Self-adaptive man-machine co-driving electric power steering control method

Abstract

The invention discloses a self-adaptive man-machine co-driving electric power steering control method, which comprises the following steps of: obtaining a closed-loop current upper limit and a smooth intervention threshold value by using a table look-up module according to the actual speed and the actual turning angle of an automobile; a smooth processing module is used to obtain a closed-loop current dynamic upper limit according to the closed-loop current upper limit, a smooth intervention threshold and the basic assistance current of the automobile; acquiring a target rotation angle and a target rotation speed of the automobile, performing closed-loop control on the actual rotation speed and the actual rotation angle of the automobile according to the target rotation speed and the target rotation angle, and obtaining a closed-loop output current; the closed-loop output current is limited through the closed-loop current dynamic upper limit, and the closed-loop current of the driving assistance system is obtained; and the motor is controlled to conduct automobile steering through the closed-loop current and the basic assisting current. According to the electric power steering control method, decoupling of the electric power steering controller and the driving assistance system is achieved, control is more direct, response is faster, and the joint debugging difficulty is reduced.

Description

Technical Field

[0001] The present invention relates to the field of automobile intelligent driving, and in particular to an electric power steering control method for adaptive human-machine co-driving. Background Art

[0002] With the development of intelligent driving technology for automobiles, OEMs are paying more and more attention to the smoothness of the feel and response speed of driving assistance systems in human-machine co-driving scenarios. The power steering system, as the execution end, has an even more critical impact on the performance of human-machine co-driving. In the prior art, human-machine co-driving is achieved by adding additional torque angle sensors or redundant mechanical structures, but these methods have complex control systems and increase additional costs. Therefore, achieving smooth human-machine co-driving without affecting the existing mechanical structure of the steering system has become the mainstream research direction.

[0003] The Chinese patent with application number CN202111610424.6 discloses "A vehicle steering control method suitable for semi-automatic driving scenarios", which places the lateral control closed loop on the steering system side, improves the control accuracy, reduces the control delay, and solves the abnormal jitter and uneven execution problems that occur during lateral control. It can accurately execute the requests of the vehicle controller and receive the torque limit of the vehicle for human-machine co-driving, which can well solve the smoothness of human-machine co-driving. However, this method relies on the torque limit signal of the whole vehicle to solve the smoothness problem. The limit depends on the torque signal sent by the EPS controller, and the message cycle of the whole vehicle is generally 20ms. Therefore, the torque limit has too much delay for the ESP controller, and it is difficult to achieve more real-time and accurate smoothing processing; Chinese patent application number CN202310309536.0 discloses "An electric power steering control method, device, vehicle and readable storage medium". This method obtains the intelligent driving torque coefficient according to the driver's hand force and vehicle speed, and realizes the transfer of control rights under human-machine co-driving by torque adjustment; Chinese patent application number CN202311078851.3 discloses "Automatic steering system for human-machine co-driving" Adaptive control method", this method judges the human-machine co-driving state by the hand torque threshold and holding time, and realizes the transition of human-machine co-driving by the co-driving coordination coefficient; Chinese patent application number CN202211222349.0 discloses "A vehicle steering control method suitable for autonomous driving scenarios", this method judges the human-machine co-driving state machine mode according to the steering wheel torque collected by the driver's hand force calculation module, calculates the upper and lower limits of the motor comfort torque corresponding to each human-machine co-driving state, and the steering wheel compensation torque, obtains the additional torque at the motor end generated by the steering wheel torque by looking up the basic power assist module, and adds it to the motor safety limit torque as the total torque requested by the steering control system to the motor in the autonomous driving scenario.

[0004] However, all of the above methods rely on the torque value of the torque sensor to determine the transition state of human-machine co-driving, and the fluctuation of the torque value is generally around ±0.3Nm. Although some fluctuations can be filtered out by the torque threshold and holding time, it will also cause some discomfort in the hand feel and bring certain delays. Therefore, it is difficult to take into account the smoothness and real-time performance of the transition of human-machine co-driving. Summary of the invention

[0005] The main purpose of the present invention is to solve the technical problems described in the background technology.

