Adaptive control method for human-machine co-driving steering system

Abstract

This invention discloses an adaptive control method for a human-machine co-driving steering system. Based on a safe vehicle speed, the initial output torque of the angle closed-loop control, and the co-driving coordination coefficient, the method calculates the coordinated basic power assist output torque and the final output torque of the angle closed-loop control. After limiting the final output torque of the angle closed-loop control, the two are superimposed as the final output torque of the steering system's power assist motor. The purpose of this invention is to improve the robustness of driver assistance functions during system vibrations, and to more accurately identify driver intentions, thereby smoothly coordinating the driver's and advanced driver assistance system's control over the steering system, enhancing the driving experience.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and in particular to an adaptive control method for a human-machine co-driving steering system. Background Technology

[0002] In autonomous driving scenarios, electric power steering systems, in addition to providing basic lane-keeping assistance, need to respond precisely and quickly based on the application scenario and driver intent, while ensuring a smooth driving experience. Currently, most driver assistance systems on the market rely on capacitive steering wheels or torsion bars maintaining a torque exceeding a certain value for a period to determine driver intent. When a driver intervention is detected, the assistance function disengages, resulting in abrupt driver intervention and insufficient support for emergency avoidance functions, thus failing to adequately guarantee driver safety. In contrast, a steering system control method that supports human-machine co-driving and emergency avoidance can significantly improve the smoothness and safety of driving. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an adaptive control method for a human-machine co-driving steering system. The purpose is to improve the robustness of the driver assistance function when the system vibrates, and at the same time, to more accurately identify the driver's intentions, thereby smoothly coordinating the driver's and the advanced driver assistance system's control over the steering system and improving the driving experience.

[0004] To solve the above-mentioned technical problems, the present invention provides an adaptive control method for a human-machine co-driving steering system, comprising:

[0005] Step 1: The electronic power steering system needs to receive signals related to driving assistance functions. These signals include the road keeping assist system enable signal, road keeping assist system request status, and road keeping assist system request angle from the advanced driver assistance system; the steering system control unit status, power steering motor rotor speed, power steering motor rotor acceleration, torsion bar torque, steering wheel angular velocity, steering wheel angle, lane departure warning system request status, lane departure warning system control status, and safe vehicle speed.

[0006] Step 2: Determine the status of the driver assistance function based on the road keeping assist system enable signal, steering system control unit status, torsion bar torque, steering wheel angle, safe vehicle speed, and road keeping assist system request status;

[0007] Step 3: Calculate the driver's hand torque based on the power steering motor rotor acceleration, torsion bar torque, steering wheel angle, and steering wheel angular velocity;

[0008] Step 4: Determine the current human-machine co-driving status based on the road keeping assist system request status, driver assistance function status, safe vehicle speed, and driver's hand torque;

[0009] Step 5: Determine the current vibration state of the steering system based on the power steering motor rotor acceleration, the lane departure warning system request status, and the lane departure warning system control status;

[0010] Step 6: Calculate the desired rack position and the current rack position based on the road keeping assist system's requested angle and steering wheel angle;

[0011] Step 7: Calculate the current rack speed based on the rotor speed of the power assist motor;

[0012] Step 8: Based on the current human-machine co-driving state, the vibration state of the steering system, the desired rack position, the current rack position, and the current rack speed, calculate the desired rack movement speed of the steering system, and then combine it with the current rack speed to calculate the initial output torque of the angle closed-loop control.

[0013] Step 9: Calculate the co-driving coordination coefficient based on the safe vehicle speed, driver's hand torque, and current human-machine co-driving status;

[0014] Step 10: Based on the safe vehicle speed, the initial output torque of the angle closed-loop control, and the co-driving coordination coefficient, calculate the coordinated basic power assist output torque and the final output torque of the angle closed-loop control. After limiting the final output torque of the angle closed-loop control, the two are superimposed as the final output torque of the steering system power assist motor.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0016] 1. Receives status requests from the advanced driver assistance system controller, supporting both normal lane keeping assist and emergency avoidance functions, thus expanding the application scenarios of assisted driving and ensuring driver safety.

[0017] 2. It can more accurately identify the driver's intentions, thereby smoothly coordinating the driver's and advanced driver assistance systems' control of the steering system and improving the driving experience.

