Nested adaptive super-twisting sliding mode control design for a vehicle steer-by-wire system

摘要

This paper presents a nested adaptive super-twisting sliding mode (NASTSM) control scheme for a vehicle Steer-by-Wire (SbW) system. Firstly, the plant model of the SbW system is expressed as a second-order differential equation from the steering motor input voltage to the front wheel steering angle. Specifically, the model of the self-aligning torque is elaborated in detail and compared with a simplified one. Next, an NASTSM controller is designed for the SbW system, which adopts a nested adaptive law to promote tracking accuracy by dealing with complex time-varying external disturbances and a super-twisting sliding mode (STSM) control component to guarantee strong robustness while alleviating chattering phenomenon. The stability of the NASTSM control system is verified in the sense of Lyapunov. Finally, experiments are carried out under various conditions. The experimental results show that the proposed NASTSM controller owns superiority in terms of not only higher tracking precision and stronger robustness, but also less dependence on the information of plant models compared with a conventional adaptive sliding mode (CASM) controller. (C) 2018 Elsevier Ltd. All rights reserved.