<title>Compact piezohydraulic actuation system</title>

Abstract

Design and analysis of a scalable piezohydraulic actuation system is presented. Efficiency analysis of frequency rectification demonstrates that hydraulic actuation transfers the maximum amount of work from the actuator to the load. The ratio of peak electrical power to average power delivered caries from 8 percent to 25 percent depending on the piezoelectric coupling coefficient, highlighting the need for efficient power electronics to minimize heat dissipation in the system and minimize volume. A lumped parameter system model demonstrates that fluid compliance is the limiting facto in the stiffness of a bidirectional actuator that does not require hydraulic accumulators or four-way valves. A benchtop experiment consisting of a piezoelectric shock actuator, pumping chamber, and a linear hydraulic cylinder is developed and tested to determine the effect of friction on the micron- level motion of the actuator. The effects of friction are minimized by applying a pneumatic precharge to the system and driving the actuator at its maximum voltage level. Friction is not deemed a limiting factor to the development of a piezohydraulic system with stroke outputs on the order of 100 micrometers per cycle.