[0006] To achieve the above object, the present invention provides an adaptive human-machine co-driving electric power steering control method, the adaptive human-machine co-driving electric power steering control method comprising:

[0007] Using a table lookup module, according to the actual speed and actual turning angle of the vehicle, a closed-loop current upper limit and a smoothing intervention threshold are obtained;

[0008] Using a smoothing processing module, a closed-loop current dynamic upper limit is obtained according to the closed-loop current upper limit, the smoothing intervention threshold and the basic power-assisting current of the vehicle;

[0009] Obtaining a speed command and a rotation angle command of the vehicle, performing closed-loop control on the rotation angle command, the speed command and the actual rotation angle, and obtaining a closed-loop output current;

[0010] The closed-loop output current is limited by the closed-loop current dynamic upper limit to obtain a closed-loop current of a driving assistance system;

[0011] The motor is controlled by the closed-loop current of the driving assistance system and the basic power-assisting current to steer the vehicle.

[0012] In one embodiment, the step of using a smoothing processing module to obtain a closed-loop current dynamic upper limit according to the closed-loop current upper limit, the smoothing intervention threshold and the basic assist current of the vehicle comprises:

[0013] According to the closed-loop current upper limit and the smooth intervention threshold, a smooth function is constructed, wherein the smooth function is a monotonically decreasing function in which the closed-loop current dynamic upper limit decreases smoothly with the basic assist current;

[0014] The basic assisting current is acquired, and a closed-loop current dynamic upper limit of the basic assisting current is obtained according to the basic assisting current and the smoothing function.

[0015] In one embodiment, the step of performing closed-loop control on the rotation angle command, the rotation speed command and the actual rotation angle to obtain a closed-loop output current further comprises:

[0016] Obtaining a rotation angle error according to the actual rotation angle and the rotation angle command, and obtaining a target rotation speed through the rotation angle error;

[0017] The actual speed of the vehicle is acquired, a speed error is obtained according to the actual speed and the target speed, and a closed-loop output current is obtained according to the speed error.

[0018] In one embodiment, the step of obtaining a rotation angle error according to the actual rotation angle and the rotation angle command, and obtaining a target rotation speed through the rotation angle error comprises:

[0019] Using the table lookup module, obtaining a turning angle safety range according to the actual vehicle speed of the vehicle;

[0020] Performing safety restrictions on the turning angle command according to the turning angle safety range;

[0021] The difference between the actual rotation angle and the rotation angle command after safety limitation is calculated to obtain a rotation angle error, and the target rotation speed is obtained according to the rotation angle error.

[0022] In one embodiment, the step of obtaining the target rotation speed through the rotation angle error is replaced by:

[0023] The rotation angle error is input into the angle loop to obtain the target rotation speed.

[0024] In one embodiment, the step of obtaining a speed error according to the actual speed and the target speed, and obtaining a closed-loop output current according to the speed error comprises:

[0025] Using the table lookup module, a speed safety range is obtained according to the actual speed of the vehicle;

[0026] Performing safety restrictions on the speed command according to the speed safety range;

[0027] A speed error is obtained according to the actual speed and the speed command after safety limitation, and a closed-loop output current is obtained through the speed error.

[0028] In one embodiment, the step of safely limiting the speed command according to the rotation angle safety range includes:

[0029] Using an overshoot suppression module to limit the overshoot of the speed command after safety limitation;

[0030] limiting the target speed according to the speed command after overshoot limitation;

[0031] The step of obtaining a speed error according to the actual speed and the speed command after safety limitation, and obtaining a closed-loop output current through the speed error is replaced by:

[0032] The difference between the actual speed and the target speed after limitation is calculated to obtain a speed error, and a closed-loop output current is obtained through the speed error.

[0033] In one embodiment, the step of obtaining the target rotation speed according to the rotation angle error is replaced by:

[0034] The speed error is input into the speed loop to obtain a closed-loop output current.

[0035] In one embodiment, after the step of limiting the closed-loop output current by the closed-loop current dynamic upper limit, the step further includes:

[0036] Using the table lookup module, obtaining a feedforward current according to the actual vehicle speed and the actual turning angle;

[0037] The step of obtaining the closed-loop current of the driving assistance system is replaced by:

[0038] The feedforward current is superimposed on the closed-loop output current after limitation to obtain a closed-loop current of the driving assistance system.

[0039] In one embodiment, the step of controlling the motor to steer the vehicle by using the closed-loop current and the basic assist current is replaced by:

[0040] A compensation current is obtained, and a motor is controlled by the closed-loop current, the basic power-assisting current and the compensation current to steer the vehicle.

