Observer-based interval type-2 fuzzy control of steering and lateral stability for steer-by-wire vehicles with time delay

This paper investigated observer-based fuzzy control for the lateral stability of steer-by-wire vehicles with time delay. An integrated dynamics model of the vehicle steer-by-wire system and lateral dynamics was established. The vehicle's longitudinal velocity was considered time-varying, and an interval type-2 fuzzy method was adopted to address the nonlinearity and membership function uncertainty caused by varying velocity. Considering that the vehicle sideslip angle and front wheel steering angular velocity were difficult to measure online, an observer-based H infinity controller was proposed. Furthermore, the time delay was considered in the controller design due to the time required for signal transmission and control force generation. The performance of the designed control method was verified by simulations and real-time hardware-in-the-loop testing. The results showed that the designed controller could improve the lateral stability and steering accuracy of the steer-by-wire vehicles under parameter uncertainty, external disturbance, and time delay.