A by-wire independent steering cross drive steering redundancy control method

Abstract

The application discloses a kind of drive steering redundancy control methods of linear control independent steering cross drive steering, belong to vehicle engineering technical field, comprising the following steps: S1: steering angle dynamics analysis is carried out to each angle module wheel, and wheel rotation angle estimated value is calculated;S2: according to wheel rotation angle estimated value, in combination with steering detection angle of kingpin steering gear, steering abnormal angle module with abnormal steering function is screened;S3: for steering abnormal angle module, according to rotation angle estimated value, in combination with steering detection angle of kingpin steering gear, wheel rotation angle measurement value is confirmed;then according to wheel rotation angle measurement value, the fault angle module of kingpin steering gear failure is screened;S4: for fault angle module, determine fault type;S5: according to fault type, re-allocate the wheel driving torque and wheel rotation angle of each angle module, obtain the target wheel driving torque and target wheel rotation angle of each angle module.The application can control vehicle normal driving when kingpin steering gear fails.

Description

Technical Field

[0001] This invention belongs to the field of vehicle engineering technology and relates to a control method based on distributed drive, and more particularly to a steer-by-wire independent steering cross-drive redundancy control method. Background Technology

[0002] Traditional chassis steering systems are mechanical steering systems. During steering, the steering angle of each wheel conforms to the Ackermann principle or satisfies an Ackermann-like steering principle. That is, when the driver turns the steering wheel, the mechanical structure constrains the steering wheels to rotate a certain angle according to the Ackermann steering principle, and the center axes of the four wheels approximately intersect at a single point when the vehicle is turning. With the rise of cornering modules, the steering wheel and each wheel are controlled by electrical signals, allowing for independent steering. This means there is no rigid geometric relationship between the steering wheel's rotation angle and the wheel's steering angle; the steering angle of each wheel is determined by the chassis domain controller after analyzing the driver's intentions and the vehicle's own state. Traditional chassis still have mechanical redundancy in case of steering motor failure. However, when the steering motor of a wire-controlled steering actuator fails, the steering angle and driving torque of the other steering wheels need to be redistributed to achieve the driver's intended trajectory or ensure emergency parking. Currently, there is a lack of methods to achieve the original driver's intended trajectory or emergency parking by distributing driving torque among the four hub motors when a single or multiple wheel steering motors fail and cannot provide power. Summary of the Invention

[0003] This invention provides a steer-by-wire independent steering cross-drive steering redundancy control method, which aims to solve the problem that existing steer-by-wire independent steering distributed drive vehicles lack effective redundancy control means when a single or multiple wheel kingpin steering gear fails, resulting in the vehicle being unable to follow the driving trajectory and having poor driving safety.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a steer-by-wire independent steering cross-drive redundancy control method, comprising the following steps: S1: Performing dynamic analysis of the steering angle of each corner module wheel to calculate the estimated wheel angle; S2: Based on the estimated wheel angle and the kingpin steering detection angle, filtering out abnormal steering angle modules with malfunctioning steering function; S3: For the abnormal steering angle module, confirming the wheel angle measurement value based on the estimated angle and the kingpin steering detection angle; then filtering out faulty angle modules with kingpin steering failure based on the measured wheel angle; S4: Determining the fault type for the faulty angle module; S5: Based on the fault type, redistributing the wheel driving torque and wheel angle of each corner module to obtain the target wheel driving torque and target wheel angle of each corner module.

[0005] To optimize the above technical solution, the specific measures also include: Further, in step S1, the method for calculating the estimated wheel angle is as follows: A height sensor is installed between the lower control arm of the corner module and the vehicle frame. This height sensor measures a voltage reflecting the movement of the lower control arm. Based on the voltage output from the height sensor, the vertical force on the wheel is calculated. ; In the formula, The vertical force on the wheel, The values ​​1, 2, 3, and 4 represent the front left corner module, front right corner module, rear left corner module, and rear right corner module, respectively. The height sensor outputs voltage. The average value of the output voltage of all corner module height sensors. , For the total mass of the vehicle. It is the acceleration due to gravity; Based on the vertical force of the wheel, calculate the lateral force of the wheel and the longitudinal force of the tire: ; In the formula, The force acting on the side of the wheel. This refers to the vehicle's lateral acceleration. ; In the formula, For the longitudinal force of the tire, For the driving torque of the wheels, The rolling resistance coefficient of the wheel. For the wheel radius, Let be the moment of inertia of the wheel about its axis of rotation. This refers to the wheel's angular acceleration; Based on the lateral force of the wheel and the longitudinal force of the tire, calculate the estimated value of the wheel rotation angle: ; ; ; In the formula, For the longitudinal force of the wheel, This is the lateral force of the tire. This is the estimated value for the wheel rotation angle.

[0006] Further, in step S2, the kingpin steering detection angle includes a first wheel steering angle and a second wheel steering angle; the first wheel steering angle is... , The subscript represents the rotation angle at the output of the steering motor. The values ​​1, 2, 3, and 4 represent the front left corner module, front right corner module, rear left corner module, and rear right corner module, respectively. The reduction ratio of the reducer; the second wheel steering angle is the rotation angle at the output end of the reducer. The method for filtering abnormal corner modules is as follows: when a corner module does not meet the requirements... , and Furthermore, if the duration exceeds 5-15 communication cycles, the steering function malfunctions, indicating an abnormal angle module; where, This is the estimated wheel angle. The communication period refers to the time interval between vehicle signal updates.

