Vehicle steering wheel control method, device, equipment and medium

Abstract

The invention discloses a vehicle steering wheel control method, device and equipment and a medium, and the method comprises the steps that when a driver loosens a vehicle steering wheel, initial parameters of a steering wheel assembly of a vehicle are obtained; constructing a self-adaptive integral nonsingular terminal sliding mode surface of the steering wheel assembly based on the initial steering wheel angle; updating the initial external disturbance torque based on the adaptive integral nonsingular terminal sliding mode surface and the initial parameters to obtain a transition external disturbance torque and a transition input torque; the initial steering wheel rotation angle is updated through the transition external disturbance torque, the transition input torque and the initial parameters, and a transition steering wheel rotation angle is obtained; and the transition external disturbance torque and the transition input torque are updated based on the transition steering wheel rotation angle until the obtained target transition steering wheel rotation angle is smaller than a preset value, and steering wheel control is completed. The problems that in the prior art, a single steering wheel return mode cannot meet return control requirements in different working conditions, and the return accuracy of a steering wheel is low are solved.

Description

Background Art

[0002] In the field of modern automobiles, the electric power steering system (EPS) is highly favored due to its excellent advantages. It has higher energy efficiency, significantly reduces energy consumption, and has an extremely fast response speed, being able to quickly feedback on driving operations. Among them, good steering return performance is particularly crucial, which can enable the vehicle to quickly return to a straight line after turning, greatly improving the stability of the vehicle during steering and creating a more comfortable driving experience for the driver.

[0003] However, in the prior art, the method of controlling the steering wheel return of the vehicle is relatively single, unable to meet the return control requirements in different working conditions, resulting in a relatively low return accuracy of the steering wheel. Summary of the Invention

[0004] In order to overcome the problem that the single steering wheel return method in the prior art cannot meet the return control requirements in different working conditions, resulting in a relatively low return accuracy of the steering wheel, this application provides a vehicle steering wheel control method, device, equipment and medium.

[0005] In the first aspect, to solve the above technical problems, this application provides a vehicle steering wheel control method, including:

[0006] In response to the instruction from the driver to release the vehicle steering wheel, obtain the initial parameters of the vehicle's steering wheel assembly, where the initial parameters include the initial steering wheel angle, moment of inertia, damping coefficient, and initial external disturbance torque;

[0007] Based on the initial steering wheel angle, construct an adaptive integral non-singular terminal sliding mode surface of the steering wheel assembly;

[0008] Based on the adaptive integral non-singular terminal sliding mode surface and the initial parameters, perform an update operation on the initial external disturbance torque to obtain the transitional external disturbance torque and transitional input torque of the steering wheel assembly;

[0009] Use the transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient to update the initial steering wheel angle to obtain the transitional steering wheel angle of the steering wheel assembly;

[0010] Based on the transitional steering wheel angle, update the transitional external disturbance torque and transitional input torque until the obtained target transitional steering wheel angle is less than the preset value, so as to perform return control on the vehicle steering wheel.

[0011] In the second aspect, this application also provides a vehicle steering wheel control device, including:

[0012] An acquisition module, configured to obtain the initial parameters of the vehicle's steering wheel assembly in response to the instruction from the driver to release the vehicle steering wheel, where the initial parameters include the initial steering wheel angle, moment of inertia, damping coefficient, and initial external disturbance torque;

[0013] A building block for constructing an adaptive integral nonsingular terminal sliding mode surface of a steering wheel assembly based on an initial steering wheel angle.

[0014] A first update module for updating an initial external disturbance torque based on the adaptive integral nonsingular terminal sliding mode surface and initial parameters to obtain a transitional external disturbance torque and a transitional input torque of the steering wheel assembly.

[0015] A second update module for updating the initial steering wheel angle by using the transitional external disturbance torque, the transitional input torque, the moment of inertia, and the damping coefficient to obtain a transitional steering wheel angle of the steering wheel assembly.

[0016] An angle determination module for updating the transitional external disturbance torque and the transitional input torque based on the transitional steering wheel angle until the obtained target transitional steering wheel angle is less than a preset value to perform a return-to-center control on the vehicle steering wheel.

[0017] In a third aspect, the present application further provides a computing device, including a memory, a processor, and a program stored on the memory and running on the processor. When the processor executes the program, the steps of a vehicle steering wheel control method as described above are implemented.

[0018] In a fourth aspect, the present application further provides a computer-readable storage medium. Instructions are stored in the computer-readable storage medium. When the instructions run on a terminal device, the terminal device is caused to execute the steps of a vehicle steering wheel control method.

[0019] The beneficial effects of the present application are as follows: First, by responding to the instruction issued by the driver to release the vehicle steering wheel, the initial parameters of the steering wheel assembly of the vehicle are obtained, including the initial steering wheel angle, moment of inertia, damping coefficient, and initial external disturbance torque, and an adaptive integral nonsingular terminal sliding mode surface of the steering wheel assembly is constructed based on the initial steering wheel angle. Second, since the adaptive integral nonsingular terminal sliding mode surface can effectively reduce the system steady-state error of the steering wheel assembly, the initial external disturbance torque is updated based on the adaptive integral nonsingular terminal sliding mode surface and the initial parameters to reduce the influence of the system steady-state error on the external disturbance torque and the input torque, and improve the accuracy of the updated transitional external disturbance torque and transitional input torque of the steering wheel assembly. Then, the initial steering wheel angle is updated using the transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient to obtain the transitional steering wheel angle of the steering wheel assembly, so as to control the vehicle steering wheel to rotate to the angle of the transitional steering wheel angle, and the transitional external disturbance torque and transitional input torque are updated based on the transitional steering wheel angle until the obtained target transitional steering wheel angle is less than the preset value, and the return control of the vehicle steering wheel is completed this time. In this way, by gradually updating the external disturbance torque and input torque during the process of controlling the vehicle steering wheel to perform the return control, the steering wheel angle is gradually adjusted, so that the rotation strategy of the vehicle steering wheel can flexibly respond to external disturbances in various working conditions, thereby meeting the return control requirements of different working conditions and improving the return accuracy of the vehicle steering wheel. Description of the Drawings

[0020] Figure 1 It is a schematic flowchart of a vehicle steering wheel control method shown in an exemplary embodiment of the present application;

[0021] Figure 2 It is a schematic structural diagram of a vehicle steering wheel control device shown in an exemplary embodiment of the present application. Detailed Embodiments

[0022] The following embodiments are further explanations and supplements to the present application and do not constitute any limitation to the present application.

