A tubular dielectric elastomer actuator: Fabrication, characterization and active vibration isolation

Physicists and chemists have long sought to develop lightweight materials that grow or shrink significantly in length or volume when subjected to electric stimulation. A new material of this type is Dielectric Electro-Active Polymer (DEAP), which when utilised as an actuator, has the potential to be an effective replacement for many conventional actuators. DEAP has a range of properties that place it somewhere between those of piezoceramics and shape memory alloys (SMA's). DEAP actuators, among many other applications, have the potential to be used in active vibration control (AVC). The overall goal of this work was to investigate the viability of using a DEAP actuator in active vibration isolation (AVI). In the experimental setup, a mass, representing an instrument for example, was intended to be isolated from ground vibration, generated by an electrodynamic shaker, by placing an active isolator (the DEAP actuator) between the shaker and mass. First, this paper introduces the basic characteristics of one type of DEAP material, called PolyPower®. Among the actuator types, constructed from PolyPower material, those having a tubular shape are investigated here. The static and dynamic characteristics of the actuators as well as the frequency response function are of special interest from the AVC point of view, and are investigated for the tubular type PolyPower actuators. Experimental results are presented. Feedforward control approach was used in all experiments. Least mean squared (LMS) adaptive algorithm was used to optimize the control parameters iteratively in order to minimize the displacement of the solid mass caused by the shaker. Three different types of controller, single harmonic controller, double harmonic controller and FIR controller were used for tonal isolation. The implications associated with the actuator?s nonlinearities and the performance of the three controllers was assessed. FIR controller was also used for broadband isolation and the proper choices of its parameters were experimentally determined