Design and test of a compact large-stroke dual-drive linear-motion system

This paper presents the design, modelling, analysis, and test of a piezo-actuated dual-drive linear motion system, capable of millimeter stroke with nanometer resolution. The primary actuator is a two-stage bridge-type amplifier with hybrid flexure hinges, which is driven by a piezo-stack actuator and generates output stroke greater than 6 mm. The micro actuation is directly driven by an extra piezo-stack to achieve resolution of 20 nm. A very large amplification ratio of 91 is achieved, which implies not only large stroke but also compactness. An inherent characteristic for the multi-stage compliant displacement amplifier, ‘kick-back’ phenomenon, is first analyzed and eliminated by using the stiffness distribution method. The architectural parameters are optimized by genetic algorithm to find the trade-off among natural frequency, stroke and stiffness ratio. The optimized design was then fabricated and tested. The superiority of the proposed system is remarkable compared with other similar works. The concept and approach outlined are generic and can be extended to this class of actuators.