[0018] 3. It can monitor the vibration status of the steering system in real time and adaptively adjust the control parameters of the driver assistance function according to the severity of the vibration, thereby improving the robustness of the driver assistance function. Attached Figure Description

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0020] Figure 1 The software system architecture for implementing the control method of this invention is shown in the figure;

[0021] Figure 2 This is a schematic diagram of the logic jump state of the driver assistance function of the present invention;

[0022] Figure 3 This is a schematic diagram of the driver's hand torque algorithm of the present invention;

[0023] Figure 4 This is a diagram showing the jitter state transition of the steering system of the present invention. Detailed Implementation

[0024] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can fully understand other advantages and technical effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through different specific embodiments, and the details in this specification can also be applied based on different viewpoints, with various modifications or changes made without departing from the overall design concept of the invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. The following exemplary embodiments of the present invention can be implemented in many different forms and should not be construed as being limited to the specific embodiments set forth herein. It should be understood that these embodiments are provided to make the disclosure of the present invention thorough and complete, and to fully convey the technical solutions of these exemplary embodiments to those skilled in the art.

[0025] In this embodiment, the software system architecture for implementing the control method of the present invention is as follows: Figure 1 As shown, it mainly includes a CAN communication input module, an auxiliary driving function status judgment module, a driver's hand torque calculation module, a human-machine co-driving control module, a vibration monitoring module, a basic power assist module, an angle closed-loop control module, a motor control module, and a CAN communication output module.

[0026] This embodiment provides an adaptive control method for a human-machine co-driving steering system, including the following steps:

[0027] Step 1: The electronic power steering system needs to receive signals related to driving assistance functions. These signals include the road keeping assist system enable signal, road keeping assist system request status, and road keeping assist system request angle from the advanced driver assistance system; the steering system control unit status, power steering motor rotor speed, power steering motor rotor acceleration, torsion bar torque, steering wheel angular velocity, steering wheel angle, lane departure warning system request status, lane departure warning system control status, and safe vehicle speed.

[0028] Step 2: Determine the status of the driver assistance function based on the road keeping assist system enable signal, steering system control unit status, torsion bar torque, steering wheel angle, safe vehicle speed, and road keeping assist system request status;

[0029] Step 3: Calculate the driver's hand torque based on the power steering motor rotor acceleration, torsion bar torque, steering wheel angle, and steering wheel angular velocity;

[0030] Step 4: Determine the current human-machine co-driving status based on the road keeping assist system request status, driver assistance function status, safe vehicle speed, and driver's hand torque;

[0031] Step 5: Determine the current vibration state of the steering system based on the power steering motor rotor acceleration, the lane departure warning system request status, and the lane departure warning system control status;

[0032] Step 6: Calculate the desired rack position and the current rack position based on the road keeping assist system's requested angle and steering wheel angle;

[0033] Step 7: Calculate the current rack speed based on the rotor speed of the power assist motor;

[0034] Step 8: Based on the current human-machine co-driving state, the vibration state of the steering system, the desired rack position, the current rack position, and the current rack speed, calculate the desired rack movement speed of the steering system through the closed-loop control module, and then calculate the initial output torque of the angle closed-loop control by combining the current rack speed.

[0035] Step 9: Calculate the co-driving coordination coefficient based on the safe vehicle speed, driver's hand torque, and current human-machine co-driving status;

[0036] Step 10: Based on the safe vehicle speed, the initial output torque of the angle closed-loop control, and the co-driving coordination coefficient, calculate the coordinated basic power assist output torque and the final output torque of the angle closed-loop control. After limiting the final output torque of the angle closed-loop control, the two are superimposed as the final output torque of the steering system power assist motor.

[0037] Specifically, in step 2, when the steering system control unit is in normal condition, and the steering wheel angle and safe speed are within the allowable range, and the driver has no intention to disengage the assisted driving function, if the road keeping assist system request state is in emergency avoidance state, then the assisted driving function state is in emergency avoidance state; if the road keeping assist system request state is in non-emergency avoidance state, then the assisted driving function state is in non-emergency avoidance state.

