Active Contraints for Tool-Shaft Collision Avoidance in Minimally Invasive Surgery

Recent advances in teleoperation-based robotic-assisted Minimally Invasive Surgery (MIS) have made significant inroads in clinical adoption. However, such master-slave surgical systems create a physical separation between the surgeon and the patient. The concept of Active Constraints (ACs) provides guidance and sensory information to surgical robot operators in a form of haptic, visual or audible cues. This work proposes a novel ACs approach to avoid surgical tool-clashing and collision of the tool-shaft with delicate anatomy using elasto-plastic frictional force control. The presented framework is designed to reduce the occurence of direct coupling during electrocautery and to protect high-risk regions in Minimally Invasive Partial Nephrectomy (MIPN). Moreover, we combine aforementioned ACs methods and propose a solution when simultaneous penetration of both constraints occurs. The proposed methodology is implemented on the teleoperated da Vinci Surgical System using the da Vinci Research Kit (dVRK) and its performance is demonstrated through three types of user experiments. The experimental results show that the developed algorithms are of significant benefit in performing the tasks with ACs assistance.