Design and Kinematic Optimization of a Two Degrees-of-Freedom Planar Remote Center of Motion Mechanism for Minimally Invasive Surgery Manipulators

Abstract

Minimally invasive surgery (MIS) requires four degrees-of-freedom (DOFs) (pitch, translation, yaw, and roll) at the incision point, but the widely used planar remote center of motion (RCM) mechanisms only provide one degree-of-freedom. The remaining three DOFs are achieved through external means (such as cable-pulleys or actuators mounted directly on the distal-end) which adversely affect the performance and design complexity of a surgical manipulator. This paper presents a new RCM mechanism which provides the two most important DOFs (pitch and translation) by virtue of its mechanical design. Kinematics of the new mechanism is developed and its singularities are analyzed. To achieve maximum performance in the desired workspace region, an optimal configuration is also evaluated. The design is optimized to yield maximum manipulability and tool translation with smallest size of the mechanism. Unlike the traditional planar RCM mechanisms, the proposed design does not rely on external means to achieve translation DOF, and therefore, offers potential advantages. The mechanism can be a suitable choice for surgical applications demanding a compact distal-end or requiring multiple manipulators to operate in close proximity.

Synthesis and methodology for optimal design of a parallel remote center of motion mechanism: Application to robotic eye surgery

“…Nisar et al proposed an alternative mechanism in [32]. Here, the presence of a downward protruding link is addressed, which can be considered as undesirable for surgical robotics as it moves in the direction of the patient.…”

The Raven Open Surgical Robotic Platforms: A Review and Prospect

“…Several groups citing the Raven system have developed complete or nearly complete surgical robotic systems [6][7][8][9][10][11][12]. These systems often address new surgical procedures (such as pediatric cases or needle guidance) [6,9,10] novel delivery modes [8] or integration of industrial manipulators into surgery [12] Numerous groups have developed new hardware influenced by the Raven design [12][13][14][15][16][17][18][19][20][21][22] or focused on numerical optimization of mechansims [23]. Key aspects of these designs are minimally invasive character, often making a contribution such as novel mechanisms for decoupling motion at the laparoscopic entry port [13], decoupling drive axes [16], or reducing weight and size [19].…”

New remote centre of motion mechanism for robot-assisted minimally invasive surgery

“…Under the constraint imposed by the ‘minimally invasive’ incision, two tangential motions of the instrument must be confined at the incision port to ensure patient safety [ 4 ]. Hence, the instrument has four degrees of freedom (DOFs), namely, pitch, translation, roll, and yaw [ 5 ]. For convenience, the concept of the remote centre of motion (RCM) has been devised to describe the pitching and yawing movements around the incision port [ 6 ], and RCM generation is one of the requisite terms for an MIS robot that is directly related to patient safety.…”

“…This approach can be applied regardless of the robot structure and has the great advantage of robot design simplification. However, it is difficult to guarantee safety in the case of electronic-component or power malfunction; thus, this method is rarely used in commercialised models [ 5 ].…”

“…The parallelogram mechanism is commonly adopted in MIS robots having high rigidity and, such as the Neurobot [ 19 ], BlueDRAGON [ 20 ], and the famous da Vinci Surgical System (Intuitive Surgical Inc.) [ 21 ]. In addition, many manipulators have been developed based on this architecture, which have diverse structural forms [ 5 , 20 , 22 – 32 ]. However, a conflict exists between the mechanism movement range and structure.…”