Active Differential Control for Improved Handling Performance of Front-Wheel-Drive High-Performance Vehicles

Abstract

This paper presents an active differential control system to improve handling and acceleration performance. Conventional front-wheel-drive cars have certain disadvantages including a lack of acceleration and excessive understeer during acceleration in turn. To address this problem, we propose understeer prevention logic. First, for a rapid response, the driving torque is distributed in advance to the inner and outer wheels according to the magnitude of the estimated traction potential in the wheels. If wheel spin occurs, then additional driving torque is transmitted to the outer wheel in proportion to the increment of the inner wheel speed versus the outer wheel. However, the torque transfer to the outer wheel is limited in proportion to the excess speed of the outer wheel compared with the non-driving wheel to prevent power slides. Oversteer prevention logic can improve yaw damping. The algorithm transmits driving torque from the outer wheel to the inner wheel in proportion to the yaw rate that exceeds the target. This algorithm was then evaluated via vehicle tests. The electronic limited slip differential with the proposed algorithm was applied to mass production, and it received positive feedback from international media.