Adaptive electric power steering control method for human-machine co-driving

Abstract

This invention discloses an adaptive human-machine co-driving electric power steering control method, comprising: using a lookup table module to obtain a closed-loop current upper limit and a smoothing intervention threshold based on the vehicle's actual speed and actual steering angle; using a smoothing processing module to obtain a closed-loop current dynamic upper limit based on the closed-loop current upper limit, the smoothing intervention threshold, and the vehicle's basic power assist current; obtaining the vehicle's target steering angle and target speed, performing closed-loop control on the vehicle's actual speed and actual steering angle based on the target speed and target steering angle to obtain a closed-loop output current; limiting the closed-loop output current through the closed-loop current dynamic upper limit to obtain the closed-loop current of the driving assistance system; and controlling the motor to steer the vehicle using the closed-loop current and the basic power assist current. The electric power steering control method proposed in this invention achieves decoupling between the electric power steering controller and the driving assistance system, resulting in more direct control, faster response, and reduced integration difficulty.

Description

Technical Field

[0001] This invention relates to the field of intelligent driving for automobiles, and more particularly to an adaptive human-machine co-driving electric power steering control method. Background Technology

[0002] With the development of intelligent driving technology in automobiles, OEMs are paying increasing attention to the smoothness and responsiveness of driver assistance systems in human-machine co-driving scenarios. The power steering system, as the actuator, has a particularly critical impact on human-machine co-driving performance. Current technologies achieve human-machine co-driving by adding extra torque angle sensors or redundant mechanical structures, but these methods complicate the control system and increase costs. Therefore, achieving smooth human-machine co-driving without affecting the existing steering system's mechanical structure has become the mainstream research direction.

[0003] Chinese patent application number CN202111610424.6 discloses "A vehicle steering control method applicable to semi-autonomous driving scenarios". It puts the control closed loop of lateral control at the steering system end, which improves the control accuracy, reduces the control delay, and solves the problems of abnormal jitter and uneven execution in the lateral control process. It can accurately execute the requests of the vehicle controller and receive the torque limit value of the vehicle for human-machine co-driving, which can effectively solve the smoothness of human-machine co-driving. However, this method relies on the vehicle's torque limit signal to solve the smoothness problem. This limit, in turn, depends on the torque signal sent by the EPS controller. Since the vehicle's message cycle is typically 20ms, this torque limit has too much delay for the ESP controller, making it difficult to achieve more real-time and precise smoothing. Chinese patent application CN202310309536.0 discloses "An Electric Power Steering Control Method, Device, Vehicle, and Readable Storage Medium," which obtains the intelligent driving torque coefficient by looking up a table based on the driver's hand force and vehicle speed, and achieves the transfer of control under human-machine co-driving through torque adjustment. Chinese patent application CN202311078851.3 discloses "The Self-Driving Steering System of Human-Machine Co-driving..." The "Adaptive Control Method" determines the human-machine co-driving state by using a hand torque threshold and holding time, and achieves the transition of human-machine co-driving through a co-driving coordination coefficient. Chinese patent application number CN202211222349.0 discloses "A Steering Control Method for Automobiles Applicable to Autonomous Driving Scenarios". This method determines the human-machine co-driving state machine mode based on the steering wheel torque collected by the driver's hand force calculation module, calculates the upper and lower limits of motor comfort torque and steering wheel compensation torque corresponding to each human-machine co-driving state, obtains the additional torque at the motor end generated by the steering wheel torque by looking up a table of the basic power assist module, and adds it to the motor safety limit torque as the total torque requested by the steering control system for 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. The fluctuation of this torque value is generally around ±0.3Nm. Although some fluctuations can be filtered out by torque threshold and holding time, it will also bring some discomfort in the feel and a certain delay. Therefore, it is difficult to balance the smoothness and real-time performance during the transition of human-machine co-driving. Summary of the Invention

[0005] The main objective of this invention is to solve the technical problems described in the background section.

