Adaptive Optimal Valve Control for a Resonance Fluid Actuator

In this article, an optimal control scheme for a piezo - hydraulic actuator exploiting resonance effects is presented. The proposed actuator relies its operation on the significant pressure built up in a fluid pipe during resonance. The actuator's piston houses a valve which rectifies the wave's motion into direct mechanical motion. The discretization of the partial differential equation from the compressible Navier - Stokes equations that captures the fluid - wave propagation leads to a state space description suitable for the development of control algorithms. The valve and piezo dynamics can be embedded in this model for examining the overall performance of the actuator. An optimal controller is designed to maximize the differential pressure across the piston leading to a bang-bang type of control input. The phase and pulse width of the control effort are adjusted based on an adaptive scheme using the gradient of the cost function. Simulation studies are offered for verifying the actuator's principle of operation. In comparison to a passive valve configuration this scheme offers a significant improvement measured by the generated blocking forces.