A control method for EPS steering hand force following angle gain

Abstract

The invention relates to the field of automobile steering gears, and specifically discloses a control method for EPS steering hand force gain with angle, comprising obtaining a steering wheel angle, a vehicle speed and a holding state of the steering wheel; determining a basic target hand force according to the steering wheel angle, determining a vehicle speed coefficient according to the vehicle speed, and determining a holding coefficient according to the holding state; calculating a target hand force, which is the product of the basic target hand force, the vehicle speed coefficient and the holding coefficient; comparing the target hand force with the actual hand force to determine a current compensation value for the gain with angle; superimposing the current compensation value for the gain with angle and a power-assisting current of an EPS system to generate a target current for a steering motor, and driving the steering motor to work with the target current; achieving decoupling of a hand force gain with angle function and a power-assisting function, reducing the difficulty of steering system calibration workload, and having strong versatility.

Description

Technical Field

[0001] The invention relates to the technical field of automobile steering gears, and in particular to a control method for EPS steering hand force following angle gain. Background Art

[0002] The working principle of the automobile electric power steering system, EPS (Electric Power Steering), is to control the output torque of the steering motor according to the hand force of the driver to assist the driver in completing the steering action. The development of EPS has improved the control characteristics of the automobile steering force and reduced the burden on the driver. As the requirements for automobile performance become higher and higher, higher requirements are placed on the performance of the EPS system.

[0003] When the driver operates the steering wheel to change direction back and forth in the middle position, or turns the steering wheel to a certain angle, in order to create a clear torque establishment and make the driver feel the steering wheel angle, the driver's hand force is required to increase with the increase of the steering wheel angle, forming an obvious sense of force establishment. The commonly used method in the prior art is to realize the hand force gain function with angle by calibrating the power-assist curve. However, the input signal of the power-assist curve is the hand force, and the output signal is the motor torque. There is no relationship between the hand force and the angle. The load of the EPS steering motor can only generate the gain with angle as the angle of the car tire increases. Therefore, this method of calibration causes a large calibration workload, and is strongly related to the vehicle state and the tire wear state. It is difficult to achieve the hand force gain effect with angle throughout the life cycle of the vehicle. The gain effect with angle can also be achieved by adjusting the friction of the EPS column, but each adjustment requires reprocessing and disassembly of the EPS, which costs a lot. It is generally not recommended to achieve the gain effect with angle in this way.

[0004] It can be seen that the prior art has complicated steps for the calibration of the power assist system and lacks good operability and stability for the power assist effect for the user. Summary of the invention

[0005] The purpose of the present invention is to provide a control method for EPS steering hand force following angle gain to solve the problems of complicated calibration steps for the power assist system in the prior art and lack of good maneuverability and stability for the power assist effect for the user.

[0006] To this end, the present invention provides a method for controlling an EPS steering hand force gain with an angle, and the method for controlling an EPS steering hand force gain with an angle comprises:

[0007] Get the steering wheel angle, vehicle speed, and steering wheel holding status;

[0008] determining a basic target hand force according to the steering wheel angle, determining a vehicle speed coefficient according to the vehicle speed, and determining a grip coefficient according to a grip state of the steering wheel;

[0009] Calculating a target hand force, where the target hand force is the product of the basic target hand force, the vehicle speed coefficient and the grip coefficient;

[0010] Comparing the target hand force with the actual hand force to determine the angular gain current compensation value;

[0011] The angular gain current compensation value is superimposed on the power assist current of the EPS system to generate a target current for the steering motor, and the steering motor is driven to work with the target current.

[0012] As a preferred technical solution of the control method of EPS steering hand force following angle gain, determining the basic target hand force according to the steering wheel angle includes:

[0013] Determine the basic target hand force T according to the following formula θ ,

[0014] ,

[0015] Among them, k1, k2, and k3 are the calibrated adjustment coefficients, k1, k2, and k3 are all greater than 0, T max is the maximum value of the target hand force, θ1, θ2 and θ3 are the calibrated angle thresholds, and 0<θ1<θ2<θ3.

