Experimental Analysis of Laser Interferometry-Based Robust Motion Tracking Control of a Flexure-Based Mechanism

This paper presents experimental analysis of laser interferometry-based closed-loop robust motion tracking control for flexure-based four-bar micro/nano manipulator. To enhance the accuracy of micro/nano manipulation, laser interferometry realized robust motion tracking control is established with the experimental facility. This paper contains brief discussions about the error sources associated with the laser interferometry-based sensing and measurement technique, along with detailed error analysis and estimation. Comparative error analysis of capacitive position sensor-based system and laser interferometry-based system is also presented. Robust control demonstrates high precision and accurate motion tracking of the four-bar flexure-based mechanism. The experimental results demonstrate precise motion tracking, where resultant closed-loop position tracking error is of the order of +/- 20 nm, and a steady-state error of about +/- 10 nm. With the experimental study and error analysis, we offer evidence that the laser interferometry-based closed-loop robust motion tracking control can minimize positioning and tracking errors during dynamic motion. Note to Practitioners-This paper was motivated by the need of precise manipulation and effective motion control of flexure-based micro/nano manipulators and a need of faster, sensitive, and extremely precise measuring devices. Ultra-precise manipulation is one of the very important techniques in the field of micro/nano engineering. In general, flexure-based mechanisms driven by piezoelectric actuators are the most commonly employed components for micro/nano manipulation. Generally, in the studies of flexure-based mechanisms, the emphasis has been mostly confined to the mechanical design, kinematic modeling and stiffness analysis. Limited effort has been made to demonstrate an effective motion tracking control for flexure-based mechanism. In this research, laser interferometry-based sensing and measurement system is proposed and implemented for the intelligent motion control of flexure-based manipulator. As a part of this research, enhancement in the positioning accuracy and tracking performance with the laser interferometry-based feedback is investigated. The focus is given to examine and characterise the sensing modality of the laser-based sensing and measurement system. The experimental results presented in this paper demonstrate effective, precise and accurate position tracking of flexure-based mechanism. Future research based on laser interferometry-based closed-loop control for precise and accurate motion tracking of the flexure-based planar mechanisms is under investigation.