043] Figure 2 is a schematic flow chart of a method for controlling a power assist motor in one embodiment of the present invention;

[0044] Figure 3 yes Figure 2 A schematic diagram of an implementation process of step S20;

[0045] Figure 4 yes Figure 2 A schematic diagram of an implementation process of step S10;

[0046] Figure 5 yes Figure 1 A structural schematic diagram of a mid-assist motor control device;

[0047] Figure 6 yes Figure 1 Another structural schematic diagram of the mid-assist motor control device. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The power assist motor control method provided by the embodiment of the present invention can be applied in the following aspects: Figure 1 In the power-assist motor control system, the power-assist motor control system includes a power-assist motor control device and a power-assist motor, wherein the power-assist motor control device communicates with the power-assist motor. The power-assist motor control device is used to: obtain the vehicle speed, steering column angle and steering column speed of the vehicle, and calculate the target protection torque based on the vehicle speed, steering column angle and steering column speed, and the target protection torque changes with the vehicle speed; when the rack of the steering gear is in the end protection area and moves to the end position, the original power-assist torque of the power-assist motor is adjusted according to the target protection torque to obtain the desired torque of the power-assist motor, and the power assist of the power-assist motor to the steering column is controlled according to the desired torque.

[0050] During the operation of the vehicle, the power-assist motor control device obtains the vehicle speed, steering column angle and steering column speed, and calculates the target protection torque based on the vehicle speed, steering column angle and steering column speed. The target protection torque changes with the vehicle speed. Then, when the rack of the steering gear is in the terminal protection area and moves to the terminal position, the original power-assist motor torque is adjusted according to the target protection torque to obtain the desired torque of the power-assist motor, and the output torque of the power-assist motor is controlled according to the desired torque, thereby changing the power assistance to the steering column and suppressing the terminal impact. In this embodiment, during the terminal protection, not only the steering column angle and speed are considered, but also the influence of the vehicle speed is considered. The target protection torque is calculated by the vehicle speed, steering column angle and steering column speed, so that the target protection torque changes with the vehicle speed, thereby adjusting the power assistance of the power-assist motor to the steering column, achieving the purpose of limiting the rack movement based on the vehicle speed, steering column angle and steering column speed, alleviating the terminal collision impact at different vehicle speeds, and ensuring that the vehicle has a good rack terminal protection effect under various vehicle speed conditions.

[0051] Among them, the power-assisting motor control device can be a motor controller, which is electrically connected to the power-assisting motor; the power-assisting motor control device can also be other devices on the vehicle, such as an electronic control unit ECU, a vehicle controller, etc.

[0052] In this embodiment, the power-assist motor control system includes a power-assist motor control device and a power-assist motor, which is only an exemplary description. In other embodiments, the power-assist motor control system also includes other devices, such as Figure 1The data acquisition device is used to cut vehicle-related data, and the data acquisition device includes a vehicle speed sensor, a steering column angle sensor, etc.

[0053] In one embodiment, if Figure 2 As shown, a method for controlling a booster motor is provided, and the method is applied in Figure 1 The power assist motor control system in FIG. 1 is taken as an example to illustrate the invention, which includes the following steps:

[0054] S10: Obtaining the vehicle speed, steering column angle and steering column speed, and calculating a target protection torque based on the vehicle speed, steering column angle and steering column speed.

[0055] During vehicle operation, the power-assisted motor control device obtains the vehicle speed, steering column angle and steering column speed in real time, and calculates the target protection torque based on the vehicle speed, steering column angle and steering column speed, where the target protection torque changes with the vehicle speed.

[0056] In this embodiment, the vehicle speed and steering column angle are collected in real time by a data collection device, wherein the data collection device includes a vehicle sensor for collecting vehicle speed and an angle sensor installed on the steering column for collecting steering column angle; the steering column accuracy is not packaged, and after collecting the steering column angle, the steering column rotation speed can be obtained based on the change of the steering column angle. In other embodiments, the data collection device can also include a rotation speed sensor installed on the steering column for collecting the steering column rotation speed.

[0057] After obtaining the vehicle speed, steering column angle and steering column speed, the power-assisted motor control device calculates the protection torque of the rack based on the vehicle speed, steering column angle and steering column speed, and calculates the target protection torque, so that the target protection torque changes with the changes in vehicle speed, steering column angle and steering column speed, providing different protection torques for different vehicle speed conditions and different steering column states.

[0058] S20: When the rack of the steering gear is in the end protection area and moves toward the end position, the original power-assisting torque of the power-assisting motor is adjusted according to the target protection torque to obtain the desired torque of the power-assisting motor, and the power-assisting motor for the steering column is controlled according to the desired torque.

[0059] When the target protection torque is calculated based on the vehicle speed, the steering column angle and the steering column speed, and it is determined that the rack of the steering gear is in the terminal protection area and is moving to the terminal position, the original power-assisting torque of the power-assisting motor is adjusted according to the target protection torque to obtain the desired torque of the power-assisting motor, and the power-assisting motor on the steering column is controlled according to the desired torque. Among them, the desired torque is the original power-assisting torque minus the target protection torque, that is, when the rack of the steering gear is in the terminal protection area and moves to the terminal position, the power-assisting motor on the steering column is reduced, thereby limiting the movement of the rack to the terminal position, thereby reducing the terminal impact and protecting the terminal. The desired torque of the power-assisting motor is obtained based on the original power-assisting value minus the target protection torque value, and is processed after the most basic power-assisting function calculation, which will not affect other functions of the electric power steering system.

