Abstract

The remote center of motion (RCM) mechanism is an important part of a minimally invasive surgery (MIS) robot. As a practical type of RCM mechanisms, 2R1T RCM mechanisms are synthesized in this paper using a modified screw theory method. Differing from the conventional screw theory method, the modified method brings forward the assessment of different wrench systems, and proposes several general subchains to satisfy each geometrical condition of the wrench system, which can ensure the motion continuity to a great degree. First, the motion pattern and the twist system of 2R1T RCM mechanisms are presented. According to the reciprocal rules of screw theory, three corresponding wrench systems, along with the geometrical conditions for them, are enumerated. After assessing these wrench systems by the comparison of their geometrical conditions, the optimum wrench system is selected for synthesis, and then it is decomposed into sub-wrench-systems. To satisfy each condition of the sub-wrench-systems, several general subchains are proposed, and consequently some preferred general chains are constructed by the serial assembly of the corresponding subchains. These general chains are applied to the leg synthesis. Finally, practical examples of 2R1T RCM mechanisms are constructed by assembling the legs.

Highlights

  • Invasive surgery (MIS) robots have attracted considerable attention in recent years [1,2]

  • In a Minimally invasive surgery (MIS) robot, the surgical tool should be capable of 3-DOF rotation around the incision and 1-DOF translation along the axis of the instrument

  • As a practical type of remote center of motion (RCM) mechanisms, 2-DOF rotation and 1-DOF translation (2R1T) RCM mechanisms are synthesized in this paper using a modified screw theory method

Read more

Summary

Introduction

Invasive surgery (MIS) robots have attracted considerable attention in recent years [1,2]. The conditions for each wrench are analyzed in detail, and each condition can be satisfied by a serial of newly-constructed subchains; by assembling the corresponding subchains, some general chains which satisfy all the conditions are obtained. On this basis, legs with each sub-wrench-system are synthesized. Compared with the conventional screw theory based synthesis processes, this paper brings forward the assessment of different wrench systems, and proposes several general subchains for each geometrical condition, which can ensure the motion continuity of the mechanisms to a large degree

Type synthesis method based on screw theory
Preparation for type synthesis
The wrench systems of the 2R1T RCM mechanism
Synthesis of legs
Condition analysis
Synthesis of 2R1T RCM mechanisms
Conclusions
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call