Resonant Fluid Actuator: Modeling, Identification, and Control

In this article a novel piezo-hydraulic actuator exploiting resonance effects is presented. The operation of the proposed resonant fluid actuator (RFA) relies on the significant pressure raised in a fluid pipe during wave resonance. The piston of the actuator houses a valve, which rectifies the wave´s motion into direct mechanical motion. A state-space model, derived from the compressible Navier-Stokes equations, is formed by linearizing these equations and then discretizing them using the Chebyshev collocation method. In order to track the deformable control space, the resulting equations are reformed in an Arbitrary Lagrangian Eulerian framework. The fluid model is augmented with the valve and piezo dynamics, and, therefore, the final model is capable of capturing the performance of the RFA. The overall model is formulated in a time-variant state-space form and an optimal controller is designed to maximize the differential pressure across the piston. Experimental studies are used to investigate the efficacy of the proposed modeling approach, via utilization of a wavelet transform and finite element analysis. Simulation studies and experimental data are offered for verification of the actuator´s principle of operation.