[0007] Further, in step S3, the method for confirming the wheel rotation angle measurement value is as follows: when When, the second wheel steering angle is used as the wheel steering angle measurement value; when , and When, the first wheel steering angle is used as the measured value of the wheel steering angle; when , and When, the second wheel steering angle is used as the wheel steering angle measurement value; when , and When the wheel angle is estimated, the wheel angle is used as the wheel angle measurement.

[0008] Further, in step S3, the method for screening the fault angle module is as follows: when the difference between the measured wheel angle and the angle control output value is greater than 1° and the duration exceeds 3 to 8 control cycles, the kingpin steering system is faulty, and this is the fault angle module. The control cycle refers to the time interval for the vehicle chassis to complete one complete control cycle.

[0009] Further, in step S4, the method for determining the fault type is as follows: when the change in the wheel angle measurement value between two adjacent control cycles is less than 0.5°, the fault type is kingpin steering gear jamming; when the bus current of the steering motor is less than 0.5A, the fault type is complete failure of the steering motor; when the bus current of the steering motor is not less than 0.5A and less than the rated bus current, the fault type is partial failure of the steering motor.

[0010] Further, step S5 includes the following steps: S51: First, based on the yaw moment provided by the fault angle module when it malfunctions, allocate the yaw moment provided by the target of the normal angle module, and allocate the longitudinal force of the target wheel of the normal angle module according to the proportional weight of the real-time wheel vertical force of the normal angle module; then, calculate the target wheel angle and target wheel driving torque of the normal angle module according to the yaw moment provided by the target of the normal angle module and the longitudinal force of the target wheel; S52: When the fault type is kingpin steering gear sticking and steering motor complete failure, first allocate the yaw moment provided by the target of the fault angle module according to the proportional weight of the real-time wheel vertical force of the fault angle module; if the fault type is kingpin steering gear sticking, the wheel angle of the fault angle module remains unchanged, and calculate the target wheel driving torque of the fault angle module according to the wheel angle and the yaw moment provided by the target when the fault angle module malfunctions; if the fault type is steering motor complete failure, the fault angle... The wheel angle of the module is decoupled from the steering motor control and satisfies the steering dynamics equation of the angle module. Combining the steering dynamics equation of the angle module and the yaw moment provided by the target of the fault angle module, the target driving torque of the wheel of the fault angle module is calculated. When the fault type is a partial failure of the steering motor, the target lateral force of the wheel of the fault angle module is allocated according to the proportional weight of the real-time vertical force of the wheel of the fault angle module. Then, combined with the longitudinal force of the tire when the fault angle module fails, the target wheel angle of the fault angle module is calculated. Again, the yaw moment provided by the target of the fault angle module is allocated according to the proportional weight of the real-time vertical force of the wheel of the fault angle module. Combined with the target wheel angle of the fault angle module, the target driving torque of the wheel of the fault angle module is calculated. According to the proportional weight of the real-time vertical force of the wheel of the normal angle module, the yaw moment provided by the final target of the normal angle module is allocated again. Combined with the target wheel angle of the normal angle module, the final target driving torque of the wheel of the normal angle module is calculated.

[0011] Further, in step S51, the method for obtaining the target wheel rotation angle and target wheel driving torque of the normal angle module is as follows: Based on the yaw moment provided by the faulty angle module when it fails, allocate the yaw moment provided by the target of the normal angle module: ; ; In the formula, Indicates the normal angle module. The values ​​1, 2, 3, and 4 represent the faulty corner modules, specifically the left front corner module, right front corner module, left rear corner module, and right rear corner module, respectively. , The yaw moment provided for the normal angle module target, The total required yaw moment for the vehicle. This provides yaw moment when the fault angle module fails. This represents the number of fault angle modules; The fault angle module's wheel position vector relative to the vehicle's center of mass. and These are the longitudinal force on the wheel and the lateral force on the wheel when the fault angle module fails, respectively. Based on the proportional weight of the real-time vertical force of the wheel in the normal angle module, the longitudinal force of the target wheel in the normal angle module is allocated: ; In the formula, For the longitudinal force of the target wheel in the normal angle module, This refers to the real-time vertical force of the wheel in the normal angle module. For the total longitudinal force required by the vehicle; Based on the yaw moment provided by the normal angle module target and the longitudinal force of the wheel target, calculate the lateral force of the normal angle module wheel target; then, combining the longitudinal force of the normal angle module wheel target and the lateral force of the wheel target, calculate the longitudinal force of the normal angle module tire target and the wheel target rotation angle; finally, based on the longitudinal force of the normal angle module tire target, calculate the driving torque of the normal angle module wheel target.

[0012] Further, in step S52, when the fault type is kingpin steering gear jamming and steering motor complete failure, the method for allocating the yaw moment provided by the fault angle module target according to the proportional weight of the real-time wheel vertical force of the fault angle module is as follows: ; ; In the formula, The yaw moment provided for the fault angle module target, For the fault angle module, real-time wheel vertical force. For the vehicle's real-time yaw moment, For the vehicle's moment of inertia, Real-time angular acceleration of the vehicle; When the fault type is kingpin steering gear sticking, the calculation method for the target driving torque of the fault angle module wheel is as follows: based on the yaw moment provided by the fault angle module target and the wheel rotation angle at the time of the fault, calculate the target longitudinal force of the fault angle module tire, and then calculate the target driving torque of the fault angle module wheel. When the fault type is complete failure of the steering motor, the calculation method for the target driving torque of the wheel of the fault angle module is as follows: After the steering motor completely fails, according to the steering dynamics equation of the angle module, the wheel angle of the fault angle module satisfies the following relationship with the target longitudinal force and the target lateral force of the tire: ; In the formula, The wheel angle of the fault angle module after the steering motor completely fails. Main sales offset For tire trail, and These are the target longitudinal force and target lateral force of the tire in the fault angle module, respectively. The moment of inertia of the fault angle module rotating about the main pin line. The coefficient of friction; Based on the aforementioned relationship, and combined with the yaw moment provided by the fault angle module target, the longitudinal force of the fault angle module tire target is calculated, and then the driving torque of the fault angle module wheel target is calculated.

