Torque distribution control method for distributed driving electric vehicle adapting to ramp driving

Abstract

The invention discloses a torque distribution control method for a distributed driving electric vehicle adapting to ramp driving. The method comprises the following steps: constructing a longitudinal motion tracking controller based on ESO-PI and a yaw motion controller based on SMC, and respectively calculating an expected longitudinal moment and an additional yaw moment through the longitudinal motion tracking controller based on ESO-PI and the yaw motion controller based on SMC; and constructing an optimal torque distribution controller fused with anti-slip control, and calculating an expected motor torque through the optimal torque distribution controller fused with anti-slip control based on the expected longitudinal torque and the additional yawing torque so as to perform torque distribution control of the distributed driving electric vehicle. According to the invention, the problems of instability, slipping and large energy loss when the distributed driving vehicle runs on a ramp and a low-adhesion road surface are effectively solved, and the motion tracking precision, the running stability and the energy economy of the vehicle are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle control technology, and more specifically to a torque distribution control method for distributed drive electric vehicles adapted to slope driving. Background Technology

[0002] With the widespread application of electric vehicles in complex road conditions such as mountainous areas and off-road terrain, distributed drive electric vehicles with four-wheel independent drive have shown significant advantages in terms of drive anti-slip, differential steering, and fault-tolerant control due to their redundant drive capabilities and independent control characteristics.

[0003] In existing technologies, torque distribution control in distributed drive vehicles often employs a hierarchical control structure: the upper-level controller is responsible for motion tracking, while the lower-level controller is responsible for torque distribution. The upper level typically uses a PI controller for longitudinal control and sliding mode control or model predictive control for yaw control; the lower level uses methods such as quadratic programming to distribute torque with the goal of minimizing tire load rate.

[0004] However, existing methods have the following problems: they do not take into account the driving conditions on slopes, cannot accurately estimate the road slope angle, and affect the power distribution of the whole vehicle; when turning on a slope, the vertical load on the tires changes drastically, which can easily lead to slippage and instability; and traditional strategies have high energy loss and short driving range when driving on slopes. Summary of the Invention

[0005] To address the aforementioned shortcomings in the prior art, this invention provides a distributed drive electric vehicle torque distribution control method adapted to slope driving.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A torque distribution control method for distributed drive electric vehicles adapted to slope driving includes the following steps: S1. Construct a longitudinal motion tracking controller based on ESO-PI and a yaw motion controller based on SMC, and calculate the desired longitudinal torque and additional yaw torque respectively using the longitudinal motion tracking controller based on ESO-PI and the yaw motion controller based on SMC. S2. Construct an optimized torque distribution controller that integrates anti-slip control, and calculate the desired motor torque based on the desired longitudinal torque and additional yaw torque through the optimized torque distribution controller that integrates anti-slip control, so as to perform torque distribution control of distributed drive electric vehicles.

[0007] Further, step S1 includes the following steps: S11. Construct an ESO slope torque compensation controller based on an extended state observer, and a PI speed controller based on a PI controller to construct an ESO-PI based longitudinal motion tracking controller. The ESO slope torque compensation controller observes the road slope and vehicle mass in real time, calculates the slope longitudinal compensation torque by combining vehicle state parameters, calculates the expected longitudinal torque under the deviation between the expected longitudinal vehicle speed and the actual longitudinal vehicle speed by the PI controller, and calculates the expected longitudinal torque based on the slope longitudinal compensation torque and the expected longitudinal torque under the deviation between the expected longitudinal vehicle speed and the actual longitudinal vehicle speed. S12. Construct an SMC yaw motion controller based on sliding diaphragm control, and calculate the additional yaw torque through the SMC-based yaw motion controller.

[0008] Further, in step S11, the desired longitudinal moment is calculated based on the longitudinal compensation moment of the ramp and the desired longitudinal moment under the deviation between the desired longitudinal speed and the actual longitudinal speed, and is expressed as:

[0009] in: For the desired longitudinal moment, For the overall vehicle quality, It is the acceleration due to gravity. For the wheel radius, For road slope, For vehicle yaw angle, , These are all parameters for a PI torque controller. For the desired longitudinal speed, This refers to the actual longitudinal speed. For time.

[0010] Further, step S2 includes the following steps: S21. Construct an optimal torque distribution controller, combine the observed wheel slip rate with road conditions to construct an anti-skid controller, and construct an optimal torque distribution controller that integrates anti-skid control based on the optimal torque distribution controller and the anti-skid controller. S22. Based on the desired longitudinal torque, additional yaw torque, and lower-level controller, calculate the anti-slip control torque and optimal torque, and calculate the desired motor torque according to the anti-slip control torque and optimal torque to perform torque distribution control of distributed drive electric vehicles.

