Kinematic Design of a Novel Spatial Remote Center-of-Motion Mechanism for Minimally Invasive Surgical Robot

2015 ◽  
Vol 9 (1) ◽  
Author(s):  
Jianmin Li ◽  
Yuan Xing ◽  
Ke Liang ◽  
Shuxin Wang

To deliver more value to the healthcare industry, a specialized surgical robot is needed in the minimally invasive surgery (MIS) field. To fill this need, a compact hybrid robotic wrist with four degrees of freedom (DOFs) is developed for assisting physicians to perform MIS. The main body of the wrist is a 2DOF parallel mechanism with a remote center-of-motion (RCM), which is located outside the mechanism. From the mechanical point of view, it is different from existing 2DOF spherical mechanisms, since there is no physical constraint on the RCM. Other DOFs of the wrist are realized by a revolute joint and a prismatic joint, which are serially mounted on the movable platform of the parallel mechanism. The function of these DOFs is to realize the roll motion and the in-out translation of the surgical tool. Special attention is paid to the parallel RCM mechanism. The detailed design is provided and the kinematic equations are obtained in the paper. Further, the Jacobian matrix is derived based on the kinematic equations. Finally, the paper examines the singularity configurations and implements the condition number analysis to identify the kinematic performance of the mechanism.

2010 ◽  
Vol 4 (3) ◽  
Author(s):  
Shorya Awtar ◽  
Tristan T. Trutna ◽  
Jens M. Nielsen ◽  
Rosa Abani ◽  
James Geiger

This paper presents a new minimally invasive surgical (MIS) tool design paradigm that enables enhanced dexterity, intuitive control, and natural force feedback in a low-cost compact package. The paradigm is based on creating a tool frame that is attached to the surgeon’s forearm, making the tool shaft an extension of the latter. Two additional wristlike rotational degrees of freedom (DoF) provided at an end-effector that is located at the end of the tool shaft are manually actuated via a novel parallel-kinematic virtual center mechanism at the tool input. The virtual center mechanism, made possible by the forearm-attached tool frame, creates a virtual two-DoF input joint that is coincident with the surgeon’s wrist, allowing the surgeon to rotate his/her hand with respect to his/her forearm freely and naturally. A cable transmission associated with the virtual center mechanism captures the surgeon’s wrist rotations and transmits them to the two corresponding end-effector rotations. This physical configuration allows an intuitive and ergonomic one-to-one mapping of the surgeon’s forearm and hand motions at the tool input to the end-effector motions at the tool output inside the patient’s body. Moreover, a purely mechanical construction ensures low-cost, simple design, and natural force feedback. A functional decomposition of the proposed physical configuration is carried out to identify and design key modules in the system—virtual center mechanism, tool handle and grasping actuation, end-effector and output joint, transmission system, tool frame and shaft, and forearm brace. Development and integration of these modules leads to a proof-of-concept prototype of the new MIS tool, referred to as FlexDex™, which is then tested by a focused end-user group to evaluate its performance and obtain feedback for the next stage of technology development.


2016 ◽  
Vol 10 (4) ◽  
Author(s):  
Kang Kong ◽  
Jianmin Li ◽  
Huaifeng Zhang ◽  
Jinhua Li ◽  
Shuxin Wang

Robot-assisted minimally invasive surgery (MIS) has shown tremendous advances over the traditional techniques. To improve dexterity and back-drivability of the existing planar remote center-of-motion (RCM) mechanism, on which an active prismatic joint is required to drive the surgical tool move in–out of the patient's body, a two degrees-of-freedom (DOFs) planar RCM mechanism is proposed by constructing virtual parallelograms in this paper. The mechanism can be considered as a generalized double parallelogram; both of the actuated joints are revolute joints. This feature enhances the intrinsic back-drivability of the mechanism. The mathematical framework is introduced first to prove that the mechanism could execute RCM. Then, the inverse kinematics of the planar mechanism is solved, and the Jacobian matrix is derived in this paper. Further, the singularity and the kinematic performance based on the kinematic equations are investigated, and the workspace of the mechanism is verified. Finally, a prototype was built to test the function of the proposed RCM mechanism. The results show that the mechanism can fulfill the constraint of MIS, and it can be used as the basic element of the active manipulator in an MIS robot.


2012 ◽  
Vol 6 (2) ◽  
Author(s):  
Chin-Hsing Kuo ◽  
Jian S. Dai

A crucial design challenge in minimally invasive surgical (MIS) robots is the provision of a fully decoupled four degrees-of-freedom (4-DOF) remote center-of-motion (RCM) for surgical instruments. In this paper, we present a new parallel manipulator that can generate a 4-DOF RCM over its end-effector and these four DOFs are fully decoupled, i.e., each of them can be independently controlled by one corresponding actuated joint. First, we revisit the remote center-of-motion for MIS robots and introduce a projective displacement representation for coping with this special kinematics. Next, we present the proposed new parallel manipulator structure and study its geometry and motion decouplebility. Accordingly, we solve the inverse kinematics problem by taking the advantage of motion decouplebility. Then, via the screw system approach, we carry out the Jacobian analysis for the manipulator, by which the singular configurations are identified. Finally, we analyze the reachable and collision-free workspaces of the proposed manipulator and conclude the feasibility of this manipulator for the application in minimally invasive surgery.


2011 ◽  
Vol 8 (2) ◽  
pp. 173-190 ◽  
Author(s):  
Philip R. Roan ◽  
Andrew S. Wright ◽  
Thomas S. Lendvay ◽  
Mika N. Sinanan ◽  
Blake Hannaford

Minimally invasive surgical procedures have improved the standard of patient care by reducing recovery time, chance of infection, and scarring. A recent review estimates that leaks occur in 3% to 6% of bowel anastomoses, resulting in “increased morbidity and mortality and adversely [affecting] length of stay, cost, and cancer recurrence” [23]. Many of these leaks are caused by poor handling and ischemic tissue.Detecting a change in temperature can indicate ischemic tissue. The optical absorption spectrum of a tissue can be used to detect tissue oxygen concentration and tissue ischemia. The electrical impedance of tissue changes as ischemia progresses.This article describes the development of a minimally invasive surgical tool with integrated sensors for replicating ischemia detection measurements during routine manipulation of the tissue. To be useful, this tool should be feasible for use in a real operating room, providing real-time feedback and diagnosis to the surgeon. The design of the tool and choice of the sensors leverages existing work in physiological measurements and surgical tool design.The tool includes a thermistor for measuring the temperature, four LEDs and a photodiode for measuring local optical absorption, and four electrodes for measuring the electrical impedance. The sensors are located on a 7 mm square sensor head, which is mounted to a minimally invasive grasper. A strain gauge and optical encoder monitor the applied force and position of the tool, and a motor controls both. This allows the tool to control the tool-tissue interface. Sensor accuracy has been validated through calibration.


2018 ◽  
Vol 15 (04) ◽  
pp. 1850017
Author(s):  
Guoli Song ◽  
Che Hou ◽  
Yiwen Zhao ◽  
Xingang Zhao ◽  
Jianda Han

Design of the hollow modular joint plays an important role in modern robot layout, fixation, and wiring. In this paper, a hollow modular joint that meets the requirement of a minimally invasive surgical robot is proposed. The mechanical and control design is sequentially illustrated, and the torque sensor and its optimization are provided. Furthermore, a free-force control method is introduced. To analyze the designed module, the simulation of the redundant robot, comprised of the designed joint in seven degrees of freedom, is presented. The results of analyses showed that the designed hollow modular joint is valid and effective.


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