[0060] Among them, according to the torque-based control of the power assist of the power-assist motor to the steering column, the desired torque can be input into the current calculation module in the traditional electric power steering system, and based on the characteristics of the traditional electric power steering system, the target current corresponding to the desired torque is calculated, and then the target current is output to the power-assist motor through the power-assist motor control module, and the speed of the power-assist motor is adjusted by the target current, thereby adjusting the power assist of the power-assist motor to the steering column. The greater the speed of the power-assist motor, the greater the power assist of the power-assist motor to the steering column. The rotation of the power-assist motor is controlled by the desired torque, thereby applying a certain torque to the rack, thereby protecting the end.

[0061] Among them, the original power-assisting torque of the power-assisting motor refers to the power-assisting torque of the power-assisting motor in the electric power-assisting steering system without the rack end protection function. In the electric power-assisting steering system without the rack end protection function, the actual turning torque for operating the steering gear is the sum of the original power-assisting torque and the turning torque applied by the driver on the steering wheel (i.e., the turning torque applied to the steering column).

[0062] Among them, the end protection area is an area close to the end position of the rack, and the end protection area includes an area from the starting position to the end position. In this embodiment, in order to reduce the amount of data processing, only when the rack is determined to enter the end protection area based on the steering column angle, the target protection torque is calculated based on the vehicle speed, the steering column angle and the steering column speed, and only when the rack is in the end protection area and moves to the end position, the rack may have an end collision and it is necessary to restrict the movement of the rack and apply a protection torque to reduce the power assist of the power assist motor to the steering column. At this time, it is necessary to adjust the original power assist torque of the power assist motor according to the target protection torque to obtain the expected torque of the power assist motor, and control the power assist of the power assist motor to the steering column according to the expected torque; when far away from the end position, the rack is unlikely to have an end collision, so there is no need to apply a protection torque, and the power assist motor can be controlled according to the original power assist torque.

[0063] In one embodiment, before adjusting the original assist torque of the assist motor according to the target protection torque, it is necessary to determine whether the rack is in the end protection area according to the steering column angle, and determine whether the rack moves toward the end position. If the rack is in the end protection area and moves toward the end position, the original assist torque of the assist motor is adjusted according to the target protection torque to obtain the desired torque of the assist motor, so as to control the resistance of the assist motor to the steering column according to the desired torque; if the rack is not in the end protection area or the rack does not move to the end position, there is no need to perform end protection on the rack, and the resistance of the assist motor to the steering column is controlled according to the original assist torque of the assist motor.

[0064] Among them, if the absolute value of the steering column angle is greater than the preset angle (the preset angle is the steering column angle corresponding to the starting position), it is determined that the rack is in the end protection area; if the steering column rotation speed is the same as the direction of the steering column angle, it is determined that the rack moves to the end position; if the steering column rotation speed is different from the direction of the steering column angle, it is determined that the rack moves to the starting position, that is, the rack is away from the end position.

[0065] In this embodiment, the target protection torque is calculated based on the vehicle speed, steering column angle and steering column speed by obtaining the vehicle speed, the steering column angle and the steering column speed, and the target protection torque changes with the vehicle speed. Then, when the rack of the steering gear is in the terminal protection area and moves to the terminal position, the original power-assisting torque of the power-assisting motor is adjusted according to the target protection torque to obtain the desired torque of the power-assisting motor, and the output torque of the power-assisting motor is controlled according to the desired torque, thereby changing the power-assisting effect on the steering column and suppressing the terminal impact. In this embodiment, when performing terminal protection, not only the steering column angle and speed are considered, but also the influence of the vehicle speed is considered. The target protection torque is calculated by the vehicle speed, the steering column angle and the steering column speed, so that the target protection torque changes with the vehicle speed, thereby adjusting the power-assisting effect of the power-assisting motor on the steering column, achieving the purpose of limiting the rack movement based on the vehicle speed, the steering column angle and the steering column speed, alleviating the terminal collision impact at different vehicle speeds, and ensuring that the vehicle has a good rack terminal protection effect under various vehicle speed conditions.

[0066] In one embodiment, if Figure 3 As shown, in step S20, the original power-assisting torque of the power-assisting motor is adjusted according to the target protection torque to obtain the desired torque of the power-assisting motor, and the power-assisting motor is controlled according to the desired torque, which specifically includes the following steps:

[0067] S21: Subtract the target protection torque from the original assist torque to obtain the desired torque.

[0068] After obtaining the target protection torque, the target protection torque is subtracted from the original power-assist torque to obtain the desired torque. The positive and negative signs of the target protection torque correspond to the direction of the steering column angle, that is, if the direction of the steering column angle is positive, the sign of the target protection torque is positive, and if the direction of the steering column angle is negative, the sign of the target protection torque is negative. The positive and negative signs of the target protection torque correspond to the direction of the steering column angle. During the movement of the rack to the end position, it is ensured that the desired torque is the original power-assist value minus the target protection torque value, so as to reduce the current torque of the power-assist motor and reduce the end impact.

[0069] S22: Calculate a target current of the power-assisting motor according to the desired torque, and input the target current into a motor controller of the power-assisting motor, so as to perform closed-loop control on the control current of the power-assisting motor through the motor controller.