[0013] Furthermore, in step S52, when the fault type is a partial failure of the steering motor, the method for obtaining the target wheel angle and target wheel driving torque of the fault angle module is as follows: Based on the proportional weight of the real-time vertical force of the wheel in the fault angle module, the target lateral force of the wheel in the fault angle module is allocated: ; In the formula, The force on the wheel target of the fault angle module. For the fault angle module, real-time wheel vertical force. The total required lateral force for the vehicle. For the total mass of the vehicle. This refers to the vehicle's lateral acceleration. The target wheel rotation angle of the fault angle module is calculated based on the lateral force of the target wheel in the fault angle module and the longitudinal force of the tire at the time of fault. The yaw moment provided by the target of the fault angle module is then allocated again based on the proportional weight of the real-time vertical force of the wheel in the fault angle module: ; ; In the formula, The yaw moment provided for the fault angle module target, For the vehicle's real-time yaw moment, For the vehicle's moment of inertia, Real-time angular acceleration of the vehicle; Based on the yaw moment provided by the fault angle module target and the wheel target rotation angle, the longitudinal force of the fault angle module tire target is calculated, and then the driving torque of the fault angle module wheel target is calculated. Based on the proportional weight of the real-time vertical force of the wheels in the normal angle module, the yaw moment provided by the final target of the normal angle module is redistributed: ; In the formula, The yaw moment provided for the final target of the normal angle module; Based on the yaw moment and wheel target angle provided by the final target of the normal angle module, the longitudinal force of the final target of the tire of the normal angle module is calculated, and then the driving torque of the final target of the wheel of the normal angle module is calculated.

[0014] The beneficial effects of this invention are as follows: This invention provides a cross-drive steering redundancy control method for steerable independent steering, which can solve the problem of how to achieve the original trajectory or emergency stop by distributing driving torque through four hub motors when a single or multiple wheel steering motors fail and cannot provide power in distributed drive and steerable independent steering vehicles. Specifically, this method addresses three operating conditions: stuck corner module chassis steering motor or planetary reducer (i.e., stuck kingpin steering), partial failure of the steering motor insufficient to provide sufficient steering driving torque, and complete failure of the steering motor to provide no steering driving torque. It performs cross-system steering redundancy control between the drive system and the rotation system, mainly including angle redundancy, corner module fault diagnosis, and wheel driving torque and angle redistribution. By equipping each corner module kingpin steering unit with hardware and algorithm redundancy of angle sensors, when the steering function of a corner module fails, the current wheel angle can be measured in real time and the fault type can be determined. Then, based on the angle measurement value and the fault type, the wheel driving torque and angle are redistributed, ultimately achieving vehicle control. Attached Figure Description

[0015] Figure 1 This is a flowchart of the steer-by-wire independent steering cross-drive redundancy control method of the present invention; Figure 2 This is a dynamic analysis diagram of each corner module in the tire coordinate system and the vehicle coordinate system; Figure 3 This is a schematic diagram of the height sensor installation; Figure 4 This is a schematic diagram of the installation of an absolute magnetic encoder and a rotary transformer; The labels in the attached diagram are: 1. Lower crossarm; 2. Height sensor; 3. Steering motor; 4. Absolute magnetic encoder; 5. Reducer; 6. Rotary transformer. Detailed Implementation

[0016] The specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0017] like Figure 1 As shown, this invention provides a steer-by-wire independent steering cross-drive steering redundancy control method, comprising the following steps: S1: Perform dynamic analysis of the steering angle of each corner module wheel and calculate the estimated value of the wheel steering angle.

[0018] S2: Based on the wheel angle estimation value and combined with the kingpin steering gear steering detection angle, filter out abnormal steering angle modules with abnormal steering function.

[0019] S3: For abnormal steering angle modules, based on the estimated steering angle and the kingpin steering detection angle, confirm the wheel steering angle measurement value. Then, based on the wheel steering angle measurement value, filter out the faulty angle modules with kingpin steering failures. If the steering function of all angle modules is normal, then normal driving is possible.

[0020] S4: For faulty corner modules, determine the fault type. If there is a corner module with abnormal steering function but no fault in the kingpin steering system, it indicates a mechanical fault, and the vehicle should be taken out of service.

[0021] S5: Based on the fault type, reallocate the wheel driving torque and wheel rotation angle of each corner module to obtain the target wheel driving torque and target wheel rotation angle of each corner module.

[0022] Dynamic analysis of each module in the tire coordinate system and the vehicle coordinate system as follows Figure 2 As shown.

[0023] Specifically, in step S1, the method for calculating the estimated wheel angle is as follows: Figure 3 As shown, a height sensor 2 is installed between the lower crossarm 1 of the corner module and the vehicle frame. The height sensor 2 is used to measure the voltage reflecting the amount of lower crossarm movement. Specifically, the height sensor 2 can convert the height of the lower crossarm movement into an angle through the geometric relationship between its upper and lower arms. During the rotation of the upper arm, the resistance value of the internal resistor changes, thereby changing the output voltage. The voltage increases when the lower crossarm moves upward and decreases when it moves downward. Therefore, by detecting the output voltage of the height sensor, the amount of lower crossarm movement can be calculated, thereby determining the vertical load distribution of the vehicle.

