A fault-tolerant control method for a hub motor driven vehicle

Abstract

The invention discloses a fault-tolerant control method for a hub motor driven vehicle, comprising the following steps: force analysis of a hub motor driven vehicle; calculation of tire lateral stiffness; hub motor fault modeling; hub motor driven vehicle model design considering hub motor faults; and fault-tolerant controller design. The invention can quickly perform reasonable vehicle control according to hub motor faults, thereby greatly improving the safety of hub motor driven vehicles.

Description

Technical Field

[0001] The present invention belongs to the field of automobile intelligent driving, and in particular relates to a fault-tolerant control method for a hub motor driven automobile. Background Art

[0002] As the number of electrical devices in a vehicle driven by an in-wheel motor increases, the risk of failure increases.

[0003] Therefore, when the hub motor of a hub motor-driven vehicle fails, it is very important to be able to quickly and reasonably control the vehicle according to the hub motor failure. Currently, there are relatively few studies on fault-tolerant control of hub motor-driven vehicles. Considering hub motor failures and performing fault-tolerant control on hub motor-driven vehicles is of great significance to the driving safety of hub motor-driven vehicles. Summary of the invention

[0004] In order to solve the above-mentioned deficiencies in the prior art, the present invention proposes a fault-tolerant control method for a hub motor driven vehicle, so as to quickly perform reasonable vehicle control according to the hub motor failure, thereby greatly improving the safety of the hub motor driven vehicle.

[0005] The present invention solves the technical problem by adopting the following technical solution: a fault-tolerant control method for a hub motor driven vehicle, comprising the following steps:

[0006] Step 1: Use formula (1) to analyze the stress of the hub motor driven vehicle:

[0007] (1);

[0008] In formula (1), is the yaw rate of the vehicle, is the longitudinal velocity of the vehicle, is the lateral velocity of the vehicle, is the mass of the vehicle, is the vehicle's moment of inertia, is the vehicle front wheel turning angle, is the composite coefficient of air resistance, is the relative longitudinal velocity of the vehicle, is the air resistance, The resultant lateral force on the front axle of the vehicle is The resultant lateral force on the rear axle of the vehicle is The resultant longitudinal force on the front axle of the vehicle, The resultant longitudinal force on the rear axle of the vehicle is is the distance from the front axle of the vehicle to the center of mass, is the distance from the vehicle's rear axle to the center of mass, is the additional yaw moment of the vehicle, is the composite cornering stiffness of the front axle tire, is the composite cornering stiffness of the rear axle tire, is the longitudinal force of the right front wheel, is the longitudinal force of the left front wheel, is the longitudinal force of the right rear wheel, is the longitudinal force of the left rear wheel;

[0009] Step 2: Calculate the tire cornering stiffness using formula (2):

[0010] (2);

[0011] In formula (2), , , , are respectively the nominal cornering stiffness of the front tire, the nominal cornering stiffness of the rear tire, the amplitude of the change in the cornering stiffness of the front tire, and the amplitude of the change in the cornering stiffness of the rear tire; is the maximum value of the front tire cornering stiffness, is the maximum value of the rear tire cornering stiffness, is the minimum value of the front tire cornering stiffness, , is the adjustment coefficient of the front and rear tire cornering stiffness, ;

[0012] Step 3: Use formula (3) to complete the hub motor fault modeling:

[0013] (3);

[0014] In formula (3), is the output torque of the hub motor after the failure, is the expected output torque of the hub motor, is the hub motor failure coefficient, is the hub motor bias fault torque;

[0015] Step 4: Calculate the failure coefficient of each wheel hub motor according to the actual output torque and expected output torque of each wheel hub motor of the vehicle taken in real time, and complete the design of the wheel hub motor driven vehicle model considering the wheel hub motor failure;

[0016] Step 5: Design a fault-tolerant controller to complete the design of a closed-loop augmented control system for a hub motor-driven vehicle that takes hub motor failures into account.

[0017] Preferably, step 4 includes: step 4.1, using formula (4) to describe the dynamic model of the wheel hub motor driven vehicle:

[0018] (4);

[0019] In formula (4), , , , ,

[0020] ,

[0021] , ;

[0022] is the effective radius of the tire, They are the expected output torques of the hub motors for the right front wheel, left front wheel, right rear wheel, and left rear wheel, respectively. They are the bias fault torques of the hub motors of the right front wheel, left front wheel, right rear wheel, and left rear wheel respectively;

[0023] Step 4.2: Select the fault coefficients of the four wheel hub motors respectively. It is the antecedent variable of Takagi-Sugeno fuzzy model of wheel hub motor drive vehicle;

[0024] (5);

[0025] In formula (5), For variables The maximum value of For variables The minimum value of For variables The maximum value of For variables The minimum value of For variables The maximum value of For variables The minimum value of For variables The maximum value of For variables The minimum value of , , , , , , are the membership functions respectively;

[0026] Step 4.3: Calculate the fault coefficient of each wheel hub motor according to the actual output torque and expected output torque of each wheel hub motor of the vehicle taken in real time. The membership function of the hub motor is used to complete the design of the hub motor drive vehicle model considering the hub motor failure using formula (6):

[0027] (6);

[0028] In formula (6), is the normalized membership function.