[0016] As a preferred technical solution of the control method of EPS steering hand force following angle gain, determining the vehicle speed coefficient according to the vehicle speed includes:

[0017] Determine the vehicle speed coefficient k according to the following formula v ,

[0018] ,

[0019] Among them, V1 and V2 are the calibrated speed thresholds and V1<V2, k vmin is the lower limit of the vehicle speed coefficient.

[0020] As a preferred technical solution of the control method of EPS steering hand force following angle gain, the determination of the grip coefficient includes:

[0021] In response to the holding state being the first state, outputting a holding coefficient less than 1, and the holding coefficient decreases with the duration of the first state;

[0022] In response to the holding state being the second state, outputting a holding coefficient greater than 1, and the holding coefficient increases with the duration of the second state;

[0023] Among them, the first state satisfies one-handed holding or the holding distance is less than a first distance threshold, the second state satisfies the holding distance is greater than a second distance threshold, and the holding coefficient is greater than 0.9 and less than 1.1.

[0024] As a preferred technical solution of the control method of the EPS steering hand force following angle gain, in the first state, before the duration of the first state reaches the first preset duration, the holding coefficient is determined by the following formula; after the duration of the first state reaches the first preset duration, the holding coefficient is fixed to 0.9;

[0025] k t =1-t1 / t,

[0026] where k t is the holding coefficient, t is the first preset time length, and t1 is the duration of the first state.

[0027] As a preferred technical solution of the control method of the EPS steering hand force following angle gain, in the second state, before the duration of the second state reaches the first preset duration, the holding coefficient is determined by the following formula, and after the duration of the second state reaches the first preset duration, the holding coefficient is fixed to 1.1;

[0028] k t =1+t2 / t,

[0029] Wherein, t2 is the duration of the second state.

[0030] As a preferred technical solution of the control method of EPS steering hand force following angle gain, the following angle gain current compensation value is determined by the following formula:

[0031] ,

[0032] Among them, err T is the difference between the target hand force and the actual hand force, i T is the angular gain current compensation value, k p is the proportional control coefficient, and c is the comparison coefficient.

[0033] As a preferred technical solution of the EPS steering hand force following angle gain control method, the EPS steering hand force following angle gain control method further includes: determining the opening and closing timing of the following angle gain function:

[0034] If the operation state continues for a second preset time, the follow angle gain function is turned on;

[0035] If the idle state lasts for a third preset time, the follow-angle gain function is turned off;

[0036] The operating state satisfies that the absolute value of the motor speed is greater than the first speed threshold, and the absolute value of the hand force is greater than the first hand force threshold, and the idle state satisfies that the absolute value of the motor speed is less than the second speed threshold, and the absolute value of the hand force is less than the second hand force threshold.

[0037] As a preferred technical solution of the control method of EPS steering hand force following angle gain, in the calculation of the target hand force, the target hand force is less than the maximum value of the target hand force.

[0038] As a preferred technical solution of the control method of EPS steering hand force following angle gain, the holding state is determined by installing a pressure sensor on the steering wheel and collecting pressure data of the pressure sensor.

[0039] The beneficial effects of the present invention are:

[0040] The present invention provides a control method for EPS steering hand force follow-angle gain, which calculates compensation current through vehicle speed, steering wheel angle, motor speed and driver hand force to achieve the control effect of follow-angle gain, and the method does not affect other EPS functions in normal control, and designs follow-angle target hand force curves under different vehicle speed conditions, calculates target hand force value through speed target hand force curve according to vehicle speed and steering wheel angle, performs closed-loop control by target hand force value and actual hand force value to obtain follow-angle gain current compensation value, and superimposes with EPS power-assist current to obtain steering motor target current, drives motor to work, and realizes steering hand force follow-angle gain function. The method has high control accuracy and fast response speed, realizes decoupling of hand force follow-angle gain function and power-assist function, reduces the difficulty of steering system calibration work, and has strong versatility.

