Dynamics of Steering System with Freeplay and Dry Friction - Comparative Simulation Investigation for 2WS and 4WS Vehicles

This paper continues a subject-matter of simulation studies of a car motion with inclusion of freeplay and dry friction, but in comparison to our SAE paper 2002-01-0619 (concerning to mechanical 2WS steering systems) in this paper also power assisted 2WS as well as 4WS steering systems are also the subjects of studies.

The paper presents mathematical models and simulation studies of a car handling with regard to freeplay and friction in steering system. The models are customizable for several structures of steering system. Descriptions of freeplay and friction non-linearities base on special piecewise-linear projections. Elaborated models are used for digital simulation and sensitivity analyses concerning typical open road tests of passenger car. The paper describes these investigations and presents exemplary results. They show complexity of stick-slip phenomenon and car dynamics sensitivity on the freeplay and friction in the 2WS and 4WS structures. The presented models and results may be interesting and useful for researches working on non-linear dynamics and problems of vehicle active safety.