[0038] Specifically, in step 2, the driver's intention to disengage the driver assistance function is determined based on the torsion bar torque. When the torsion bar torque is greater than the disengagement threshold M0 and remains for a set time T0, it is determined that the driver intends to disengage the driver assistance function. When the torsion bar torque is less than the disengagement threshold M1 and remains for a certain time T1, it is determined that the driver does not intend to disengage the driver assistance function. M0, T0, M1, and T1 are calibrable variables.

[0039] Specifically, in step 2, when the assisted driving function is in an emergency avoidance state, if the torsion bar torque is greater than the assisted driving function exit threshold M3 and remains for a set time T3, it is determined that the driver intends to exit the assisted driving function; if the torsion bar torque is less than the assisted driving function exit threshold M4 and remains for a certain time T4, it is determined that the driver does not intend to exit the assisted driving function. M3, T3, M4, and T4 are calibrable variables.

[0040] Specifically, in step 3, such as Figure 3 As shown, the method for calculating the driver's hand torque includes the following steps:

[0041] Step 31: Perform FIR filtering on the rotor acceleration of the power assist motor to obtain the filtered rotor acceleration. Combine this with the rotor's moment of inertia to calculate the torque generated by the rotor's moment of inertia. An example calculation formula is as follows:

[0042] A RotFIR =X C0 *A Rotn +X C1 *A Rotn-1 +X C2 *A Rotn-2

[0043] M Rot =A RotFIR *I Rot *X Rot

[0044] in:

[0045] A RotFIR This refers to the filtered rotor acceleration of the booster motor.

[0046] A Rotn A Rotn-1 A Rotn-2 These are the rotor accelerations of the assist motor received in the current cycle, the previous cycle, and the two previous cycles, respectively.

[0047] X C0 X C1 X C2 These are the filter coefficients of the FIR filter;

[0048] M Rot The torque generated by the rotational inertia of the motor rotor;

[0049] I Rot To assist the rotational inertia of the motor rotor;

[0050] X Rot This is a correction factor that can be calibrated according to vehicle speed.

[0051] Step 32: Apply PT1 filtering to the steering wheel angular velocity to obtain the filtered steering wheel angular velocity. Calculate the steering wheel angular acceleration, and then combine this with the steering wheel's moment of inertia to calculate the torque generated by the steering wheel's moment of inertia. An example calculation formula is as follows:

[0052] V SWPT1

[0053] A SW =(V SWPT1 -V SWPT1last ) / T

[0054] M SW =A SW *I SW *X SW

[0055] in:

[0056] V SW The angular velocity of the steering wheel;

[0057] V SWPT1 The steering wheel angular velocity after second-order PT1 filtering;

[0058] V SWPT1last The steering wheel angular velocity of the second-order PT1 filter in the previous cycle;

[0059] V SWPT11last The steering wheel angular velocity of the first-order PT1 filter in the previous cycle;

[0060] X 1SW X 2SW These are the filter coefficients of the first-order PT1 filter and the second-order PT1 filter, respectively.

[0061] A SW This refers to the acceleration due to the steering wheel angle.

[0062] T is the sampling period;

[0063] M SW The torque generated by the rotational inertia of the steering wheel;

[0064] I SW The moment of inertia of the steering wheel;

[0065] X SW This is a correction factor that can be calibrated according to vehicle speed.

[0066] Step 33: Perform PT1 filtering on the torsion bar torque to obtain the filtered torsion bar torque; an exemplary calculation formula is as follows:

[0067] M TBPT1 =((M) TB -M TBPT11last )*X 1TB +M TBPT11last )-M TBPT1last )*X 2TB +M TBPT1last

[0068] in:

[0069] M TB For torsion bar torque;

[0070] M TBPT1 The torsion bar torque after second-order PT1 filtering;

[0071] M TBPT1last The torsion bar torque is the torque of the second-order PT1 filter in the previous cycle.

[0072] M TBPT11last The torsion bar torque is the torque of the first-order PT1 filter in the previous cycle.

[0073] X 1TB X 2TB These are the filter coefficients of the first-order PT1 filter and the second-order PT1 filter, respectively.

