A study on using electric power steering to reduce the effort required for handling

Abstract

This paper proposes a design method that uses electric power steering (EPS) to reduce the effort required for handling in a vehicle. To accomplish this, the design must reduce the physical effort required of the driver, improve the controllability of vehicle dynamics, and adjust steering feedback to adopt the driver's characteristics. The influence of the stability factor and rear cornering compliance on handling and the effects of modifying these conditions were investigated. In addition, in order to compensate for the influence of these factors, EPS compensation features are addressed. Thus, desired steering characteristics are discussed as a function of steering frequency and yaw rate magnitude based on yaw rate and a Lissajous figure of steering torque. The influence of the stability factor and rear cornering compliance on a stable handling feeling are proven by simulation and linear analysis, and the conditions that cause a loss of this feeling of stability, even when vehicle dynamics are stable, are explored. EPS compensation functions are proposed against the influence of the stability factor and rear cornering compliance on the sense of handling. Furthermore, other EPS functions are proposed to compensate for the response from yaw rate to steering torque and to help the driver better understand the vehicle's behavior. Finally, the effects of EPS compensation functions on reducing the effort required for handling are demonstrated by a test where a single lane change was performed.

Keywords

• steering system
• vehicle dynamics
• eps control
• maneuverability