[0041] Furthermore, the present invention fine-tunes the target hand force by introducing the judgment logic of the holding state, and can adaptively adjust the target hand force in combination with the different hand force application states of the driver. Usually, the driving state includes one-handed and two-handed holding. In the EPS system, it is considered that there are certain differences in different holding postures. For example, when controlling the steering angle, when holding the steering wheel with both hands, the steering angle error is usually smaller, because both hands can control the direction more accurately. When controlling with one hand, the error is usually a little larger. Therefore, it is necessary to increase the target hand force value to compensate for the difference caused by different holding postures. After EPS obtains the holding state and the distance between the holdings from the whole vehicle, it usually adjusts the target hand force appropriately under different states and distances, which can effectively increase the driver's maneuverability and stability.

[0042] Furthermore, the angular gain function of the present invention is independent of the vehicle state and the tire wear state, and can ensure that the hand force angular gain is maintained at a good effect throughout the entire life cycle of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flow chart of a method for controlling EPS steering hand force following angle gain in an embodiment of the present invention;

[0044] Figure 2 is a graph of the hand force curve with angle target in an embodiment of the present invention;

[0045] Figure 3 This is a flow chart of grip coefficient adjustment in an embodiment of the present invention;

[0046] Figure 4 is a control flow chart of enabling the follow-angle gain in an embodiment of the present invention;

[0047] Figure 5 4 is a control block diagram of the gain current in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature "above", "above" and "above" the second feature include the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature "below", "below" and "below" the second feature include the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0052] In this embodiment, the control method is based on a column-type electric power steering system (Column-EPS), equipped with a 2.5-ton VAN vehicle, and an EPS controller with RH850 as the main MCU is used to implement the control method of the EPS steering hand force angular gain. The steering motor adopts a three-pole permanent magnet synchronous motor (PMSM) with a torque of 4.3Nm and a rated speed of 1050r / min.

[0053] See also Figure 1 As shown, this embodiment provides a method for controlling EPS steering hand force following angle gain, and the method for controlling EPS steering hand force following angle gain includes:

[0054] Step S1, obtaining a steering wheel angle, a vehicle speed, and a grip state of the steering wheel;

[0055] Step S2, determining a basic target hand force according to the steering wheel angle, determining a vehicle speed coefficient according to the vehicle speed, and determining a grip coefficient according to the grip state of the steering wheel;

[0056] Step S3, calculating the target hand force, where the target hand force is the product of the basic target hand force, the vehicle speed coefficient and the grip coefficient;

[0057] Step S4, comparing the target hand force with the actual hand force to determine the angular gain current compensation value;

[0058] Step S5, superimposing the angular gain current compensation value with the power assist current of the EPS system to generate a target current for the steering motor, and driving the steering motor to work with the target current.

[0059] Specifically, in this embodiment, the steering wheel angle is acquired by the MCU collecting the steering wheel angle signal and converting it, the vehicle speed is acquired by the MCU parsing the message on the CAN bus, and the actual hand force is acquired by the MCU collecting the steering wheel torque sensor signal and converting it. The grip state is determined by installing a pressure sensor on the steering wheel and collecting the pressure data of the pressure sensor.

[0060] In the above embodiment, the compensation current is calculated by vehicle speed, steering wheel angle, motor speed and driver's hand force to achieve the control effect of the follow-angle gain. This method does not affect other EPS functions in normal control. By designing the follow-angle target hand force curve under different vehicle speed conditions, the target hand force value is calculated by the speed target hand force curve according to the vehicle speed and steering wheel angle, and the follow-angle gain current compensation value is obtained by closed-loop control based on the target hand force value and the actual hand force value. The steering motor target current is superimposed with the EPS power-assisting current to drive the motor to work and realize the steering hand force follow-angle gain function. This method has high control accuracy and fast response speed, realizes the decoupling of the hand force follow-angle gain function and the power-assisting function, reduces the difficulty of steering system calibration work, and has strong versatility. The follow-angle gain function is independent of the vehicle state and tire wear state, and can achieve a good effect of the hand force follow-angle gain throughout the life cycle of the vehicle.

