Experimental application of subspace model identification of an unstable system

Abstract

In this paper, an experimental application of subspace identification on an unstable inverted pendulum is considered. The work presents the controller design for the cart-inverted pendulum system. Modeling of an inverted pendulum system is discussed. The linearized model of the nonlinear system has one unstable and two stable poles. A PID controller is designed based on the pole placement method. Using this PID settings on the experimental system, the closed loop data are collected for the servo problem. A suitable transfer function model is identified using the subspace identification method. Based on this model, a PID controller is designed by the pole placement method. The performances of the two PID controllers are evaluated experimentally and compared.