Joint control method of electric power steering system and differential power system for four-wheel independent-drive electric automobile

Abstract

The invention discloses a joint control method of an electric power steering system and a differential power system for a four-wheel independent-drive electric automobile, comprising: when an automobile steers, comparing a collected steering wheel torque Thw with a set power torque Tzl to determine a power mode, and perform torque distribution shown specifically as follows: when Thw is greater than Tzl, judging a running speed V and the maximum speed Vmax of the automobile, and when V is greater than Vmax, entering a damping control mode. The damping control current is: when Thw is less than Tzl, judging a corner direction sgn (V) of a steering wheel of the automobile and an angular velocity direction sgn (omega) of the steering wheel: when sgn (V) is equal to sgn (omega), the automobile is steering and enters a basic power control mode, and when sgn (V) is not equal to sgn (omega), the steering wheel of the automobile is returning, and enters a returning mode. The returning control current is: IHZ = kP(thetaco - thetac) + ki x the integral of (thetaco - thetac)dt. In the formula, IHZ is the control current, thetac0 = 0 is an ideal corner of the steering wheel, thetac0 is actuallya corner of the steering wheel, and ki and kp are integral and scaling factor. By monitoring the steering wheel torque and speed of the automobile in the running process, the invention controls powermotor current for improving steering stability of the automobile in running.

Description

technical field [0001] The invention relates to a combined control method of an electric power steering system and a differential power assist system for a four-wheel independently driven electric vehicle, belonging to the field of automobile power assistance. Background technique [0002] Achieving differential power steering is a major advantage of four-wheel drive electric vehicles. Since the invention of the automobile, scholars at home and abroad have been looking for a control method that takes into account both "lightness" and "sensitivity" for the steering system of the automobile. For a four-wheel independent drive electric vehicle equipped with an electric power steering system (English abbreviation: EPS), the most basic requirements of the steering system are light steering at low speeds, stable steering at high speeds and a certain road feel. The research shows that if the steering is light as the premise, the car will appear "too sensitive" when driving at high...

AI Technical Summary

Problems solved by technology

The research shows that if the steering is light as the premise, the car will appear "too sensitive" when driving at high speed, the overshoot phenomenon is serious, the driver cannot feel the "road feel", and the car "floating" driving experience is extremely poor

Due to the inability to obtain a good sense of the road, the driver cannot fully understand the vehicle condition and cannot judge the stability of the vehicle, which can easily lead to dangerous vehicle conditions

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