Continuous-time feedforward Proportional-Integral-Plus control

Most of the research into Non-Minimal State Space (NMSS), Proportional-Integral- Plus (PIP) control system design has been in the discrete-time domain. However, continuous- time models can have a number of advantages, particularly for fast sampled systems or when it is essential that the control system responds quickly to an unexpected disturbance. The present article applies continuous-time NMSS/PIP design to two practical examples, namely a connected pair of DC electric motors in the laboratory, and a nonlinear simulation of a hydraulic power-take-off element for a wave energy converter. Both applications include measured disturbance inputs. Therefore, the article also develops and evaluates feedforward control structures, including one based on an extended continuous-time NMSS model.