[0074] Step 34: Calculate the driver's hand torque based on the data obtained in steps 31 to 33; an exemplary calculation formula is as follows:

[0075] M DTI =M TBPT1 +|M SW -M Rot |*Sign(M SW +M Rot )

[0076] M DT =Min(|M DTI |,M DTMAX )*Sign(M DTI )

[0077] in:

[0078] M SW The torsion bar torque after second-order PT1 filtering;

[0079] M RotThe torque generated by the rotational inertia of the motor rotor;

[0080] M DTI This is the superimposed driver's hand torque;

[0081] M DT For the driver's hand torque;

[0082] M DTMAX To limit the output torque value to saturation;

[0083] Sign(M DTI () represents the numerical symbol for the driver's hand torque after superposition;

[0084] Sign(M SW +M Rot () represents the numerical symbol of the superposition of the rotational inertia and torque of the steering wheel and the motor;

[0085] Min(|M DTI |,M DTMAX () represents the minimum of the absolute value of the superimposed driver's hand torque and the saturation limit output torque value.

[0086] If any of the signals—power assist motor rotor acceleration, steering wheel angular velocity, or torsion bar torque—exceeds the valid range, the driver's hand torque is set to an invalid value.

[0087] Specifically, in step 4, the human-machine co-driving state includes driver intervention state, temporary fault state, permanent fault state, emergency avoidance mode and human-machine co-driving mode.

[0088] In this embodiment, the logical transition state of the driver assistance function is as follows: Figure 2As shown, T1 represents the road keeping assist system being enabled; when T1 is satisfied, the function is activated. T2 represents the road keeping assist system being disabled; when T2 is satisfied, the function is deactivated. T5 / T12 / T17 represent torsion bar torque exceeding a certain value for a certain period of time; when T5 / T12 / T17 are satisfied, the system enters driver intervention mode. T20 represents torsion bar torque falling below a certain value for a certain period of time; when T20 is satisfied, the system exits driver intervention mode and returns to initialization. T6 / T13 / T18 represent the current system occurrence type. For issues such as exceeding vehicle speed limits, invalid signal reception, or internal steering system malfunctions, when T6 / T13 / T18 are met, the system enters a temporary fault state, and this type of fault can be recovered in the current ignition cycle; T22 indicates that issues such as exceeding vehicle speed limits, invalid signal reception, or internal steering system malfunctions have been resolved, the system exits the temporary fault state, and returns to initialization; T7 / T14 / T19 / T21 / T23 indicate a serious internal EPS malfunction, and the current ignition cycle cannot be recovered; T3 indicates that the road keeping assist system request is in a non-emergency avoidance state. In the "Let the Mode Be" mode, since T3 has lower priority than T5 / T6 / T7, when T3 is met (meaning the current vehicle speed and hand force are within a certain range and the input signals are valid), the system will enter the non-emergency avoidance activation mode. The default mode in the non-emergency avoidance activation mode is the non-human-machine co-driving mode. T8 represents the driver's hand torque being greater than a certain value for a certain period of time and the driver's hand torque being valid; when T8 is met, the system enters the human-machine co-driving mode. T9 represents the driver's hand torque being less than a certain value for a certain period of time and the driver's hand torque being valid; when T9 is met, the system enters the human-machine co-driving mode. Entering non-human-machine co-driving mode; T10 / T15 represents the road keeping assist system request status as no request. When T10 / T15 is satisfied, the function will actively exit; T4 represents the road keeping assist system request status as emergency avoidance mode, with a lower priority than T5 / T6 / T7. Therefore, when T4 is satisfied, it is assumed that the current vehicle speed and hand force are within a certain range and the input signals are valid, and the system will enter the emergency avoidance activation mode; similarly, T11 has a lower priority than T12 / T13 / T14. When T11 is satisfied, the system will enter the emergency avoidance activation mode.

[0089] Specifically, in step 5, the vibration state of the steering system includes vibration forward monitoring state, vibration reverse monitoring state, initialization state, and attenuation state.