[0006] To achieve the above objectives, the present invention provides an adaptive human-machine co-driving electric power steering control method, which includes: Using a lookup table module, the upper limit of closed-loop current and the smooth intervention threshold are obtained based on the actual vehicle speed and actual turning angle. Using a smoothing module, the dynamic upper limit of the closed-loop current is obtained based on the upper limit of the closed-loop current, the smoothing intervention threshold, and the basic assist current of the vehicle. The vehicle's speed command and steering angle command are obtained, and closed-loop control is performed on the steering angle command, the speed command, and the actual steering angle to obtain the closed-loop output current; The closed-loop output current is limited by the dynamic upper limit of the closed-loop current to obtain the closed-loop current of the driving assistance system. The vehicle is steered by controlling the motor using the closed-loop current of the driving assistance system and the basic assist current.

[0007] In one embodiment, the step of using a smoothing module to obtain the dynamic upper limit of the closed-loop current based on the upper limit of the closed-loop current, the smoothing intervention threshold, and the vehicle's base assist current includes: Based on the upper limit of the closed-loop current and the smooth intervention threshold, a smoothing function is constructed. The smoothing function is a monotonically decreasing function in which the dynamic upper limit of the closed-loop current decreases smoothly with the base assist current. Obtain the base assist current, and based on the base assist current and the smoothing function, obtain the closed-loop current dynamic upper limit of the base assist current.

[0008] In one embodiment, the step of performing closed-loop control on the steering angle command, the rotation speed command, and the actual steering angle to obtain the closed-loop output current further includes: The angle error is obtained based on the actual angle and the angle command, and the target rotation speed is obtained through the angle error. The actual rotational speed of the vehicle is obtained, the rotational speed error is obtained based on the actual rotational speed and the target rotational speed, and the closed-loop output current is obtained based on the rotational speed error.

[0009] In one embodiment, the step of obtaining the angle error based on the actual angle and the angle command, and obtaining the target rotational speed through the angle error, includes: Using the lookup module, the safe turning angle range is obtained based on the actual speed of the vehicle. The cornering command is subject to safety restrictions based on the defined cornering safety range; The difference between the actual rotation angle and the rotation angle command after the safety limit is calculated to obtain the rotation angle error, and the target rotation speed is obtained through the rotation angle error.

[0010] In one embodiment, the step of obtaining the target rotational speed through the angle error is replaced by: The target rotational speed is obtained by inputting the rotational angle error into the angle loop.

[0011] In one embodiment, the step of obtaining the speed error based on the actual speed and the target speed, and obtaining the closed-loop output current based on the speed error, includes: Using the lookup module, the safe speed range is obtained based on the actual vehicle speed. The rotational speed command is subject to safety restrictions based on the specified rotational speed safety range; The speed error is obtained based on the actual speed and the speed command after the safety limit, and the closed-loop output current is obtained through the speed error.

[0012] In one embodiment, the step of safely limiting the speed command according to the speed safety range includes... The overshoot suppression module is used to limit the overshoot of the speed command after the safety limit; The target speed is limited according to the speed command after overshoot limitation; The step of obtaining the speed error based on the actual speed and the speed command after the safety limit, and then obtaining the closed-loop output current from the speed error, is replaced by: The difference between the actual rotational speed and the target rotational speed after limitation is calculated to obtain the rotational speed error, and the closed-loop output current is obtained through the rotational speed error.

[0013] In one embodiment, the step of obtaining the closed-loop output current based on the speed error is replaced by: The speed error is input into the speed loop to obtain the closed-loop output current.

[0014] In one embodiment, after the step of limiting the closed-loop output current by the dynamic upper limit of the closed-loop current, the method further includes: Using the lookup module, the feedforward current is obtained based on the actual vehicle speed and the actual turning angle; The step of obtaining the closed-loop current of the driver assistance system is replaced by: The feedforward current is superimposed with the limited closed-loop output current to obtain the closed-loop current of the driving assistance system.

[0015] In one embodiment, the step of controlling the vehicle steering by the motor through the closed-loop current and the base assist current is replaced by: The compensation current is obtained, and the motor is controlled to steer the vehicle through the closed-loop current, the basic assist current, and the compensation current.

