Robust stabilization of underactuated inertia wheel pendulum system based on disturbance observer

An inertia wheel pendulum (IWP) is a mechanical system with two degrees of freedom (DOF) and a control input. This paper studies the robust stabilization of this underactuated system. Firstly, we design a disturbance observer to estimate the value of disturbance existed in the system. Secondly, the nonlinear state equations of the IWP are given by a coordinate transformation. After that, a Lyapunov function is designed for this nonlinear system. And a robust stabilizing controller is developed utilizing the Lyapunov theory, an idea of controller switching and the estimated disturbance value. Finally, the effectiveness of our presented method is verified through a numerical example.