Assisted power controlling method for electric power assisted steering system

Abstract

The invention discloses an assisted power controlling method for an electric power assisted steering system. The method includes the steps that a microprogrammed control unit (MCU) collects a torque signal and a vehicle speed signal of a steering wheel to calculate to obtain power assisted motor target electric current Im of the power assisted steering system and meanwhile, collects current actual electric current Ireal of a power assisted motor; stretch factors alpha (e) and alpha (ec) of an input domain and stretch factors Beta (e, ec) of an output domain are obtained by the aid of control thoughts of a varying domain and a functional expression; a fuzzy control unit is combined with stretch factors of the varying domain to obtain control parameter modification values delta Kp and delta Ki through fuzzy reasoning; the calculation is performed to obtain an incremental value of a duty ratio of pulse-width modulation (PWM) by an incremental PI algorithm, and the motor is controlled in a PWM driving mode to output power assisted torque. By means of the assisted power controlling method for the electric power assisted steering system, defects such as nonlinearity and multiple coupling of the electric power assisted steering system can be effectively overcome by the established fuzzy control strategy, the stretch factors can adjust the domains in an on-line mode, and adaptive ability and control accuracy of the system are improved.

Description

technical field [0001] The invention belongs to the technical field of motor vehicle electric control, and relates to a power assist control method of an electric power steering system of an automobile. Background technique [0002] The steering system is one of the key systems that affect the handling stability and driving safety of the car. The Electric Power Steering System (EPS) is a new type of power steering system following the Hydraulic Power Steering System (HEPS). Compared with the advantages, it can not only save energy, improve the safety of the car, but also be conducive to environmental protection. It is a high-tech closely related to the development theme of modern automobiles, and it is an inevitable trend in the development of automobile steering systems. [0003] Electric power steering is based on the mechanical steering system, with the on-board battery as the energy source, the power assist motor as the power, and the torque and vehicle speed as the inpu...

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Problems solved by technology

[0004] The purpose of the present invention is to overcome the defects of limited self-adaptability and low control precision of the above-mentioned electric power steering control method in the prior art, and disclose an electric power steering power assist control method. The technical solution adopted by the patent of the pr

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