[0024] Calculate the vertical force on the wheel based on the output voltage of the height sensor: ; In the formula, The vertical force on the wheel, The values ​​1, 2, 3, and 4 represent the front left corner module, front right corner module, rear left corner module, and rear right corner module, respectively. The output voltage of the altitude sensor. The average value of the output voltage of all corner module height sensors. , For the total mass of the vehicle. This is the acceleration due to gravity.

[0025] Calculate the lateral force on the wheel and the longitudinal force on the tire based on the vertical force on the wheel: ; In the formula, This refers to the lateral force exerted on the wheel, specifically the lateral force of the wheel within the vehicle's coordinate system. The lateral acceleration of the vehicle is measured by the IMU.

[0026] ; In the formula, This refers to the longitudinal force of the tire, that is, the longitudinal force of the tire in the tire coordinate system. For the driving torque of the wheels, The rolling resistance coefficient of the wheel. For the wheel radius, Let be the moment of inertia of the wheel about its axis of rotation. The wheel angular acceleration is calculated by filtering and differentiating the angular position signal of the hub motor rotor.

[0027] Calculate the estimated wheel angle based on the lateral force on the wheel and the longitudinal force on the tire: ; ; ; In the formula, This refers to the longitudinal force of the wheel, that is, the longitudinal force of the wheel in the vehicle's coordinate system. This refers to the tire's lateral force, which is the force exerted by the tire in the tire's coordinate system. This is an estimated value for the wheel rotation angle.

[0028] In step S2, the kingpin steering system steering angle detection includes the first wheel steering angle and the second wheel steering angle. The first wheel steering angle is... , The rotation angle at the output of the steering motor is detected by an absolute magnetic encoder 4 mounted on the steering motor 3, such as... Figure 4 As shown. Specifically, when the magnet of the absolute magnetic encoder 4 rotates with the motor shaft, the change in magnetic field strength or direction is captured by the sensor array and decoded by the ASIC chip into a unique absolute angle value. , This refers to the reduction ratio of the reducer. The steering angle of the second wheel is the rotation angle at the output end of the reducer. The result was obtained through the rotary transformer 6 installed on the reducer 5, such as... Figure 4 As shown. Specifically, an AC excitation signal is applied to the stator winding of the rotary transformer 6, and the magnetic field induced in the rotor winding changes with the rotation angle, outputting two orthogonal sine and cosine signals. A dedicated decoding chip converts the analog signals into digital angle values. .

[0029] The filtering method for abnormal corner modules is as follows: when a corner module does not meet the requirements... , and If the duration exceeds 5-15 communication cycles, the steering function is abnormal, indicating an abnormal angle module.

[0030] In step S3, the method for confirming the wheel angle measurement value is as follows: when At that time, the absolute magnetic encoder and rotary transformer were functioning normally, but the redundant backup of the wheel angle estimation algorithm failed, so the second wheel steering angle was used as the wheel angle measurement value.

[0031] when , and At that time, the absolute magnetic encoder and the wheel angle estimation algorithm redundancy backup were normal, but the rotary transformer failed, so the first wheel steering angle was used as the wheel angle measurement value.

[0032] when , and At that time, the redundant backup of the rotary transformer and the wheel angle estimation algorithm was normal, but the absolute magnetic encoder malfunctioned, so the second wheel steering angle was used as the wheel angle measurement value.

[0033] when , and When the rotary transformer and absolute magnetic encoder malfunction, the wheel angle estimation value is used as the wheel angle measurement value.

[0034] The screening method for fault angle modules is as follows: when the difference between the wheel angle measurement value and the angle control output value is greater than 1° and the duration exceeds 3 to 8 control cycles, the kingpin steering system is faulty, which is a fault angle module.

[0035] In step S4, the method for determining the fault type is as follows: When the change in wheel angle measurement between two adjacent control cycles is less than 0.5°, the fault type is master pin steering sticking.

[0036] When the bus current of the steering motor is less than 0.5A, the fault type is complete failure of the steering motor.

[0037] When the bus current of the steering motor is not less than 0.5A and is less than the rated bus current, the fault type is steering motor partial failure.

[0038] Step S5 includes the following steps: S51: First, based on the yaw moment provided by the faulty angle module when it fails, allocate the yaw moment provided by the normal angle module target. Then, based on the proportional weight of the real-time wheel vertical force of the normal angle module, allocate the longitudinal force of the wheel target of the normal angle module. Next, based on the yaw moment provided by the normal angle module target and the longitudinal force of the wheel target, calculate the wheel target rotation angle and wheel target driving torque of the normal angle module.

[0039] Specifically, the method for obtaining the target wheel rotation angle and target wheel driving torque of the normal angle module is as follows: Based on the yaw moment provided by the faulty angle module when it fails, allocate the yaw moment provided by the target of the normal angle module: ; ; In the formula, Indicates the normal angle module. The values ​​1, 2, 3, and 4 represent the faulty corner modules, specifically the left front corner module, right front corner module, left rear corner module, and right rear corner module, respectively. , The yaw moment provided for the normal angle module target, The total required yaw moment for the vehicle. This provides yaw moment when the fault angle module fails. This represents the number of fault angle modules. The fault angle module's wheel position vector relative to the vehicle's center of mass. , This is the distance from the vehicle's center of gravity to the front axle. This is the distance from the vehicle's center of gravity to the rear axle. This is the length of the front axle. Rear axle length and These represent the longitudinal force on the wheel and the lateral force on the wheel when the fault angle module fails, respectively.

