Vibration control of pitch movement using command shaping techniques– Experimental investigation

This paper investigates the development of feedforward control strategies for vibration control of pitch movement (1 DOF) of a twin rotor multi-input multi-output system (TRMS) using command shaping techniques. Command shaping is a feedforward method used to reduce residual vibrations during motion in flexible systems. The TRMS is a laboratory platform designed for control experiments. In certain aspects, its behaviour resembles that of a helicopter. Feedforward controllers are designed for resonance suppression produced by the main rotor, which produces pitch movement around the longitudinal axis, while the lateral axis (yaw movement) is physically constrained. Three feed-forward controllers: input-shaper, low-pass filter and band-stop filter are designed based on the natural frequencies and damping ratios of the system. The three controllers are assessed in terms of level of vibration reduction at the system’s natural frequencies. Their performances are compared with an unshaped input (single-switch bang-bang signal) that is used to determine the dynamic response of the system.