[0041] The present invention does not rely on the torque limit issued by the driving assistance system controller, but dynamically limits the current through a smoothing processing module, and continuously adjusts the actual state and target state of the car through closed-loop control. The control logic of human-machine co-driving is at the steering system end, and the control is more direct and the response is faster; there is no need to filter the hand torque signal through thresholds and holding times, thereby reducing unnecessary delays; the driving assistance system current is directly smoothly transitioned to the power-assisting current, and the feel is smoother; compared with the traditional human-machine co-driving method, this method is decoupled from the host computer in terms of control and does not rely on the host computer of the automatic driving assistance system. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0043] Figure 1It is a flowchart of an electric power steering control method according to an embodiment of the present invention;

[0044] Figure 2 A block diagram of overall current output in an electric power steering controller according to an embodiment of the present invention;

[0045] Figure 3 A schematic diagram of a closed-loop control input and output interface of a driving assistance system in an embodiment of the present invention;

[0046] Figure 4 is a closed-loop control block diagram of a driving assistance system in one embodiment of the present invention;

[0047] Figure 5 is a block diagram of a table lookup module in one embodiment of the present invention;

[0048] Figure 6 is a schematic diagram of a smoothing processing module in an embodiment of the present invention;

[0049] Figure 7 It is a schematic diagram of the smooth transition between the basic current curve and the closed-loop current curve of the driving assistance system when the human and the machine are driving together in one embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to better understand the above technical solution, exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0051] The present invention provides an adaptive human-machine co-driving electric power steering control method, referring to Figure 1-7 In one embodiment, the adaptive human-machine co-driving electric power steering control method includes:

[0052] S110, using a table lookup module to obtain a closed-loop current upper limit and a smoothing intervention threshold according to the actual vehicle speed and actual turning angle of the vehicle;

[0053] Among them, the closed-loop current upper limit refers to the maximum current value allowed to pass during the operation of the closed-loop control system, which is used to set the safety boundary and protect the system components to prevent the electrical components in the system from overheating, burning or damage due to excessive current, and ensure the stability of the system; the smooth intervention threshold refers to the basic power-assistance current threshold of the electric power steering when the driver intervenes in the human-machine co-driving scenario of the driving assistance system, which is used to control the start timing of the smoothing mechanism (for example, when the basic power-assistance current in the system reaches or exceeds the smooth intervention threshold, the smoothing module starts to work and smoothes the current signal), achieves a smooth transition, and optimizes the system performance; the table lookup module mainly performs corresponding query operations based on the two key parameters of the current actual vehicle speed and actual turning angle of the car, and then obtains the two important data indicators of the closed-loop current upper limit and the smooth intervention threshold. The actual vehicle speed and the actual turning angle reflect the actual driving state and steering situation of the car at the moment. Through the pre-set corresponding relationship table (which can be understood as a table storing relevant indicator data under different vehicle speed and turning angle combinations), the reasonable closed-loop current upper limit and smooth intervention threshold under this state can be accurately determined.

[0054] In this step, the actual vehicle speed and the actual turning angle are constantly changing with the driving operation and driving conditions to adapt to the changing driving conditions of the car.

[0055] S120, using a smoothing processing module to obtain a closed-loop current dynamic upper limit according to the closed-loop current upper limit, the smoothing intervention threshold, and the basic power-assisting current of the vehicle;

[0056] Among them, the basic assist current is a basic current value originally existing in the electric steering assist system, which is used to provide initial assist as the basis for control and will be affected by vehicle speed, turning angle and rotation speed: for example, as the vehicle speed increases, the system may gradually reduce the assist current, but this reduction is relative to the basic assist current. The basic assist current always exists, but its proportion in the total assist current will change.

[0057] In this step, the closed-loop current upper limit, smooth intervention threshold, and basic power-assisting current obtained by the table lookup module are used as input data. The smoothing processing module makes reasonable adjustments to the current and finally obtains the closed-loop current dynamic upper limit, which is based on input parameters (such as actual vehicle speed, actual turning angle, and basic power-assisting current, etc.). Compared with the initial closed-loop current upper limit, this closed-loop current dynamic upper limit is more in line with the requirements of smooth and reasonable transition of current changes during the actual operation of the car, which can make the subsequent current control more in line with the actual driving scene when it changes dynamically, and avoid current mutations that may affect the driving experience and steering stability.

[0058] S130, obtaining a speed command and a rotation angle command of the vehicle, performing closed-loop control on the rotation angle command, the speed command and the actual rotation angle, and obtaining a closed-loop output current;

[0059] Among them, the speed command and the turning angle command are issued by the DAS. Closed-loop control is an automatic control process based on the feedback principle. It can continuously adjust the input according to the actual situation of the system output to reach or approach the predetermined target value; the closed-loop output current is based on the difference between the actual state of the car (actual speed, actual turning angle and actual speed, etc.) and the target state (target turning angle and target speed, etc.). The current value obtained after the closed-loop control mechanism is used to drive the motor and other components to adjust the steering of the car. The purpose is to make the actual operating state of the car as close as possible to the target set state.