[0040] The calculation methods for the longitudinal force on the wheel and the lateral force on the wheel when the fault angle module fails are as follows: Calculate the longitudinal force on the tires when the fault angle module fails, based on the wheel driving torque. ; ; In the formula, This refers to the longitudinal force on the tire when the fault angle module fails. This refers to the wheel drive torque when the fault angle module fails. For the fault angle module, real-time wheel vertical force. The height sensor of the fault angle module outputs a voltage in real time, at which time... This refers to the vertical force on the wheel calculated from the output voltage of the height sensor in the fault angle module when a fault occurs. For the fault angle module, the real-time wheel angular acceleration at this time This refers to the wheel angular acceleration obtained from the fault angle module when a fault occurs.

[0041] Based on the longitudinal force of the tire and the wheel rotation angle at the time of the fault angle module failure, the lateral force of the tire at the time of the fault angle module failure is obtained: ; In the formula, This refers to the tire lateral force when the fault angle module fails. This refers to the wheel angle when the fault angle module fails, specifically the wheel angle measurement value obtained from S3. The vertical force of the wheel is still calculated from the output voltage of the height sensor of the fault angle module when the fault occurs.

[0042] Based on the tire lateral force, tire longitudinal force, and wheel rotation angle at the time of fault angle module failure, calculate the longitudinal force and lateral force of the wheel at the time of fault angle module failure:

[0043] .

[0044] Based on the proportional weight of the real-time vertical force of the wheel in the normal angle module, the longitudinal force of the target wheel in the normal angle module is allocated: ; ; In the formula, For the longitudinal force of the target wheel in the normal angle module, This refers to the real-time vertical force of the wheel in the normal angle module. The height sensor of the normal angle module outputs a voltage in real time. This refers to the vertical force on the wheel calculated from the output voltage of the height sensor of the normal angle module after the normal angle module adjusts according to the yaw moment provided by its target. The longitudinal force required by the vehicle.

[0045] Based on the yaw moment provided by the normal angle module target and the longitudinal force of the wheel target, calculate the lateral force of the wheel target of the normal angle module: ; In the formula, This represents the position vector of the wheel relative to the vehicle's center of mass in the normal angle module. The force is the lateral force on the target wheel of the normal angle module.

[0046] Combining the longitudinal force and lateral force of the wheel target in the normal angle module, calculate the longitudinal force of the tire target and the wheel target rotation angle in the normal angle module:

[0047]

[0048] ; In the formula, , and These represent the target longitudinal force of the tire, the target lateral force of the tire, and the target wheel rotation angle, respectively, for the normal angle module. The vertical force of the wheel is calculated by the output voltage of the height sensor of the normal angle module after the yaw moment provided by the normal angle module is adjusted according to the target.

[0049] Then, based on the target longitudinal force of the tires in the normal angle module, calculate the target driving torque of the wheels in the normal angle module: ; In the formula, The target driving torque for the wheels of the normal angle module. For the real-time wheel angular acceleration of the normal angle module, at this time... The vertical force of the wheel, calculated by the output voltage of the height sensor of the normal angle module after adjustment according to the yaw moment provided by its target, is still the same. The wheel angular acceleration of the normal angle module is obtained after the normal angle module is adjusted according to the yaw moment provided by its target.

[0050] S52: When the fault type is kingpin steering gear sticking and steering motor complete failure, first allocate the yaw moment provided by the fault angle module according to the proportional weight of the real-time wheel vertical force of the fault angle module: ; ; In the formula, The yaw moment provided for the fault angle module target, For the vehicle's real-time yaw moment, Let be the moment of inertia of the vehicle about the z-axis. The real-time angular acceleration of the vehicle is indirectly calculated from the vehicle's angular velocity using a differential algorithm and Kalman filtering. The vehicle's angular velocity is measured by an IMU. This refers to the vehicle angular acceleration adjusted by the normal angle module according to the target wheel rotation angle and target wheel driving torque. The vertical force of the wheel is calculated by the output voltage of the height sensor of the fault angle module after the normal angle module is adjusted according to its target wheel rotation angle and target wheel driving torque.

[0051] If the fault type is master pin steering sticking, the wheel angle of the fault angle module remains unchanged. Based on the wheel angle when the fault angle module fails and the yaw moment provided by the target, the target driving torque of the wheel of the fault angle module is calculated.

[0052] Specifically, based on the yaw moment provided by the fault angle module target and the wheel rotation angle at the time of failure, the longitudinal force of the tire target of the fault angle module is calculated:

[0053]

[0054]

[0055] ; In the formula, , , and These are the longitudinal force on the wheel target, the lateral force on the wheel target, the longitudinal force on the tire target, and the lateral force on the tire target, respectively, at this time... The vertical force of the wheel is calculated by the height sensor output voltage of the faulty angle module after the normal angle module is adjusted according to the target wheel angle and the target wheel driving torque.

[0056] Then, based on the target longitudinal force of the tires in the fault angle module, the target driving torque of the wheels in the fault angle module is calculated: ; In the formula, The target driving torque for the wheel of the fault angle module is at this time. The vertical force of the wheel, calculated by the height sensor output voltage of the faulty angle module after the normal angle module adjusts according to its target wheel rotation angle and target wheel driving torque, is still the same. The wheel angular acceleration of the faulty angle module is obtained after the normal angle module is adjusted according to its target wheel rotation angle and target wheel driving torque.

[0057] If the fault type is complete failure of the steering motor, the wheel angle of the faulty angle module is out of control of the steering motor and satisfies the steering dynamics equation of the angle module. Combining the steering dynamics equation of the angle module and the yaw moment provided by the target of the faulty angle module, the target driving torque of the wheel of the faulty angle module is calculated.