[0061] Specifically, determining the basic target hand force based on the steering wheel angle includes:

[0062] Get the steering wheel angle θ,

[0063] Determine the basic target hand force T according to the following formula θ ,

[0064] ,

[0065] Among them, k1, k2, and k3 are the calibrated adjustment coefficients, k1, k2, and k3 are all greater than 0, T max is the maximum value of the target hand force, θ1, θ2 and θ3 are the calibrated angle thresholds, and 0<θ1<θ2<θ3. It should be understood that the target hand force finally determined is also less than the maximum value of the target hand force T max The steering wheel angle has two directions, clockwise and counterclockwise. The angles in both directions are assigned positive values ​​for judgment, which can be applied to both directions of the steering wheel. In detail, the basic target hand force is the basic value of the target hand force finally determined, and it is the most relevant item for the state of the EPS steering wheel. Therefore, different angle thresholds are set to output basic target hand forces with different increase amplitudes in different angle ranges.

[0066] In some embodiments, θ1=15°, θ2=550°, θ3=600°, k1=0.517 (N·m2 / °), k2=0.0028 (N·m / °), k3=0.0018 (N·m / ° 2 ), in implementation, it can also be calibrated to other values ​​in combination with actual needs and scenarios. It should be understood that in the above embodiments, k1, k2, and k3 are all provided with corresponding dimensions for the unification of dimensions.

[0067] As a preferred technical solution for the control method of EPS steering hand force following angle gain, determining the vehicle speed coefficient according to the vehicle speed includes:

[0068] Determine the vehicle speed coefficient k according to the following formula v ,

[0069] ,

[0070] Among them, V1 and V2 are the calibrated speed thresholds and V1<V2, k vmin is the lower limit of the vehicle speed coefficient. In detail, the reason for setting the vehicle speed coefficient is that the target hand force should increase linearly with the increase of vehicle speed in consideration of the driving control stability. In some embodiments, V1=5Km / h, V2=110Km / h, k vmin =0.2. In implementation, it can also be calibrated to other values ​​based on actual needs and scenarios.

[0071] For example, under the premise of a stable grip coefficient, the following angle target hand force curve of this embodiment is plotted as follows: Figure 2 As shown in the figure, when the steering wheel angle is within a small angle, the hand force should be clearly established, and the ratio of the target hand force to the steering wheel angle is large. When the angle exceeds the small angle range, the hand feel should be smooth, and the target hand force increases slowly as the angle increases. When the steering wheel angle approaches the end, the target hand force should be increased quickly so that the driver can feel that the steering has become significantly heavier and the steering wheel has reached its limit. And as the vehicle speed increases, the target hand force also increases accordingly. It can effectively combine the driver's actual driving status.

[0072] Specifically, the determination of the grip coefficient includes:

[0073] In response to the holding state being the first state, outputting a holding coefficient less than 1, and the holding coefficient decreases with the duration of the first state;

[0074] In response to the holding state being the second state, outputting a holding coefficient greater than 1, and the holding coefficient increases with the duration of the second state;

[0075] Among them, the first state satisfies one-handed holding or the holding distance is less than the first distance threshold, the second state satisfies the holding distance is greater than the second distance threshold, and the holding coefficient is greater than 0.9 and less than 1.1.

[0076] Specifically, in the first state, before the duration of the first state reaches the first preset duration, the holding coefficient is determined by the following formula; after the duration of the first state reaches the first preset duration, the holding coefficient is fixed to 0.9;

[0077] k t =1-t1 / t,

[0078] where k tis the holding coefficient, t is the first preset time length, and t1 is the duration of the first state.

[0079] As a preferred technical solution of the control method of the EPS steering hand force following angle gain, in the second state, before the duration of the second state reaches the first preset duration, the holding coefficient is determined by the following formula, and after the duration of the second state reaches the first preset duration, the holding coefficient is fixed to 1.1;

[0080] k t =1+t2 / t,

[0081] Wherein, t2 is the duration of the second state.