[0060] Due to the changing driving conditions, the driving state will be adjusted in real time. In this step, the target state and actual state of the car are closed-loop controlled, and the actual state and target state affect each other (for example, the target state obtained according to the actual situation will be used as the input of the next closed-loop control).

[0061] S140, limiting the closed-loop output current by using the closed-loop current dynamic upper limit to obtain a closed-loop current of a driving assistance system;

[0062] In this step, the closed-loop output current is limited by the closed-loop current dynamic upper limit obtained by the smoothing module.

[0063] S150, controlling the motor to steer the vehicle by using the closed-loop current and the basic power-assisting current.

[0064] Among them, the motor is the motor of EPS (Electric Power Steering System).

[0065] It is important to know that EPS (Electric Power Steering System) is a steering system that uses an electric motor to provide auxiliary steering force; DAS usually refers to basic driving assistance systems, such as lane departure warning, forward collision warning, etc. These functions are mainly reminders and warnings and do not directly interfere with the driver's driving operations. Among them, EPS mainly focuses on the steering operation of the car driver, and provides appropriate steering assistance according to factors such as vehicle speed and turning angle to improve driving comfort and convenience. DAS focuses on the vehicle's automatic driving or assisted driving functions, such as lane keeping and adaptive cruise control. The control objectives and logics of the two are different. If the coupling between EPS and DAS is too large, when DAS intervenes or adjusts, it may affect EPS, causing the driver to feel unnatural steering force changes and affecting driving safety. Conversely, the working state of EPS may also interfere with the normal operation of DAS, making it difficult for DAS to accurately achieve its control goals; and the smoothing processing module receives parameters such as the basic assist current and outputs the closed-loop current dynamic upper limit, which can limit the impact of the current output by DAS on EPS. For example, when DAS needs to output a large current to adjust the direction of the vehicle, the closed-loop current dynamic upper limit output by the smoothing processing module can prevent the current from excessively affecting the normal operation of EPS and avoid sudden and unexpected changes in the steering assistance provided by EPS.

[0066] In this embodiment, the smoothing processing module is used to effectively reduce the mutual interference between EPS and DAS by limiting the current. DAS only needs to issue speed instructions and angle instructions, and the EPS controller handles the limitations, thereby achieving decoupling between the two and enabling them to work better together to provide the vehicle with a better driving experience and more reliable assisted driving functions. At the same time, the PI parameters (referring to the parameters in the PI controller, which is a commonly used feedback controller) cooperate with the host computer, making the control more direct and reducing the difficulty of debugging the host computer algorithm.

[0067] In one embodiment, referring to Figure 5 The table lookup module includes a first two-dimensional table, a second two-dimensional table, a third two-dimensional table, a first one-dimensional table and a first one-dimensional table. The table lookup module can be used to query by inputting the turning angle and the vehicle speed. Specifically, the feedforward current can be queried by inputting the actual turning angle and the actual vehicle speed in the first two-dimensional table, the closed-loop current upper limit can be queried by inputting the actual turning angle and the actual vehicle speed in the second two-dimensional table, the smoothing intervention threshold can be queried by inputting the actual turning angle and the actual vehicle speed in the third two-dimensional table, the speed safety range can be queried by inputting the actual vehicle speed in the first one-dimensional table, and the turning angle safety range can be queried by inputting the actual vehicle speed in the second one-dimensional table, wherein the turning angle and the vehicle speed are the actual turning angle and the actual vehicle speed of the car, and all table lookup methods are piecewise linear interpolation table lookups, and all tables can be calibrated separately.

[0068] In one embodiment, referring to Figure 6 and Figure 7 The step of using a smoothing processing module to obtain a closed-loop current dynamic upper limit according to the closed-loop current upper limit, the smoothing intervention threshold and the basic assist current of the vehicle in S110 includes:

[0069] S111, constructing a smoothing function according to the closed-loop current upper limit and the smoothing intervention threshold, wherein the smoothing function is a monotonically decreasing function in which the closed-loop current dynamic upper limit decreases smoothly with the basic assist current;

[0070] S112, acquiring the basic assisting current, and obtaining a closed-loop current dynamic upper limit of the basic assisting current according to the basic assisting current and the smoothing function.

