Development of Large-Angle Rear-Wheel Steering System Perfecting Small-Turn Performance and Natural Steering Feeling at Low Velocity

In the 1980's, rear-wheel steering systems were widely spread among Japanese automobiles for improvement in making a small turn at a low velocity as a main purpose. However, almost all the rear-wheel steering systems disappeared due to high cost and unnatural feeling at the time of steering. Recently, the increasing number of manufactures adopt the rear-wheel steering systems for purposes of improving steering responsiveness and vehicle stability. However, it is strongly recognized that the unnatural feeling given to a driver, which is represented by “teacup-ride like feeling”, during anti-phase steering at the low velocity is a characteristic of the rear wheel steering. In this study, control laws were developed with a side-slip angle and a yaw rate being set as target vehicle characteristics, and a large-angle rear-wheel steering system perfecting natural feeling and small-turn performance was developed.