ENHANCEMENT OF MECHANICAL WORK OUTPUT OF A PIEZO-STACK USING A NON-LINEAR MOTION TRANSMISSION MECHANISM

摘要

A non-linear motion transmission mechanism for improving the mechanical work output of a piezoelectric stack actuator is presented. This improvement in work is achieved by exploiting the mismatch of an actuator's external output load such as a constant force or spring load and the stack's force-displacement capability, which is described by a linear decrease in the possible force output with extensional displacement. The motion transmission mechanism consists of a simple linkage that couples the stack to the load. As the stack is actuated, the linkage changes the mechanical advantage or leverage of the stack, thereby tailoring the load to the stack's force-displacement behavior. A kinematic model is used to predict the maximum quasi-static mechanical work output that can be obtained. Optimization of the model geometry results in a transmission with a theoretical work enhancement of 36.9 % for a constant load and a theoretical work enhancement that approaches 100 % for a spring load. The transmission work enhancement is verified with an experimental test setup that demonstrates a work output improvement of 27.1% for the constant load.