Active Disturbance Rejection Control of the Inertia Wheel Pendulum through a Tangent Linearization Approach

A flatness based approach is proposed for the linear Active Disturbance Rejection Control (ADRC) stabilization of a nonlinear inertia wheel pendulum (IWP) around its unstable equilibrium point, subject to unmodelled dynamics and disturbances. The approach exploits the cascade structure, provided by the flatness property, of the tangent linearization of the underactuated system which allows designing a high gain linear cascaded Extended State Observer (ESO) of the Generalized Proportional Integral (GPI) type. This class of linear observers is employed to build an Active Disturbance Rejection Control controller with a lower order of complexity regarding other ADRC classic schemes. Experimental results demonstrate the effectiveness and feasibility of the proposed approach, as well as a better behavior with respect to a classic control technique in the presence of disturbances.