A Novel Flexure-Based Hybrid Mechanism for Micropositioning: Design, Analysis and Experimental Verification

Flexure mechanisms, precision actuation, and micro/nanoscale sensing and control are the fundamental building blocks for precision engineering, micro/nanopositioning systems, and instrumentation for micro/nanoscale manufacturing. Furthermore, a growing number of applications require both millimeter-scale workspace range and nanometer-scale resolution from a single positioning stage. However, achieving simultaneous long-range displacement and nanometer-scale precision positioning remains a significant challenge in micropositioning systems. This paper presents a novel hybrid flexure-based mechanism that integrates a voice coil motor (VCM) for a millimeter-scale positioning of a long-range motion stage, with a piezoelectric actuator (PEA) for the high-resolution positioning stage. The two stages are not connected directly: the piezoelectric actuator drives a bridge-type displacement amplifier whose output reaches the platform through decoupling parallelogram flexures, mechanically isolating the precision motion stage from the long-range motion input. Under closed-loop control, the coupled displacement of the hybrid motion is approximately 0.15%, compared with about 0.3% when the long-range stage is driven alone by the VCM, improving positional accuracy and stability during combined motion. This architecture provides a continuous transition between coarse and fine motion positioning without exposing the piezoelectric stack to adverse loading effects. Analytical modeling, finite element analysis, and experimental validation show that the system delivers a travel range of 2 mm with a resolution of 10 nm in the long-range stage and 5 nm in the high-precision stage. Experimental results show that the hybrid mode improves sensing and control specification for the rise time from 32.40 ms to 18.90 ms, the settling time from 51.90 ms to 32.10 ms, and the overshoot from 24.65% to 5.70% relative to long-range motion actuation alone.