Advances in robust control of mobile wheeled inverted pendulum

Abstract

There has been increasing interest in a type of underactuated mechanical systems, mobile-wheeled inverted-pendulum (MWIP) models, which are widely used in autonomous robotics and intelligent vehicles. To cope with the model uncertainties and external disturbances, several robust controllers are designed for the MWIP models. For the velocity-tracking problem of the MWIP systems, we proposed two sliding-mode-control (SMC) methods. There is still a steady tracking error when the first SMC method is used. By assuming a novel sliding surface, the second SMC method is designed to solve this problem. Using a coordinate transformation, the non-“Class-I” type underactuated MWIP system is presented as a semistrict feedback form which is convenient for controller design. A dynamic surface controller with a nonlinear disturbance observer (DSCNDO) is then designed to solve the balance control problem of the MWIP systems. The proposed DSCNDO can compensate the external disturbances and the model uncertainties to improve the system performance significantly. The stabilities of the closed-loop MWIP systems using the proposed methods are proved by Lyapunov theorem. The effectiveness of all the methods is verified by numerical simulations.