[0058] Specifically, after the steering motor completely fails, according to the steering dynamics equation of the angle module, the wheel angle of the failed angle module satisfies the following relationship with the target longitudinal force and the target lateral force of the tire: ; In the formula, The wheel angle of the fault angle module after the steering motor completely fails. Main sales offset For tire trail, The moment of inertia of the fault angle module rotating about the main pin line. is the coefficient of friction.

[0059] Based on the above relationship and the yaw moment provided by the fault angle module target, calculate the longitudinal force of the fault angle module tire target:

[0060]

[0061]

[0062] ; At this time The vertical force of the wheel is calculated by the output voltage of the height sensor of the fault angle module after the normal angle module is adjusted according to its target wheel rotation angle and target wheel driving torque.

[0063] Then, based on the target longitudinal force of the tires in the fault angle module, the target driving torque of the wheels in the fault angle module is calculated: ; At this time The vertical force of the wheel is calculated by the height sensor output voltage of the faulty angle module after the normal angle module has adjusted according to its target wheel rotation angle and target wheel driving torque. The wheel angular acceleration of the faulty angle module is obtained after the normal angle module is adjusted according to its target wheel rotation angle and target wheel driving torque.

[0064] When the fault type is a partial failure of the steering motor, the target lateral force of the wheel in the fault angle module is allocated according to the proportional weight of the real-time vertical force of the wheel in the fault angle module. This, combined with the longitudinal force of the tire at the time of the fault angle module failure, is used to calculate the target steering angle of the wheel in the fault angle module. Then, based on the proportional weight of the real-time vertical force of the wheel in the fault angle module, the yaw moment provided by the target of the fault angle module is allocated, and combined with the target steering angle of the wheel in the fault angle module, the target driving torque of the wheel in the fault angle module is calculated. Finally, based on the proportional weight of the real-time vertical force of the wheel in the normal angle module, the yaw moment provided by the final target of the normal angle module is allocated again, and combined with the target steering angle of the wheel in the normal angle module, the final target driving torque of the wheel in the normal angle module is calculated.

[0065] Specifically, based on the proportional weight of the real-time vertical force of the wheel in the fault angle module, the target lateral force of the wheel in the fault angle module is allocated: ; In the formula, For the total required lateral force of the vehicle, at this time The vertical force of the wheel is calculated by the height sensor output voltage of the faulty angle module after the normal angle module has adjusted according to its target wheel rotation angle and target wheel driving torque. The lateral acceleration of the vehicle is measured after the normal angle module is adjusted according to the target wheel rotation angle and target wheel driving torque.

[0066] Calculate the target wheel rotation angle of the fault angle module based on the lateral force on the target wheel and the longitudinal force on the tire at the time of fault: ; ; In the formula, The target wheel rotation angle for the fault angle module is at this time. The vertical force of the wheel is calculated by the output voltage of the height sensor of the faulty angle module after the normal angle module is adjusted according to its target wheel rotation angle and target wheel driving torque.

[0067] The yaw moment provided by the target of the fault angle module is then allocated again based on the proportional weight of the real-time vertical force of the wheel in the fault angle module: ; ; In the formula, The yaw moment provided to the target of the fault angle module, at this time The vertical force on the wheel is calculated from the output voltage of the height sensor of the fault angle module after the fault angle module is adjusted according to the lateral force on the target wheel. The vehicle angular acceleration is adjusted by the fault angle module according to the force on the target side of its wheels.

[0068] Based on the yaw moment provided by the fault angle module target and the wheel target rotation angle, calculate the longitudinal force of the tire target in the fault angle module:

[0069]

[0070]

[0071] ; In the formula, and These are the final wheel target lateral force and the final tire target lateral force of the fault angle module after the yaw moment provided by the fault angle module target is allocated. The vertical force of the wheel is still calculated by the output voltage of the height sensor of the fault angle module after the fault angle module adjusts the force on the side of the target wheel.

[0072] Then, based on the target longitudinal force of the tires in the fault angle module, the target driving torque of the wheels in the fault angle module is calculated: ; At this time The vertical force of the wheel is still calculated by the output voltage of the height sensor of the fault angle module after the fault angle module adjusts according to the force on the side of the wheel target. The wheel angular acceleration of the fault angle module is obtained after the fault angle module is adjusted according to the force on the side of its wheel target.

[0073] Based on the proportional weight of the real-time vertical force of the wheels in the normal angle module, the yaw moment provided by the final target of the normal angle module is redistributed: ; ; In the formula, The yaw moment provided for the final target of the normal angle module, at this time The vertical force on the wheel is calculated by the output voltage of the height sensor of the normal angle module after the fault angle module is adjusted according to the lateral force of its wheel target. The vehicle angular acceleration is still adjusted by the fault angle module according to the force on the target side of its wheels.

[0074] Based on the yaw moment and wheel target rotation angle provided by the normal angle module's final target, calculate the longitudinal force of the tire at the final target of the normal angle module:

[0075]

[0076]

[0077] ; In the formula, , , These represent the final longitudinal force of the wheel target, the final lateral force of the wheel target, the final longitudinal force of the tire target, and the final lateral force of the tire target, respectively, for the normal angle module. The vertical force of the wheel is calculated by the output voltage of the height sensor of the normal angle module after the fault angle module adjusts the force according to the target lateral force of the wheel.

[0078] Then, based on the final target longitudinal force of the tire in the normal angle module, the final target driving torque of the wheel in the normal angle module is calculated: ; In the formula, For the final target driving torque of the normal angle module wheel, at this time The vertical force of the wheel is calculated by the output voltage of the height sensor of the normal angle module after the faulty angle module adjusts according to the lateral force of its wheel target. The wheel angular acceleration of the normal angle module is obtained after the fault angle module is adjusted according to the force on the side of its wheel target.

