Wheel transmission instability power redistribution control method for automobile

Abstract

The invention provides a wheel transmission instability power redistribution control method for an automobile, and the method specifically comprises the following steps: S1, obtaining vehicle operation data through a high-precision sensor, the vehicle operation data comprises vehicle operation state data and vehicle surrounding environment data, the high-precision sensor comprises a wheel speed sensor, an acceleration sensor, a gyroscope, an environment sensing camera and a radar; s2, analyzing the vehicle operation data, and identifying an early sign of wheel instability; s3, when it is recognized that the wheels have the instability risk, a dynamic power redistribution mechanism is started to optimize torque output of all the wheels, and the instability state is corrected; and S4, comprehensively considering the control targets of the wheel slip rate, the lateral stability and the trajectory tracking capability, and balancing conflicts among the targets by adopting a multi-target optimization algorithm to obtain an optimal power distribution scheme.

Description

Technical Field

[0001] The invention relates to the field of automobile control, and in particular to a method for controlling wheel transmission instability power redistribution for an automobile. Background Art

[0002] With the rapid development of electric vehicle technology, the requirements for electric vehicle range, power performance and driving safety are also increasing. However, during the driving process of electric vehicles, especially in complex and changeable road environments and driving conditions, the wheel transmission system often faces the risk of instability. This instability may be caused by a variety of factors, such as uneven road surface, tire wear, improper drive motor control, etc., which may cause wheel slippage, side sliding or loss of control, seriously affecting the stability and safety of the vehicle.

[0003] Traditional wheel transmission control strategies often focus on optimizing a single objective, such as only considering wheel slip control or trajectory tracking capabilities, while ignoring the mutual influence and constraints of other control objectives. This single-objective optimization method often cannot meet the comprehensive performance requirements of electric vehicles under complex working conditions, and may even cause the vehicle to lose control or cause an accident in some cases.

[0004] In addition, the wheel drive system of electric vehicles is also at risk of sensor and actuator failure. Sensor failure may cause the vehicle to be unable to accurately perceive the surrounding environment and its own status, while actuator failure may affect the vehicle's power output and response speed. These failures may have a serious impact on the stability and safety of the vehicle, especially at high speeds or in emergency situations.

[0005] Therefore, in order to improve the wheel transmission stability and safety of electric vehicles, it is necessary to develop a power redistribution control strategy that comprehensively considers multiple control objectives. This strategy should be able to monitor the vehicle status and environmental changes in real time, dynamically adjust the torque output of each wheel to correct the instability and keep the vehicle running stably. At the same time, the strategy should also have fault diagnosis and fault-tolerant control functions, and be able to automatically adjust the control strategy when the sensor or actuator fails to ensure that the vehicle can still run safely and stably. For this purpose, a power redistribution control strategy for wheel transmission instability of electric vehicles is proposed. Summary of the invention

[0006] The main purpose of the present invention is to provide a method for controlling power redistribution when the wheel transmission is unstable for an automobile, which is used to redistribute power when the automobile is in an unstable state to ensure safe and stable operation of the vehicle.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a method for controlling wheel transmission instability power redistribution for an automobile, characterized in that it specifically comprises the following steps:

[0008] Step S1, obtaining vehicle operation data through high-precision sensors, wherein the vehicle operation data includes vehicle operation status data and vehicle surrounding environment data, and the high-precision sensors include wheel speed sensors, acceleration sensors, gyroscopes, environment perception cameras and radars;

[0009] Step S2, analyzing the vehicle operation data to identify early signs of wheel instability;

[0010] Step S3: when it is identified that a wheel has an instability risk, a dynamic power redistribution mechanism is activated to optimize the torque output of each wheel and correct the instability;

[0011] Step S4, comprehensively considering the control objectives of wheel slip rate, lateral stability, and trajectory tracking capability, using a multi-objective optimization algorithm to balance the conflicts between the objectives and obtain the optimal power distribution plan.