[0016] This invention does not rely on torque limits issued by the driver assistance system controller. Instead, it dynamically limits the current through a smoothing module and continuously adjusts the vehicle's actual and target states through closed-loop control. The control logic for human-machine co-driving is located at the steering system end, resulting in more direct control and faster response. It eliminates the need to filter the torque signal using thresholds and holding times, reducing unnecessary delays. The driver assistance system current and the power assist current are directly and smoothly connected, resulting in a smoother feel. Compared to traditional human-machine co-driving methods, this method decouples the control from the host computer and does not rely on the host computer of the autonomous driving assistance system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating an electric power steering control method according to an embodiment of the present invention. Figure 2 This is a block diagram of the overall current output in the electric power steering controller according to one embodiment of the present invention; Figure 3 This is a schematic diagram of the closed-loop control input / output interface of a driving assistance system according to an embodiment of the present invention; Figure 4 This is a closed-loop control block diagram of a driving assistance system according to an embodiment of the present invention; Figure 5 This is a block diagram of a table lookup module in one embodiment of the present invention; Figure 6 This is a schematic diagram of a smoothing module in one embodiment of the present invention; Figure 7 This is a schematic diagram illustrating the smooth transition between the base current curve and the closed-loop current curve of the driving assistance system during human-machine co-driving in one embodiment of the present invention. Detailed Implementation

[0019] To better understand the above technical solutions, exemplary embodiments of this disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0020] This 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: S110, using a lookup table module, the upper limit of closed-loop current and the smooth intervention threshold are obtained based on the actual vehicle speed and actual turning angle of the vehicle; The closed-loop current upper limit refers to the maximum allowable current value during the operation of the closed-loop control system. It sets safety boundaries, protects system components, and prevents excessive current from causing overheating, burnout, or damage to electrical components, ensuring system stability. The smooth intervention threshold refers to the basic power steering assist current threshold when the driver intervenes in a human-machine co-driving scenario. It controls the activation timing of the smoothing mechanism (e.g., when the basic assist current in the system reaches or exceeds the smooth intervention threshold, the smoothing module starts working to smooth the current signal), achieving a smooth transition and optimizing system performance. The lookup module mainly performs corresponding lookup operations based on the vehicle's current actual speed and actual steering angle to obtain the two important data indicators: the closed-loop current upper limit and the smooth intervention threshold. Actual speed and actual steering angle reflect the vehicle's current driving and steering conditions. Through a pre-set correspondence table (which can be understood as a table storing relevant indicator data under different combinations of speed and steering angle), the reasonable closed-loop current upper limit and smooth intervention threshold under this state can be accurately determined.

[0021] In this step, the actual vehicle speed and actual steering angle are constantly changing with driving operations and driving conditions to adapt to the ever-changing driving situation of the car.

[0022] S120, using a smoothing module, the dynamic upper limit of the closed-loop current is obtained based on the upper limit of the closed-loop current, the smoothing intervention threshold, and the basic assist current of the vehicle. The base assist current is a basic current value that is originally present in the electric power steering system. It is used to provide initial assistance as a control basis and is affected by vehicle speed, steering 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 base assist current. The base assist current always exists, but its proportion in the total assist current will change.

[0023] In this step, the closed-loop current upper limit, smoothing intervention threshold, and the vehicle's basic assist current obtained from the lookup module are used as input data. The smoothing module adjusts the current appropriately to ultimately derive the dynamic upper limit of the closed-loop current. This dynamic upper limit is adjusted based on input parameters (such as actual vehicle speed, actual steering angle, and basic assist current). Compared to the initial closed-loop current upper limit, this dynamic upper limit better reflects the requirement for smooth and reasonable transitions in current changes during actual vehicle operation. This allows subsequent current control to better match real-world driving scenarios during dynamic changes, avoiding sudden current changes that could affect driving experience and steering stability.

[0024] S130, acquire the vehicle's speed command and steering angle command, perform closed-loop control on the steering angle command, the speed command and the actual steering angle, and obtain the closed-loop output current; Among them, the speed command and steering angle command are issued by DAS. Closed-loop control is an automatic control process based on the feedback principle. It can continuously adjust the input according to the actual output of the system to achieve or approach the predetermined target value. The closed-loop output current is the current value obtained after calculation by the closed-loop control mechanism based on the difference between the actual state of the car (actual speed, actual steering angle and actual speed, etc.) and the target state (target steering angle and target speed, etc.). It is used to adjust the steering of the car by driving the motor and other components. The purpose is to make the actual operating state of the car as close as possible to the target set state.