[0029] Preferably, step 5 includes: step 5.1, defining an augmented state matrix , use formula (7) to complete the design of the augmented control system of the hub motor driven vehicle considering the hub motor failure:

[0030] (7)

[0031] In formula (7), , , , ;

[0032] Step 5.2: Use equation (8) to design a fault-tolerant controller:

[0033] (8);

[0034] In formula (8), is the fault-tolerant controller gain, is the normalized membership function;

[0035] Step 5.3, substituting the designed fault-tolerant controller into equation (7) can obtain the closed-loop augmented control system of the hub motor driven vehicle considering the hub motor failure:

[0036] (9);

[0037] In formula (9), by adjusting Control the closed-loop augmented control system of the hub motor driven vehicle taking into account the hub motor failure;

[0038] And use formula (10) to calculate the system control output:

[0039] (10); In formula (10), the system control output is the difference between the actual value of the vehicle longitudinal speed and the target value of the longitudinal speed, and the difference between the actual value of the vehicle yaw angular velocity and the target value of the yaw angular velocity.

[0040] Compared with the existing prior art, the beneficial effects of the present invention are:

[0041] 1. The present invention designs a fault-tolerant control method for a hub motor driven vehicle taking into account hub motor failures. The fault-tolerant control method can well combine the hub motor failures that occur in hub motor driven vehicles, calculate the degree of hub motor failure based on real-time collected hub motor data, and automatically adjust the driving torque of the vehicle's four hub motors through an algorithm, thereby ensuring the vehicle's driving stability and improving the driving safety of hub motor driven vehicles.

[0042] 2. The present invention establishes a hub motor driven vehicle model taking into account hub motor failures based on the Takagi-Sugeno fuzzy method, which can well integrate hub motor failures into the hub motor driven vehicle dynamics model, and provides an accurate vehicle dynamics model for subsequent fault-tolerant control algorithms.

[0043] 3. The present invention models the hub motor fault, which can well consider the hub motor bias fault torque and output efficiency loss fault, avoid considering a single type of fault, and improve the accuracy of hub motor fault modeling.

[0044] 4. The vehicle model of the present invention takes into account the nonlinear changes in tire forces and calculates the real-time tire cornering stiffness. The nonlinear changes in tire forces are more dramatic due to the wheel structure of the hub motor-driven car. Therefore, the vehicle model of the present invention can well solve the problem of nonlinear changes in tire forces and improve the accuracy of the vehicle dynamics model. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0047] In this embodiment, a method for fault-tolerant control of a hub motor driven vehicle is to collect information in real time through sensors to calculate hub motor faults and tire cornering stiffness, input external input signals of vehicle target speed and vehicle target yaw rate into a hub motor driven vehicle model considering hub motor faults, and control the expected output torque of each hub motor through a fault-tolerant controller to maintain safe driving of the vehicle. Specifically, the method is performed in the following steps:

[0048] Step 1: Use formula (1) to analyze the stress of the hub motor driven vehicle:

[0049] (1);

[0050] In formula (1), is the yaw rate of the vehicle, is the longitudinal velocity of the vehicle, is the lateral velocity of the vehicle, is the mass of the vehicle, is the vehicle's moment of inertia, is the vehicle front wheel turning angle, is the composite coefficient of air resistance, is the relative longitudinal velocity of the vehicle, is the air resistance, The resultant lateral force on the front axle of the vehicle is The resultant lateral force on the rear axle of the vehicle is The resultant longitudinal force on the front axle of the vehicle, The resultant longitudinal force on the rear axle of the vehicle is is the distance from the front axle of the vehicle to the center of mass, is the distance from the vehicle's rear axle to the center of mass, is the additional yaw moment of the vehicle, is the composite cornering stiffness of the front axle tire, is the composite cornering stiffness of the rear axle tire, is the longitudinal force of the right front wheel, is the longitudinal force of the left front wheel, is the longitudinal force of the right rear wheel, is the longitudinal force on the left rear wheel.

[0051] In this embodiment, the sensor collects vehicle status information in real time to calculate the tire cornering stiffness.

