Force Tracking Control of Fluidic Flexible Matrix Composite Variable Stiffness Structures

Abstract

Active valve control is investigated for force tracking of fluidic flexible matrix composite (F²MC) variable stiffness structures through analytical and experimental studies. F²MC structures are based upon fluid-filled flexible matrix composite tubes, and previous investigations have shown that several orders of magnitude change in stiffness can theoretically be achieved by opening and closing the inlet valve to the tubes. In this article, a simple analytical model of the F²MC system is developed that captures the dynamics of the composite tube, the servovalve, and the flow of the fluid through the valve. A combined observer/ regulator control system is determined using linearized equations of motion and is applied to the non-linear system. Analysis and experimental results demonstrate that the F²MC system can track a desired force—displacement curve using active valve control.