[0011] Further, in step S21, the optimal torque distribution controller is represented as:

[0012] in: This is the input to the optimal torque distribution controller. ( () represents the longitudinal force of each tire. Indicates the front left tire. Indicates the front right tire. Indicates the rear left tire. Indicates the rear right tire. This is the matrix transpose operator. It is the coefficient matrix of the quadratic terms. It is a diagonal matrix. For each tire, the coefficients of the quadratic term are... This is the inequality constraint coefficient matrix. For one The identity matrix, The inequality constraint matrix is... For the inequality constraints of each tire, This is the equation constraint coefficient matrix. For vehicle yaw angle, These are the constraint coefficients for each tire equation. These are the equality constraint coefficients. This is the motor torque. To add yaw moment, For minimum state constraints, This is the maximum torque of the tire. For the wheel radius, For maximum state constraints, , All are target weight coefficients. For each tire, the coefficient of adhesion. The force exerted vertically downwards on each tire. To output the desired torque to each tire controller, For each tire torque coefficient.

[0013] Further, in step S21, the anti-slip controller is represented as:

[0014] in: To control the torque for slip prevention, , , All are PID anti-slip controller coefficients. These are the coefficients of adhesion for each tire. , Indicates the front left tire. Indicates the front right tire. Indicates the rear left tire. Indicates the rear right tire. The optimal slip ratio for the current road surface. For time, These are the slip rates corresponding to each tire. The optimal rate of change of slip ratio This represents the rate of change of wheel slip ratio.

[0015] Further, in step S22, the desired motor torque is calculated based on the anti-slip control torque and the optimal torque, expressed as:

[0016] in: These represent the expected motor torque for each tire. , Indicates the front left tire. Indicates the front right tire. Indicates the rear left tire. Indicates the rear right tire. Optimize the torque for each tire. These are the anti-skid control torques for each tire.

[0017] The beneficial effects of this invention are as follows: (1) This invention constructs a longitudinal motion tracking controller based on ESO-PI and a yaw motion controller based on SMC, and calculates the desired longitudinal torque and additional yaw torque by the longitudinal motion tracking controller based on ESO-PI and the yaw motion controller based on SMC respectively, thereby improving the accuracy of the upper controller in calculating the desired longitudinal torque and additional yaw torque of the whole vehicle. (3) This invention constructs an optimized torque distribution controller that integrates anti-slip control, and calculates the desired motor torque based on the desired longitudinal torque and the additional yaw torque, so as to carry out torque distribution control of distributed drive electric vehicles. This solves the problem of wheel slippage when distributed drive vehicles drive at differential speed on slopes, improves the vehicle's driving ability on complex roads, and further reduces the energy consumption of the whole vehicle. Attached Figure Description

[0018] Figure 1 A schematic diagram of a distributed drive electric vehicle torque distribution control method to adapt to slope driving. Figure 2 A statistical chart of wheel slip rate without anti-skid control; Figure 3 This is a statistical chart of wheel slip rate with anti-skid control. Detailed Implementation

[0019] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0020] like Figure 1 As shown, the torque distribution control method for distributed drive electric vehicles adapted to slope driving includes steps S1-S2, as detailed below: S1. Construct a longitudinal motion tracking controller based on ESO-PI and a yaw motion controller based on SMC, and calculate the desired longitudinal torque and additional yaw torque using the longitudinal motion tracking controller based on ESO-PI and the yaw motion controller based on SMC, respectively.

[0021] In an optional embodiment of the present invention, step S1 includes the following steps: S11. Construct an ESO slope torque compensation controller based on an extended state observer, and a PI speed controller based on a PI controller to build an ESO-PI based longitudinal motion tracking controller. The ESO slope torque compensation controller observes the road slope and vehicle mass in real time, calculates the slope longitudinal compensation torque by combining vehicle state parameters, calculates the expected longitudinal torque under the deviation between the expected longitudinal vehicle speed and the actual longitudinal vehicle speed by the PI controller, and calculates the expected longitudinal torque based on the slope longitudinal compensation torque and the expected longitudinal torque under the deviation between the expected longitudinal vehicle speed and the actual longitudinal vehicle speed.