[0025] Due to the variability of driving conditions, the driving status will be adjusted in real time. In this step, closed-loop control is performed on the target state and the actual state of the car. The actual state and the target state affect each other (for example, the target state obtained based on the actual situation will be used as the input for the next closed-loop control).

[0026] S140, the closed-loop output current is limited by the closed-loop current dynamic upper limit to obtain the closed-loop current of the driving assistance system; In this step, the closed-loop output current is limited by the dynamic upper limit of the closed-loop current obtained by the smoothing module.

[0027] S150, the motor is controlled to steer the vehicle by means of the closed-loop current and the basic assist current.

[0028] The motor in question is the motor for EPS (Electric Power Steering) system.

[0029] It's important to know that EPS (Electric Power Steering) is a steering system that uses an electric motor to provide auxiliary steering force; DAS usually refers to basic driver assistance systems, such as lane departure warning and forward collision warning. These functions mainly serve to remind and warn, and do not directly interfere with the driver's driving operations. EPS primarily focuses on the driver's steering input, providing appropriate steering assistance based on factors such as vehicle speed and steering angle to improve driving comfort and convenience. DAS, on the other hand, focuses on the vehicle's autonomous driving or driver assistance functions, such as lane keeping and adaptive cruise control. Their control objectives and logic differ. If the coupling between EPS and DAS is too strong, DAS intervention or adjustments may affect EPS, causing unnatural steering force changes for the driver and impacting driving safety. Conversely, the operating state of EPS may also interfere with the normal operation of DAS, making it difficult for DAS to accurately achieve its control objectives. The smoothing module, by receiving parameters such as the basic assist current, outputs a closed-loop current dynamic upper limit, which can limit the impact of the DAS's current on EPS. For example, when DAS needs to output a large current to adjust the vehicle's direction, the smoothing module's closed-loop current dynamic upper limit can prevent this current from excessively affecting the normal operation of EPS, avoiding sudden and undesirable changes in the steering assistance provided by EPS.

[0030] In this embodiment, the smoothing module effectively reduces the mutual interference between EPS and DAS by limiting the current. DAS only needs to issue speed and angle commands, and the EPS controller handles the limiting, thus decoupling the two and enabling them to work together better to provide a better driving experience and more reliable driver assistance functions for the vehicle. At the same time, the PI parameters (referring to the parameters in the PI controller, which is a commonly used feedback controller) work in conjunction with the host computer to make the control more direct and reduce the difficulty of debugging the host computer algorithm.

[0031] In one embodiment, reference Figure 5The 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 second one-dimensional table. Users can perform queries by inputting the turning angle and vehicle speed. Specifically, inputting the actual turning angle and actual vehicle speed into the first two-dimensional table allows querying the feedforward current; inputting the actual turning angle and actual vehicle speed into the second two-dimensional table allows querying the closed-loop current upper limit; inputting the actual turning angle and actual vehicle speed into the third two-dimensional table allows querying the smoothing intervention threshold; inputting the actual vehicle speed into the first one-dimensional table allows querying the safe speed range; and inputting the actual vehicle speed into the second one-dimensional table allows querying the safe turning angle range. Here, the turning angle and vehicle speed refer to the actual turning angle and actual vehicle speed of the vehicle. All lookup methods are piecewise linear interpolation lookups, and all tables can be calibrated separately.

[0032] In one embodiment, reference Figure 6 and Figure 7 S110, the step of using a smoothing module to obtain the dynamic upper limit of the closed-loop current based on the upper limit of the closed-loop current, the smoothing intervention threshold, and the basic assist current of the vehicle, includes: S111, Based on the upper limit of the closed-loop current and the smooth intervention threshold, a smoothing function is constructed. The smoothing function is a monotonically decreasing function in which the dynamic upper limit of the closed-loop current decreases smoothly with the base assist current. S112, obtain the basic assist current, and obtain the closed-loop current dynamic upper limit of the basic assist current based on the basic assist current and the smoothing function.

