A Study on Steering Control for a Joystick Car Drive System

Abstract

This paper presents a study on steering control algorithm for a joystick car drive system. The joystick drive system allows a handicapped person to drive a car by using a joystick with small force and short stroke. However, a wrong joystick operation, such as a sudden and wide steering, when a vehicle running in a very high speed results in a car accident quite easily. The other hand, quite sensitive steering control is required around the center of steering angle when a car runs along a straight line. When parking a car, a large steering angle provides easier parking maneuvering to a driver. To realize these requirements and solve some problems, we propose a steering control method with variable steering sensitivity and steering limitation based on a vehicle velocity. First, a dynamic model of a car running with rotation to define a risk for rollover of a car. From the dynamic model, we get limitation of steering angles as a function of the vehicle velocity. The limitation function is verified by the drive test taken by the real van running on the public road including highway and parking lot. The control method is successfully implemented on a microcomputer based controller for the joystick car drive system.