[0052] Step 2: Calculate the tire cornering stiffness using formula (2):

[0053] (2);

[0054] In formula (2), , , , They are respectively the nominal cornering stiffness of the front tire, the nominal cornering stiffness of the rear tire, the amplitude of the change in the cornering stiffness of the front tire, and the amplitude of the change in the cornering stiffness of the rear tire. is the maximum value of the front tire cornering stiffness, is the maximum value of the rear tire cornering stiffness, is the minimum value of the front tire cornering stiffness, is the minimum value of the front tire cornering stiffness, , is the adjustment coefficient of the front and rear tire cornering stiffness, usually taken as .

[0055] In this embodiment, the sensor collects the actual output torque of each hub motor in real time to calculate the hub motor bias fault torque and output efficiency loss fault.

[0056] Step 3: Use formula (3) to complete the hub motor fault modeling:

[0057] (3);

[0058] In formula (3), is the output torque of the hub motor after the failure, is the expected output torque of the hub motor, is the hub motor failure coefficient, is the hub motor bias fault torque.

[0059] Step 4: Calculate the failure coefficient of each wheel hub motor according to the actual output torque and expected output torque of each wheel hub motor of the vehicle taken in real time, and complete the design of the wheel hub motor driven vehicle model considering the wheel hub motor failure;

[0060] Step 4.1, use equation (4) to describe the dynamic model of the wheel hub motor driven vehicle:

[0061] (4);

[0062] In formula (4), , , , ,

[0063] ,

[0064] , ;

[0065] is the effective radius of the tire. They are the expected output torques of the hub motors for the right front wheel, left front wheel, right rear wheel, and left rear wheel, respectively. They are the bias fault torques of the right front wheel, left front wheel, right rear wheel and left rear wheel hub motors respectively.

[0066] Step 4.2: Select the fault coefficients of the four wheel hub motors respectively It is the antecedent variable of Takagi-Sugeno fuzzy model of wheel hub motor drive vehicle.

[0067] (5);

[0068] In formula (5), For variables The maximum value of For variables The minimum value of For variables The maximum value of For variables The minimum value of For variables The maximum value of For variables The minimum value of For variables The maximum value of For variables The minimum value of , , , , , , are the membership functions respectively.

[0069] Step 4.3: Calculate the fault coefficient of each wheel hub motor according to the actual output torque and expected output torque of each wheel hub motor of the vehicle taken in real time. The membership function of the hub motor is used to complete the design of the hub motor drive vehicle model considering the hub motor failure using formula (6):

[0070] (6);

[0071] In formula (6), is the normalized membership function.

[0072] In this embodiment, the external input is the vehicle target speed and the vehicle target yaw rate. The vehicle sensor detects the current vehicle actual speed and the vehicle actual yaw rate in real time, calculates the difference between the vehicle speed and the target value and the actual value of the vehicle yaw rate, and maintains the normal operation of the vehicle by controlling the expected output torque of each wheel hub motor. When a wheel hub motor failure occurs, the expected output torque of each wheel hub motor is adjusted to maintain safe driving of the vehicle.

[0073] Step 5: Design a fault-tolerant controller to complete the design of a closed-loop augmented control system for a hub motor-driven vehicle that takes hub motor failure into consideration;

[0074] Step 5.1: Define the augmented state matrix .Use formula (7) to complete the design of the augmented control system of the hub motor driven vehicle considering the hub motor failure:

[0075] (7);

[0076] In formula (7), , , , ;

[0077] Step 5.2: Use equation (8) to design a fault-tolerant controller:

[0078] (8);

[0079] In formula (8), is the fault-tolerant controller gain, is the normalized membership function.

[0080] Step 5.3, substituting the designed fault-tolerant controller into equation (7) can obtain the closed-loop augmented control system of the hub motor driven vehicle considering the hub motor failure:

[0081] (9); In formula (9), by adjusting Control the closed-loop augmented control system of the hub motor driven vehicle taking into account the hub motor failure;

[0082] And use formula (10) to calculate the system control output:

[0083] (10);

[0084] In formula (10), the system control output is the difference between the actual value of the vehicle longitudinal speed and the target value of the longitudinal speed, and the difference between the actual value of the vehicle yaw rate and the target value of the yaw rate.

[0085] Working principle: Figure 1 As shown, the hub motor fault model collects the actual output torque of each hub motor in real time through sensors to calculate the hub motor fault. The sensor collects vehicle status information in real time to calculate the tire lateral stiffness. The external input is the vehicle target speed and the vehicle target yaw angular velocity. The above three signals are input into the hub motor driven car model considering the hub motor fault. When the hub motor fault occurs, the fault-tolerant controller will correct the expected output torque of each hub motor to maintain safe driving of the vehicle. When there is no hub motor fault, the controller will normally output the expected output torque of each hub motor to maintain the normal operation of the vehicle.

