Fiber Bragg Grating-Based Triaxial Force Sensor With Parallel Flexure Hinges

Abstract

During cardiac surgery, the excessive or insufficient contact force between the tip of catheter and heart tissue will lead to the cardiac penetration or noneffective ablative lesion. Usually, the surgeon can only estimate the force at the distal end roughly from their experience by operating the catheter's proximal handle. In this paper, we design a fiber Bragg grating-based triaxial force sensor with parallel flexure hinges to sense the contact force. The proposed mechanism integrated with parallel flexure hinges is capable of achieving an excellent lateral and axial stiffness balance to guarantee the resolution at each direction with the same order of magnitude. The mathematical model is built to design a suitable stiffness configuration and validate the design reasonability. The model-based and model-free methods are adopted to decouple lateral and axial force components. Experimental results demonstrate that the developed 8 French size force sensor can successfully achieve the triaxial force prediction with <1 g resolution using both decoupling methods. And the model-free method can accomplish a higher accuracy with RMS error <1% of full scale of [-100 g, 100 g] along the lateral direction and [0 g, 100 g] along the axial compression direction.

Surgical Applications of Compliant Mechanisms: A Review

“…A challenge with multi-axial force sensors lies in the decoupling of forces along the axes as observed in the study by Gao et al [131]. Linear decoupling methods proved to be inaccurate since local deformation of flexures affects the strains measured.…”

Laser-Profiled Continuum Robot with Integrated Tension Sensing for Simultaneous Shape and Tip Force Estimation

“…For error correction, X-ray fluoroscopy was used at intervals to obtain 2D projections of the continuum manipulator during the procedure, 26 but it carries the risk associated with the excessive exposure of ionising radiation to both patients and surgeons. For the force sensing of continuum robots, several force sensors based on FBG sensors have been developed by our previous work, [27][28][29] however, all of them require additional sensing elements, and the inner lumens of continuum manipulators are always occupied. They are not suitable for our application of optical biopsy with the demand of an inner lumen inside continuum manipulators.…”

Kinetostatic and Dynamic Modeling of Flexure-Based Compliant Mechanisms: A Survey

“…A comparative review on the accuracy of compliance equations for circular flexure hinges within a wide range of geometric parameters was provided in 2008 [70]. These investigations on the kinetostatics of flexure hinges provided powerful tools and guidelines on designing multitudinous flexure hinges [71][72][73][74][75].…”