With minimally invasive surgery (MIS), also called endoscopic surgery, in which an endoscope and special instruments are inserted into the body cavity through small incisions, the traum a to the body, the post-operative pain and the length of hospital stay are reduced significantly compared to traditional open surgery. Nevertheless, MIS has inherent drawbacks, which hinder the conduct of operations. An im portant obstacle in MIS, which is the concern of this thesis, is the significant degradation of kinesthetic/force feedback (haptic feedback) to the surgeon from the instrument and its interaction with tissue. To tackle this and other limitations of MIS, assisting robots may be used during interventions. The current surgical robotic technology solves several problems of MIS, yet it stops short of restoring feedback of instrum ent/tissue contacts to the surgeon. Lack of haptic feedback in robot-assisted MIS is regarded both as a safety concern and a performance limiting factor.

This thesis pertains to devices and methods required for incorporating contact feedback in master-slave robotic MIS systems. In terms of devices, novel mechanisms are designed including a surgical end-effector (slave) with full force sensing capabilities and a surgeon-robot interface (master) with full force feedback capabilities. These two mechanisms are used to form a master-slave environment for studying the effect of haptic interaction on performance during soft-tissue MIS. IP-based master-slave communication enables a user to haptically teleoperate the slave through the master.

In terms of methods for instrum ent/tissue contact feedback, kinesthetic force feedback and visual substitution for haptic feedback are considered. Using the masteriii slave system, haptic teleoperation experiments involving a simple surgical task are conducted, and the system performance is assessed in terms of objective criteria that evaluate accurate transmission to the surgeon of certain task-related information that is critical in the context of soft-tissue applications. Next, the master-slave system is used to conduct experiments involving a simple surgical task where the users’ performance in terms of optimal application of forces is compared for situations in which haptic feedback is substituted or augmented by the corresponding visual stimuli.