[0023] In the prior art, the return control of the steering wheel of a steer-by-wire vehicle mainly adopts traditional methods such as PID (Proportional-Integral-Derivative Controller) control and sliding mode control. These methods can achieve the return control of the steering wheel to a certain extent, but in complex working conditions, such as low-speed and high-speed driving, road surface unevenness, etc., there are problems such as unsatisfactory return performance and overshoot of the steering wheel angle, and cannot meet the higher requirements of drivers for the accuracy and safety of vehicle control.

[0024] The unsatisfactory return performance is reflected in the following aspects: when driving at low speeds, the tires are in full contact with the ground, resulting in high friction, which leads to insufficient return of the steering wheel, affecting the vehicle's straight-line driving stability. The steering wheel angle overshoot is reflected in the following aspects: when driving at high speeds, uneven road surfaces will increase lateral acceleration, and existing control methods are difficult to quickly and accurately adjust the steering wheel return torque, which is prone to overshoot, causing discomfort to the driver and even affecting the vehicle's handling. The low accuracy of control is reflected in the following aspects: the existing control methods have large errors in tracking the steering wheel return process, and cannot achieve precise control, making it difficult to meet the vehicle's steering wheel return requirements under different working conditions.

[0025] For the uncertain factors in the system, such as changes in tire parameters and road conditions, the existing control methods have poor adaptability, which can easily lead to a decrease in control effect.

[0026] In order to solve the above problems, the embodiments of the present application provide a vehicle steering wheel control method, device, equipment and medium, and these embodiments will be described in detail below.

[0027] In this application, all actions related to the acquisition of signals, information or data are carried out in strict compliance with the relevant data protection laws and policies of the country where they are located, and with the authorization of the owner of the corresponding device.

[0028] Owner refers to the person or entity that owns or controls the relevant device (which may be a device, system or other tool that can collect data).

[0029] In the field of intelligent connected vehicles, “owners” mainly include:

[0030] (1) Automobile manufacturers: As vehicle hardware and system developers, they control the underlying hardware and software platforms of the vehicle and have the right to manage and control the data generated by vehicle operation, such as driving and fault data.

[0031] (2) Parts suppliers: They provide key components for automobiles and have certain ownership of the data collected and processed by the components, which is used for product optimization and after-sales service, such as data generated by sensors and chips.

[0032] (3) Vehicle owner or user: The actual user of the vehicle, who has the right to decide how and to what extent vehicle data is used, such as whether to share data such as driving trajectory and driving habits, and has the need and right to protect the privacy of his or her own relevant data.

[0033] (4) Service providers: provide software, data analysis and other services, and have the right to use and manage the acquired and processed data under the framework of the agreement, but the ownership usually belongs to other entities.

[0034] A vehicle steering wheel control method provided by an embodiment of the present application can be specifically executed by a server. It should be noted that the server can be an independent server or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, Content Delivery Network (CDN), and big data and artificial intelligence platforms. There is no limitation here.

[0035] Please refer to Figure 1 , Figure 1 which shows a vehicle steering wheel control method according to an exemplary embodiment of the present application. As Figure 1 shown, the present application provides a vehicle steering wheel control method, including:

[0036] Step S11, in response to an instruction from the driver to release the vehicle steering wheel, obtain the initial parameters of the steering wheel assembly of the vehicle. The initial parameters include the initial steering wheel angle, moment of inertia, damping coefficient, and initial external disturbance torque;

[0037] Step S12, construct an adaptive integral nonsingular terminal sliding mode surface of the steering wheel assembly based on the initial steering wheel angle;

[0038] Step S13, perform an update operation on the initial external disturbance torque based on the adaptive integral nonsingular terminal sliding mode surface and the initial parameters to obtain the transitional external disturbance torque and transitional input torque of the steering wheel assembly;

[0039] Step S14, update the initial steering wheel angle using the transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient to obtain the transitional steering wheel angle of the steering wheel assembly;

[0040] Step S15, update the transitional external disturbance torque and transitional input torque based on the transitional steering wheel angle until the obtained target transitional steering wheel angle is less than a preset value to perform a return control on the vehicle steering wheel.

[0041] A vehicle steering wheel control method according to an embodiment provided by this application. First, by responding to an instruction from the driver to release the vehicle steering wheel, initial parameters of the steering wheel assembly of the vehicle are obtained, including the initial steering wheel angle, moment of inertia, damping coefficient, and initial external disturbance torque, and an adaptive integral nonsingular terminal sliding mode surface of the steering wheel assembly is constructed based on the initial steering wheel angle. Secondly, since the adaptive integral nonsingular terminal sliding mode surface can effectively reduce the system steady-state error of the steering wheel assembly, the initial external disturbance torque is updated based on the adaptive integral nonsingular terminal sliding mode surface and the initial parameters to reduce the influence of the system steady-state error on the external disturbance torque and the input torque, and improve the accuracy of the updated transitional external disturbance torque and transitional input torque of the steering wheel assembly. Then, the initial steering wheel angle is updated using the transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient to obtain the transitional steering wheel angle of the steering wheel assembly, so as to control the vehicle steering wheel to rotate to the angle of the transitional steering wheel angle, and the transitional external disturbance torque and transitional input torque are updated based on the transitional steering wheel angle until the obtained target transitional steering wheel angle is less than a preset value, and the vehicle steering wheel return-to-center control for this time is completed. In this way, by gradually updating the external disturbance torque and input torque during the process of controlling the vehicle steering wheel to return to center, the angle of the steering wheel is gradually adjusted, so that the rotation strategy of the vehicle steering wheel can flexibly respond to external disturbances in various working conditions, thereby meeting the return-to-center control requirements of different working conditions and improving the return-to-center accuracy of the vehicle steering wheel. Among them, the preset value is 0.5°. When the target transitional steering wheel angle is less than 0.5°, the degree of the steering wheel returning to center has been able to complete the vehicle return. By setting the return-to-center target as an angle range, the inclusiveness of the vehicle steering wheel for return-to-center control can be improved, thereby improving the return performance of the vehicle.

