Design and Assessment of a Z-Axis Precision Positioning Stage With Centimeter Range Based on a Piezoworm Motor

This study presents a compact high precision positioner which is designed specifically for vertical axis motion with centimeter range based on a piezoworm motor arranged in flexure frames. The piezoworm motor for providing motion in Z axis is developed in complementary clamp configuration, provided that no power is required to maintain a fixed vertical position, holding the payload against the force of gravity at any time to ensure the safe climbing. Two identical amplified piezoelectric actuators are used in parallel for the extender section to achieve longer and equal step motion in vertical direction. The design is extended to a prototype where the actuator is integrated into a stage body, maintaining a compact size. After assembly, buckling effect on the stationary clamp flexures is evident due to the applied compressive load. Hence the positioner is evaluated through several tests in open loop with the aid of counterweights, ranging from 2-3.3 kg. Experiments on the inertially counterbalanced stage show that it is capable of providing a speed of 5.4 mm/s, an output force of 8.8 N, a travel range of 20 mm, and a possible resolution of 120 nm.