Command Shaping for Systems with Time Delay

Delays in a feedback control system are a nonlinearity that can greatly degrade performance or lead to instability. Communication delays are prevalent in control over large distances and Internet-based operations. Process and/or sensor delays are common in biological and chemical systems. While feedback controllers have been developed to account for these delays, often the aggressiveness of the control effort must be tempered to avoid instability, overshoot or other unwanted effects. Command shaping´s efficacy in reducing the unwanted dynamics is investigated in this paper. Using a second-order system (mass under PD control) as a test bed, command shapers are used to reduce the additional overshoot that delays in the system create.