[0090] In this embodiment, the steering system's vibration state transitions as follows: Figure 4As shown, T1 represents a motor rotor acceleration greater than a certain value, the lane departure warning system request state is not a request for activation, and the lane departure warning system control state is not active. When T1 is satisfied, the system enters the jitter forward monitoring state; T3 represents a motor rotor acceleration less than a certain reverse value, the lane departure warning system request state is not a request for activation, and the lane departure warning system control state is not active. When T3 is satisfied, the system enters the jitter reverse monitoring state; T2 / T4 represent a lane departure warning system request state is a request for activation or a lane departure warning system control state is active. When T2 / T4 is satisfied, the system returns to the initialization state; T9 represents a rotor acceleration less than a certain reverse value. And for a certain period of time, when T9 is met, the count is incremented by one; T10 represents the rotor acceleration being less than a certain value in the forward direction for a certain period of time, when T10 is met, the count continues to increment by one; T5 / T7 represents the count reaching 200 times, when T5 / T7 is met, the time is reset to zero, and it jumps to the decay state; T6 represents the rotor acceleration being greater than a certain value in the reverse direction, when T6 is met, it jumps back to the forward monitoring state; T8 represents the rotor acceleration being less than a certain value in the reverse direction, when T8 is met, it jumps back to the reverse monitoring state; T11 represents when the count is reset to zero or the lane departure warning system request state is request activation or the lane departure warning system control state is activated, when T11 is met, it returns to the initialization state.

[0091] Specifically, in step 6, the formulas for calculating the desired rack position and the current rack position are as follows:

[0092] P DesRP =W Des *R W2RP *X

[0093] P ActRP =W Act *R W2RP *X

[0094] in:

[0095] P DesRP The desired rack position;

[0096] W Des Request an angle for the road-keeping assist system;

[0097] P ActRP This indicates the current rack position.

[0098] W Act The current steering wheel angle;

[0099] R W2RP This represents the change in rack position corresponding to a unit change in steering wheel angle.

[0100] X is a compensation coefficient that takes into account factors such as gear backlash and transmission ratio. It is a calibrable constant that varies with the angle.

[0101] Specifically, in step 7, the calculation of the current rack speed is as follows:

[0102] V ActRSpd =V RotSpd *R RotSpd2RSpd

[0103] in:

[0104] V ActRSpd This represents the current rack movement speed;

[0105] V RotSpd The speed of the electronic rotor;

[0106] R RotSpd2RSpd This represents the rack movement distance corresponding to a unit change in rotor speed.

[0107] Specifically, in step 8, the step of calculating the initial output torque of the angle closed-loop control is as follows:

[0108] Step 81: Based on the desired rack position, filter it through a mean low-pass filter and calculate the difference between it and the current rack position of the steering system;

[0109] Step 82: Combine the rack position difference result with the outer loop P parameter of the closed loop control module to calculate the desired rack movement speed of the steering system, and calculate the difference between it and the current rack movement speed of the steering system.

[0110] Step 83: Combine the rack and pinion speed difference result with the inner loop PI parameters of the closed loop control module to calculate the initial output torque of the angle closed loop control.

[0111] Preferably, in step 8, when the system switches from a non-human-machine co-driving state to a human-machine co-driving state, the inner loop I parameter needs to be reduced to zero along a preset gradient and kept at zero to prevent control overshoot caused by an excessively large inner loop I parameter when the assisted driving state switches from a human-machine co-driving state to a non-human-machine co-driving state.

[0112] Preferably, in step 8, when the steering system vibration state is set, the PID parameters of the dual-loop PID control system need to be replaced. The replaced PID parameters change with the safe vehicle speed and the number of vibrations. The higher the number of vibrations, the smaller the PID parameters.

[0113] Specifically, in step 9, the calculation steps for the co-drive coordination coefficient are as follows:

[0114] Step 91: Based on the safe vehicle speed and the driver's hand torque, calculate the gradient limit X of the angle control tuning coefficient using three-dimensional linear interpolation.RPCGradup Angle control tuning coefficient descent gradient limit X RPCGraddown Basic assist tuning coefficient ascent gradient limit X SFCGradup Basic assist tuning coefficient descent gradient limit X SFCGraddown ;

[0115] Step 92, if the current human-machine co-driving state is a human-machine co-driving invalid state, the angle control target tuning coefficient X RPCtarg Equal to 1, the basic assist target tuning coefficient X SFCtarg Equals 1; if the current human-machine co-driving state is not a human-machine co-driving state, the angle control target tuning coefficient X is 1. RPCtarg Equal to 1, the basic assist target tuning coefficient X SFCtarg Equals 0;

