Development of a generalized model for force and torque feedback in robotic minimally invasive cardiothoracic surgery: Identification of conditions and restrictions

Introduction: the procedures in minimally invasive cardiothoracic surgery (MICS) aim to reduce the complications of major dissections. However, in the absence of direct contact of the surgeon with the tissue, he receives a partial sense of touch and strength, which can lead to procedural errors, inadequate force applied to the tissue and fatigue during surgery. The inclusion of robotic devices with the MICS technique has enhanced the technical skills of the surgeon to manipulate tissue, an d although the market devices still do not have tactile feedback, research in robotic prototypes that incorpor ate feedback of force and torque is being done. OBJECTIVE: to propose the conditions and restrictions related to the integration of force and torque feedback in robotics MICS applicable to different configurations of manipulators and analyze the implementation of those conditions in a surgical simulator. MATERIAL AND METHODS: from the analysis of needs during cardiothoracic procedures and conditions of minimally invasive surgery, we identified the requirements to ensure reflection of force and performed a mathematical analysis of such considerations. Finally, mathematical analysis were verified by modeling and simulation techniques using the Matlab® computing platform. RESULTS: three types of considerations were argued: a) Kinematic: the existence of a fixed point; the way to guarantee it for robotic MICS procedures, and the trajectories of motion followed by the controller in the applications of Cardiothoracic Surgery, b) Dynamic: the impact of external forces on the manipulator and the way to consider them in the development of controllers that allow the surgeon to feel a sense of contact with the tissue, c) Sensory: requirements of the force sensors and necessary relationship between the number of sensors and actuators to feedback force in MICS robotics. Subsequently these considerations were implemented in a simulator and were checked for compliance. CONCLUSIONS: the conditions related to the incorporation of a force sensor and the perception of the surgeon in terms of touch and force applied turns out to be important in robotics MICS procedures and requires the inclusion of a control system that enables the optimization of telepresence procedures.