The Vehicle Road Load Problem -An Approach by Non-Linear Modeling.

摘要

A method to accurately characterize the road experience of the vehicle is a prerequisite for accurate dynamometer testing. In the usual coast down technique,the vehicle road load force is calculated from a numerical derivative of the speed versus time measurements. This study significantly improves the coast down technique by eliminating the differentiation of the speed-time data while maintaining the ability to treat the forces on the vehicle as a general quadratic function of vehicle speed. A model equation for the forces on a freely decelerating vehicle is constructed;this equation is analytically transformed into an expression for the speed of the freely decelerating vehicle as a function of time. This intrinsically non-linear equation is then computer fitted to the speed versus time data recorded from the vehicle. Road load measurements results by this method are compared with results by the drive shaft torque method.