Design of a minimum surface-effect tendon-based microactuator for micromanipulation

A piezoelectric (PZT) stack-based actuator was developed to provide a means of actuation with dynamic characteristics appropriate for small-scale manipulation. In particular, the design incorporates a highly nonlinear, large-ratio transmission that provides approximately two orders of magnitude motion amplijication from the PZT stack. In addition to motion amplijication, the nonlinear transmission was designed via optimization methods to distort the highly non-unifarm properties of a piezoelectric actuator so that the achievable actuation force is nearly constant throughout the actuator workspace. The package also includes sensors that independently meas: ure actuator output force and displacement, so that a manipulator structure need not incorporate sensors nor the associated wires. Specifically, the actuator was designed to output a maximum force of at least one Newton through a stroke of at least one millimeter. For purposes of small-scale precision position ana7or force control, the actuatorhensor package was designed to eliminate stick-slip f iction and backlash. The overall dimensions of the actuatorhensor package are approximately 40 x 65 x 25 mm.