Vibration Control of a Flexible Link Manipulator Using Smart Structures

Abstract

The active vibration suppression of a flexible link manipulator using a smart structure (piezoelectric actuator) is investigated. For this purpose, a Finite Element (FE) model is developed for the modal and transient analysis of a cantilever beam and a flexible link manipulator. The novelty of this work is in the development of an accurate finite element model of a piezoelectric and beam/manipulator. Also, the effect of the placement of the piezoelectric actuator along the beam, based on the controllability of the system states and using FE analysis, is investigated. To avoid system instability, a collocated sensor-actuator pair is used and a proportional control strategy is employed to adjust the voltage applied to the piezoelectric actuator so as to control vibrations. For the flexible link manipulator, it is shown that the vibration is well suppressed during and at the end of a maneuver by locating the piezoelectric actuator at the optimum location. The effect of the controller gain on the vibration behavior of the system is investigated and the optimum controller gain is found using two main evaluation criteria; these are the contribution of the dominant frequencies in the response and the error norms of the vibration amplitudes.