[0012] Preferably, step S3 specifically includes the following steps:

[0013] Step S301, define a vehicle state vector X=[x, y, θ, v, ω]∧T, where x and y represent the position of the vehicle's center of mass in the global coordinate system, θ represents the vehicle's heading angle, v represents the vehicle speed, and ω represents the yaw rate;

[0014] Step S302, define a control input vector U=[T_lf, T_rf, T_lr, T_rr]∧T, where T_lf, T_rf, T_lr, and T_rr represent the driving torques of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, respectively;

[0015] Step S303: Establish a state space equation X=f(X,U) according to the vehicle dynamics model, where f(X,U) represents the state transfer function of the vehicle dynamics model;

[0016] Step S304: When the wheel transmission is identified to be unstable, solve the following optimization problem to obtain the optimal control input U:

[0017]

[0018] The constraints are:

[0019] X=f(X,U),X(0)=X0,U min ≤U≤U max

[0020] Among them, X des is the desired vehicle state vector, X0 is the initial state vector, U prev is the control input of the previous moment, λ is the weight coefficient, W is the weight matrix, U min and U maxare the minimum and maximum values ​​of the control input respectively.

[0021] Preferably, in step S304, a sliding mode control SMC algorithm is used for solving, and the sliding mode control SMC algorithm uses a sliding mode surface in the following form:

[0022] s=c1e+c2e,

[0023] Among them, e represents the vehicle state error, c1 and c2 are positive constants, which are used to adjust the convergence speed and stability of the sliding surface.

[0024] Preferably, the multi-objective optimization algorithm in step S4 specifically includes the following steps:

[0025] Step S401: determine the control targets of wheel slip rate control, lateral stability control, and trajectory tracking ability control, and establish corresponding objective functions respectively. Let each objective function be J i (U), i = 1, 2, ..., n;

[0026] Step S402, standardizing the objective function;

[0027] Step S403: Using a weighted sum method, multiple standardized objective functions are combined into a comprehensive objective function:

[0028]

[0029] Among them, J(U) is the comprehensive objective function, ω is the weight coefficient of each control objective, and satisfies

[0030] Step S404: Use the gradient descent method or Newton's method to solve the minimum value of J(U) to obtain the optimal control input U.

[0031] Preferably, the method further comprises: step S6, a fault diagnosis and fault-tolerant control method, wherein step S6 specifically comprises the following steps:

[0032] Step S601: using redundant sensor information, data verification, and threshold judgment methods to monitor the working status of the sensor in real time and diagnose whether the high-precision sensor is faulty;

[0033] Step S602: Determine whether the actuator fails or has performance degradation by monitoring the response speed and output torque parameters of the actuator;

[0034] Step S603: When a high-precision sensor or actuator fault is diagnosed, the fault handling strategy is immediately initiated:

[0035] If a high-precision sensor fails, redundant sensor data replacement, estimated value replacement, or faulty sensor isolation is used;

[0036] If an actuator fails, the backup actuator can be switched, the control strategy can be adjusted, or the performance requirements can be reduced.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1) The present invention can quickly identify early signs of wheel transmission instability by integrating high-precision sensors and monitoring the vehicle's operating status in real time, and immediately activate the dynamic power redistribution mechanism and accurately calculate and optimize the torque output of each wheel, effectively correct the instability state, and prevent the vehicle from slipping, sliding or losing control, thereby significantly improving the driving stability and safety of electric vehicles under complex working conditions;

[0039] 2) The present invention adopts a multi-objective optimization algorithm, comprehensively considers the control objectives of wheel slip rate, lateral stability, and trajectory tracking ability, and solves the optimal control input through a weighted sum method. At the same time, the present invention also has fault diagnosis and fault-tolerant control functions, which can monitor the working status of sensors and actuators in real time. Once a fault is found, the fault handling strategy is immediately started and the parameters and models in the control strategy are adjusted, ensuring that the vehicle can still maintain stable driving when the sensor or actuator fails, reducing the safety risks caused by the fault and improving the reliability and durability of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flow chart according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0042] A method for controlling wheel transmission instability power redistribution for an automobile comprises the following steps:

[0043] Step S1, obtaining vehicle operation data through high-precision sensors, wherein the vehicle operation data includes vehicle operation status data and vehicle surrounding environment data, and the high-precision sensors include wheel speed sensors, acceleration sensors, gyroscopes, environment perception cameras and radars;

[0044] Step S2, analyzing the vehicle operation data to identify early signs of wheel instability;

