Output tracking control of nonminimum phase systems via causal inversion

This paper introduces a new design procedure for output tracking control of nonminimum phase systems. This new controller achieves stable ε-tracking of a reference profile given in real time via a causal inversion approach. In contrast to stable inversion, the causal inversion approach does not require precalculation. In contrast to nonlinear regulation, the causal inversion approach avoids the numerical intractability of solving nonlinear PDEs and transient errors are significantly smaller. As an example, a causal inversion-based controller is designed for tip trajectory tracking of a one-link flexible manipulator. Simulation results demonstrate its effectiveness in output tracking.