Development of roll attitude control theory for semi-active suspension system 2000-05-0177

A bodywork roll attitude during cornering is not a simple rotary motion around the geometrical roll center. It is a complicated rotary motion including vertical motion under the influence of a lot of forces caused by suspension links and components. This motion affects not only vehicle dynamics, but also roll feeling evaluated by a driver. Therefore a vehicle roll attitude is recognized as one of factors to characterize the vehicle handling performance, and a suspension system is designed considering this point. Concerning the roll feeling, it is known that human being feels insecurity and discomfort toward "floating," and the vertical motion during cornering has a relationship with subjective ratings by a driver.

Tis paper presents the roll attitude control theory "Virtual Damper Control (VDC)" considering above behavior, and confirms the effects by comparing with current anti-roll control. The trait of VDC is to create a down roll attitude by defining virtual dampers inside of the corner. From the simulation study and the experiments using actual vehicle, the following results were verified. 1. The roll attitude created by VDC improved the roll feeling and the sense of security of driver. 2. The roll attitude created by VDC decreases the amount of weight transfer about 20% and improved the balance of tire lateral force distribution ratio about 5%. 3. From the results of above effects, the yaw response was improved and it decreased the steering wheel inputs.