Development of a Maximum Energy Extraction Control for the Smart Spring

Abstract

Most active vibration suppression approaches have attempted to suppress structural vibrations through the use of active material actuators, such as piezoceramic, that are incorporated into a structure to act directly against vibratory loads. These approaches require the actuators to simultaneously supply significant force and deflection to effectively suppress vibration. Unfortunately, successful implementation of these approaches has been hindered by the electromechanical limitations of piezoceramic actuators due to high power requirements in active vibration control applications. The Smart Spring concept is a unique approach that is designed to actively control combinations of dynamic impedance characteristics of a structure, such as the stiffness, damping, and effective mass to suppress vibration. The Smart Spring does not use actuators to perform work directly against excitation loads, but rather adaptively varies the effective structural impedance properties. Therefore, the piezoceramic actuators in the Smart Spring are not required to simultaneously produce large forces and deflections. Thus, the concept requires considerably less power because it enables active vibration control in an indirect manner. This study demonstrates the ability of the Smart Spring to control dynamic impedance characteristics of a structure through numerical simulations and experimental investigations. In addition, the development of a feedback control system is demonstrated. According to the control strategy, the impedance characteristics of the Smart Spring are continuously changing in order to maximize the extraction of the mechanical energy of the system.