Vibration control of pitch movement using command shaping techniques

This paper investigates the development of feedforward control strategies for vibration control of pitch movement of a twin rotor multi-input multi-output system (TRMS) using command shaping techniques. The TRMS is a laboratory platform designed for control experiments. Three feedforward controllers: input-shaper, low-pass filtered and band-stop filtered, are designed based on the natural frequencies and damping ratios of the system for resonance suppression produced by the main rotor around the longitudinal axis, while the lateral axis is physically constrained. Performances of the three controllers are assessed in terms of level of vibration reduction at the system´s natural frequencies. The response of the system (pitch movement) to the shaped and filtered inputs is compared with its response to the unshaped input. Simulation results are presented in time and frequency domains.