An Adaptive Finite-Time Sliding Mode Control for Retinal Vein Micro-Puncture With Silicon Phantom

Retinal vein occlusion (RVO) is a prevalent ocular pathology that may result in hemorrhage and even blindness. Currently, a procedure termed retinal vein cannulation (RVC), involving puncturing the retinal vein and injecting medication, has been developed. However, RVC requires extremely high precision at the micron scale. To address the challenges in the micro-puncturing process of the RVC, an adaptive finite-time sliding mode (AFSM) control scheme with a smooth motion generator has been proposed to assist surgeons in achieving precise micro-punctures using a piezo-actuated stage. Firstly, an S-curve-based smooth motion planning approach incorporating force feedback is designed to detect the successful micro-puncture state, thus addressing the challenge of limited force perception during the procedure. Subsequently, an AFSM control scheme has been developed to track the desired motion. Finally, a micro-puncture system, equipped with a silicon phantom, is established for experimental purposes. The experimental results demonstrate that the proposed control scheme significantly enhances the tracking performance during the micro-puncture process. The smooth motion planning and AFSM control scheme prove to be effective for the automatic control of the piezo-actuated end-effector, thereby providing improved assistance to surgeons in the RVC process.
Note to Practitioners
—During the procedure of retinal vein micro-puncture, it is crucial to ensure a smooth motion planning and accurate tracking to guide the needle tip into the retinal vein lumen. In light of the difficulties in lack of depth perception, a motion generator has been proposed with an adaptive micro-puncture state detection mechanism based on force feedback. To reliably track the desired motion, the AFSM controller is designed to ensure tracking accuracy and robustness, and finite-time stability. In particular, the adaptive gain of the AFSM controller does not require uncertain prior information, making it friendly to clinical applications. The experimental results based on silicone phantom, demonstrate the effectiveness of the controller in achieving successful micro-puncture with precise tracking performance. The implementation of the AFSM controller enables the automated micro-puncture task, reducing the risk of damage during operation.