[0070] After obtaining the desired torque, the target current of the power-assist motor is calculated according to the desired torque, and the target current is input into the motor controller of the power-assist motor, so as to perform closed-loop control on the control current of the power-assist motor through the motor controller, that is, taking the target current as the control target, dynamically adjust the output current of the power-assist motor so that the output current is consistent with the target current. By performing closed-loop control on the control current of the power-assist motor, it is ensured that the output current of the power-assist motor is the target current, and the power-assist error caused by the output current not being consistent with the target current due to other reasons is reduced, and the control accuracy of the power-assist motor is improved, thereby improving the power-assist control effect of the steering column, and further improving the terminal protection effect.

[0071] In this embodiment, the target protection torque is subtracted from the original assist torque to obtain the expected torque, the positive and negative signs of the target protection torque correspond to the direction of the steering column angle, and the target current of the assist motor is calculated according to the expected torque, and the target current is input into the motor controller of the assist motor so as to perform closed-loop control on the control current of the assist motor through the motor controller. The specific steps of adjusting the original assist torque of the assist motor according to the target protection torque to obtain the expected torque of the assist motor and controlling the assist motor according to the expected torque are clarified, which plays a role in reducing the current torque of the assist motor during the movement of the rack to the end position, reducing the end impact, and improving the control accuracy of the assist motor by performing closed-loop control on the control current of the assist motor, thereby improving the end protection effect.

[0072] In one embodiment, if Figure 4 As shown, in step S10, the target protection torque is calculated based on the vehicle speed, the steering column angle and the steering column speed, which specifically includes the following steps:

[0073] S11: Determine a reference speed according to the steering column angle.

[0074] After obtaining the sum of the vehicle speed, the steering column angle and the steering column rotation speed, it is necessary to determine a reference rotation speed according to the steering column angle, wherein the reference rotation speed decreases as the rack moves toward the end position.

[0075] Specifically, it is necessary to first obtain a pre-calibrated reference speed curve, which can be calibrated according to actual vehicle test data. The reference speed curve includes reference speed values ​​corresponding to different steering column angles. Then, a reference speed query is performed on the reference speed curve according to the steering column angle determined in real time, and the reference speed value corresponding to the steering column angle is found as the reference speed.

[0076] Among them, in the reference speed curve, the reference speed value decreases as the absolute value of the steering column angle increases, because the greater the absolute value of the steering column angle, the closer the rack is to the end position, so the reference speed decreases as the rack moves toward the end position. For example, in the reference speed curve, the reference speed corresponding to the starting position of the end protection area is relatively large, and as it approaches the end position, the reference speed gradually decreases or even approaches 0.

[0077] S12: Determine a rotation speed difference between a steering column rotation speed and a reference rotation speed.

[0078] After the reference speed is determined, a speed difference between the steering column speed and the reference speed is determined.

[0079] S13: Calculating the damping force according to the speed difference and the vehicle speed to obtain the damping torque, and determining the target protection torque according to the damping torque.

[0080] After determining the speed difference between the steering column speed and the reference speed, the damping force is calculated according to the speed difference and the vehicle speed to obtain the damping torque, and the target protection torque is determined according to the damping torque.

[0081] It should be understood that the conventional rack end protection method controls the damping force of the end protection damping based on the steering column rotation speed when the steering column rotates to a position close to the limit, that is, when the rack moves to a position close to the end, so as to minimize the impact and reduce mechanical damage. In the conventional damping force calculation, the damping force is proportional to the steering column rotation speed. The defect of this method is that when entering the end protection area (i.e., the starting position), there is often a large steering column rotation speed. At this time, the damping force is calculated based on the rotation speed, and a large damping force is calculated, resulting in a large force mutation when entering the end protection area, affecting the driver's feel. In this embodiment, the actual steering column rotation speed is evaluated using a reference rotation speed that decreases as the rack moves to the end position, and the damping force is calculated using the speed difference between the actual steering column rotation speed and the reference rotation speed. A smaller damping force can be obtained at the starting position, which reduces the force mutation when entering the end protection area, optimizes the driver's feel at the critical point, and increases the damping force at the end position, so that the impact at the end position is smaller. While ensuring the end protection effect, the driver's feel is also taken into account, improving the driving experience.

[0082] In this embodiment, a reference speed is determined according to the steering column angle, and the reference speed decreases as the rack moves to the end position. Then, the speed difference between the steering column speed and the reference speed is determined, and then the damping force is calculated according to the speed difference and the vehicle speed to obtain the damping torque, and the target protection torque is determined according to the damping torque. The steps of calculating the target protection torque based on the vehicle speed, the steering column angle and the steering column speed are refined. In the process of calculating the target protection torque, the speed difference between the actual steering column speed and the reference speed is used to calculate the damping force, and then the target protection torque is determined according to the damping torque for subsequent power assistance control, which reduces the sudden change of force when entering the end protection area, optimizes the driver's feel at the critical point, ensures the end protection effect, and takes into account the driver's feel, thereby improving the driving experience.

[0083] In one embodiment, before step S13, that is, before calculating the damping force according to the speed difference and the vehicle speed to obtain the damping torque, the method further includes the following steps:

[0084] S14: Determine whether the rotation speed difference is greater than a preset value.

[0085] Before calculating the damping force to obtain the damping torque based on the speed difference and vehicle speed, it is necessary to compare the actual steering column speed with the reference speed, that is, to determine whether the speed difference between the steering column speed and the reference speed is greater than a preset value, so as to determine whether it is necessary to apply damping force to the steering column based on the comparison result.