[0082] For details, see Figure 3 As shown, the vehicle obtains the holding state (first state State1, second state State2) and the holding distance After that, the state and holding distance are judged. When the (holding state == State1) condition is met, the timing variable Start accumulating, That is, the duration of the first state, when >First preset duration Stop accumulation when the compensation coefficient By adjusting the timing variable Make The corresponding changes occur within the specified time to reach the final compensation coefficient, thereby reducing the target hand force, and Satisfy the requirements within the scope , which can ensure the driving safety of the driver;

[0083] When the (holding state == State2) condition is met, the timing variable Start accumulating, That is, the duration of the second state, when Stop accumulation when the compensation coefficient By adjusting the timing variable Make changes within a specified time to reach the final compensation coefficient, thereby increasing the target hand force, and Also meets the requirements within the scope , ensuring the driver's robustness. , , the first distance threshold , the second distance threshold , The above parameters are all determined through actual vehicle calibration, and can also be calibrated to other values ​​in implementation based on actual needs and scenarios. By introducing the judgment logic of the holding state to fine-tune the target hand force, the target hand force can be adaptively adjusted in combination with the different hand force application states of the driver. Usually, there are one-handed and two-handed holding states in the driving state. In the EPS system, there are certain differences in different holding postures. For example, when controlling the steering angle, when holding the steering wheel with both hands, the steering angle error is usually smaller, because both hands can control the direction more accurately. When controlling with one hand, the error is usually a little larger. Therefore, it is necessary to increase the target hand force value to compensate for the differences caused by different holding postures. After EPS obtains the holding state and the distance between the holdings from the whole vehicle, it usually adjusts the target hand force appropriately under different states and distances, which can effectively increase the driver's maneuverability and stability.

[0084] Specifically, the angular gain current compensation value is determined by the following formula,

[0085] ,

[0086] Among them, err T is the difference between the target hand force and the actual hand force, i T is the angular gain current compensation value, k p is the proportional control coefficient, c is the comparison coefficient. Set k p = 4 (A / N·m), c = 80 (A 2 / N·m), both of which have dimensions to ensure the uniformity of dimensions. They are determined through real vehicle calibration and can also be calibrated to other values ​​in implementation based on actual needs and scenarios.

[0087] See also Figure 4 As shown in the figure, t`` is the timing variable for starting the gain function, and t` is the timing variable for closing the gain function. To avoid computing power consumption, the opening and closing timing of the angle gain function is determined by the following method:

[0088] If the operation state continues for a second preset time t3, the follow angle gain function is turned on;

[0089] If the idle state continues for a third preset time t4, the follow angle gain function is turned off;

[0090] The operating state meets the absolute value of the motor speed Greater than the first speed threshold , and the absolute value of hand strength Greater than the first hand force threshold , the idling state satisfies the absolute value of the motor speed Less than the second speed threshold , and the absolute value of hand strength Less than the second hand force threshold Set n2 = 20 prm / s, n1 = 50 prm / s, T1 = 1.2 N·m, T2 = 0.4 N·m, t3 = 2 min, t4 = 1 min, all determined by on-vehicle calibration, and satisfy n1 < n2, T1 < T2. The calibration parameters in this implementation are all stored in the non-volatile memory and read out each time power is applied. Specifically, the absolute value of the motor speed is collected by the MCU for the motor rotor angle signal and calculated based on its change rate.