[0042] Optionally, constructing the adaptive integral nonsingular terminal sliding mode surface of the steering wheel assembly based on the initial steering wheel angle includes:

[0043] Obtain the desired steering wheel angle of the steering wheel;

[0044] Using the desired steering wheel angle and the initial steering wheel angle, calculate the state error value of the vehicle steering wheel;

[0045] Input the state error value into a preset initial sliding mode surface for processing to obtain the adaptive integral nonsingular terminal sliding mode surface of the steering wheel assembly.

[0046] In this embodiment provided by the present application, by performing error replacement processing on the state error value between the expected steering wheel angle of the steering wheel and the initial steering wheel angle when the driver releases the steering wheel of the vehicle in a preset initial sliding mode surface, the obtained adaptive integral non-singular terminal sliding mode surface can meet the basic control requirements of the current working condition, facilitating improving the pertinence of the update when subsequently using the adaptive integral non-singular terminal sliding mode surface to update the initial external disturbance torque, so that the update operation can be highly matched with the current working condition, thereby improving the accuracy of the steering wheel return control. Among them, the expected steering wheel angle is the steering angle at which the steering wheel completes the return control.

[0047] In an exemplary embodiment provided by the present application, the adaptive integral non-singular terminal sliding mode surface s is expressed as:

[0048]

[0049] e = x 1d -x 1

[0050] Among them, e represents the state error value, and λ, p, q, and β all represent sliding mode surface parameters. Both p and q are positive odd numbers and satisfy represents the integral of e from 0 to t, and x 1d represents the expected steering wheel angle, usually the steering angle at the center position of the steering wheel, that is, x 1d = 0, and x 1 represents the initial steering wheel angle;

[0051] Optionally, based on the adaptive integral non-singular terminal sliding mode surface and the initial parameters, an update operation is performed on the initial external disturbance torque to obtain the transitional external disturbance torque and the transitional input torque of the steering wheel assembly, including:

[0052] Using the adaptive integral non-singular terminal sliding mode surface to adaptively update the initial external disturbance torque to obtain the transitional external disturbance torque of the steering wheel assembly;

[0053] Using the adaptive integral non-singular terminal sliding mode surface, the initial steering wheel angle, the moment of inertia, the damping coefficient, and the transitional external disturbance torque, calculate the transitional input torque of the steering wheel assembly.

[0054] In this embodiment provided by the present application, an adaptive integral nonsingular terminal sliding mode surface is used to adaptively update the initial external disturbance torque, so as to improve the matching degree between the updated transitional external disturbance torque and the return-to-center control under the current working condition. And the adaptive integral nonsingular terminal sliding mode surface, the initial steering wheel angle, the moment of inertia, and the damping coefficient are used to perform a secondary update on the transitional external disturbance torque, and the transitional input torque of the steering wheel assembly is calculated, so that the updated transitional input torque matches the return-to-center control under the current working condition, thereby improving the accuracy of the subsequent return-to-center control of the steering wheel. At the same time, the adaptive integral nonsingular terminal sliding mode surface can ensure that the system state of the steering wheel assembly converges within a finite time, and the integral term in the adaptive integral nonsingular terminal sliding mode surface can realize the self-adaptation of estimating and compensating external disturbances, thereby eliminating the steady-state error in the obtained transitional external disturbance torque and transitional input torque.

[0055] In an exemplary embodiment provided by the present application, the transitional input torque of the steering wheel assembly is calculated by using the adaptive integral nonsingular terminal sliding mode surface, the initial steering wheel angle, the moment of inertia, the damping coefficient, and the transitional external disturbance torque, so that the adaptive integral nonsingular terminal sliding mode surface s satisfies Improve the matching degree between the adaptive integral nonsingular terminal sliding mode surface and the steering wheel assembly and the current working condition. Then the calculation formula of the transitional input torque is as follows:

[0056]

[0057] Where, T cmd represents the transitional input torque, J sw represents the moment of inertia, B sw represents the damping coefficient, θ sw represents the initial steering wheel angle, F fric (x 2 ) represents the friction torque related to the rotational speed corresponding to the initial steering wheel angle, k represents the switching gain, and k>0, T dist represents the transitional external disturbance torque, e represents the state error value, and λ, p, q, β all represent sliding mode surface parameters, p and q are both positive odd numbers, and satisfy

[0058] Optionally, using the adaptive integral nonsingular terminal sliding mode surface to adaptively update the initial external disturbance torque to obtain the transitional external disturbance torque of the steering wheel assembly includes:

[0059] Using a preset update period and the adaptive integral nonsingular terminal sliding mode surface to construct an external disturbance torque adaptive model;

[0060] The initial external disturbance torque is input into the external disturbance torque adaptive model for processing to obtain the transitional external disturbance torque of the steering wheel assembly.

[0061] In this embodiment provided by the present application, an external disturbance torque adaptive model is constructed by using a preset update period and an adaptive integral nonsingular terminal sliding mode surface, so that the adaptive matching degree of the external disturbance torque adaptive model with the return-to-center control under the current working condition meets the requirements. When obtaining the initial external disturbance torque of the steering wheel assembly, it can be directly input into the external disturbance torque adaptive model to obtain the transitional external disturbance torque, realizing the adaptive update of the external disturbance torque, thereby improving the update efficiency of the external disturbance torque, and further improving the control efficiency of the subsequent return-to-center control of the vehicle steering wheel based on the external disturbance torque.