[0116] Step 93: If the current human-machine co-driving state is human-machine co-driving state, calculate the angle control target tuning coefficient X by three-dimensional linear interpolation based on the safe vehicle speed and the driver's hand torque. RPCtarg (0≤X RPCtarg ≤1) and the basic assist target tuning coefficient X SFCtarg (0≤X SFCtarg ≤1);

[0117] Step 94, Angle control tuning coefficient X RPC Follow angle control target tuning coefficient X RPCtarg The ascent gradient changes, and the ascent gradient is controlled by the angle-controlled tuning coefficients and the ascent gradient limit X. RPCGradup Amplitude limiting, descent gradient controlled by angle, tuning coefficient, descent gradient limit X RPCGraddown Limiting.

[0118] Angle control tuning coefficient X RPC The specific calculation formula is as follows:

[0119] X RPC =X RPClast +X RPCGradup (X RPCtarg >X RPClast +X RPCGradup )

[0120] X RPC =X RPClast -X RPCGraddown (X RPCtarg <X RPClast -X RPCGraddown )

[0121] X RPC =X RPCtarg (X RPClast -X RPCGraddown ≤X RPCtarg

[0122] in:

[0123] X RPC The tuning coefficient is used to control the angle.

[0124] X RPClast The angle control tuning coefficient is the value of the previous cycle.

[0125] X RPCtarg The tuning coefficients for the angle control target;

[0126] X RPCGradup The angle control tuning coefficient rise gradient limit;

[0127] X RPCGraddown The gradient limit for the descent of the tuning coefficient is used to control the angle.

[0128] Step 95, Basic Aid Tuning Coefficient X SFC Follow the basic assist target tuning coefficient X SFCtarg The ascent gradient changes, and the ascent gradient is affected by the base boost tuning coefficient and the ascent gradient limit X. SFCGradup Amplitude limiting, descent gradient is affected by the base boost tuning coefficient, descent gradient limit X SFCGraddown Limiting.

[0129] X SFC =X SFClast +X SFCGradup (X SFCtarg >X SFClast +X SFCGradup )

[0130] X SFC =X SFClast -X SFCGraddown (X SFCtarg <X SFClast -X SFCGraddown )

[0131] X SFC =X SFCtarg (X SFClast -X SFCGraddown ≤X SFCtarg ≤X SFClast +X SFCGradup )

[0132] in:

[0133] X SFC Basic tuning coefficients;

[0134] X SFClast The previous cycle value of the basic auxiliary tuning coefficient;

[0135] X SFCtargThe basic tuning coefficients for the target target;

[0136] X SFCGradup The basic assists in setting the gradient limit for the tuning coefficients.

[0137] X SFCGraddown This serves as the basis for lowering the gradient limit of the tuning coefficient.

[0138] Specifically, in step 10, the steps for calculating the final output torque of the power steering motor are as follows:

[0139] Step 101: Based on the safe vehicle speed, calculate the torque output limit of the angle closed-loop control at the current vehicle speed using linear interpolation. Then, calculate the final output torque of the angle closed-loop control using the following formula:

[0140] M RPCout =Min(|M RPC |*X RPC M RPCMAX )*Sign(M RPC )

[0141] in:

[0142] M RPCout The final output torque is determined by angle closed-loop control;

[0143] M RPC This is the initial output torque for angle closed-loop control;

[0144] M RPCMAX The torque output limit for the angle closed-loop control at the current vehicle speed;

[0145] X RPC The tuning coefficient is used to control the angle.

[0146] Sign(M RPC ) represents the numerical symbol for the initial output torque of the angle closed-loop control;

[0147] Min(|M RPC |*X RPC M RPCMAX ) is the smaller of the absolute value of the initial output torque of the angle closed-loop control and the torque output limit of the angle closed-loop control at the current vehicle speed.

[0148] Step 102, the formula for calculating the final output torque of the power steering motor is as follows:

[0149] M out =M RPCout +M SFC *X SFC

[0150] in:

[0151] M out This provides the final output torque of the power steering motor.

[0152] M RPCout The final output torque is determined by angle closed-loop control;

[0153] M SFC The initial output torque for basic assist;

[0154] X SFC This serves as the foundation for the tuning coefficients.