[0071] Specifically, Figure 6 As shown, the smoothing function (constructed by the smoothing processing module) is a monotonically decreasing function in which the dynamic upper limit of the closed-loop current of the driving assistance system decreases smoothly with the basic power-assisting current. The smoothing function is constructed as follows:

[0072] Formula (1) I Dlimit =f(I A )

[0073] Among them, I A The real-time target base boost current, I Dlimit The dynamic upper limit value of the driving assistance system current PI regulation (closed-loop current dynamic upper limit);

[0074] Here we take the simplest linear relationship:

[0075] Formula (2)I Dlimit =a·I A +b

[0076] In order to make the function monotonically decreasing, let a = -(I Dmax / I Thr ), b=I Dmax , then:

[0077] Formula (3)I Dlimit =-(I Dmax / I Thr )·I A +I Dmax

[0078] Among them, I ThrIt is the power assist current threshold value during the return to center intervention (the power assist current threshold value during the return to center intervention refers to the specific value that the power assist current needs to reach when the steering wheel automatic return to center function is triggered. When the power assist current reaches or exceeds this threshold value, the system will consider that the steering action has been completed or the conditions for return to center have been met, thereby starting the return to center control program and starting to execute the return to center operation of the steering wheel), which is obtained by looking up the table in the table lookup module and can be calibrated; I Dmax It is the maximum value of the upper limit of the current PI regulation of the driving assistance system (the maximum value of the closed-loop current), which is obtained by looking up the table by the table lookup module and can be calibrated.

[0079] When I A <=I Thr When I A >I Thr When the closed-loop current of the driving assistance system exits naturally, this ensures that the closed-loop positive current and the power-assisting current are naturally connected and transitioned, with one increasing while the other decreases.

[0080] like Figure 7 As shown in the figure, according to the closed-loop current upper limit and the smooth intervention threshold, the basic power-assisting current flows through the constructed smooth function to obtain the closed-loop current dynamic upper limit; the curve of the smooth function must pass through (T1, I1) (I1 is equal to 0 at this time) and (T2, I2), T1 is the moment when the driving assistance system current begins to intervene; T2 is the moment when the basic power-assisting is completely withdrawn; I1 is the basic power-assisting threshold when the driving assistance system current smoothly intervenes, and this threshold varies with the (actual) turning angle and (actual) vehicle speed; I2 is the maximum upper limit of the closed-loop adjustment current of the driving assistance system, and this limit varies with the (actual) turning angle and (actual) vehicle speed; the range from 0 to T1 is the human driving area. At this stage, the basic power-assisting current plays a major role, and the current is relatively stable, providing a basic power-assisting support for manual driving, such as in the car's In the power steering system, a certain amount of steering assistance is provided to the driver to make driving operations easier; the interval from T1 to T2 is the transition zone. In this stage, the basic assistance current begins to decrease, and the superimposed current in the transition zone gradually increases and superimposed on the basic assistance current. At this time, the system is transitioning from manual driving mode to automatic driving. A smooth transition is achieved by adjusting the current to avoid sudden changes from causing shocks to the system. For example, when automatic driving intervenes, the current of the motor is gradually adjusted to achieve a smooth handover of steering, acceleration and other operations; after T2 is the machine driving zone. In this stage, the closed-loop current of the driving assistance system reaches a relatively high and relatively stable value I2. In the automatic driving mode, the current control of the system reaches a new stable state to meet the various needs of automatic driving, such as precise steering control, speed control, etc.

[0081] In one embodiment, referring to Figure 3 and Figure 4In S130, the step of performing closed-loop control on the rotation angle command, the rotation speed command and the actual rotation angle to obtain a closed-loop output current includes:

[0082] S131, obtaining a rotation angle error according to the actual rotation angle and the rotation angle command, and obtaining a target rotation speed according to the rotation angle error;

[0083] S132, obtaining an actual rotation speed of the vehicle, obtaining a rotation speed error according to the actual rotation speed and the target rotation speed, and obtaining a closed-loop output current according to the rotation speed error.

[0084] like Figure 3 As shown in the figure, it is a schematic diagram of the input and output interface of the closed-loop control of the driving assistance system. The input signals include the host computer commands of the driving assistance system (enable, angle commands and speed commands), the internal signals of the EPS controller (actual angle, actual speed and basic assist current) and the vehicle signal (vehicle speed). The output is a smooth output current of the driving assistance system.