[0022] This invention calculates the desired longitudinal moment based on the longitudinal compensation moment of the ramp and the desired longitudinal moment under the deviation between the desired longitudinal speed and the actual longitudinal speed, expressed as:

[0023] in: For the desired longitudinal moment, For the overall vehicle quality, It is the acceleration due to gravity. For the wheel radius, For road slope, For vehicle yaw angle, , These are all parameters for a PI torque controller. For the desired longitudinal speed, This refers to the actual longitudinal speed. For time.

[0024] S12. Construct an SMC yaw motion controller based on sliding diaphragm control, and calculate the additional yaw torque through the SMC-based yaw motion controller.

[0025] S2. Construct an optimized torque distribution controller that integrates anti-slip control, and calculate the desired motor torque based on the desired longitudinal torque and additional yaw torque through the optimized torque distribution controller that integrates anti-slip control, so as to perform torque distribution control of distributed drive electric vehicles.

[0026] In an optional embodiment of the present invention, step S2 includes the following steps: S21. Construct an optimal torque distribution controller, combine the observed wheel slip rate with road conditions to construct an anti-skid controller, and construct an optimal torque distribution controller that integrates anti-skid control based on the optimal torque distribution controller and the anti-skid controller.

[0027] The optimal torque distribution controller is represented as:

[0028] in: This is the input to the optimal torque distribution controller. ( () represents the longitudinal force of each tire. Indicates the front left tire. Indicates the front right tire. Indicates the rear left tire. Indicates the rear right tire. This is the matrix transpose operator. It is the coefficient matrix of the quadratic terms. It is a diagonal matrix. For each tire, the coefficients of the quadratic term are... This is the inequality constraint coefficient matrix. For one The identity matrix, The inequality constraint matrix is... For the inequality constraints of each tire, This is the equation constraint coefficient matrix. For vehicle yaw angle, These are the constraint coefficients for each tire equation. These are the equality constraint coefficients. This is the motor torque. To add yaw moment, For minimum state constraints, This is the maximum torque of the tire. For the wheel radius, For maximum state constraints, , All are target weight coefficients. For each tire, the coefficient of adhesion. The force exerted vertically downwards on each tire. To output the desired torque to each tire controller, For each tire torque coefficient.

[0029] Specifically, since the lateral force of the tires cannot be directly controlled, this invention only considers controlling the longitudinal force. By combining the wheel dynamics model and solving the expression of the above-mentioned optimal torque distribution controller, the optimal torque of each tire can be obtained. .

[0030] Anti-slip controller, represented as:

[0031] in: To control the torque for slip prevention, , , All are PID anti-slip controller coefficients. These are the coefficients of adhesion for each tire. , Indicates the front left tire. Indicates the front right tire. Indicates the rear left tire. Indicates the rear right tire. The optimal slip ratio for the current road surface. For time, These are the slip rates corresponding to each tire. The optimal rate of change of slip ratio This represents the rate of change of wheel slip ratio.

[0032] Specifically, when an electric vehicle turns on a slope, the vertical load on a particular wheel decreases while the torque demand increases. This causes the tire of that wheel to exceed its traction limit, resulting in severe slippage, decreased vehicle stability, and increased tire power loss. When an electric vehicle turns on a low-traction slope, the wheel slip ratios with and without anti-slip control are as follows: Figure 2 and Figure 3 As shown. By Figure 2 It is known that when a vehicle travels on a low-traction slope, the wheel slips violently due to the change in vertical load on the wheel and the increase in the required driving torque. To address this problem, this invention introduces an anti-slip controller. When the wheel slip ratio exceeds the optimal slip ratio, the anti-slip controller rapidly adjusts the wheel output torque to suppress the rapid increase in the slip ratio and maintain it near the optimal slip ratio.

[0033] S22. Based on the desired longitudinal torque, additional yaw torque, and lower-level controller, calculate the anti-slip control torque and optimal torque, and calculate the desired motor torque according to the anti-slip control torque and optimal torque to perform torque distribution control of distributed drive electric vehicles.

[0034] This invention calculates the desired motor torque based on the anti-slip control torque and the optimal torque, expressed as:

[0035] in: These represent the expected motor torque for each tire. , Indicates the front left tire. Indicates the front right tire. Indicates the rear left tire. Indicates the rear right tire. Optimize the torque for each tire. These are the anti-skid control torques for each tire.

[0036] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A torque distribution control method for distributed drive electric vehicles adapted to slope driving, characterized in that, The following steps are involved: S1. Construct a longitudinal motion tracking controller based on ESO-PI and a yaw motion controller based on SMC, and calculate the desired longitudinal torque and additional yaw torque respectively using the longitudinal motion tracking controller based on ESO-PI and the yaw motion controller based on SMC. S2. Construct an optimized torque distribution controller that integrates anti-slip control, and calculate the desired motor torque based on the desired longitudinal torque and additional yaw torque through the optimized torque distribution controller that integrates anti-slip control, so as to perform torque distribution control of distributed drive electric vehicles.