[0086] Among them, the preset value is greater than or equal to 0.

[0087] S15: If the speed difference is less than or equal to a preset value, the power assist mode of the power assist motor is determined to be a basic protection mode, so as to calculate a basic protection torque according to the vehicle speed and the steering column angle, and use the basic protection torque as a target protection torque.

[0088] After determining whether the speed difference between the steering column speed and the reference speed is greater than the preset value, if the speed difference between the steering column speed and the reference speed is less than or equal to the preset value, it means that the steering column speed is low and does not exceed the limit, and the steering wheel rotation speed is within the allowable range, then the power assist mode of the power assist motor is determined as the basic protection mode, so as to calculate the basic protection torque according to the vehicle speed and the steering column angle, and use the basic protection torque as the target protection torque to control the power assist motor to reduce the power assist to the steering column, so as to reduce the power assist of the power assist motor to ensure the terminal protection performance and provide the driver with the terminal feel when the steering wheel is turned slowly to enter the terminal protection area.

[0089] S16: If the speed difference is greater than a preset value, the power assist mode of the power assist motor is determined to be a speed damping mode, so as to calculate a damping torque according to the speed difference and the vehicle speed.

[0090] After determining whether the speed difference between the steering column speed and the reference speed is greater than a preset value, if the speed difference between the steering column speed and the reference speed is greater than the preset value, it means that the steering column speed is greater than the reference speed, which means that the steering column speed is too large and the steering wheel is rotating at a faster speed. In order to limit the movement speed of the rack to the end position, a damping force needs to be applied to the steering column, and the power assist mode of the power assist motor is determined to be a speed damping mode, so as to calculate the damping torque according to the speed difference and the vehicle speed, and thus obtain the target protection torque according to the damping torque. Among them, the target protection torque in the speed damping mode is greater than the target protection torque in the basic protection mode, that is, a larger protection torque is provided based on the damping force when the steering wheel is rotated faster, so as to quickly reduce the steering column speed, thereby further reducing the end impact and improving the end protection effect.

[0091] In this embodiment, before calculating the damping force according to the speed difference and the vehicle speed to obtain the damping torque, it is determined whether the speed difference is greater than a preset value. If the speed difference is less than or equal to the preset value, the power-assisting mode of the power-assisting motor is determined to be the basic protection mode, so as to calculate the basic protection torque according to the vehicle speed and the steering column angle, and use the basic protection torque as the target protection torque; if the speed difference is greater than the preset value, the power-assisting mode of the power-assisting motor is determined to be the speed damping mode, so as to calculate the damping torque according to the speed difference and the vehicle speed, and calculate the target protection torque according to the damping torque, the target protection torque in the speed damping mode is greater than the target protection torque in the basic protection mode, the steering column speed is used to determine the power-assisting mode, the basic protection mode is entered at a low steering column speed, the feel of the rack entering the terminal protection area is provided, the role of buffering and reminding the driver is played, the speed damping mode is entered when the steering column speed is large, a larger target protection torque is given to prevent terminal impact, and the steering feel and terminal protection performance are guaranteed under both fast and slow steering column speeds.

[0092] In addition, in the traditional terminal protection method, the protection torque (the amount of power reduction or the damping force) is proportional to the steering column angle (i.e., the steering column angular position) and the steering column speed. The two variables act on the protection torque at the same time, and the influence of a single factor cannot be distinguished. In the present invention, the target protection torque is calculated according to the steering column angle in the lower basic protection mode, and the target protection torque is calculated according to the vehicle speed in the speed damping mode. That is, the steering column position and the steering column speed are respectively used as variables to calculate the corresponding protection torque, and the angle type is selected according to the size of the steering column speed (i.e., the speed difference), or the angle type and the speed type are superimposed. The calibration is simpler and more flexible in use.

[0093] In one embodiment, after the damping force is calculated according to the speed difference and the vehicle speed to obtain the damping torque, the target protection torque is determined according to the damping torque, including: obtaining the basic protection torque calculated according to the vehicle speed and the steering column angle, and taking the sum of the damping torque and the basic protection force as the target protection torque. That is, in the speed damping mode, the basic protection torque is first calculated according to the vehicle speed and the steering column angle, and then the sum of the damping torque and the basic protection force is taken as the target protection torque. In the basic protection mode, the bracket takes the basic protection torque as the target protection torque, so that when the steering wheel is turned slowly to enter the terminal protection area, the power assist is reduced but no additional damping force is generated, providing the hand feel of the terminal. When the steering wheel is turned quickly, a damping force is generated on the basis of reducing the power assist, so as to quickly reduce the steering column speed, and both fast and slow rotations have good hand feel and terminal protection performance.

[0094] In one embodiment, step S13, i.e., calculating the damping force according to the speed difference and the vehicle speed to obtain the damping torque, specifically includes the following steps:

[0095] S131: Determine the maximum damping torque according to the vehicle speed, and determine the damping coefficient according to the speed difference.

[0096] S132: The product of the maximum damping torque and the protection coefficient is taken as the damping torque.