[0086] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A fault-tolerant control method for a hub motor driven vehicle, characterized in that: The steps include: Step 1: Use formula (1) to analyze the stress of the hub motor driven vehicle: (1) In formula (1), is the vehicle’s yaw rate, is the longitudinal velocity of the vehicle, is the lateral velocity of the vehicle, is the mass of the vehicle, is the vehicle's moment of inertia, is the front wheel turning angle of the vehicle, is the composite coefficient of air resistance, is the relative longitudinal velocity of the vehicle, is the air resistance, The resultant lateral force on the front axle of the vehicle, The resultant lateral force on the rear axle of the vehicle is The resultant longitudinal force on the front axle of the vehicle, The resultant longitudinal force on the rear axle of the vehicle is is the distance from the front axle of the vehicle to the center of mass, is the distance from the vehicle's rear axle to the center of mass, is the additional yaw moment of the vehicle, is the composite cornering stiffness of the front axle tire, is the composite cornering stiffness of the rear axle tire, is the longitudinal force of the right front wheel, is the longitudinal force of the left front wheel, is the longitudinal force of the right rear wheel, is the longitudinal force of the left rear wheel; Step 2: Calculate the tire cornering stiffness using formula (2): (2) In formula (2), , , , are respectively the nominal cornering stiffness of the front tire, the nominal cornering stiffness of the rear tire, the amplitude of the change in the cornering stiffness of the front tire, and the amplitude of the change in the cornering stiffness of the rear tire; is the maximum value of the front tire cornering stiffness, is the maximum value of the rear tire cornering stiffness, is the minimum value of the front tire cornering stiffness, , is the adjustment coefficient of the front and rear tire cornering stiffness, ; Step 3: Use formula (3) to complete the hub motor fault modeling: (3) In formula (3), is the output torque of the hub motor after the failure, is the expected output torque of the hub motor, is the hub motor failure coefficient, is the hub motor bias fault torque; Step 4: Calculate the failure coefficient of each wheel hub motor according to the actual output torque and expected output torque of each wheel hub motor of the vehicle taken in real time, and complete the design of the wheel hub motor driven vehicle model considering the wheel hub motor failure; Step 5: Design a fault-tolerant controller to complete the design of a closed-loop augmented control system for a hub motor-driven vehicle that takes hub motor failure into consideration; The step 4 includes: step 4.1, using formula (4) to describe the dynamic model of the wheel hub motor driven vehicle: (4) In formula (4), , , , , ， ， ； is the effective radius of the tire, They are the expected output torques of the hub motors for the right front wheel, left front wheel, right rear wheel, and left rear wheel, respectively. They are the bias fault torques of the hub motors of the right front wheel, left front wheel, right rear wheel, and left rear wheel respectively; Step 4.2: Select the fault coefficients of the four wheel hub motors respectively. It is the antecedent variable of Takagi-Sugeno fuzzy model of wheel hub motor drive vehicle; (5)； In formula (5), For variables The maximum value of For variables The minimum value of For variables The maximum value of For variables The minimum value of For variables The maximum value of For variables The minimum value of For variables The maximum value of For variables The minimum value of , , , , , , are the membership functions respectively; Step 4.3: Calculate the fault coefficient of each wheel hub motor according to the actual output torque and expected output torque of each wheel hub motor of the vehicle taken in real time. The membership function of the hub motor is used to complete the design of the hub motor drive vehicle model considering the hub motor failure using formula (6): (6)； In formula (6), is the normalized membership function; The step 5 comprises: Step 5.1: Define the augmented state matrix , use formula (7) to complete the design of the augmented control system of the hub motor driven vehicle considering the hub motor failure: (7) In formula (7), , , , ; Step 5.2: Use equation (8) to design a fault-tolerant controller: (8) In formula (8), is the fault-tolerant controller gain, is the normalized membership function; Step 5.3, substituting the designed fault-tolerant controller into equation (7) can obtain the closed-loop augmented control system of the hub motor driven vehicle considering the hub motor failure: （9）； In formula (9), by adjusting Control the closed-loop augmented control system of the hub motor driven vehicle taking into account the hub motor failure; And use formula (10) to calculate the system control output: (10); In formula (10), the system control output is the difference between the actual value of the vehicle longitudinal speed and the target value of the longitudinal speed, and the difference between the actual value of the vehicle yaw angular velocity and the target value of the yaw angular velocity.

2. An electronic device, comprising a memory and a processor, characterized in that: The memory is used to store a program that supports the processor to execute the fault-tolerant control method described in claim 1, and the processor is configured to execute the program stored in the memory.

3. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the fault-tolerant control method according to claim 1 are executed.

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