[0045] Step S3: when it is identified that a wheel has an instability risk, a dynamic power redistribution mechanism is activated to optimize the torque output of each wheel and correct the instability;

[0046] Step S4, comprehensively considering the control objectives of wheel slip rate, lateral stability, and trajectory tracking capability, using a multi-objective optimization algorithm to balance the conflicts among the objectives and obtain an optimal power distribution plan;

[0047] Step S5: Based on the actual operation data of the vehicle, the control parameters and algorithm model are continuously optimized by using an adaptive algorithm or a reinforcement learning algorithm to improve the adaptability and effectiveness of the control strategy.

[0048] The step S3 specifically includes the following steps:

[0049] Step S301, define the vehicle state vector X = [x, y, θ, v, ω] T , where x and y represent the position of the vehicle's center of mass in the global coordinate system, θ represents the vehicle's heading angle, v represents the vehicle's speed, and ω represents the yaw rate;

[0050] Step S302: define the control input vector U = [T_lf, T_rf, T_lr, T_rr] T , where T_lf, T_rf, T_lr, and T_rr represent the driving torques of the left front, right front, left rear, and right rear wheels, respectively;

[0051] Step S303: Establish a state space equation X=f(X,U) according to the vehicle dynamics model, where f(X,U) represents the state transfer function of the vehicle dynamics model;

[0052] Step S304: When the wheel transmission is identified to be unstable, the SMC or MPC algorithm is used to solve the following optimization problem to obtain the optimal control input U:

[0053]

[0054] The constraints are:

[0055] X=f(X,U),X(0)=X0,U min ≤U≤U max

[0056] Among them, X des is the desired vehicle state vector, X0 is the initial state vector, U prev is the control input of the previous moment, λ is the weight coefficient, W is the weight matrix, U min and U max are the minimum and maximum values ​​of the control input respectively.

[0057] The sliding mode control SMC algorithm adopts the following sliding surface:

[0058] s=c1e+c2e,

[0059] Among them, e represents the vehicle state error, c1 and c2 are positive constants, which are used to adjust the convergence speed and stability of the sliding surface.

[0060] The multi-objective optimization algorithm in step S4 specifically includes the following steps:

[0061] Step S401: determine the control targets of wheel slip rate control, lateral stability control, and trajectory tracking ability control, and establish corresponding objective functions respectively. Let each objective function be J i (U), i = 1, 2, ..., n, n is the number of control targets; where the objective function J i (U) using the Min-max normalization function type in the prior art;

[0062] Step S402: Standardize the objective function. Since the dimensions and importance of each control objective are different, each objective function needs to be standardized to make it comparable.

[0063] Step S403: Using a weighted sum method, multiple standardized objective functions are combined into a comprehensive objective function:

[0064]

[0065] Among them, J(U) is the comprehensive objective function, ω is the weight coefficient of each control objective, and satisfies

[0066] Step S404: Use the gradient descent method or Newton's method to solve the minimum value of J(U) to obtain the optimal control input U.

[0067] Preferably, the wheel transmission instability power redistribution control method further includes: step S6, fault diagnosis and fault tolerance control method, step S6 specifically includes the following steps:

[0068] Step S601: using redundant sensor information, data verification, and threshold judgment methods to monitor the working status of the sensor in real time and diagnose whether the high-precision sensor is faulty;

[0069] Step S602: Determine whether the actuator fails or has performance degradation by monitoring the response speed and output torque parameters of the actuator;

[0070] Step S603: When a high-precision sensor or actuator fault is diagnosed, the fault handling strategy is immediately initiated:

[0071] If a high-precision sensor fails, redundant sensor data replacement, estimated value replacement, or faulty sensor isolation is used;

[0072] If an actuator fails, use the backup actuator switch, control strategy adjustment or reduce performance requirements;

[0073] Step S604: Based on the fault handling, the parameters and models in the control strategy are adjusted to adapt to the vehicle dynamics characteristics after the fault. By real-time monitoring of the vehicle status and control effect, the control strategy is continuously optimized to ensure that the vehicle can still operate safely and stably in the event of a fault.