[0097] After obtaining the real-time speed of the vehicle, the maximum damping torque is determined according to the speed, and the damping coefficient is determined according to the speed difference between the steering column speed and the reference speed, and then the product of the maximum damping torque and the protection coefficient is used as the damping torque. Among them, the damping coefficient is proportional to the speed difference. The larger the speed difference, that is, the larger the steering column speed, the larger the damping coefficient, thereby obtaining a larger damping torque, and then the target protection torque is larger, which can quickly reduce the power assist of the power motor to the steering column, thereby achieving the purpose of starting the current rack movement and improving the terminal protection effect. The reference speed curve has a larger speed reference value when entering the terminal protection area. Therefore, even if the speed enters the terminal protection area at a high speed, the speed difference is small, that is, the damping force is small, and there will be no excessive mutation due to excessive speed, which will cause uncomfortable steering feel. The speed reference value gradually decreases as it approaches the terminal position, so that the damping force increases smoothly, ensuring the feel, and ensuring that there is enough damping force before reaching the terminal position to effectively protect the terminal.

[0098] Among them, determining the maximum damping torque according to the vehicle speed includes: obtaining maximum damping torque data, the maximum damping torque data is the maximum damping torque value allowed at different vehicle speeds obtained by pre-calibration based on actual vehicle test data, and then searching the maximum damping torque value corresponding to the vehicle speed in the maximum damping torque data as the maximum damping torque. In this embodiment, the actual vehicle data is used to determine the maximum damping torque value allowed at different vehicle speeds, and then the damping coefficient is calculated based on the steering column speed, and then the damping torque obtained by multiplication improves the accuracy of the maximum damping torque, thereby improving the accuracy of the subsequent target protection torque, and further ensuring good terminal protection performance at different vehicle speeds.

[0099] In this embodiment, the maximum damping torque is determined according to the vehicle speed, and the damping coefficient is determined according to the speed difference, and then the product of the maximum damping torque and the protection coefficient is used as the damping torque. The specific steps of calculating the damping force according to the speed difference and the vehicle speed to obtain the damping torque are clarified. The maximum damping torque value is determined by the vehicle speed, and then the damping coefficient is calculated according to the steering column speed, and then the damping torque obtained by multiplication makes the damping torque change with the change of vehicle speed and steering column speed, that is, the target protection torque changes with the change of vehicle speed and steering column speed, to ensure good terminal protection performance at different vehicle speeds and speeds.

[0100] In one embodiment, step S15, i.e., calculating the basic protection torque according to the vehicle speed and the steering column angle, specifically includes the following steps:

[0101] S151: determining a maximum basic protection torque according to the vehicle speed, and determining a protection coefficient according to the steering column angle;

[0102] S152: The product of the maximum basic protection moment and the protection coefficient is taken as the basic protection moment.

[0103] After obtaining the real-time speed of the vehicle, it is necessary to determine the maximum basic protection torque according to the vehicle speed, and determine the protection coefficient according to the steering column angle, and then use the product of the maximum basic protection torque and the protection coefficient as the basic protection torque.

[0104] Among them, the protection factor increases with the increase of the absolute value of the steering column angle, that is, the protection factor increases with the movement of the rack to the end position. For example, the protection factor corresponding to the starting position of the end protection area is 1, and as the rack moves to the end position, the protection factor gradually increases to 1. Since the protection factor increases with the movement of the rack to the end position, the basic protection torque increases smoothly with the movement of the rack to the end position, so that the expected torque decreases with the movement of the rack to the end position, that is, the movement speed of the rack decreases, and no sudden change occurs, which can effectively reduce the end collision impact.

[0105] Among them, determining the maximum basic protection torque according to the vehicle speed includes: obtaining maximum basic protection torque data, the maximum basic protection torque data is the maximum basic protection torque value allowed at different vehicle speeds that is pre-calibrated according to actual vehicle test data, and then searching the maximum basic protection torque value corresponding to the vehicle speed in the maximum basic protection torque data as the maximum basic protection torque. In this embodiment, the actual vehicle data is used to determine the maximum basic protection torque value allowed at different vehicle speeds, and then the damping coefficient is determined according to the steering column angle, and then the basic protection torque obtained by multiplication improves the accuracy of the maximum basic protection torque, thereby improving the accuracy of the subsequent target protection torque, and further ensuring good terminal protection performance at different vehicle speeds.

[0106] In this embodiment, the maximum basic protection torque is determined according to the vehicle speed, and the protection coefficient is determined according to the steering column angle, and the product of the maximum basic protection torque and the protection coefficient is used as the basic protection torque. The specific steps for calculating the basic protection torque according to the vehicle speed and the steering column angle are clarified, so that the damping torque changes with the vehicle speed and the steering column angle, that is, the target protection torque changes with the vehicle speed and the steering column angle, to ensure good terminal protection performance at different vehicle speeds and steering column angles.

[0107] In one embodiment, a protection coefficient is determined based on a steering column angle, including: determining the total length of an end protection area, the protection area including a starting position and an end position of protection, and determining the shortest distance between the position of the steering column angle and the starting position, and then dividing the shortest distance by the total length of the protection area to obtain the protection coefficient, that is, the protection coefficient gradually changes with the position of the steering column, so that the basic protection torque changes smoothly without sudden changes, thereby providing an accurate basis for subsequent end protection.