[0033] Specifically, such as Figure 6 As shown, the smoothing function (constructed by the smoothing module) is a monotonically decreasing function that smoothly decreases the dynamic upper limit of the closed-loop current of the driving assistance system as the base assist current decreases. The smoothing function is constructed as follows: Formula (1) I Dlimit = f(I A ) Among them, I A For the real-time target base current, I Dlimit This is the dynamic upper limit of the PI regulation of the current in the driver assistance system (dynamic upper limit of closed-loop current). Taking the simplest linear relationship, we have: Formula (2) I Dlimit = a·I A + b To make the function monotonically decreasing, let a = -(I Dmax / I Thr b = I Dmax Then we have: Formula (3) I Dlimit = -( I Dmax / IThr )·I A + I Dmax Among them, I Thr The power assist current threshold for steering wheel return-to-center intervention (the power assist current threshold for steering wheel return-to-center intervention refers to the specific value of the power assist current required to trigger the automatic steering wheel return-to-center function. When the power assist current reaches or exceeds this threshold, the system considers the steering action to be completed or the conditions for return-to-center to be met, thereby initiating the return-to-center control program and starting the steering wheel return-to-center operation), is derived from a lookup table module and can be calibrated; I Dmax This is the maximum value of the upper limit of the PI regulation of the driving assistance system current (maximum closed-loop current), which is obtained from the lookup table module and can be calibrated.

[0034] When I A <= I Thr At that time, the closed-loop current of the driving assistance system naturally intervenes, when I A >I Thr At this time, the closed-loop current of the driving assistance system will naturally exit; this ensures that the closed-loop return current and the assist current will naturally connect and transition, with one increasing and the other decreasing.

[0035] like Figure 7 As shown, based on the upper limit of the closed-loop current and the smoothing intervention threshold, the basic assist current is flowed through a constructed smoothing function to obtain the dynamic upper limit of the closed-loop current. The curve of the smoothing function must pass through two points: (T1, I1) (where I1 equals 0) and (T2, I2). T1 is the moment when the driver assistance system current begins to intervene; T2 is the moment when the basic assist is completely disengaged. I1 is the basic assist threshold when the driver assistance system current smoothly intervenes, and this threshold varies with the (actual) steering angle and (actual) vehicle speed. I2 is the maximum upper limit of the closed-loop adjustment current of the driver assistance system, and this limit varies with the (actual) steering angle and (actual) vehicle speed. The interval from 0 to T1 is the human driving zone. In this stage, the basic assist current mainly plays a role, and the current is relatively stable, providing basic assistance support for manual driving, such as in a car. In the power steering system, a certain amount of steering assistance is provided to the driver, making driving easier. The T1-T2 interval is the transition zone. During this stage, the base assist current begins to decrease, while the superimposed current in the transition zone gradually increases and superimposes on the base assist current. At this time, the system is transitioning from manual driving mode to autonomous driving mode. The current is adjusted to achieve a smooth transition and avoid sudden changes that could impact the system. For example, when autonomous driving intervenes, the motor current is gradually adjusted to achieve a smooth handover of steering, acceleration, and other operations. After T2 is the autonomous driving zone. In this stage, the closed-loop current of the driver assistance system reaches a relatively high and stable value I2. In autonomous driving mode, the current control of the system reaches a new stable state to meet the various needs of autonomous driving, such as precise steering control and speed control.

[0036] In one embodiment, reference Figure 3 and Figure 4 In step S130, the step of performing closed-loop control on the angle command, the speed command, and the actual angle to obtain the closed-loop output current includes: S131, the angle error is obtained based on the actual angle and the angle command, and the target rotation speed is obtained through the angle error; S132, obtain the actual rotational speed of the vehicle, obtain the rotational speed error based on the actual rotational speed and the target rotational speed, and obtain the closed-loop output current based on the rotational speed error.

[0037] like Figure 3 The diagram shows the input / output interface of the closed-loop control of the driver assistance system. The input signals include the host computer commands of the driver assistance system (enable, steering angle command, and speed command), the internal signals of the EPS controller (actual steering angle, actual speed, and basic assist current), and the vehicle signal (vehicle speed). The output is a smooth output current of the driver assistance system.

