Robust adaptive motion/force control for wheeled inverted pendulums

Previous works for wheeled inverted pendulums usually eliminate nonholonomic constraint force in order to make the control design easier, under the assumption that the friction force from the ground is as large as needed. Nevertheless, such an assumption is unfeasible in practical applications. In this paper, adaptive robust motion/force control for wheeled inverted pendulums is investigated with parametric and functional uncertainties. The proposed robust adaptive controls based on physical properties of wheeled inverted pendulums make use of online adaptation mechanism to cancel the unmodelled dynamics. Based on Lyapunov synthesis, the proposed controls ensure that the system outputs track the given bounded reference signals within a small neighborhood of zero, and guarantee the semi-global uniform boundedness of all closed loop signals. The effectiveness of the proposed controls is verified through extensive simulations.