[0085] In one embodiment, referring to Figure 3 and Figure 4 In S131, a rotation angle error is obtained according to the actual rotation angle and the rotation angle command, and a step of obtaining a target rotation speed through the rotation angle error comprises:

[0086] S1311, using the table lookup module to obtain a turning angle safety range according to the actual speed of the vehicle;

[0087] Specifically, refer to Figure 5 The corner safety range is obtained by looking up the vehicle speed through the second one-dimensional table.

[0088] S1312, performing safety restrictions on the turning angle command according to the turning angle safety range;

[0089] Among them, the turning angle safety range refers to the safe range of steering angles allowed by the steering system during vehicle driving. Limiting the turning angle command within the turning angle safety range can prevent the vehicle from oversteering and causing dangerous situations such as loss of control.

[0090] S1313, calculating the difference between the actual rotation angle and the rotation angle command after safety limitation to obtain a rotation angle error, and obtaining a target rotation speed through the rotation angle error.

[0091] Figure 3This is a schematic diagram of the closed-loop control input and output interface (the vehicle speed is the actual vehicle speed, and the steering angle is the actual steering angle). The input signal includes three parts: DAS host computer command, EPS controller internal signal, and vehicle signal. The output is a smooth DAS output current. The DAS host computer command includes DAS enable command, steering angle command, and speed command; EPS controller internal signals include actual steering angle, actual speed, and basic power assist current; vehicle signals include vehicle speed; Figure 4 It is a closed-loop control block diagram (the vehicle speed is the actual vehicle speed, the steering angle is the actual steering angle, and the speed is the actual speed). It mainly includes a table lookup module, a smoothing processing module, an angle loop, a speed loop, an overshoot suppression module, and a limiting module (Limit), and finally outputs a smooth output current of the driving assistance system.

[0092] In one embodiment, referring to Figure 4 , the step of obtaining the target speed through the rotation angle error is replaced by:

[0093] The rotation angle error is input into the angle loop to obtain the target rotation speed.

[0094] Among them, the angle ring is mainly responsible for handling the steering angle-related control of the vehicle. It obtains the target angle and the actual angle and calculates the angle error between the two. Based on this error, the angle ring will output the corresponding control signal to adjust the vehicle's steering system so that the actual angle can quickly and accurately approach the target angle, thereby achieving precise steering operations of the vehicle and ensuring that the vehicle drives along the desired path. For example, in an autonomous driving scenario, the vehicle needs to turn according to the planned route, and the angle ring can ensure that the actual steering angle of the vehicle meets the route planning requirements. During the driving process of the vehicle, it will be disturbed by various factors, such as uneven road surface and side wind, which may cause the actual steering angle of the vehicle to deviate from the expected. The angle ring will monitor and correct these deviations in real time, so that the vehicle can still maintain a stable steering state in a complex driving environment and improve driving safety. For example, when encountering side winds while driving at high speed, the angle ring will automatically adjust the steering system to keep the vehicle driving in a straight line or turning according to the predetermined curve.

[0095] In one embodiment, referring to Figure 4 The step of obtaining a speed error according to the actual speed and the target speed, and obtaining a closed-loop output current according to the speed error comprises:

[0096] S1321, using the table lookup module to obtain a speed safety range according to the actual speed of the vehicle;

[0097] Specifically, using the table lookup module, the speed safety range can be obtained according to the actual vehicle speed by looking up the first one-dimensional table.

[0098] S1322, safely limiting the speed command according to the speed safety range;

[0099] Among them, the speed safety range refers to the safe range of the steering wheel speed. When the vehicle speed is high, it will be unsafe if the steering wheel speed is too fast.

[0100] S1323, obtaining a speed error according to the actual speed and the speed command after safety limitation, and obtaining a closed-loop output current through the speed error.

[0101] In one embodiment, referring to Figure 4 S1322, the step of safely limiting the speed command according to the rotation angle safety range includes:

[0102] S13221, using an overshoot suppression module to limit the overshoot of the speed command after safety limitation;

[0103] S13222, limiting the target speed according to the speed command after overshoot limitation;

[0104] The step of obtaining a speed error according to the actual speed and the speed command after safety limitation, and obtaining a closed-loop output current through the speed error is replaced by:

[0105] The difference between the actual speed and the target speed after limitation is calculated to obtain a speed error, and a closed-loop output current is obtained through the speed error.

[0106] Among them, the overshoot suppression module monitors the angle error in real time. The smaller the angle error, the lower the limit value, so as to eliminate the jitter caused by frequent adjustments near the target angle.

