Robust time-delay control

A method is presented to minimize residual vibration of structures or lightly damped servomechanisms. The method, referred to as the proportional plus multiple delay (PPMD) control, involves the use of multiple time delays in conjunction with a proportional part to cancel the dynamics of the system in a robust fashion. An interesting characteristic of the controller involves addition of a basic single time-delay control unit in cascade to the existing controller, for every additional requirement of robustness. It is shown that the proposed timedelay controller produces results that are exactly the same as those obtained by the shaped input technique. In addition, it is simpler to arrive at the relative amplitudes of the timedelayed signals for any number of delays even in a multi-input setting.