A case study of robust control experiment on one-link flexible robot arm

A linear model of a one-link flexible robot arm is only an approximation to the real system, whose parameters are subject to change due to working conditions. The paper presents a simple experiment to demonstrate the necessity of robust control to industrial robots. Two control techniques, linear quadratic Gaussian (LQG) and loop shaping, are used to design controllers for our laboratory flexible robot arm. The LQG controller yields an optimal closed-loop performance for the nominal system, but when plant parameters are perturbed, the performance significantly degrades. On the other hand, under the same perturbations, a loop shaping controller can robustly maintain the system stability and result in an acceptable performance. The agreement between simulation results and experimental results provides an initial step to our laboratory setup which is presently planned for the introduction of a robust control class.