[0062] In an exemplary embodiment provided by the present application, the construction process of the external disturbance torque adaptive model is as follows:

[0063] Assume that the external disturbance torque T dist is bounded, that is, |T dist | ≤ T max , then consider that the Lyapunov function V satisfies to perform adaptive restriction on the external disturbance torque adaptive model. The Lyapunov function is expressed as: where γ > 0 represents the adaptive gain, represents the disturbance estimation value, and s represents the adaptive integral nonsingular terminal sliding mode surface.

[0064] Therefore, to make define the external disturbance torque adaptive law as: Then use the Euler method to discretize and update the disturbance estimation value according to the external disturbance torque adaptive law to obtain the external disturbance torque adaptive model. The external disturbance torque adaptive model is expressed as: where Δt represents the update period.

[0065] Optionally, the initial steering wheel angle is updated by using the transitional external disturbance torque, the transitional input torque, the moment of inertia, and the damping coefficient to obtain the transitional steering wheel angle of the steering wheel assembly, including:

[0066] Calculate the first derivative of the initial steering wheel angle with respect to time;

[0067] Obtain the frictional torque of the steering wheel assembly corresponding to the first derivative;

[0068] Based on the first derivative, the frictional torque, the transitional external disturbance torque, the transitional input torque, the moment of inertia, and the damping coefficient, update to obtain the transitional steering wheel angle of the steering wheel assembly.

[0069] In this embodiment provided by the present application, by calculating the first derivative of the initial steering wheel angle with respect to time, obtaining the frictional torque of the steering wheel assembly corresponding to the first derivative, and based on the first derivative, frictional torque, transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient, the transitional steering wheel angle of the steering wheel assembly is updated so that the steering wheel returns to the transitional steering wheel angle. In this way, when updating the steering wheel angle, the frictional torque of the steering wheel assembly is considered, so that the influence brought by the return friction can be reduced during the return control of the steering wheel, thereby improving the accuracy of the return control of the steering wheel.

[0070] Optionally, updating the transitional steering wheel angle of the steering wheel assembly based on the first derivative, frictional torque, transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient includes:

[0071] Based on the first derivative, frictional torque, transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient, a dynamic model of the steering wheel assembly is constructed;

[0072] The dynamic model is converted into a state-space form to obtain a target model;

[0073] Based on the target model, the transitional steering wheel angle of the steering wheel assembly is calculated.

[0074] In this embodiment provided by the present application, the dynamic model of the steering wheel assembly constructed based on the first derivative, frictional torque, transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient is converted into a state-space form to form a target model that can match the return control state of the current working condition, and based on the matched target model, the transitional steering wheel angle of the steering wheel assembly is directly calculated, improving the matching degree of the steering wheel angle with the current working condition, thereby improving the control accuracy during the return control of the steering wheel.

[0075] In an exemplary embodiment provided by the present application, when constructing the dynamic model of the steering wheel assembly, the influences of factors such as inertia, damping, and friction on steering and return are fully considered. The inertia factor determines the resistance of the moment of inertia generated by the mass distribution of the steering wheel during rotation to the change of the motion state; the damping factor reflects the effect of the resistance to motion generated by the steering wheel assembly system during motion due to viscosity and other effects; the friction factor describes the influence of the frictional force between the components of the steering wheel and with the outside world on the return process.

[0076] The constructed dynamic model of the steering wheel assembly is expressed as:

[0077]

[0078] Among them, J sw represents the moment of inertia, represents the first derivative The first derivative with respect to time, also represents the initial steering wheel angle θ sw The second derivative with respect to time, represents the initial steering wheel angle θ sw The first derivative with respect to time, represents the initial steering wheel angle θ sw The corresponding friction torque related to the rotational speed, B sw represents the damping coefficient, T cmd represents the transitional input torque, T dist represents the transitional external disturbance torque.

[0079] To facilitate the subsequent return-to-center control design, the dynamic model is converted into the state-space form. Let x 1 = θ sw , Then there is: The target model is obtained:

[0080]

[0081] Then, using the target model, and the relationship between the first derivative x 1 and the second derivative x 2 : Based on the first derivative, friction torque, transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient at each update, update the system states x 1 and x 2 , to obtain the transitional steering wheel angle of the updated steering wheel assembly.

[0082] Optionally, based on the first derivative, friction torque, transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient, the transitional steering wheel angle of the steering wheel assembly is updated, including:

[0083] Using the preset Euler method, a discretized model at the current time is constructed based on the first derivative, friction torque, transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient;

[0084] Based on the discretized model, the transitional steering wheel angle of the steering wheel assembly in the next update cycle is calculated.

[0085] In this embodiment provided by the present application, a discretization model at the current time is constructed by using the preset Euler method based on the first derivative, frictional torque, transitional external disturbance torque, transitional input torque, moment of inertia, and damping coefficient, and the transitional steering wheel angle of the steering wheel assembly in the next update cycle is calculated based on the discretization model. In this way, by using the Euler method with a relatively small amount of calculation to calculate the transitional steering wheel angle of the steering wheel assembly, the amount of calculation in the steering wheel return control process can be reduced, thereby improving the return control efficiency of the vehicle steering wheel.

[0086] In an exemplary embodiment provided by the present application, the discretization model at the current time constructed by using the Euler method is expressed as:

[0087]

[0088] Among them, the system state x 1 (t + Δt) represents the transitional steering wheel angle in the next update cycle, Δt represents the update cycle, and the system state x 1 (t) represents the initial steering wheel angle in the current update cycle, and the system state x 2 (t) represents the first derivative of the transitional steering wheel angle with respect to time in the current update cycle, and the system state x 2 (t + Δt) represents the first derivative of the transitional steering wheel angle with respect to time in the next update cycle, J sw represents the moment of inertia, F fric (x 2 (t)) represents the frictional torque related to the rotational speed corresponding to the initial steering wheel angle x 1 (t) in the current update cycle, B sw represents the damping coefficient, T cmd (t) represents the transitional input torque in the current update cycle, and T dist (t) represents the transitional external disturbance torque in the current update cycle.

