Multi positive feedback control method for active vibration suppression in flexible structures

Abstract

This paper presents a novel controller for active vibration reduction in piezoelectric-actuated flexible structures. The new Multi Positive Feedback (MPF) control consists of two sections where each operates using a set of actuators. One section uses position and the other uses velocity feedback to perform real-time vibration control. The 90° phase difference between the feedbacks leads to non-zero resultant control output. This property results in a more effective operation of the available actuators. Sections of the MPF controller are designed based on the concept of the Modified Positive Position Feedback (MPPF) control approach, where the damping of the control system is increased by addition of a first-order term parallel to a second-order compensator. The controller is designed to simultaneously control single or multi resonant frequency vibrations. Due to the high influence of gain values on the control performance, H2 and H∞ norms are used to optimize these gains. For validation purposes, the controller is verified here numerically and experimentally for vibration control of a clamped–clamped beam and a cantilever at resonance. According to the results, the MPF controller has a superior performance compared to the MPPF controller, in addition to effective suppression on both vibration displacement and velocity. Using the MPF controller in multimode and by utilizing the H∞ gain optimization method, vibration displacement amplitudes were reduced to 19.4% of the uncontrolled state for the beam.