[0091] Working process: Please refer to Figure 5 As shown, for a single control cycle, the MCU collects the three-phase motor currents ia, ib, ic, and the rotor angle θr of the steering motor, and obtains the D-axis feedback current id and Q-axis feedback current iq of the motor through coordinate transformation. The MCU detects and calculates the load torque T m and the motor speed n in real time, and obtains the D-axis target current i * d according to the T-n curve of the motor. From i * d and id, D-axis current control is performed to obtain the D-axis voltage Ud. The EPS controller collects the driver's hand force T through the torque sensor, combines the assist curve and vehicle speed V to obtain the assist curve output value i epc . The MCU collects and calculates the steering wheel angle, combines the vehicle speed, driver's hand force, motor speed, and holding coefficient, calculates the angle-dependent gain current compensation value i T and determines whether the angle-dependent gain function is enabled. When the angle-dependent gain function is enabled, i epc is added to i T to obtain the steering motor target current i * q; when the angle-dependent gain function is disabled, i epc is added to 0 to obtain the steering motor target current i * q. Using the steering motor target current i * q for Q-axis current control to obtain the Q-axis voltage Uq. SVPWM control is performed by Ud, Uq, and θr to generate a PWM waveform to drive the three-phase inverter to act and output three-phase voltages, controlling the EPS steering motor to work and outputting assistance.

[0092] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the device, method and computer program product according to various embodiments of the present application. In this regard, each box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based device that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0093] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for controlling EPS steering hand force following angle gain, characterized in that: include: Get the steering wheel angle, vehicle speed, and steering wheel holding status; determining a basic target hand force according to the steering wheel angle, determining a vehicle speed coefficient according to the vehicle speed, and determining a grip coefficient according to a grip state of the steering wheel; Calculating a target hand force, where the target hand force is the product of the basic target hand force, the vehicle speed coefficient and the grip coefficient; Comparing the target hand force with the actual hand force to determine the angular gain current compensation value; The angular gain current compensation value is superimposed on the power assist current of the EPS system to generate a target current of the steering motor, and the steering motor is driven to work with the target current; Wherein, determining the basic target hand force according to the steering wheel angle includes: Determine the basic target hand force T according to the following formula θ , ， Among them, k1, k2, k3 are the calibrated adjustment coefficients, k1, k2, k3 are all greater than 0, θ is the steering wheel angle, T max is the maximum value of the target hand force, θ1, θ2 and θ3 are the calibrated angle thresholds, and 0<θ1<θ2<θ3; Determining the vehicle speed coefficient according to the vehicle speed includes: Determine the vehicle speed coefficient k according to the following formula v , ， Among them, V1 and V2 are the calibrated speed thresholds and V1<V2, k vmin is the lower limit of the vehicle speed coefficient; The determination of the grip coefficient includes: In response to the holding state being the first state, outputting a holding coefficient less than 1, and the holding coefficient decreases with the duration of the first state; In response to the holding state being the second state, outputting a holding coefficient greater than 1, and the holding coefficient increases with the duration of the second state; The first state satisfies one-handed holding or the holding distance is less than a first distance threshold, and the second state satisfies the holding distance is greater than a second distance threshold, and the holding coefficient is greater than 0.9 and less than 1.1; The angular gain current compensation value is determined by the following formula: ， Among them, err T is the difference between the target hand force and the actual hand force, i T is the angular gain current compensation value, k p is the proportional control coefficient, and c is the comparison coefficient.

2. The control method of EPS steering hand force following angle gain according to claim 1, characterized in that: The EPS steering hand force following angle gain control method further includes: determining the opening and closing timing of the following angle gain function: If the operation state continues for a second preset time, the follow angle gain function is turned on; If the idle state lasts for a third preset time, the follow-angle gain function is turned off; The operating state satisfies that the absolute value of the motor speed is greater than the first speed threshold, and the absolute value of the hand force is greater than the first hand force threshold, and the idle state satisfies that the absolute value of the motor speed is less than the second speed threshold, and the absolute value of the hand force is less than the second hand force threshold.

3. The control method of EPS steering hand force following angle gain according to claim 2, characterized in that: In the calculation of the target hand force, the target hand force is less than the maximum value of the target hand force.

4. The control method of EPS steering hand force following angle gain according to claim 3, characterized in that: The holding state is determined by installing a pressure sensor on the steering wheel and collecting pressure data of the pressure sensor.

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