Four wheels steering control for vehicle with constraints on side slip Angle is studied in this paper.

A desirable vehicle model with the best performance of side slip Angle and yaw rate is established through connecting direct yaw moment control (DYC) with four wheel steering (4ws) system.

Through linearizing nonlinear vehicle model, vehicle side-slip Angle estimation algorithms based on generalized Kalman filter and generalized Luenberger observer are formulated.