[0079] In this invention, unless otherwise stated, scientific and technical terms used herein have the meanings commonly understood by those skilled in the art.

[0080] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A steer-by-wire independent steering cross-drive redundancy control method, characterized in that: Includes the following steps: S1: Perform dynamic analysis of the steering angle of each corner module wheel and calculate the estimated value of the wheel steering angle; The method for calculating the estimated wheel angle is as follows: A height sensor is installed between the lower control arm of the corner module and the vehicle frame. This height sensor measures a voltage reflecting the movement of the lower control arm. Based on the voltage output from the height sensor, the vertical force on the wheel is calculated. ； In the formula, The vertical force on the wheel, The values ​​1, 2, 3, and 4 represent the front left corner module, front right corner module, rear left corner module, and rear right corner module, respectively. The height sensor outputs voltage. The average value of the output voltage of all corner module height sensors. , For the total mass of the vehicle. It is the acceleration due to gravity; Based on the vertical force of the wheel, calculate the lateral force of the wheel and the longitudinal force of the tire: ； In the formula, The force acting on the side of the wheel. This refers to the vehicle's lateral acceleration. ； In the formula, For the longitudinal force of the tire, For the driving torque of the wheels, The rolling resistance coefficient of the wheel. For the wheel radius, Let be the moment of inertia of the wheel about its axis of rotation. This refers to the wheel's angular acceleration. Based on the lateral force of the wheel and the longitudinal force of the tire, calculate the estimated value of the wheel rotation angle: ； ； ； In the formula, For the longitudinal force of the wheel, This is the lateral force of the tire. This is the estimated value of the wheel rotation angle; S2: Based on the estimated wheel angle and the kingpin steering detection angle, filter out modules with abnormal steering angles that cause steering malfunctions. S3: For the steering abnormal angle module, based on the estimated angle value and the kingpin steering detection angle, confirm the wheel angle measurement value; then, based on the wheel angle measurement value, filter the fault angle modules for kingpin steering failure. S4: For the fault angle module, determine the fault type; The method for determining the fault type is as follows: When the change in the wheel angle measurement value between two adjacent control cycles is less than 0.5°, the fault type is kingpin steering sticking. When the bus current of the steering motor is less than 0.5A, the fault type is complete failure of the steering motor. When the bus current of the steering motor is not less than 0.5A and is less than the rated bus current, the fault type is a partial failure of the steering motor. S5: Based on the fault type, reallocate the wheel driving torque and wheel rotation angle of each corner module to obtain the target wheel driving torque and target wheel rotation angle of each corner module.

2. The steer-by-wire independent steering cross-drive steering redundancy control method according to claim 1, characterized in that: In step S2, the kingpin steering detection angle includes a first wheel steering angle and a second wheel steering angle; the first wheel steering angle is... , The subscript represents the rotation angle at the output of the steering motor. The values ​​1, 2, 3, and 4 represent the front left corner module, front right corner module, rear left corner module, and rear right corner module, respectively. The reduction ratio of the reducer; the second wheel steering angle is the rotation angle at the output end of the reducer. ; The method for filtering abnormal corner modules is as follows: when a corner module does not meet the requirements... , and Furthermore, if the duration exceeds 5-15 communication cycles, the steering function malfunctions, indicating an abnormal angle module; where, This is the estimated value for the wheel rotation angle.

3. The steer-by-wire independent steering cross-drive steering redundancy control method according to claim 2, characterized in that: In step S3, the method for confirming the wheel angle measurement value is as follows: when When the second wheel steering angle is used as the wheel steering angle measurement value; when , and When the first wheel steering angle is used as the wheel steering angle measurement value; when , and When the second wheel steering angle is used as the wheel steering angle measurement value; when , and When the wheel angle is estimated, the wheel angle is used as the wheel angle measurement.

4. The steer-by-wire independent steering cross-drive redundancy control method according to claim 1, characterized in that: In step S3, the method for screening the fault angle module is as follows: when the difference between the wheel angle measurement value and the angle control output value is greater than 1° and the duration exceeds 3 to 8 control cycles, the kingpin steering system is faulty, which is the fault angle module.

5. The steer-by-wire independent steering cross-drive redundancy control method according to claim 1, characterized in that: Step S5 includes the following steps: S51: First, based on the yaw moment provided by the faulty angle module when it fails, allocate the yaw moment provided by the normal angle module target, and allocate the longitudinal force of the normal angle module wheel target according to the proportional weight of the real-time wheel vertical force of the normal angle module; then, calculate the wheel target rotation angle and wheel target driving torque of the normal angle module based on the yaw moment provided by the normal angle module target and the longitudinal force of the wheel target. S52: When the fault type is kingpin steering gear jamming and steering motor complete failure, first allocate the yaw torque provided by the fault angle module target according to the proportional weight of the real-time wheel vertical force of the fault angle module. If the fault type is kingpin steering gear sticking, the wheel angle of the fault angle module remains unchanged. Based on the wheel angle when the fault angle module fails and the yaw moment provided by the target, the target driving torque of the wheel of the fault angle module is calculated. If the fault type is complete failure of the steering motor, the wheel angle of the fault angle module is out of control of the steering motor and satisfies the steering dynamics equation of the angle module. Combining the steering dynamics equation of the angle module and the yaw moment provided by the target of the fault angle module, the target driving torque of the wheel of the fault angle module is calculated. When the fault type is a partial failure of the steering motor, the target lateral force of the wheel of the fault angle module is allocated according to the proportional weight of the real-time vertical force of the wheel of the fault angle module. Then, combined with the longitudinal force of the tire when the fault angle module fails, the target turning angle of the wheel of the fault angle module is calculated. Next, according to the proportional weight of the real-time vertical force of the wheel of the fault angle module, the yaw moment provided by the target of the fault angle module is allocated. Combined with the target turning angle of the wheel of the fault angle module, the target driving torque of the wheel of the fault angle module is calculated. According to the proportional weight of the real-time vertical force of the wheel of the normal angle module, the yaw moment provided by the final target of the normal angle module is allocated again. Combined with the target turning angle of the wheel of the normal angle module, the final target driving torque of the wheel of the normal angle module is calculated.