[0089] In an exemplary embodiment provided by the present application, for the hardware-in-the-loop simulation test verification of the vehicle steering wheel control method, it is necessary to perform working condition setting and simulation environment setting.

[0090] First, perform the working condition setting:

[0091] Low-speed working condition: Referring to the steering return performance test of GB-T6323-2014, in Carsim (vehicle dynamics simulation software), set the vehicle to first perform uniform acceleration. When the speed reaches 50 km / h, perform a circular motion with a radius of 15 m. When the lateral acceleration increases to 0.4 g, wait for three seconds and then release the steering wheel.

[0092] High-speed condition: Increase the vehicle speed to 70 km / h. When the lateral acceleration is greater than 0.2 g, maintain the lateral acceleration for three seconds and then release the hand.

[0093] Secondly, set up the simulation environment:

[0094] Software and model: Use Carsim and Simulink (a modeling and analysis tool in MATLAB (scientific computing software)) for co-simulation. Build a complete model of the steer-by-wire system of the vehicle in Simulink, including models such as the steering wheel assembly, steering actuator assembly, and road feel motor, and implant the adaptive integral nonsingular terminal sliding mode control algorithm into it, that is, introduce the adaptive integral nonsingular terminal sliding mode surface into the steering wheel return control.

[0095] Simulation conditions: Conduct the simulation in the MATLAB / Simulink environment. Set parameters such as the initial driving speed and initial steering wheel angle of the vehicle to simulate different driving conditions. At the same time, add external disturbances of different intensities and forms, such as pulse disturbances and sine disturbances, to test the anti-interference ability of the steering wheel return control strategy.

[0096] Build the simulation equipment: The hardware-in-the-loop simulation equipment consists of a complete set of equipment including a steering wheel assembly, an analog data acquisition card, and a real-time machine. Among them, the steering wheel assembly consists of a steering wheel, a coupling, a reducer, a permanent magnet synchronous motor, and an angle sensor, which can truly simulate the mechanical structure and working characteristics of the vehicle steering system and accurately obtain information such as the angle and angular velocity of the steering wheel. The analog data acquisition card is used to collect the driver's operation signals, such as the steering wheel angle and throttle pedal signal, etc., and convert these signals into digital signals and transmit them to the real-time machine. The real-time machine is used to carry the co-simulation software of Carsim and Simulink and the adaptive integral nonsingular terminal sliding mode surface, which can receive the signals transmitted by the analog data acquisition card in real time, perform simulation calculations on the vehicle system, and feedback the calculation results to the steering wheel assembly in real time to achieve hardware-in-the-loop simulation verification. In this way, the hardware-in-the-loop simulation verification equipment can truly simulate the vehicle's working conditions during actual driving, including driver operation, vehicle dynamics characteristics, road conditions, etc., providing a reliable experimental basis for the development and optimization of the control strategy.

[0097] Then, perform vehicle data interaction in the simulation environment.

[0098] Data acquisition: The driver operates the steering wheel and throttle pedal to generate operation signals such as the steering wheel angle, angular velocity, and throttle pedal opening. These signals are collected by the analog data acquisition card, preprocessed, and then transmitted to the real-time machine.

[0099] Data transmission: The real-time machine receives the operation signals transmitted by the analog data acquisition card; starts the co-simulation of Carsim and Simulink, that is, calculates the real-time state information of the vehicle, such as steering wheel angle, wheel angle, vehicle speed, lateral acceleration, etc. according to the complete model of the steer-by-wire system of the vehicle and the control algorithm of the adaptive integral nonsingular terminal sliding mode surface built in Simulink, and transmits this information to the steering wheel assembly through the data transmission interface.

[0100] Result feedback: The steering wheel assembly receives the vehicle state information transmitted by the real-time machine, and converts the vehicle state information into mechanical motion and force feedback through components such as the steering wheel, coupling, and reducer; the driver obtains real-time road feeling information by feeling the resistance of the steering wheel and the driving state of the vehicle. At the same time, the steering wheel assembly also feeds back some key state information, such as steering wheel angle, angular velocity, etc. to the real-time machine, so that the real-time machine can adjust and optimize the steering wheel return control strategy.

[0101] Finally, verify the steering wheel return performance, system stability, and simulation accuracy. The steering wheel return performance includes return time, overshoot, working condition adaptability, and anti-interference ability.

[0102] Comparison of return time: Comparative experiments are carried out on three control strategies of PID control, sliding mode control, and adaptive integral nonsingular terminal sliding mode surface control strategy under low-speed and high-speed working conditions respectively. The experimental results show that the steering wheel angle return under the adaptive integral nonsingular terminal sliding mode surface control strategy has a more stable control effect. Under low-speed working conditions, the steering wheel can quickly and smoothly return to the middle position without the tendency of the steering wheel to turn in the opposite direction; under high-speed working conditions, the steering wheel angle return time is significantly shortened, and it can reach the return angle in only 3.5 s, while the steering wheel reaches the return angle after 6 s under PID control, and the steering wheel angle reaches the return angle at 3.7 s under the sliding mode controller. Therefore, compared with PID control and sliding mode control, the adaptive integral nonsingular terminal sliding mode surface control strategy has a faster response speed after the steering wheel is released, can realize the return of the vehicle steering wheel in a shorter time, and improves the driving efficiency and controllability of the vehicle. At the same time, the nonsingular terminal sliding mode control strategy can achieve precise control of the steering wheel return process, and can make the steering wheel quickly and stably return to the center position under various working conditions, effectively solving the problems of insufficient return performance and return overshoot existing in the existing control methods during low-speed and high-speed driving. In addition, through the verification of the adaptive integral nonsingular terminal sliding mode surface control strategy in the hardware-in-the-loop simulation, the problems and deficiencies existing in this control strategy can be quickly discovered, and adjusted and optimized in time, improving the reliability and effectiveness of the adaptive integral nonsingular terminal sliding mode surface control strategy.

