Four wheel independent steering electric car steering control method and system

Abstract

The invention discloses a four wheel independent steering electric car steering control method and a four wheel independent steering electric car steering control system, and solves the technical problem that a four wheel independent driving and four wheel independent steering electric car is lack of a stable and affordable steering strategy in the prior art. The four wheel independent steering electric car steering control method includes: when an electric car needs to swerve, obtaining a steering wheel turning angle and car speed of the electric car; based on a car speed and car speed transmission ratio mathematic model, obtaining a variable transmission ratio between the steering wheel angle and a rear wheel turning angle of the electric car at different car speeds; obtaining a front wheel turning angle of the electric car based on the steering wheel turning angle; obtaining a car ideal condition of the electric car based on a variable transmission ratio car ideal model, the car speed and the front wheel turning angle; simultaneously, obtaining a car virtual condition of the electric car based on a four wheel steering electric car linear two freedom model, the car speed and the front wheel turning angle; obtaining the rear wheel turning angle of the electric car based on the car ideal condition and the car virtual condition of the electric car, and controlling the electric car to swerve based on the front wheel turning angle and the rear wheel turning angle of the electric car.

Description

technical field [0001] The invention relates to the technical field of electric vehicle steering control, in particular to a steering control method and system for a four-wheel independent steering electric vehicle. Background technique [0002] The car steering system is used to change or maintain the driving direction of the car. Its function is to control the driving direction of the car according to the driver's wishes. The car steering system is very important to the driving safety of the car. Four-wheel steering (4WS, 4Wheel Steering) system has been widely used and developed because it can effectively improve the handling stability of automobiles. [0003] In the early days, 4WS cars used fixed transmission ratio front wheel steering (FWS, Front Wheel Steering) to steer, that is, the driver controls the steering of the front wheels of the car through the steering wheel, and the rear wheels follow the steering of the front wheels. The transmission ratio is a fixed tra...

AI Technical Summary

Problems solved by technology

[0006] The technical problem to be solved by the present invention is to provide a four-wheel independent steering electric vehicle steering control method for the lack of a stable and economical steering strategy for electric vehicles with four-wheel independent drive and four-wheel independent steering existing in the prior art And system, so that the vehicle has high steering sensitivity at low speed and good steering stability at high speed

[0007] It solves the technical problem that the electric vehicle with four-wheel independent drive and four-wheel independent steering lacks a stable and economical steering strategy in the prior art. The characteristics tend to be consistent, so that the vehicle has high steering sensitivity at low speeds and good steering stability at high speeds. On the other hand, the electric vehicle can be adjusted without changing the steering structure of the front wheels. The rear wheel can obtain the ideal steering characteristics of the variable transmission ratio, which greatly reduces the design cost, and the control strategy can be freely designed, avoiding the limitation of the mechanical structure

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