[0155] The present invention has been described in detail above through specific embodiments and examples, but these are not intended to limit the invention. Many modifications and improvements can be made by those skilled in the art without departing from the principles of the invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. An adaptive control method for a human-machine co-driving steering system, characterized in that, include: Step 1: The electronic power steering system needs to receive signals related to driving assistance functions. These signals include the road keeping assist system enable signal, road keeping assist system request status, and road keeping assist system request angle from the advanced driver assistance system; the steering system control unit status, power steering motor rotor speed, power steering motor rotor acceleration, torsion bar torque, steering wheel angular velocity, steering wheel angle, lane departure warning system request status, lane departure warning system control status, and safe vehicle speed. Step 2: Determine the status of the driver assistance function based on the road keeping assist system enable signal, steering system control unit status, torsion bar torque, steering wheel angle, safe vehicle speed, and road keeping assist system request status; Step 3: Calculate the driver's hand torque based on the power steering motor rotor acceleration, torsion bar torque, steering wheel angle, and steering wheel angular velocity; Step 4: Determine the current human-machine co-driving status based on the road keeping assist system request status, driver assistance function status, safe vehicle speed, and driver's hand torque; Step 5: Determine the current vibration state of the steering system based on the power steering motor rotor acceleration, the lane departure warning system request status, and the lane departure warning system control status; Step 6: Calculate the desired rack position and the current rack position based on the road keeping assist system's requested angle and steering wheel angle; Step 7: Calculate the current rack speed based on the rotor speed of the power assist motor; Step 8: Based on the current human-machine co-driving state, the vibration state of the steering system, the desired rack position, the current rack position, and the current rack speed, calculate the desired rack movement speed of the steering system, and then combine it with the current rack speed to calculate the initial output torque of the angle closed-loop control. Step 9: Calculate the co-driving coordination coefficient based on the safe vehicle speed, driver's hand torque, and current human-machine co-driving status; Step 10: Based on the safe vehicle speed, the initial output torque of the angle closed-loop control, and the co-driving coordination coefficient, calculate the coordinated basic power assist output torque and the final output torque of the angle closed-loop control. After limiting the final output torque of the angle closed-loop control, the two are superimposed as the final output torque of the steering system power assist motor.

2. The adaptive control method for the human-machine co-driving steering system according to claim 1, characterized in that, In step 2, when the steering system control unit is in normal condition, and the steering wheel angle and safe speed are within the allowable range, and the driver has no intention to disengage the driver assistance function, if the road keeping assist system request status is in emergency avoidance status, then the driver assistance function status is in emergency avoidance status; if the road keeping assist system request status is in non-emergency avoidance status, then the driver assistance function status is in non-emergency avoidance status.

3. The adaptive control method for the human-machine co-driving steering system according to claim 1, characterized in that, In step 2, the driver's intention to disengage the driver assistance function is determined based on the torsion bar torque. When the torsion bar torque is greater than the disengagement threshold M0 and remains for a set time T0, it is determined that the driver has the intention to disengage the driver assistance function. When the torsion bar torque is less than the disengagement threshold M1 and remains for a certain time T1, it is determined that the driver does not have the intention to disengage the driver assistance function.

4. The adaptive control method for the human-machine co-driving steering system according to claim 1, characterized in that, In step 2, when the assisted driving function is in emergency avoidance mode, if the torsion bar torque is greater than the assisted driving function exit threshold M3 and remains for a set time T3, it is determined that the driver intends to exit the assisted driving function. If the torsion bar torque is less than the assisted driving function exit threshold M4 and remains for a certain time T4, it is determined that the driver does not intend to exit the assisted driving function.

5. The adaptive control method for the human-machine co-driving steering system according to claim 1, characterized in that, In step 3, the method for calculating the driver's hand torque includes the following steps: Step 31: Perform FIR filtering on the acceleration of the boost motor rotor to obtain the filtered acceleration of the boost motor rotor. Combine this with the moment of inertia of the boost motor rotor to calculate the torque generated by the moment of inertia of the boost motor rotor. Step 32: Perform PT1 filtering on the steering wheel angular velocity to obtain the filtered steering wheel angular velocity, calculate the steering wheel angular acceleration, and then combine it with the steering wheel moment of inertia to calculate the torque generated by the steering wheel moment of inertia. Step 33: Perform PT1 filtering on the torsion bar torque to obtain the filtered torsion bar torque; Step 34: Calculate the driver's hand torque based on the data obtained in steps 31 to 33.