[0103] Overshoot analysis: By analyzing the variation curve of the steering wheel angle during the return process, it is found that the adaptive integral nonsingular terminal sliding mode surface control strategy can effectively reduce the overshoot of the steering wheel angle, reduce the risk of vehicle out of control caused by the steering wheel return problem, make the steering wheel return process smoother, and ensure driving safety. At the same time, it improves the stability of the vehicle during driving, reduces the risk of vehicle out of control caused by the steering wheel return problem, and ensures driving safety.

[0104] System stability includes working condition adaptability and anti-interference ability.

[0105] Working condition adaptability: The adaptive integral nonsingular terminal sliding mode surface control strategy is tested under different road conditions and vehicle speeds. The results show that this strategy can adapt to various complex working conditions and maintain the stability of the system.

[0106] Anti-interference ability: In the simulation experiment, some interference factors such as random noise and road surface mutation are introduced to test the system. The results show that the nonsingular terminal sliding mode control strategy has strong anti-interference ability, can effectively suppress the influence of interference on the system, and ensure the stable operation of the system.

[0107] Simulation accuracy includes comparison with theoretical values and verification with actual vehicles.

[0108] Comparison with theoretical values: The hardware-in-the-loop simulation results are compared with the theoretical calculated values, and it is found that the two are basically in agreement, which proves the accuracy of the simulation model and the effectiveness of the control strategy.

[0109] Verification with actual vehicles: In order to further verify the accuracy of the simulation results, the actual vehicle is tested. The test results are basically consistent with the simulation results, which further proves the feasibility and reliability of the patented technology.

[0110] In summary, in this application, first, the nonsingular terminal sliding mode control strategy is adopted to solve the singularity problem of the terminal sliding mode control, achieve the precise convergence of the system state in finite time, improve the control accuracy and response speed, enable the steering wheel to quickly and stably return to the center position after the driver releases the hand, and at the same time ensure the stable driving direction of the vehicle, improving driving safety and comfort. Compared with the traditional PID control and sliding mode control, the nonsingular terminal sliding mode control can better adapt to the nonlinear characteristics and uncertain factors of the steer-by-wire system, and has stronger robustness. At the same time, when designing the control strategy, the influence of factors such as inertia, damping, and friction on the steering wheel return is comprehensively considered, and a more perfect steering wheel return torque model is established. Through the precise control of these factors, the optimization of the steering wheel return process is realized, and the handling performance of the vehicle is improved.

[0111] Secondly, a complete hardware-in-the-loop simulation device was built, which realized the real-time acquisition of driver operation signals and the real-time feedback of vehicle state information, providing a more realistic experimental environment for the verification of control strategies. Compared with traditional pure software simulation, hardware-in-the-loop simulation can more accurately reflect the performance and characteristics of the vehicle during actual driving, improving the reliability of verification results.

[0112] Then, by optimizing the data acquisition, transmission, and processing processes, the efficiency and accuracy of hardware-in-the-loop simulation were improved. High-speed data acquisition cards and real-time operating systems were used to ensure the real-time and accurate data; by optimizing the data transmission protocol and algorithms, data transmission delays and errors were reduced; advanced data analysis and processing technologies were adopted to deeply analyze and mine the simulation data, providing strong support for the optimization of control strategies.

[0113] In the vehicle steering wheel control method according to an exemplary embodiment provided by this application, in terms of control algorithms, an adaptive control algorithm can be considered to replace the nonsingular terminal sliding mode control algorithm. The adaptive control algorithm can automatically adjust control parameters according to the real-time operating state and environmental changes of the vehicle to meet the requirements of different working conditions, further optimizing the steering wheel return performance. In terms of hardware-in-the-loop simulation, other data acquisition software can be explored to replace LabVIEW, or the simulation software combination in the real-time machine can be replaced, such as using the combination of other vehicle dynamics simulation software and control algorithm development software, to seek a more efficient and accurate simulation verification scheme.

[0114] Please refer to Figure 2 , Figure 2 which shows a vehicle steering wheel control device according to an exemplary embodiment of this application. As Figure 2 shown, this application provides a vehicle steering wheel control device 200, including:

[0115] An acquisition module 201, configured to obtain the initial parameters of the steering wheel assembly of the vehicle in response to an instruction from the driver to release the vehicle steering wheel, where the initial parameters include the initial steering wheel angle, moment of inertia, damping coefficient, and initial external disturbance torque;

[0116] A construction module 202, configured to construct an adaptive integral nonsingular terminal sliding mode surface of the steering wheel assembly based on the initial steering wheel angle;

[0117] A first update module 203, configured to perform an update operation on the initial external disturbance torque based on the adaptive integral nonsingular terminal sliding mode surface and the initial parameters to obtain the transitional external disturbance torque and transitional input torque of the steering wheel assembly;

[0118] A second update module 204, configured to update an initial steering wheel angle by using a transitional external disturbance torque, a transitional input torque, a moment of inertia, and a damping coefficient, so as to obtain a transitional steering wheel angle of the steering wheel assembly;

[0119] An angle determination module 205, configured to update the transitional external disturbance torque and the transitional input torque based on the transitional steering wheel angle until a obtained target transitional steering wheel angle is less than a preset value, so as to perform a return control on the vehicle steering wheel.