[0108] The power assist motor control method provided in this embodiment specifically includes the following steps:

[0109] S1: Obtain the real-time vehicle speed, steering column angle and steering column speed;

[0110] S2: determining whether the rack of the steering gear is in the end protection area according to the steering column angle, and determining whether the rack moves to the end position of the end protection area according to the direction of the steering column angle and the direction of the steering column rotation speed;

[0111] S3: If the rack is in the end protection area and moves to the end position, the power assist mode is determined according to the magnitude of the steering column speed and the reference speed (which can be determined by the speed difference), wherein the reference speed decreases as the rack moves to the end position;

[0112] S4: If the steering column speed is less than or equal to the reference speed, it means that the steering column speed is low and the steering wheel rotates slowly, and no additional damping force is needed, and the power-assist mode is determined to be the basic protection mode; in the basic protection mode, the basic protection torque is determined according to the vehicle speed and the steering column angle, and the basic protection torque is used as the target protection torque, so that the original power-assist torque of the power-assist motor calculated later is subtracted from the target protection torque to obtain the desired torque, and then the desired torque is input into the current calculator, and the target current corresponding to the desired torque is calculated according to the characteristics of the electric power steering system, and the speed of the power-assist motor is adjusted by the current output by the current controller (such as a PID controller). The greater the speed, the greater the power assistance generated by the power-assist motor. The desired torque is used to control the rotation of the power-assist motor, thereby applying torque to the rack to protect the end. Among them, the calculation process of determining the basic protection torque according to the vehicle speed and the steering column angle is referred to the previous text and will not be repeated here. The protection mode is determined by the steering column speed. The basic protection mode is entered at low steering column speeds, providing the feel of the rack entering the terminal area, which serves as a buffer and reminder to the driver. In addition, the damping torque is determined based on the vehicle speed and steering column speed to ensure the performance of terminal protection at all vehicle speeds. The protection coefficient that gradually changes with the position makes the protection torque change smoothly without sudden changes.

[0113] S5: If the steering column speed is greater than the reference speed, it means that the steering column speed is large and the steering wheel rotates faster. At this time, additional damping force needs to be added to limit the steering column speed, and the power-assist mode is determined to be the speed damping mode; in the speed damping mode, the damping torque is determined according to the vehicle speed and the steering column speed, and the sum of the damping torque and the basic protection torque is used as the target protection torque, so that the original power-assist torque of the power-assist motor calculated later is subtracted from the target protection torque to obtain the desired torque, and then the desired torque is input into the current calculator, and the target current corresponding to the desired torque is calculated according to the characteristics of the electric power steering system. The speed of the power-assist motor is adjusted by the current output by the current controller (such as a PID controller). The greater the speed, the greater the power assistance generated by the power-assist motor. The rotation of the power-assist motor is controlled by the desired torque, so that the torque is applied to the rack to protect the end. Among them, the calculation process of determining the basic protection torque according to the vehicle speed and the steering column angle is referred to the previous text and will not be repeated here. The protection mode is determined by the steering column speed. The speed damping mode is entered at a high steering column speed, and a larger protection torque is given to prevent terminal impact, thereby ensuring the steering feel and terminal protection performance. Among them, the reference speed curve has a larger speed reference value when entering the terminal protection area. Therefore, even if the protection state is entered at a high speed, the speed difference is also small, that is, the damping force is small, and there will not be too much mutation, thereby improving the steering feel. The speed reference gradually decreases as it approaches the terminal position, so that the damping force increases smoothly, ensuring the feel and ensuring that there is enough damping force before reaching the terminal. In addition, the terminal protection not only considers the steering column angle and speed, but also the influence of the vehicle speed. The maximum protection torque (maximum basic protection torque, maximum damping torque) is obtained by checking the vehicle speed, and then the protection coefficient is calculated according to the angle position and the speed. The protection torque obtained by multiplication changes with the change of the vehicle speed, ensuring good terminal protection performance at different vehicle speeds.

[0114] S6: If the rack is in the end protection area or the rack has not moved to the end position, there is no need to enable the end protection function for end protection. The power assist motor is directly controlled according to the original power assist torque to control the power assist of the steering column.

[0115] In this embodiment, the steering column speed and the reference speed are used to determine the power-assist mode. If the power-assist mode is the basic protection mode, the target protection torque value is the basic protection torque. If the power-assist mode is the speed damping mode, the target protection torque value is the basic protection torque plus the speed damping torque. The basic protection torque provides a hand feeling when the rack enters the terminal area, which plays a role in buffering and reminding the driver. If the steering column speed is relatively large and enters the speed damping mode, the damping force is increased on the basis of the basic protection torque, so that the impact can be effectively prevented during rapid rotation, and there is a good hand feeling and terminal protection performance at fast and slow steering column speeds. When the terminal protection is performed, not only the The steering column angle and speed also take into account the influence of vehicle speed. The maximum protection torque is obtained by checking the vehicle speed, and then the protection coefficient or damping coefficient is calculated according to the steering column angle and the steering column speed. The protection torque obtained by multiplication changes with the change of vehicle speed, ensuring good terminal protection performance at different vehicle speeds; the reference speed curve is set according to the steering column angle, the reference speed is larger at the starting position of the terminal protection, and the reference speed is 0 at the terminal position. The speed difference is used to calculate the damping force, which reduces the sudden change at the starting protection position, optimizes the hand feeling at the critical point, and increases the damping force at the terminal position, so that the impact at the terminal is smaller. In addition, in this embodiment, the steering column angle (position) and the steering column speed are used as variables to calculate the corresponding target protection torque, and then the position type is selected according to the size of the steering column speed, or the position type and the speed type are superimposed, which makes the calibration simpler and more flexible in use.

