Sideslip Angle Based Variable Slip Ratio Limiter for Direct Yaw Moment Control of Two-Input-Two-Output Motor Vehicles

This paper presents a new direct yaw moment control system for electric vehicles with two-input-two-output motor drives. The proposed system consists of two layers: yaw-rate control in the outer and driving force control in the inner. To optimize the driving force generation capability of the left and right tires during turning, a novel variable slip ratio limiter (VSRL) is developed for the driving force control (DFC). The VSRL algorithm is derived by analyzing the brush model of tire force characteristics concerning the sideslip angle of the vehicle body. The proposed system was evaluated using an actual electric vehicle prototype developed by Mitsubishi Motors. The experiments were conducted under extremely harsh conditions, such as sudden acceleration while cornering on the ice surface. Compared with the existing methods with conventional VSRL, the proposed system successfully enhances the yaw-rate tracking performance.