[0038] In one embodiment, reference Figure 3 and Figure 4 S131, the step of obtaining the angle error based on the actual angle and the angle command, and obtaining the target speed through the angle error, includes: S1311, using the lookup table module, the safe turning angle range is obtained based on the actual vehicle speed; specifically, refer to... Figure 5 The safe turning range is determined by looking up the vehicle speed in the second one-dimensional table.

[0039] S1312, The cornering command is subject to safety restrictions based on the cornering safety range; Among them, the safe turning angle range refers to the safe range of steering angles allowed by the steering system during vehicle operation. Limiting the safe turning angle range of the turning angle command can prevent the vehicle from oversteering, which could lead to dangerous situations such as loss of control.

[0040] S1313, calculate the difference between the actual rotation angle and the rotation angle command after the safety limit to obtain the rotation angle error, and obtain the target speed through the rotation angle error.

[0041] Figure 3 This is a schematic diagram of the closed-loop control input / output interface (vehicle speed is the actual vehicle speed, and steering angle is the actual steering angle). The input signal includes three parts: DAS host computer instructions, EPS controller internal signals, and vehicle signals. The output is a smooth DAS output current. The DAS host computer instructions include DAS enable instructions, steering angle instructions, and speed instructions; the EPS controller internal signals include actual steering angle, actual speed, and basic assist current; the vehicle signals include vehicle speed. Figure 4The closed-loop control block diagram (vehicle speed is the actual vehicle speed, steering angle is the actual steering angle, and speed is the actual speed) mainly includes a lookup table module, a smoothing module, an angle loop, a speed loop, an overshoot suppression module, and a limit module, ultimately outputting a smooth driving assistance system output current.

[0042] In one embodiment, reference Figure 4 The step of obtaining the target rotational speed through the rotational angle error is replaced by: The target rotational speed is obtained by inputting the rotational angle error into the angle loop.

[0043] The angle loop is primarily responsible for handling vehicle steering angle control. It calculates the steering angle error by acquiring the target and actual steering angles. Based on this error, the angle loop outputs corresponding control signals to adjust the vehicle's steering system, ensuring the actual steering angle quickly and accurately approaches the target angle. This achieves precise steering and ensures the vehicle travels along the intended path. For example, in autonomous driving scenarios, the vehicle needs to steer according to a planned route, and the angle loop ensures the actual steering angle matches the route planning requirements. During driving, the vehicle is subject to various interferences, such as uneven road surfaces and crosswinds, which may cause the actual steering angle to deviate from the expected value. The angle loop monitors and corrects these deviations in real time, maintaining a stable steering state even in complex driving environments and improving driving safety. For instance, when encountering crosswinds at high speeds, the angle loop automatically adjusts the steering system to keep the vehicle traveling in a straight line or steer along a predetermined curve.

[0044] In one embodiment, reference Figure 4 The step of obtaining the speed error based on the actual speed and the target speed, and obtaining the closed-loop output current based on the speed error, includes: S1321, Using the lookup module, the safe speed range is obtained based on the actual vehicle speed; Specifically, using the lookup table module, the safe speed range can be obtained by looking up the first one-dimensional table based on the actual vehicle speed.

[0045] S1322, The rotation speed command is subject to safety restrictions based on the specified rotation speed safety range; The safe range of engine speed refers to the safe range of steering wheel speed. When the vehicle speed is high, it is unsafe to rotate the steering wheel too fast.

[0046] S1323, the speed error is obtained based on the actual speed and the speed command after the safety limit, and the closed-loop output current is obtained through the speed error.

[0047] In one embodiment, reference Figure 4S1322, the step of limiting the speed command according to the speed safety range includes: S13221, Use the overshoot suppression module to limit the overshoot of the speed command after the safety limit; S13222, Limit the target speed according to the speed command after overshoot limitation; The step of obtaining the speed error based on the actual speed and the speed command after the safety limit, and then obtaining the closed-loop output current from the speed error, is replaced by: The difference between the actual rotational speed and the target rotational speed after limitation is calculated to obtain the rotational speed error, and the closed-loop output current is obtained through the rotational speed error.

