Trajectory Tracking for an Inverted Pendulum on a Cart: An Active Disturbance Rejection Control Approach

In this article, an Active Disturbance Rejection Control (ADRC) scheme is tested on a non-differentially flat system, with controllable linearization, to solve the problem of trajectory tracking for the inverted pendulum on a cart. Differential Flatness allows to design a control law that simultaneously achieves the trajectory tracking for the cart while regulating the inverted pendulum so that it remains near the unstable equilibrium point in spite of large perturbations. The proposed method assumes a limited knowledge of the system and relies on linear disturbance observation using linear feedback control techniques. Internal and external disturbance inputs are estimated by an Extended State Observers (ESO), which delivers these estimates to the controller for an on-line disturbance cancellation. Experiments on a laboratory prototype allowed to evaluate the proposed scheme with effective results in the presence of external disturbances.