Robust hierarchical sliding mode control of a two-wheeled self-balancing vehicle using perturbation estimation

Abstract This paper presents the design and implementation of hierarchical sliding mode control (HSMC) with perturbation estimation (PE) technique on a two-wheeled self-balancing vehicle (TWSBV), to simultaneously realize real-time balancing and velocity tracking control purposes. Considering the fact that the TWSBV system is a typical second-order underactuated system with one controlled actuator and two required control objectives, two sliding surfaces constructed by the velocity and tilt angle information are first designed and an HSMC is proposed to simultaneously achieve both balancing control and velocity control. In order to further enhance the ability of disturbance rejection of the HSMC control, the PE is used to assist with the proposed control for estimating the perturbations online such that the uncertainty bound information is not required in the control design. The excellent balancing and velocity tracking performance can be well achieved even under external disturbances. The effectiveness of the proposed control is verified by a group of comparative experimental investigations on a real TWSBV.