Estimation Method of Road Adhesion Coefficient Based on Resonant Frequency of Steering System

Abstract

The invention discloses a road adhesion coefficient estimating method base on resonant frequency of a steering system, and the road adhesion coefficient estimating method is suitable for monitoring a road adhesion coefficient in real time in a straight-line driving process of a car. The road adhesion coefficient estimating method comprises the following steps: firstly, establishing a relationship between tyre aligning stiffness and the resonant frequency of the steering system; and then, realizing road adhesion coefficient estimation by utilizing a relationship between the tyre aligning stiffness and a road adhesion coefficient. The road adhesion coefficient estimating method is convenient to apply by only utilizing motor current and a wheel speed signal while car speed, a tyre slip angle and tyre aligning torque information are not needed; and frequency domain information is utilized for estimating, so that the method has insensitive characteristic to rotation speed noises and errors of a steering wheel, and the method is also accurate.

Description

technical field [0001] The invention relates to the estimation of the road surface adhesion coefficient of the vehicle, in particular to the estimation method of the road surface adhesion coefficient based on the resonant frequency of the steering system. Background technique [0002] Electronically controlled power steering, which makes full use of the characteristics of motor torque that can be accurately observed and quickly controlled, is an important development direction of automotive electronic control technology. The precise information of the power steering motor can be used as an important source of information for other state estimation, and its application needs to be further explored. [0003] As an important environmental state of the vehicle-road adhesion coefficient: refers to the ratio of the resultant force of the longitudinal force and lateral force acting between the tire and the ground to the vertical force. Accurate estimation of road adhesion coeffici...

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Problems solved by technology

[0004] In order to solve the shortcomings of the existing method of estimating the road adhesion coefficient by using the slope of the μ-s curve and the slope of the μ-α curve, etc., it is not suitable for the conditions of small slip rate and small side slip angle, and has high sensitivity to steering wheel angle noise and steady-state error The present invention proposes a novel road surface adhesion coefficient estimation method based on the resonant frequency of the steering system. This method is suitable for real-time monitoring and estimation of the road surface adhesion coefficient during normal vehicle driving (constant speed or small acceleration / deceleration straight-line driving), and can be used at different times. When torque sensors and vehicle speed sensors are required, only rely on steering wheel angle signal processing to realize the identification of the road conditions

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