[0116] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0117] In one embodiment, a booster motor control device is provided, and the booster motor control device corresponds to the booster motor control method in the above embodiment. Figure 5 As shown, the power assist motor control device includes a calculation module 501 and a control module 502. The functional modules are described in detail as follows:

[0118] A method for controlling a power assist motor is provided, comprising:

[0119] A calculation module 501 is used to obtain the vehicle speed, steering column angle and steering column speed, and calculate a target protection torque based on the vehicle speed, steering column angle and steering column speed, where the target protection torque changes with the vehicle speed;

[0120] The control module 502 is used to adjust the original power-assisting torque of the power-assisting motor according to the target protection torque when the rack of the steering gear is in the end protection area and moves toward the end position, obtain the desired torque of the power-assisting motor, and control the power-assisting motor on the steering column according to the desired torque.

[0121] Optionally, the calculation module 501 is specifically used for:

[0122] determining a reference speed according to the steering column angle, the reference speed decreasing as the rack moves toward the end position;

[0123] determining a speed difference between a steering column speed and a reference speed;

[0124] The damping force is calculated according to the speed difference and the vehicle speed to obtain the damping torque, and the target protection torque is determined according to the damping torque.

[0125] Optionally, the calculation module 501 is further configured to:

[0126] The maximum damping torque is determined according to the vehicle speed, and the damping coefficient is determined according to the speed difference;

[0127] The product of the maximum damping torque and the protection factor is taken as the damping torque.

[0128] Optionally, the calculation module 501 is further configured to:

[0129] Acquire maximum damping torque data, where the maximum damping torque data is the maximum damping torque value allowed at different vehicle speeds obtained by pre-calibration based on actual vehicle test data;

[0130] The maximum damping torque value corresponding to the vehicle speed is found in the maximum damping torque data and is used as the maximum damping torque.

[0131] Optionally, before calculating the damping force according to the rotation speed difference and the vehicle speed to obtain the damping torque, the calculation module 501 is further configured to:

[0132] Determine whether the speed difference is greater than a preset value;

[0133] If the speed difference is less than or equal to the preset value, the power assist mode of the power assist motor is determined to be the basic protection mode, so as to calculate the basic protection torque according to the vehicle speed and the steering column angle, and use the basic protection torque as the target protection torque;

[0134] If the speed difference is greater than the preset value, the assist mode of the assist motor is determined to be the speed damping mode, so as to calculate the damping torque according to the speed difference and the vehicle speed, and the target protection torque in the speed damping mode is greater than the target protection torque in the basic protection mode.

[0135] Optionally, the calculation module 501 is further configured to:

[0136] Obtain the basic protection torque calculated according to the vehicle speed and the steering column angle;

[0137] The sum of the damping moment and the foundation protection force is taken as the target protection moment.

[0138] Optionally, the calculation module 501 is further configured to:

[0139] The maximum basic protection torque is determined according to the vehicle speed, and the protection factor is determined according to the steering column angle;

[0140] The product of the maximum basic protection moment and the protection coefficient is taken as the basic protection moment.

[0141] Optionally, the calculation module 501 is further configured to:

[0142] Determine the total length of the end protection area, which includes the starting position and the end position of the protection;

[0143] Determine the shortest distance between the steering column angle position and the starting point position;

[0144] Divide the shortest distance by the total length of the protected area to obtain the protection factor.

[0145] Optionally, the control module 502 is further configured to:

[0146] The desired torque is obtained by subtracting the target protection torque from the original power-assist torque, and the positive and negative signs of the target protection torque correspond to the direction of the steering column angle;

[0147] The target current of the power-assist motor is calculated according to the expected torque, and the target current is input into the motor controller of the power-assist motor so as to perform closed-loop control on the control current of the power-assist motor through the motor controller.

[0148] For the specific definition of the power-assist motor control device, please refer to the definition of the power-assist motor control method above, which will not be repeated here. Each module in the above-mentioned power-assist motor control device can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0149] In one embodiment, a power-assist motor control device is provided, which may be a motor controller. The power-assist motor control device includes a processor, a memory, and a network interface connected via a system bus. The processor of the power-assist motor control device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the power-assist motor control device is used to communicate with an external data acquisition device via a network connection. When the computer program is executed by the processor, a power-assist motor control method is implemented.

[0150] In one embodiment, Figure 6 As shown, a power assist motor control device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the following steps are implemented:

[0151] The vehicle speed, steering column angle and steering column speed are obtained, and a target protection torque is calculated based on the vehicle speed, steering column angle and steering column speed, where the target protection torque changes with the vehicle speed;

[0152] When the rack of the steering gear is in the end protection area and moves toward the end position, the original assist torque of the assist motor is adjusted according to the target protection torque to obtain the desired torque of the assist motor, and the assist of the assist motor to the steering column is controlled according to the desired torque.

[0153] In one embodiment, a readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0154] The vehicle speed, steering column angle and steering column speed are obtained, and a target protection torque is calculated based on the vehicle speed, steering column angle and steering column speed, where the target protection torque changes with the vehicle speed;

[0155] When the rack of the steering gear is in the end protection area and moves toward the end position, the original assist torque of the assist motor is adjusted according to the target protection torque to obtain the desired torque of the assist motor, and the assist of the assist motor to the steering column is controlled according to the desired torque.