2. The torque distribution control method for distributed drive electric vehicles adapted to slope driving according to claim 1, characterized in that, Step S1 includes the following steps: S11. Construct an ESO slope torque compensation controller based on an extended state observer, and a PI speed controller based on a PI controller to construct an ESO-PI based longitudinal motion tracking controller. The ESO slope torque compensation controller observes the road slope and vehicle mass in real time, calculates the slope longitudinal compensation torque by combining vehicle state parameters, calculates the expected longitudinal torque under the deviation between the expected longitudinal vehicle speed and the actual longitudinal vehicle speed by the PI controller, and calculates the expected longitudinal torque based on the slope longitudinal compensation torque and the expected longitudinal torque under the deviation between the expected longitudinal vehicle speed and the actual longitudinal vehicle speed. S12. Construct an SMC yaw motion controller based on sliding diaphragm control, and calculate the additional yaw torque through the SMC-based yaw motion controller.

3. The torque distribution control method for distributed drive electric vehicles adapted to slope driving according to claim 2, characterized in that, In step S11, the desired longitudinal moment is calculated based on the longitudinal compensation moment of the ramp and the desired longitudinal moment under the deviation between the desired longitudinal speed and the actual longitudinal speed, and is expressed as: in: For the desired longitudinal moment, For the overall vehicle quality, It is the acceleration due to gravity. For the wheel radius, For road slope, For vehicle yaw angle, , These are all parameters for a PI torque controller. For the desired longitudinal speed, This refers to the actual longitudinal speed. For time.

4. The torque distribution control method for distributed drive electric vehicles adapted to slope driving according to claim 1, characterized in that, Step S2 includes the following steps: S21. Construct an optimal torque distribution controller, combine the observed wheel slip rate with road conditions to construct an anti-skid controller, and construct an optimal torque distribution controller that integrates anti-skid control based on the optimal torque distribution controller and the anti-skid controller. S22. Based on the desired longitudinal torque, additional yaw torque, and lower-level controller, calculate the anti-slip control torque and optimal torque. Calculate the desired motor torque based on the anti-slip control torque and optimal torque to perform torque distribution control for distributed drive electric vehicles.

5. The distributed drive electric vehicle torque distribution control method for adapting to slope driving according to claim 4, characterized in that, In step S21, the optimal torque distribution controller is represented as: in: This is the input to the optimal torque distribution controller. ( () represents the longitudinal force of each tire. Indicates the front left tire. Indicates the front right tire. Indicates the rear left tire. Indicates the rear right tire. This is the matrix transpose operator. It is the coefficient matrix of the quadratic terms. It is a diagonal matrix. For each tire, the coefficients of the quadratic term are... This is the inequality constraint coefficient matrix. For one The identity matrix, The inequality constraint matrix is... For the inequality constraints of each tire, This is the equation constraint coefficient matrix. For vehicle yaw angle, These are the constraint coefficients for each tire equation. These are the equality constraint coefficients. This is the motor torque. To add yaw moment, For minimum state constraints, This is the maximum torque of the tire. For the wheel radius, For maximum state constraints, , All are target weight coefficients. For each tire, the coefficient of adhesion. The force exerted vertically downwards on each tire. To output the desired torque to each tire controller, For each tire torque coefficient.

6. The torque distribution control method for distributed drive electric vehicles adapted to slope driving according to claim 4, characterized in that, In step S21, the anti-slip controller is represented as: in: To control the torque for slip prevention, , , All are PID anti-slip controller coefficients. These are the coefficients of adhesion for each tire. , Indicates the front left tire. Indicates the front right tire. Indicates the rear left tire. Indicates the rear right tire. The optimal slip ratio for the current road surface. For time, These are the slip rates corresponding to each tire. The optimal rate of change of slip ratio This represents the rate of change of wheel slip ratio.

7. The torque distribution control method for distributed drive electric vehicles adapted to slope driving according to claim 4, characterized in that, In step S22, the desired motor torque is calculated based on the anti-slip control torque and the optimal torque, expressed as: in: These represent the expected motor torque for each tire. , Indicates the front left tire. Indicates the front right tire. Indicates the rear left tire. Indicates the rear right tire. Optimize the torque for each tire. These are the anti-skid control torques for each tire.

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