Compliant piezoelectric medical micro-robots with visual servoing
File(s)
Author(s)
Chen, Xu
Type
Thesis
Abstract
Precision motion actuation is critical for microsurgery and catheter-based optical fibre diagnostic and intervention tools. Traditional actuation mechanisms, such as motor, magnetic, or pneumatic systems, are difficult to miniaturise while maintaining high-resolution motion. Piezoelectric materials, when used with compliant mechanisms, offer scalable, precise, fast, and high-force actuation with adequate motion range. This thesis explores an optical fibre steering technology suitable for catheters, diagnostic optical fibres, and microsurgical tool manipulation. The proposed technology combines piezoelectric beams with compliant motion translation structures, which have been validated through a series of experiments. A flexure-based compliant mechanism was designed based on flexure characterisation results, with piezoelectric benders used to implement a three-degrees-of-freedom delta robot. The fabrication of the system utilises additive manufacturing and origami structuring techniques. Closed-loop control is achieved through a novel on-board visual feedback system. Unlike conventional optical feedback systems, this fully internal visual feedback design enhances system compactness while providing precise and reliable camera-to-marker geometry alignment. Using this approach, the compliant delta robot is demonstrated with a motion accuracy of 7.5 μm, a resolution of 10 μm, and a precision of 8 μm. The robot successfully follows a range of programmable trajectories under these specifications and compensates for external forces typically encountered during operation. The integration of piezoelectric actuation, compliant motion translation, and onboard visual feedback is expected to deliver highly precise and reliable motion control for microsurgical applications.
Version
Open Access
Date Issued
2024-06-20
Date Awarded
01/01/2025
License URL
Advisor
Yeatman, Eric
Kiziroglou, Michail
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP/P012779
Publisher Department
Electrical and Electronic Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)