Modeling and Control of a Six-Axis Parallel Piezo-Flexural Micropositioning Stage With Cross-Coupling Hysteresis Nonlinearities

Abstract

Multi-axis parallel piezo-flexural micropositioning stages are widely used in the micromanipulation field, but also suffer from the nonlinearities of the hysteresis and cross-coupling effects. Motivated by these bottlenecks, this paper presents new modeling and control methods for a six-axis parallel piezo-flexural micropositioning stage. Firstly, the micropositioning stage is designed for the requirement of the bio-micromanipulation application. Combined with a rigid-flexible coupling dynamic model, the nonlinear hysteresis of the stage is also considered and characterized by a novel fractional-order normalized Bouc-Wen (FONBW) model. To improve the motion tracking performance, a decentralized control strategy with an inverse-FONBW-based hysteresis compensator is developed to make the multi-input multi-output (MIMO) system decoupled directly in the task space, simultaneously reducing the cross-coupling and hysteresis nonlinearities. Experimental results validate the effectiveness of the proposed controller.