Retinal microsurgery, which requires surgeons to perform precise operations on delicate tissue in a tiny eye, is considered one of the most technically demanding operations. Lack of force perception is one of the major problems faced during retinal microsurgery. In order to solve the problem of lack of force sensing, many 3 degree of freedom (DOF) force sensing instruments have been developed. However, they all adopt complex structures, and the accuracy of axial force still has room for improvement. In this paper, we presented a 3-DOF force sensor based on fiber Bragg grating (FBG) sensors for retinal microsurgery. An improved FBG configuration which simplifies the structure of the force sensor and the corresponding temperature compensation method was designed. Two optical fibers with single FBG sensor and an optical fiber with dual FBG sensors are longitudinally attached along the grooves of a stainless steel tube. The calibration method used in the force sensor is a combination of linear calibration method and the least squares support vector regression (LSSVR), which can effectively reduce the influence of linear and nonlinear errors. The results of calibration experiment demonstrate that the hybrid calibration method has better accuracy than using linear or nonlinear method alone. Verification experiment and temperature compensation experiment show that the 3-DOF force sensor proposed has the ability to provide accurate and stable estimation of 3 dimensional forces in a temperature changing environment.

Epiretinal membrane peel surgery requires the surgeon to perform precise operation on delicate tissue within the narrow space of the eye, which is considered as one of the most technically demanding procedures. Using surgical robots to assist surgeons in performing operations is a recognized development direction. The automatic microforceps, as a device mounted at the end of the robotic arm and directly in contact with the affected area, has been the subject of research by many scholars. However, current research has significant shortcomings in both the calibration algorithms for the sensors and the control methods for the microforceps. In this article, we introduce an automated microforceps designed for epiretinal membrane peeling procedures. Despite its compact radial dimension of just 20 mm, the jaw of the microforceps possesses the following two degrees of freedom (DOF): 1) rotation and 2) closure. Subsequently, we analyzed the changes in the physical model of the 3-DOF force sensor after its integration into the microforceps, leading us to propose a refined calibration algorithm tailored for our designed automated microforceps. Furthermore, we introduced a force-based adaptive clamping method suitable for variety of unknown thickness films. Both polyethylene terephthalate (PET) film experiments and generalization experiments demonstrated the stability and generalizability of the adaptive clamping method.

Current teleoperated robotic systems for retinal surgery cannot effectively control subtle tool-to-tissue interaction forces. This limitation may lead to patient injury caused by the surgeon’s mistakes. To improve the safety of retinal surgery, this paper proposes a haptic shared control framework for teleoperation based on a force-constrained supervisory controller. The supervisory controller leverages Control Barrier Functions (CBFs) and the interaction model to modify teleoperated inputs when they are deemed unsafe. This method ensures that the interaction forces at the slave robot’s end-effector remain within the safe range without the robot’s dynamic model and the safety margin. Additionally, the master robot provides haptic feedback to enhance the surgeon’s situational awareness during surgery, reducing the risk of misjudgment. Finally, simulated membrane peeling experiments are conducted in a controlled intraocular surgical environment using a teleoperated robotic system controlled by a non-expert. The experimental results demonstrate that the proposed control framework significantly reduces the rate of force constraint violation.

This paper proposes an adaptive force-tracking controller for nonlinear systems with time-varying parameters, based on the practical task of peeling a film from the surface of a rigid body. The precise regulation of the peeling force by a force controller during robotic film peeling is critical for enhancing the safety and stability of the operation. Existing adaptive controllers for systems with time-varying parameters either result in large tracking errors or can only achieve closed-loop system stability, failing to track the desired force. The proposed controller employs the congelation of variables and robust adaptive control. The stability of the closed-loop system demonstrated via the corresponding Lyapunov function. Subsequent simulation results show that the tracking error of the closed-loop system with the proposed controller asymptotically converges to zero, validating the theoretical approach. Finally, experiments not only confirm the feasibility and stability of the proposed controller but also successfully demonstrate its potential for application in robotics.