[0156] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing related hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory.

[0157] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0158] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for controlling a power assist motor, It is characterized in that include: Acquiring a vehicle speed, a steering column angle, and a steering column rotation speed, and calculating a target protection torque based on the vehicle speed, the steering column angle, and the steering column rotation speed, wherein the target protection torque changes with the vehicle speed; When the rack of the steering gear is in the end protection area and moves toward the end position, the original power-assisting torque of the power-assisting motor is adjusted according to the target protection torque to obtain the desired torque of the power-assisting motor, and the power-assisting motor for the steering column is controlled according to the desired torque; Wherein, the target protection torque is calculated based on the vehicle speed, the steering column angle and the steering column speed, including: determining a reference rotation speed according to the steering column angle, wherein the reference rotation speed decreases as the rack moves toward the end position; determining a speed difference between the steering column speed and the reference speed; The damping force is calculated according to the rotation speed difference and the vehicle speed to obtain the damping torque, and the target protection torque is determined according to the damping torque.

2. The power assist motor control method according to claim 1, It is characterized in that The step of calculating the damping force according to the rotation speed difference and the vehicle speed to obtain the damping torque includes: determining a maximum damping torque according to the vehicle speed, and determining a damping coefficient according to the speed difference; The product of the maximum damping torque and the damping coefficient is taken as the damping torque.

3. The power assist motor control method according to claim 2, It is characterized in that The determining the maximum damping torque according to the vehicle speed comprises: Acquiring maximum damping torque data, wherein the maximum damping torque data is the maximum damping torque value allowed at different vehicle speeds obtained by pre-calibration based on actual vehicle test data; The maximum damping torque value corresponding to the vehicle speed is searched in the maximum damping torque data as the maximum damping torque.

4. The power assist motor control method according to claim 1, It is characterized in that Before calculating the damping force according to the rotation speed difference and the vehicle speed to obtain the damping torque, the method further includes: Determining whether the speed difference is greater than a preset value; If the speed difference is less than or equal to the preset value, determining the power assist mode of the power assist motor as the basic protection mode, calculating a basic protection torque according to the vehicle speed and the steering column angle, and using the basic protection torque as the target protection torque; If the speed difference is greater than the preset value, the assist mode of the assist motor is determined to be the speed damping mode, so as to calculate the damping torque according to the speed difference and the vehicle speed, and determine the target protection torque according to the damping torque, wherein the target protection torque in the speed damping mode is greater than the target protection torque in the basic protection mode.

5. The power assist motor control method according to claim 1, It is characterized in that The determining the target protection torque according to the damping torque comprises: Obtaining a basic protection torque calculated according to the vehicle speed and the steering column angle; The sum of the damping torque and the basic protection torque is taken as the target protection torque.

6. The power assist motor control method according to claim 1, It is characterized in that The calculating the basic protection torque according to the vehicle speed and the steering column angle includes: determining a maximum basic protection torque according to the vehicle speed, and determining a protection coefficient according to the steering column angle; The product of the maximum basic protection moment and the protection coefficient is used as the basic protection moment.

7. The power assist motor control method according to claim 6, It is characterized in that The determining of the protection factor according to the steering column angle comprises: Determine the total length of the end protection area, the protection area includes the starting position of protection and the end position; Determining the shortest distance between the position of the steering column angle and the starting point position; The protection factor is obtained by dividing the shortest distance by the total length of the protection area.

8. The power assist motor control method according to any one of claims 1 to 7, It is characterized in that The adjusting the original power-assisting torque of the power-assisting motor according to the target protection torque to obtain the desired torque of the power-assisting motor, and controlling the power-assisting motor according to the desired torque includes: Subtracting the target protection torque from the original power-assist torque to obtain the desired torque, wherein the positive and negative signs of the target protection torque correspond to the direction of the steering column angle; The target current of the power-assist motor is calculated according to the expected torque, and the target current is input into the motor controller of the power-assist motor, so as to perform closed-loop control on the control current of the power-assist motor through the motor controller.

9. A power assist motor control system, It is characterized in that The invention comprises a power-assisting motor control device and a power-assisting motor, wherein the power-assisting motor control device is used for: Acquiring a vehicle speed, a steering column angle, and a steering column rotation speed, and calculating a target protection torque based on the vehicle speed, the steering column angle, and the steering column rotation speed, wherein the target protection torque changes with the vehicle speed; When the rack of the steering gear is in the end protection area and moves toward the end position, the original power-assisting torque of the power-assisting motor is adjusted according to the target protection torque to obtain the desired torque of the power-assisting motor, and the power-assisting motor for the steering column is controlled according to the desired torque; Wherein, the target protection torque is calculated based on the vehicle speed, the steering column angle and the steering column speed, including: determining a reference rotation speed according to the steering column angle, wherein the reference rotation speed decreases as the rack moves toward the end position; determining a speed difference between the steering column speed and the reference speed; The damping force is calculated according to the rotation speed difference and the vehicle speed to obtain the damping torque, and the target protection torque is determined according to the damping torque.

10. A power assist motor control device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, It is characterized in that When the processor executes the computer program, the steps of the power assist motor control method according to any one of claims 1 to 8 are implemented.

11. A readable storage medium storing a computer program. It is characterized in that When the computer program is executed by a processor, the steps of the power assist motor control method according to any one of claims 1 to 8 are implemented.

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