Remote Center of Motion (RCM) Mechanisms for Surgical Operations

Abstract

Nowadays, surgical applications, entering the body through a small incision with laparoscopic procedures are performed and are expanding the use of robots for these operations. In existing systems, conventional robots are used for the body. Surgical procedure is carried out by a separate mechanism which is attached to the end of the robot and robot is used to positioning this mechanism. These mechanisms are called Remote Center of Motion (RCM) mechanism.In this paper, the literature on studies performed about the parallel, spherical and hybrid RCM mechanisms are examined and classified. IntroductıonThe purpose of the RCM mechanism, provide rotating around the incision point to prevent potential damage of the body tissue by the robot. Instruments enter through this incision point into the body with mechanical control and the robot works. For reasons such as robots in the operation field covering many places, the difficulty of controlling and maintenance the robot, focuses on fixing the RCM mechanisms to working area and direct drive. For this purpose, two different mechanisms profile as a parallel and spherical are developed. In addition, the spherical mechanisms are designed in two different profiles as serial and parallel. In the aforementioned method, mechanism is fixing either end of a robotic arm or directly to the working zone. For this reason, it can be said RCM point's position is fixed. However, although body structure during operation assumed to be constant, as a result of very small movements happen resulting from the organism's liveliness, for precision surgical applications, researchers tend to develop mechanisms as RCM point moving. For this purpose, Hybrid (Serial-Parallel) mechanisms have emerged. In the hybrid mechanisms, working around the RCM point performed by the serial module, shift the RCM point is performed by the parallel module. In this way, requiring very small linear movement and host rotate around incision point such as eye operations, surgical success is increases. Parallel RCM MechanismsAs well known, if a link is connected by a revolute joint at its end, all points excluding the axis of the revolute joint in this link are rotated around the axis. In this case, any point on the axis can be considered as a RCM point. This kind of RCM mechanisms is usually acted as a basic component of 2 degree of freedom (DOF) or multi-DOF RCM mechanisms because of its simple structure. The most familiar RCM mechanisms in applications are based on a parallelogram structure, which can easily compose 2-DOF RCM mechanisms. Fig. 1a-f shows a basic configuration of parallelogram-based RCM mechanisms. It is clearly shown that there exist redundant constraints in the EBCD loop. Thus by eliminating "E", "B", "C" and "D" redundant constraints, several other configurations can be derived, as shown sarpectively in Fig. 1b to 1e. In Fig. 1f, it is shown that "E" joint is completely removed. This kind of RCM mechanisms has many advantages such as a relatively large movement range, a simple structure, t...

Fuzzy Control of Laparoscopic Surgical Robot Designed for Use in Minimally Invasive Surgery

“…That is, the rotation of the point P (x, y, z) depends to only the rotary motor. Thus the motion equations of the robot are obtained in a very simple way [1]. The purpose of the robot is to turn and orient the cannula around the RCM point.…”

“…2 [3]. _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 1 Mechatronic Department, Turgut Ozal Univ., Malatya -44800, TURKEY 2 Mechatronic Eng., Firat University, Elazığ -23000, TURKEY Development of a Novel Mechanism for Minimally Invasive Surgery: In this paper, a novel robotic system that can assist minimally invasive surgery is proposed by Wang at al. The system has two subsystems: a 3-DOF arm part and 4-DOF instruments.…”

“…Surgical procedure is carried out by a separate mechanism which is attached to the end of the robot and conventional robot is used to positioning this mechanism. These mechanisms are called Remote Center of Motion (RCM) mechanism [1]. The purpose of the RCM mechanism, provide rotating around the incision point to prevent potential damage of the body tissue by the robot.…”

“…In the hybrid mechanisms, working around the RCM point performed by the serial module, shift the RCM point is performed by the parallel module. In this way, requiring very small linear movement and host rotate around incision point such as eye operations, surgical success is increases [1].…”

Hand-Eye Calibration With a Remote Centre of Motion

“…The schematic shows a magnified version of the type of movement of the camera when being used in RMIS. RCM is denoted at the trocar point to minimise a chance of a robot arm damaging the surrounding tissues [2], [3]. The camera motion is restricted around the RCM and this provides a very small motion range which is not sufficient for a decent calibration.…”