[0120] A vehicle steering wheel control device 200 according to this embodiment provided by this application. First, a obtaining module 201 responds to an instruction from a driver to release the vehicle steering wheel, and obtains initial parameters of the steering wheel assembly of the vehicle, including an initial steering wheel angle, a moment of inertia, a damping coefficient, and an initial external disturbance torque, and a construction module 202 constructs an adaptive integral nonsingular terminal sliding mode surface of the steering wheel assembly based on the initial steering wheel angle. Secondly, since the adaptive integral nonsingular terminal sliding mode surface can effectively reduce the system steady-state error of the steering wheel assembly, a first update module 203 updates the initial external disturbance torque based on the adaptive integral nonsingular terminal sliding mode surface and the initial parameters, so as to reduce the influence of the system steady-state error on the external disturbance torque and the input torque, and improve the accuracy of the updated transitional external disturbance torque and transitional input torque of the steering wheel assembly. Then, a second update module 204 updates the initial steering wheel angle by using the transitional external disturbance torque, the transitional input torque, the moment of inertia, and the damping coefficient to obtain a transitional steering wheel angle of the steering wheel assembly, so as to control the vehicle steering wheel to rotate to an angle of the transitional steering wheel angle, and an angle determination module 205 updates the transitional external disturbance torque and the transitional input torque based on the transitional steering wheel angle until the obtained target transitional steering wheel angle is less than a preset value, completing the return control of the vehicle steering wheel this time. In this way, by gradually updating the external disturbance torque and the input torque during the process of performing the return control on the vehicle steering wheel, the angle of the steering wheel is gradually adjusted, so that the rotation strategy of the vehicle steering wheel can flexibly respond to external disturbances in various working conditions, thereby meeting the return control requirements of different working conditions and improving the return accuracy of the vehicle steering wheel.

[0121] Optionally, the construction module 202 is specifically configured to:

[0122] Obtain a desired steering wheel angle of the steering wheel;

[0123] Calculate a state error value of the vehicle steering wheel by using the desired steering wheel angle and the initial steering wheel angle;

[0124] Input the state error value into a preset initial sliding mode surface for processing, so as to obtain an adaptive integral nonsingular terminal sliding mode surface of the steering wheel assembly.

[0125] Optionally, the first update module 203 is specifically configured to:

[0126] Use an adaptive integral nonsingular terminal sliding mode surface to adaptively update the initial external disturbance torque, and obtain the transitional external disturbance torque of the steering wheel assembly;

[0127] Use the adaptive integral nonsingular terminal sliding mode surface, the initial steering wheel angle, the moment of inertia, the damping coefficient, and the transitional external disturbance torque to calculate and obtain the transitional input torque of the steering wheel assembly.

[0128] Optionally, the first update module 203 is specifically configured to:

[0129] Use a preset update period and an adaptive integral nonsingular terminal sliding mode surface to construct an external disturbance torque adaptive model;

[0130] Input the initial external disturbance torque into the external disturbance torque adaptive model for processing, and obtain the transitional external disturbance torque of the steering wheel assembly.

[0131] Optionally, the second update module 204 is specifically configured to:

[0132] Calculate the first-order derivative of the initial steering wheel angle with respect to time;

[0133] Obtain the frictional torque of the steering wheel assembly corresponding to the first-order derivative;

[0134] Based on the first-order derivative, the frictional torque, the transitional external disturbance torque, the transitional input torque, the moment of inertia, and the damping coefficient, update and obtain the transitional steering wheel angle of the steering wheel assembly.

[0135] Optionally, the second update module 204 is specifically configured to:

[0136] Based on the first-order derivative, the frictional torque, the transitional external disturbance torque, the transitional input torque, the moment of inertia, and the damping coefficient, construct a dynamic model of the steering wheel assembly;

[0137] Convert the dynamic model into a state space form to obtain a target model;

[0138] Based on the target model, calculate and obtain the transitional steering wheel angle of the steering wheel assembly.

[0139] Optionally, the second update module 204 is specifically configured to:

[0140] Use the preset Euler method to construct a discretized model of the current time based on the first-order derivative, the frictional torque, the transitional external disturbance torque, the transitional input torque, the moment of inertia, and the damping coefficient;

[0141] Calculate the transitional steering wheel angle of the steering wheel assembly for the next update cycle based on the discretized model.

[0142] It should be noted that the vehicle steering wheel control device provided in the above embodiment and the vehicle steering wheel control method provided in the above embodiment belong to the same concept. The specific ways in which each module and unit perform operations have been described in detail in the method embodiment, and will not be repeated here. In practical applications, the vehicle steering wheel control device provided in the above embodiment can allocate the above functions to different functional modules as needed, that is, divide the internal structure of the device into different functional modules to complete all or part of the functions described above. This is not limited here either.

[0143] A computing device according to an embodiment of the present application includes a memory, a processor, and a program stored on the memory and running on the processor. When the processor executes the program, it implements some or all of the steps of the above vehicle steering wheel control method.

[0144] Among them, a computer can be selected as the computing device. Correspondingly, its program is computer software. And for the parameters and steps in the above computing device of the present application, reference can be made to the parameters and steps in the embodiment of the vehicle steering wheel control method in the above text, and will not be elaborated here.

[0145] A computer-readable storage medium according to an embodiment of the present application stores instructions that, when running, execute the steps of the above vehicle steering wheel control method.

[0146] Among them, the computer-readable storage medium can be a transient computer-readable storage medium or a non-transient computer-readable storage medium.

[0147] The technical solution of the embodiment of the present disclosure can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes one or more instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method of the embodiment of the present disclosure. The foregoing computer-readable storage medium can be a non-transient computer-readable storage medium, including: various media such as a USB flash drive, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk, or an optical disc that can store program codes, or can also be a transient computer-readable storage medium.

[0148] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of devices, methods, and computer program products according to various embodiments of the present application. Among them, each block in the flowchart or block diagram may represent a module, a program segment, or a part of code, and the above-mentioned module, program segment, or part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order from that marked in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram or flowchart, as well as the combination of blocks in the block diagram or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or operations, or can be implemented by a combination of dedicated hardware and computer instructions.

