Design and Experimental Verification of a Semi-Active Pitch Link for Helicopter Vibration Attenuation

Abstract

Piezoelectric materials have been used for vibration control in different engineering problems. In general, the piezoelectric vibration controllers are classified as active or passive systems. In the first case, the reverse piezoelectric effect is used and an external power source is required. In the second case, mechanical energy is converted to electrical energy based on the direct piezoelectric effect. The piezoelectric material is connected to simple electrical circuits (that uses passive elements) in order to dissipate energy. More recently, switching circuits have been used for the nonlinear treatment of the electrical output of piezoelectric materials resulting in semi-passive and semi-active controllers. Different switching circuits have been presented in the literature of piezoelectric vibration control. In some cases, the behavior of the switching controller is similar to mechanical systems used in helicopters for vibration control. One of these mechanical systems is the active pitch link presented by a Canadian research group. This system uses the combination of springs in order to control the stiffness of the pitch link. Although a remarkable control performance has been achieved with the active pitch link, some drawbacks (i.e. external voltage is required and mechanical failures) are point out by the authors. The main goal of the present project is the design and experimental verification of a self-powered piezoelectric semi-active pitch link using autonomous switching circuits. This solid-state configuration would address the issues presented by the mechanical active pitch link as well as present a good performance in vibration attenuation.