[0048] The overshoot suppression module monitors the angle error in real time. The smaller the angle error, the lower its limit, in order to eliminate the jitter caused by frequent adjustments near the target angle.

[0049] In one embodiment, reference Figure 4 The step of obtaining the closed-loop output current based on the speed error is replaced by: The speed error is input into the speed loop to obtain the closed-loop output current.

[0050] The core task of the speed control loop is to precisely control the vehicle's speed. It takes the difference between the target speed and the actual speed (i.e., speed error) as input, performs a series of calculations and processing, and then outputs a control signal to adjust the engine or motor output, stabilizing the actual speed near the target speed. For example, during cruise control, the speed control loop automatically adjusts the engine speed based on changes in driving resistance (such as climbing or descending hills) to maintain a stable vehicle speed. The speed control loop can flexibly adjust the speed according to different vehicle operating conditions (such as starting, accelerating, and decelerating) to achieve optimal power output. During start-up, it controls the engine or motor to quickly increase speed to provide sufficient torque; while at high speeds, it maintains a suitable speed to balance power and fuel economy.

[0051] It's important to understand that the angle loop and speed loop are the foundation of driver assistance system control.

[0052] In one embodiment, reference Figure 4 In step S140, after limiting the closed-loop output current using the dynamic upper limit of the closed-loop current, the method further includes: S141, using the lookup module, the feedforward current is obtained based on the actual vehicle speed and the actual turning angle; Specifically, the feedforward current can be obtained by looking up the table using the lookup module based on the actual vehicle speed and actual turning angle in the first two-dimensional table.

[0053] The step of obtaining the closed-loop current of the driver assistance system is replaced by: The feedforward current is superimposed with the limited closed-loop output current to obtain the closed-loop current of the driving assistance system.

[0054] Feedforward current is a concept used in control systems, particularly in systems involving power and motion control such as driver assistance systems (DAS). It is a current signal calculated and applied in advance based on the system's input or known disturbances, building upon feedback control. Unlike feedback control, which primarily relies on the error signal at the system output for adjustment, feedforward control attempts to intervene in the system before errors occur.

[0055] In one embodiment, reference Figure 2 The step of controlling the motor to steer the vehicle via the closed-loop current and the basic assist current in S150 is replaced by: The compensation current is obtained, and the motor is controlled to steer the vehicle through the closed-loop current, the basic assist current, and the compensation current.

[0056] The compensation current includes current losses caused by damping, friction, and inertia, while the base assist current is derived from a table of torque values.

[0057] 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 assist current to obtain a smooth driving assistance system current, which is superimposed with the compensation current and the basic assist current as the input of the current loop (inner loop), and finally acts on the motor.

[0058] As an example, refer to Figure 4This is a closed-loop control block diagram for a driver assistance system, which includes a lookup table module, a smoothing module, an angle loop, a speed loop, a limit module, and an overshoot suppression module. First, the lookup table module obtains initial current limits and thresholds based on vehicle speed and steering angle. Then, the smoothing module further processes this information to obtain the dynamic upper limit of the closed-loop current. Simultaneously, the angle loop calculates and processes the steering angle error based on the steering angle command and the actual steering angle. After overshoot suppression, this error is passed to the speed loop. The speed loop combines this error with the speed command to output the closed-loop output current. Finally, the dynamic upper limit of the closed-loop current is added to the closed-loop current of the driver assistance system, and then processed by the flexible intervention / exit module to obtain the final output current. The DAS outputs current and applies it to the motor to control the vehicle's power steering. In this process, the target speed and target angle after being limited will be used as the target angle and target speed for 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 for the next closed-loop control. The processing of the angle loop and 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. The entire process, with the coordinated action of multiple modules, achieves precise control and safety limitation of the vehicle's current, ensuring stable operation and safe operation of the vehicle under various conditions.

