Zero Phase Learning Control Using Reversed Time Input Runs

Phase lead is introduced to iterative learning control systems. The best phase lead is the one that can exactly compensate the phase lag of a system. A zero phase learning control using reversed time input runs is proposed based on the analysis in frequency domain utilizing a simple phase lead generation method. The plant itself or a nominal model is used to obtain the desired phase lead to ensure the monotonic convergence of tracking errors. The learning controller is robust to large inaccuracies of system models.