[0107] In one embodiment, referring to Figure 4 , the step of obtaining the target speed according to the rotation angle error is replaced by:

[0108] The speed error is input into the speed loop to obtain a closed-loop output current.

[0109] Among them, the core task of the speed loop is to accurately control the speed of the vehicle. It takes the difference between the target speed and the actual speed (i.e., the speed error) as input, and outputs a control signal after a series of calculations and processing to adjust the output of the engine or motor so that the actual speed is stable near the target speed. For example, when cruising at a constant speed, the speed loop will automatically adjust the engine speed according to the changes in driving resistance (such as climbing, downhill, etc.) to maintain a stable driving speed of the vehicle. The speed loop can flexibly adjust the speed to achieve the best power output according to different working conditions of the vehicle (such as starting, accelerating, decelerating, etc.). At the starting stage, it will control the engine or motor to quickly increase the speed and provide sufficient torque; when driving at high speed, it will maintain a suitable speed to balance power and fuel economy.

[0110] It is important to understand that the angle loop and speed loop are the basis of driver assistance system control.

[0111] In one embodiment, referring to Figure 4 In the S140, after the step of limiting the closed-loop output current by the closed-loop current dynamic upper limit, the step further includes:

[0112] S141, using the table lookup module to obtain a feedforward current according to the actual vehicle speed and the actual turning angle;

[0113] Specifically, using a table lookup module, the feedforward current can be obtained by looking up a first two-dimensional table according to the actual vehicle speed and the actual turning angle.

[0114] The step of obtaining the closed-loop current of the driving assistance system is replaced by:

[0115] The feedforward current is superimposed on the closed-loop output current after limitation to obtain a closed-loop current of the driving assistance system.

[0116] Among them, feedforward current is a concept used in control systems, especially in systems involving power and motion control such as vehicle driver assistance systems (DAS). It is a current signal calculated and applied in advance based on the input of the system or known interference factors on the basis of feedback control. Unlike feedback control, which mainly relies on the error signal output by the system for adjustment, feedforward control attempts to intervene in the system before the error occurs.

[0117] In one embodiment, referring to Figure 2 , the step of controlling the motor to steer the vehicle by using the closed-loop current and the basic power-assist current in S150 is replaced by:

[0118] A compensation current is obtained, and a motor is controlled by the closed-loop current, the basic power-assisting current and the compensation current to steer the vehicle.

[0119] Among them, the compensation current includes the current loss caused by damping, friction and inertia, and the basic assist current is obtained by looking up the torque table.

[0120] Specifically, referring to body 2, the closed-loop current of the driving assistance system calculated by the EPS controller is smoothly connected and transitioned with the basic power-assisting current to obtain a smooth driving assistance system current, which is superimposed with the compensation current and the basic power-assisting current as the input of the current loop (inner loop) and finally acts on the motor.

[0121] As an example, refer to Figure 4, is a closed-loop control block diagram of the driving assistance system, which includes a table lookup module, a smoothing processing module, an angle loop, a speed loop, a limit module (Limit) and an over-suppression module. First, the table lookup module obtains the initial current limit and threshold information according to the vehicle speed and the turning angle, and then further processes it through the smoothing processing module to obtain the closed-loop current dynamic upper limit. At the same time, the angle loop calculates the angle error according to the turning angle command and the actual turning angle and processes it. After overshoot suppression, it is passed to the speed loop. The speed loop outputs the closed-loop output current in combination with the speed command. Finally, the closed-loop current dynamic upper limit is added to the closed-loop current of the driving assistance system and processed by the flexible intervention / exit module to obtain the final DAS outputs current and acts on the motor to control the car's power steering; in this process, the target speed and target angle after limitation will be used as the target angle and target speed of the next closed-loop control, and the actual vehicle speed and actual angle after being affected by the closed-loop current will be used as the actual angle and actual vehicle speed of the next closed-loop control; the processing of the angle loop and the speed loop will be repeated continuously according to the actual situation (the output current will be continuously adjusted according to the angle error) to achieve precise control and stable system operation. With the coordinated effect of multiple modules, the entire process realizes precise control and safe limitation of the vehicle current, ensuring stable operation and safe operation of the vehicle under various conditions.