6. The adaptive control method for the human-machine co-driving steering system according to claim 5, characterized in that, When any one of the signals—power assist motor rotor acceleration, steering wheel angular velocity, or torsion bar torque—exceeds the valid range, the driver's hand torque is set to an invalid value.

7. The adaptive control method for the human-machine co-driving steering system according to claim 1, characterized in that, In step 4, the human-machine co-driving state includes driver intervention state, temporary fault state, permanent fault state, emergency avoidance mode and human-machine co-driving mode.

8. The adaptive control method for the human-machine co-driving steering system according to claim 1, characterized in that, In step 5, the vibration state of the steering system includes vibration forward monitoring state, vibration reverse monitoring state, initialization state, and attenuation state.

9. The adaptive control method for the human-machine co-driving steering system according to claim 1, characterized in that, In step 8, the calculation of the initial output torque of the angle closed-loop control is as follows: Step 81: Based on the desired rack position, filter it through a mean low-pass filter and calculate the difference between it and the current rack position of the steering system; Step 82: Combine the rack position difference result with the outer loop P parameter of the closed loop control module to calculate the desired rack movement speed of the steering system, and calculate the difference between it and the current rack movement speed of the steering system. Step 83: Combine the rack and pinion speed difference result with the inner loop PI parameters of the closed loop control module to calculate the initial output torque of the angle closed loop control.

10. The adaptive control method for the human-machine co-driving steering system according to claim 8, characterized in that, When the system switches from a non-human-machine co-driving state to a human-machine co-driving state, the inner loop I parameter is reduced to zero along a preset gradient and kept at zero.

11. The adaptive control method for the human-machine co-driving steering system according to claim 8, characterized in that, When the steering system vibration state is set, the PID parameters of the dual-loop PID control system are replaced. The replaced PID parameters change with the safe vehicle speed and the number of vibrations.

12. The adaptive control method for the human-machine co-driving steering system according to claim 1, characterized in that, In step 9, the calculation steps for the co-drive coordination coefficient are as follows: Step 91: Based on the safe vehicle speed and the driver's hand torque, calculate the rising gradient limit of the angle control tuning coefficient, the falling gradient limit of the angle control tuning coefficient, the rising gradient limit of the basic assist tuning coefficient, and the falling gradient limit of the basic assist tuning coefficient through three-dimensional linear interpolation. Step 92: If the current human-machine co-driving state is a human-machine co-driving invalid state, the angle control target tuning coefficient is equal to 1 and the basic assist target tuning coefficient is equal to 1; if the current human-machine co-driving state is a non-human-machine co-driving state, the angle control target tuning coefficient is equal to 1 and the basic assist target tuning coefficient is equal to 0. Step 93: If the current human-machine co-driving state is human-machine co-driving state, the angle control target tuning coefficient and the basic assist target tuning coefficient are calculated by three-dimensional linear interpolation based on the safe vehicle speed and the driver's hand torque. Step 94: The angle control tuning coefficients follow the changes in the angle control target tuning coefficients, and the rising gradient is limited by the rising gradient limit of the angle control tuning coefficients, while the falling gradient is limited by the falling gradient limit of the angle control tuning coefficients. Step 95: The base assist tuning coefficient changes with the base assist target tuning coefficient, and the upward gradient is limited by the upward gradient limit of the base assist tuning coefficient, while the downward gradient is limited by the downward gradient limit of the base assist tuning coefficient.

13. The adaptive control method for the human-machine co-driving steering system according to claim 1, characterized in that, In step 10, the steps for calculating the final output torque of the power steering motor are as follows: Step 101: Based on the safe vehicle speed, calculate the torque output limit of the angle closed-loop control at the current vehicle speed through linear interpolation, and then calculate the final output torque of the angle closed-loop control. Step 102, the formula for calculating the final output torque of the power steering motor is as follows: M out =M RPCout +M SFC *X SFC in: M out This provides the final output torque of the power steering motor. M RPCout The final output torque is determined by angle closed-loop control; M SFC The initial output torque for basic assist; X SFC This serves as the foundation for the tuning coefficients.

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