Optimized design of a compact multi-stage displacement amplification mechanism with enhanced efficiency

Abstract

Mechanically amplifying micro-stroke of actuators such as piezoelectric stacks through compliant mechanisms is an effective solution for use in micro/nano manipulation, precision positioning, gripping and manufacturing with large enough workspaces. This paper proposes a novel type of hybrid three-stage compliant displacement amplifier with a compact structure by synthesizing bridge-type and lever-type compliant mechanisms. A new index is introduced to measure its displacement amplification efficiency by considering the whole size and input stiffness. To facilitate design, the dynamic stiffness model is also derived to capture its kinetostatics and dynamics on both time and frequency domain. Then, the key structural parameters are efficiently optimized with the Pareto multi-objective optimization strategy. The capacity curve in terms of the resonance frequency, displacement amplification ratio and load capacity (output stiffness) is provided as well in a form of the Pareto optimal solution set. Experimental tests of two prototypes indicate a high displacement amplification efficiency of the current design, of which one prototype exhibits the output displacement of 0.7 mm and the resonance frequency of 874 Hz with a compact size of only 57 mm × 50 mm × 10 mm.