Variable transmission ratio control method based on rear wheel active steering

Abstract

The invention discloses a variable transmission ratio control method based on rear wheel active steering, and belongs to the technical field of automobile steering control. According to the control method, a vehicle steering model with front wheel steering as disturbance input is firstly built, and after the rotation angle of rear wheels and the rotating angle of front wheels are determined through an LQS optimal control theory, the variable transmission ratio is determined through a yaw velocity expression when an expected yaw velocity is tracked by a yaw velocity. It is ensured that an automobile has high system gains at low speed, and maneuverability of the automobile is improved; the mass center side slip angle is small when system gains at high speed are actively reduced, so that stability of the automobile travelling at high speed is ensured; the overshoot phenomenon of the automobile at high speed is reduced, and operation ride of transient response of the automobile is improved.

Description

technical field [0001] The invention discloses a variable transmission ratio control method based on rear wheel active steering, and belongs to the technical field of automobile steering control. Background technique [0002] In recent years, the four-wheel steering system is being widely used and developed because it can effectively improve vehicle handling stability. proportional control of slip angle, comprehensive control of zero slip angle μ, control of yaw angle and slip angle, multi-target yaw rate tracking control, etc. None of the control methods can satisfy both high steering sensitivity at low speeds and good steering stability at high speeds. For the traditional front-wheel steering car with fixed transmission ratio, not only the driver often needs to turn a larger steering wheel angle to control the steering movement of the car when the car is running at a low speed; The range of the steering wheel angle of operation is small, which makes the steering very sen...

AI Technical Summary

Problems solved by technology

[0002] In recent years, the four-wheel steering system is being widely used and developed because it can effectively improve vehicle handling stability. proportional control of slip angle, comprehensive control of zero slip angle μ, control of yaw angle and slip angle, multi-target yaw rate tracking control, etc. None of the control methods can meet the needs of high steering sensitivity at low speeds and good steering stability at high speeds at the same time.

For the traditional front-wheel steering car with fixed transmission ratio, not only the driver often needs to turn a larger steering wheel angle to control the steering movement of the car when the car is running at a low speed; The steering wheel angle range of the operation is small, which makes the steering very sensitive, which will cause a certain driving burden to the driver, so this method is more difficult to meet the above requirements

Although the variable transmission ratio control method can meet the requirements of sensitivity at low speeds and stability at high speeds, the traditional variable transmission ratio steering system has a complex mechanical structure and high cost, which is not conducive to popularization

Therefore, so far there is no information about the effect of the variable transmission ratio method through the active control of the rear wheels.

Images