[0122] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An adaptive electric power steering control method for human-machine co-driving, characterized in that: The electric power steering control method is used for an automobile, and the electric power steering control method comprises: Using a table lookup module, according to the actual speed and actual turning angle of the vehicle, a closed-loop current upper limit and a smoothing intervention threshold are obtained; Using a smoothing processing module, a closed-loop current dynamic upper limit is obtained according to the closed-loop current upper limit, the smoothing intervention threshold and the basic power-assisting current of the vehicle; Obtaining a speed command and a rotation angle command of the vehicle, performing closed-loop control on the rotation angle command, the speed command and the actual rotation angle, and obtaining a closed-loop output current; The closed-loop output current is limited by the closed-loop current dynamic upper limit to obtain a closed-loop current of a driving assistance system; The motor is controlled by the closed-loop current and the basic assist current to steer the vehicle.

2. The electric power steering control method for adaptive human-machine co-driving as claimed in claim 1, characterized in that: The step of using the smoothing processing module to obtain the closed-loop current dynamic upper limit according to the closed-loop current upper limit, the smoothing intervention threshold and the basic assist current of the vehicle comprises: According to the closed-loop current upper limit and the smooth intervention threshold, a smooth function is constructed, wherein the smooth function is a monotonically decreasing function in which the closed-loop current dynamic upper limit decreases smoothly with the basic assist current; The basic assisting current is acquired, and a closed-loop current dynamic upper limit of the basic assisting current is obtained according to the basic assisting current and the smoothing function.

3. The electric power steering control method for adaptive human-machine co-driving as claimed in claim 1, characterized in that: The step of performing closed-loop control on the rotation angle command, the rotation speed command and the actual rotation angle to obtain a closed-loop output current comprises: Obtaining a rotation angle error according to the actual rotation angle and the rotation angle command, and obtaining a target rotation speed through the rotation angle error; The actual speed of the vehicle is acquired, a speed error is obtained according to the actual speed and the target speed, and a closed-loop output current is obtained according to the speed error.

4. The electric power steering control method for adaptive human-machine co-driving as claimed in claim 3, characterized in that: The step of obtaining a rotation angle error according to the actual rotation angle and the rotation angle command, and obtaining a target rotation speed through the rotation angle error comprises: Using the table lookup module, obtaining a turning angle safety range according to the actual vehicle speed of the vehicle; Performing safety restrictions on the turning angle command according to the turning angle safety range; The difference between the actual rotation angle and the rotation angle command after safety limitation is calculated to obtain a rotation angle error, and the target rotation speed is obtained according to the rotation angle error.

5. The electric power steering control method for adaptive human-machine co-driving as claimed in claim 4, characterized in that: The step of obtaining the target speed through the rotation angle error is replaced by: The rotation angle error is input into the angle loop to obtain the target rotation speed.

6. The electric power steering control method for adaptive human-machine co-driving as claimed in claim 3, characterized in that: The step of obtaining a speed error according to the actual speed and the target speed, and obtaining a closed-loop output current according to the speed error comprises: Using the table lookup module, a speed safety range is obtained according to the actual speed of the vehicle; Performing safety restrictions on the speed command according to the speed safety range; A speed error is obtained according to the actual speed and the speed command after safety limitation, and a closed-loop output current is obtained through the speed error.

7. The electric power steering control method for adaptive human-machine co-driving as claimed in claim 6, characterized in that: The step of safely limiting the rotation speed command according to the rotation angle safety range comprises: Using an overshoot suppression module to limit the overshoot of the speed command after safety limitation; limiting the target speed according to the speed command after overshoot limitation; The step of obtaining a speed error according to the actual speed and the speed command after safety limitation, and obtaining a closed-loop output current through the speed error is replaced by: The difference between the actual speed and the target speed after limitation is calculated to obtain a speed error, and a closed-loop output current is obtained through the speed error.

8. The electric power steering control method for adaptive human-machine co-driving as claimed in claim 6, characterized in that: The step of obtaining the target speed according to the rotation angle error is replaced by: The speed error is input into the speed loop to obtain a closed-loop output current.

9. The electric power steering control method for adaptive human-machine co-driving as claimed in claim 1, characterized in that: After the step of limiting the closed-loop output current by the closed-loop current dynamic upper limit, the following step further comprises: Using the table lookup module, obtaining a feedforward current according to the actual vehicle speed and the actual turning angle; The step of obtaining the closed-loop current of the driving assistance system is replaced by: The feedforward current is superimposed on the closed-loop output current after limitation to obtain a closed-loop current of the driving assistance system.

10. The electric power steering control method for adaptive human-machine co-driving as claimed in claim 1, characterized in that: The step of controlling the motor to steer the vehicle by using the closed-loop current and the basic power-assist current is replaced by: A compensation current is obtained, and a motor is controlled by the closed-loop current, the basic power-assisting current and the compensation current to steer the vehicle.

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