6. The steer-by-wire independent steering cross-drive redundancy control method according to claim 5, characterized in that: In step S51, the method for obtaining the target wheel rotation angle and target wheel driving torque of the normal angle module is as follows: Based on the yaw moment provided by the faulty angle module when it fails, allocate the yaw moment provided by the target of the normal angle module: ； ； In the formula, Indicates the normal angle module. The values ​​1, 2, 3, and 4 represent the faulty corner modules, specifically the left front corner module, right front corner module, left rear corner module, and right rear corner module, respectively. , The yaw moment provided for the normal angle module target, The total required yaw moment for the vehicle. This provides yaw moment when the fault angle module fails. This represents the number of fault angle modules; The fault angle module's wheel position vector relative to the vehicle's center of mass. and These are the longitudinal force on the wheel and the lateral force on the wheel when the fault angle module fails, respectively. Based on the proportional weight of the real-time vertical force of the wheel in the normal angle module, the longitudinal force of the target wheel in the normal angle module is allocated: ； In the formula, For the longitudinal force of the target wheel in the normal angle module, This refers to the real-time vertical force of the wheel in the normal angle module. For the total longitudinal force required by the vehicle; Calculate the lateral force of the wheel target in the normal angle module based on the yaw moment provided by the target and the longitudinal force of the wheel target. Then, combining the longitudinal force and lateral force of the wheel target in the normal angle module, calculate the longitudinal force of the tire target and the wheel target rotation angle in the normal angle module; then, based on the longitudinal force of the tire target in the normal angle module, calculate the driving torque of the wheel target in the normal angle module.

7. The steer-by-wire independent steering cross-drive steering redundancy control method according to claim 6, characterized in that: In step S52, when the fault type is kingpin steering gear jamming and steering motor complete failure, the method for allocating the yaw moment provided by the fault angle module target according to the proportional weight of the real-time wheel vertical force of the fault angle module is as follows: ； ； In the formula, The yaw moment provided for the fault angle module target, For the fault angle module, real-time wheel vertical force. For the real-time yaw moment of the vehicle, For the vehicle's moment of inertia, Real-time angular acceleration of the vehicle; When the fault type is kingpin steering gear sticking, the calculation method for the target driving torque of the fault angle module wheel is as follows: based on the yaw moment provided by the fault angle module target and the wheel rotation angle at the time of the fault, calculate the target longitudinal force of the fault angle module tire, and then calculate the target driving torque of the fault angle module wheel. When the fault type is complete failure of the steering motor, the calculation method for the target driving torque of the wheel of the fault angle module is as follows: After the steering motor completely fails, according to the steering dynamics equation of the angle module, the wheel angle of the failed angle module satisfies the following relationship with the target longitudinal force and the target lateral force of the tire: ； In the formula, The wheel angle of the fault angle module after the steering motor completely fails. Main sales offset For tire trail, and These are the target longitudinal force and target lateral force of the tire in the fault angle module, respectively. The moment of inertia of the fault angle module rotating about the main pin line. The coefficient of friction; Based on the aforementioned relationship, and combined with the yaw moment provided by the fault angle module target, the longitudinal force of the fault angle module tire target is calculated, and then the driving torque of the fault angle module wheel target is calculated.

8. The steer-by-wire independent steering cross-drive steering redundancy control method according to claim 6, characterized in that: In step S52, when the fault type is a partial failure of the steering motor, the method for obtaining the target wheel angle and target wheel driving torque of the fault angle module is as follows: Based on the proportional weight of the real-time vertical force of the wheel in the fault angle module, the target lateral force of the wheel in the fault angle module is allocated: ； In the formula, The force on the wheel target of the fault angle module. For the fault angle module, real-time wheel vertical force. The total required lateral force for the vehicle. For the total mass of the vehicle. This refers to the vehicle's lateral acceleration. The target wheel rotation angle of the fault angle module is calculated based on the lateral force of the target wheel in the fault angle module and the longitudinal force of the tire at the time of fault. The yaw moment provided by the target of the fault angle module is then allocated again based on the proportional weight of the real-time vertical force of the wheel in the fault angle module: ； ； In the formula, The yaw moment provided for the fault angle module target, For the vehicle's real-time yaw moment, For the vehicle's moment of inertia, Real-time angular acceleration of the vehicle; Based on the yaw moment provided by the fault angle module target and the wheel target rotation angle, the longitudinal force of the fault angle module tire target is calculated, and then the driving torque of the fault angle module wheel target is calculated. Based on the proportional weight of the real-time vertical force of the wheels in the normal angle module, the yaw moment provided by the final target of the normal angle module is redistributed: ； In the formula, The yaw moment provided for the final target of the normal angle module; Based on the yaw moment and wheel target angle provided by the final target of the normal angle module, the longitudinal force of the final target of the tire of the normal angle module is calculated, and then the driving torque of the final target of the wheel of the normal angle module is calculated.

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