[0074] The fault diagnosis and fault-tolerant control mechanism also includes fault alarm and recording steps, which record the fault diagnosis results and fault-tolerant control process, trigger the fault alarm mechanism, and promptly notify the driver or maintenance personnel for processing. At the same time, the fault data and fault-tolerant control experience are accumulated to optimize future fault diagnosis and fault-tolerant control strategies.

[0001] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for controlling wheel transmission instability power redistribution for an automobile, characterized in that: The specific steps include: Step S1, obtaining vehicle operation data through high-precision sensors, wherein the vehicle operation data includes vehicle operation status data and vehicle surrounding environment data, and the high-precision sensors include wheel speed sensors, acceleration sensors, gyroscopes, environment perception cameras and radars; Step S2, analyzing the vehicle operation data to identify early signs of wheel instability; Step S3: when it is identified that a wheel has an instability risk, a dynamic power redistribution mechanism is activated to optimize the torque output of each wheel and correct the instability; Step S4, comprehensively considering the control objectives of wheel slip rate, lateral stability, and trajectory tracking capability, using a multi-objective optimization algorithm to balance the conflicts between the objectives and obtain the optimal power distribution plan.

2. A method for controlling wheel transmission instability power redistribution for a vehicle according to claim 1, characterized in that: The step S3 specifically includes the following steps: Step S301, define a vehicle state vector X=[x, y, θ, v, ω]∧T, where x and y represent the position of the vehicle's center of mass in the global coordinate system, θ represents the vehicle's heading angle, v represents the vehicle speed, and ω represents the yaw rate; Step S302, define a control input vector U=[T_lf, T_rf, T_lr, T_rr]∧T, where T_lf, T_rf, T_lr, and T_rr represent the driving torques of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, respectively; Step S303: Establish a state space equation X=f(X,U) according to the vehicle dynamics model, where f(X,U) represents the state transfer function of the vehicle dynamics model; Step S304: When the wheel transmission is identified to be unstable, solve the following optimization problem to obtain the optimal control input U: The constraints are: X=f(X,U),X(0)=X0,U min ≤U≤U max Among them, X des is the desired vehicle state vector, X0 is the initial state vector, U prev is the control input of the previous moment, λ is the weight coefficient, W is the weight matrix, U min and U max are the minimum and maximum values ​​of the control input respectively.

3. A method for controlling wheel transmission instability power redistribution for a vehicle according to claim 2, characterized in that: In step S304, a sliding mode control SMC algorithm is used for solving the problem. The sliding mode control SMC algorithm uses a sliding surface in the following form: s=c1e+c2e, Among them, e represents the vehicle state error, c1 and c2 are positive constants, which are used to adjust the convergence speed and stability of the sliding surface.

4. The method for controlling wheel transmission instability power redistribution for a vehicle according to claim 1, characterized in that: The multi-objective optimization algorithm in step S4 specifically includes the following steps: Step S401: determine the control targets of wheel slip rate control, lateral stability control, and trajectory tracking ability control, and establish corresponding objective functions respectively. Let each objective function be J i (U), i = 1, 2, ..., n; Step S402, standardizing the objective function; Step S403: Using a weighted sum method, multiple standardized objective functions are combined into a comprehensive objective function: Among them, J(U) is the comprehensive objective function, ω is the weight coefficient of each control objective, and satisfies Step S404: Use the gradient descent method or Newton's method to solve the minimum value of J(U) to obtain the optimal control input U.

5. The method for controlling wheel transmission instability power redistribution for a vehicle according to claim 1, characterized in that: The method further includes: step S6, a fault diagnosis and fault-tolerant control method, wherein step S6 specifically includes the following steps: Step S601: using redundant sensor information, data verification, and threshold judgment methods to monitor the working status of the sensor in real time and diagnose whether the high-precision sensor is faulty; Step S602: Determine whether the actuator fails or has performance degradation by monitoring the response speed and output torque parameters of the actuator; Step S603: When a high-precision sensor or actuator fault is diagnosed, the fault handling strategy is immediately initiated: If a high-precision sensor fails, redundant sensor data replacement, estimated value replacement, or faulty sensor isolation is used; If an actuator fails, the backup actuator can be switched, the control strategy can be adjusted, or the performance requirements can be reduced.

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