Road surface condition determining method and suspension controlling device

摘要

A determining method of this invention includes a step of continuously measuring the relative movement between the wheel and the vehicle body by use of a linear stroke sensor while a motor vehicle is running; a step of creating spectral distribution by subjecting the output of the linear stroke sensor to the frequency analysis; a step of calculating characteristic values inherent to various types of road surfaces; and a step of specifying the type of the road surface based on the calculated characteristic values. When the type of the road surface is specified, the control device of this invention changes the damping force of the suspension to a level corresponding to the type of the road surface.