[0149] Those skilled in the art know that the present application can be implemented as a system, a method, or a computer program product. Therefore, the present disclosure can be specifically implemented in the following forms: it can be entirely hardware, or entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software, which is generally referred to as a "module" or "device" in this article. In addition, in some embodiments, the present application can also be implemented in the form of a computer program product in one or more computer-readable media, which contains computer-readable program code. The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or component, or any combination of the above.

[0150] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0151] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A vehicle steering wheel control method, characterized in that: include: In response to a driver's instruction to release the vehicle steering wheel, obtaining initial parameters of the steering wheel assembly of the vehicle, the initial parameters including an initial steering wheel angle, a moment of inertia, a damping coefficient, and an initial external disturbance torque; An adaptive integral non-singular terminal sliding mode surface of the steering wheel assembly is constructed based on the initial steering wheel angle; performing an updating operation on the initial external disturbance torque based on the adaptive integral non-singular terminal sliding mode surface and the initial parameters to obtain a transitional external disturbance torque and a transitional input torque of the steering wheel assembly; updating the initial steering wheel angle by using the transition external disturbance torque, the transition input torque, the moment of inertia and the damping coefficient to obtain a transition steering wheel angle of the steering wheel assembly; The transition external disturbance torque and the transition input torque are updated based on the transition steering wheel angle until the obtained target transition steering wheel angle is less than a preset value, so as to perform return control on the vehicle steering wheel.

2. The method according to claim 1, characterized in that The adaptive integral non-singular terminal sliding mode surface of the steering wheel assembly is constructed based on the initial steering wheel angle, comprising: Obtaining a desired steering wheel angle of the steering wheel; Calculating a state error value of the vehicle steering wheel using the expected steering wheel angle and the initial steering wheel angle; The state error value is input into a preset initial sliding surface for processing to obtain an adaptive integral non-singular terminal sliding surface of the steering wheel assembly.

3. The method according to claim 1, characterized in that The updating operation of the initial external disturbance torque based on the adaptive integral non-singular terminal sliding mode surface and the initial parameters to obtain the transitional external disturbance torque and the transitional input torque of the steering wheel assembly includes: Adaptively updating the initial external disturbance torque by using the adaptive integral non-singular terminal sliding mode surface to obtain a transitional external disturbance torque of the steering wheel assembly; The transition input torque of the steering wheel assembly is calculated using the adaptive integral non-singular terminal sliding surface, the initial steering wheel angle, the moment of inertia, the damping coefficient and the transition external disturbance torque.

4. The method according to claim 3, characterized in that The method of adaptively updating the initial external disturbance torque by using the adaptive integral non-singular terminal sliding mode surface to obtain the transitional external disturbance torque of the steering wheel assembly includes: Using a preset update cycle and the adaptive integral non-singular terminal sliding surface, an external disturbance torque adaptive model is constructed; The initial external disturbance torque is input into the external disturbance torque adaptive model for processing to obtain a transitional external disturbance torque of the steering wheel assembly.

5. The method according to any one of claims 1 to 4, characterized in that: The updating of the initial steering wheel angle by using the transitional external disturbance torque, the transitional input torque, the moment of inertia and the damping coefficient to obtain the transitional steering wheel angle of the steering wheel assembly comprises: Calculating a first-order derivative of the initial steering wheel angle with respect to time; Obtaining the friction torque of the steering wheel assembly corresponding to the first-order derivative; A transition steering wheel angle of the steering wheel assembly is updated based on the first-order derivative, the friction torque, the transition external disturbance torque, the transition input torque, the moment of inertia and the damping coefficient.

6. The method according to claim 5, characterized in that The updating and obtaining of the transition steering wheel angle of the steering wheel assembly based on the first-order derivative, the friction torque, the transition external disturbance torque, the transition input torque, the moment of inertia and the damping coefficient comprises: constructing a dynamic model of the steering wheel assembly based on the first-order derivative, the friction torque, the transitional external disturbance torque, the transitional input torque, the moment of inertia and the damping coefficient; Converting the dynamic model into a state space form to obtain a target model; A transition steering wheel angle of the steering wheel assembly is calculated based on the target model.

7. The method according to claim 5, characterized in that The updating and obtaining of the transition steering wheel angle of the steering wheel assembly based on the first-order derivative, the friction torque, the transition external disturbance torque, the transition input torque, the moment of inertia and the damping coefficient comprises: Using a preset Euler method, a discretization model of the current time is constructed based on the first-order derivative, the friction torque, the transitional external disturbance torque, the transitional input torque, the moment of inertia and the damping coefficient; A transition steering wheel angle of the steering wheel assembly in the next update cycle is calculated based on the discretization model.

8. A vehicle steering wheel control device, characterized in that: include: an acquisition module, configured to acquire initial parameters of a steering wheel assembly of the vehicle in response to a driver's instruction to release the vehicle steering wheel, the initial parameters including an initial steering wheel angle, a moment of inertia, a damping coefficient, and an initial external disturbance torque; A construction module, used for constructing an adaptive integral non-singular terminal sliding surface of the steering wheel assembly based on the initial steering wheel angle; A first updating module, configured to update the initial external disturbance torque based on the adaptive integral non-singular terminal sliding surface and the initial parameters to obtain a transition external disturbance torque and a transition input torque of the steering wheel assembly; a second updating module, configured to update the initial steering wheel angle by using the transitional external disturbance torque, the transitional input torque, the moment of inertia and the damping coefficient, so as to obtain a transitional steering wheel angle of the steering wheel assembly; The steering angle determination module is used to update the transition external interference torque and the transition input torque based on the transition steering wheel angle until the obtained target transition steering wheel angle is less than a preset value, so as to perform return control on the vehicle steering wheel.

9. A computing device comprising a memory, a processor, and a program stored in the memory and running on the processor, characterized in that: When the processor executes the program, the steps of a vehicle steering wheel control method as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, and when the instructions are executed on a terminal device, the terminal device executes the steps of a vehicle steering wheel control method as described in any one of claims 1 to 7.

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