[0059] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. An adaptive human-machine co-driving electric power steering control method, characterized in that, The electric power steering control method is used in automobiles, and the electric power steering control method includes: Using a lookup table module, the upper limit of closed-loop current and the smooth intervention threshold are obtained based on the actual vehicle speed and actual turning angle. Using a smoothing module, the dynamic upper limit of the closed-loop current is obtained based on the upper limit of the closed-loop current, the smoothing intervention threshold, and the basic assist current of the vehicle. The vehicle's speed command and steering angle command are obtained, and closed-loop control is performed on the steering angle command, the speed command, and the actual steering angle to obtain the closed-loop output current; The closed-loop output current is limited by the dynamic upper limit of the closed-loop current to obtain the closed-loop current of the driving assistance system. The motor is controlled to steer the vehicle by the closed-loop current and the basic assist current. The step of using a smoothing module to obtain the dynamic upper limit of the closed-loop current based on the upper limit of the closed-loop current, the smoothing intervention threshold, and the basic assist current of the vehicle includes: Based on the upper limit of the closed-loop current and the smooth intervention threshold, a smoothing function is constructed. The smoothing function is a monotonically decreasing function in which the dynamic upper limit of the closed-loop current decreases smoothly with the base assist current. Obtain the base assist current, and obtain the closed-loop current dynamic upper limit of the base assist current based on the base assist current and the smoothing function; The step of performing closed-loop control on the rotation angle command, the speed command, and the actual rotation angle to obtain the closed-loop output current includes: The angle error is obtained based on the actual angle and the angle command, and the target rotation speed is obtained through the angle error. The actual rotational speed of the vehicle is obtained, the rotational speed error is obtained based on the actual rotational speed and the target rotational speed, and the closed-loop output current is obtained based on the rotational speed error.

2. The adaptive human-machine co-driving electric power steering control method as described in claim 1, characterized in that, The step of obtaining the angle error based on the actual angle and the angle command, and obtaining the target rotational speed through the angle error, includes: Using the lookup module, the safe turning angle range is obtained based on the actual speed of the vehicle. The cornering command is subject to safety restrictions based on the defined cornering safety range; The difference between the actual rotation angle and the rotation angle command after the safety limit is calculated to obtain the rotation angle error, and the target rotation speed is obtained through the rotation angle error.

3. The adaptive human-machine co-driving electric power steering control method as described in claim 2, characterized in that, The step of obtaining the target rotational speed through the rotational angle error is replaced by: The target rotational speed is obtained by inputting the rotational angle error into the angle loop.

4. The adaptive co-piloting electric power steering control method of claim 1, wherein, The step of obtaining the speed error based on the actual speed and the target speed, and obtaining the closed-loop output current based on the speed error, includes: Using the lookup module, the safe speed range is obtained based on the actual vehicle speed. The rotation speed command is subject to safety restrictions based on the aforementioned safe rotation speed range; The speed error is obtained based on the actual speed and the speed command after the safety limit, and the closed-loop output current is obtained through the speed error.

5. The adaptive man-machine co-steering control method of electric power steering according to claim 4, wherein, The step of limiting the speed command according to the speed safety range includes: The overshoot suppression module is used to limit the overshoot of the speed command after the safety limit; The target speed is limited according to the speed command after overshoot limitation; The step of obtaining the speed error based on the actual speed and the speed command after the safety limit, and then obtaining the closed-loop output current from the speed error, is replaced by: The difference between the actual rotational speed and the target rotational speed after limitation is calculated to obtain the rotational speed error, and the closed-loop output current is obtained through the rotational speed error.

6. The adaptive human-machine co-driving electric power steering control method as described in claim 4, characterized in that, The step of obtaining the closed-loop output current based on the speed error is replaced by: The speed error is input into the speed loop to obtain the closed-loop output current.

7. The adaptive co-piloting electric power steering control method of claim 1, wherein, The step of limiting the closed-loop output current by the dynamic upper limit of the closed-loop current further includes: Using the lookup module, the feedforward current is obtained based on the actual vehicle speed and the actual turning angle; The step of obtaining the closed-loop current of the driver assistance system is replaced by: The feedforward current is superimposed with the limited closed-loop output current to obtain the closed-loop current of the driving assistance system.

8. The adaptive co-piloting electric power steering control method of claim 1, wherein, The step of controlling the motor to steer the vehicle using the closed-loop current and the basic assist current is replaced by: The compensation current is obtained, and the motor is controlled to steer the vehicle through the closed-loop current, the basic assist current, and the compensation current.

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