Page 260 - Flexible Robotics in Medicine

CHAPTER 11

Comparative mechanical analysis for

flexible bending manipulators with

quad-tendon antagonistic pairs

Deren Meng, Wenjun Xu and Hongliang Ren
Department of Biomedical Engineering, National University of Singapore, Singapore

With the application of computer-aided and robot-assisted system integrated into surgery, flexible
bending manipulators have been studied and widely used in minimally invasive surgeries. In this
report, tendon-driven flexible bending manipulators in tight and irregular space have been studied.
The study analyzes different designs of these tendon-driven manipulators in terms of varying
backbone support and tendon guiding mechanism. Design analysis and bending motion model are
investigated, and simulations on the force, displacement, and stress are done with Ansys
Workbench. The finished prototype of the manipulating system can achieve the desired bending
motion. The proposed design is validated by prototype development and experiment.

11.1 Introduction

Recent advances in engineering make it possible to overcome the traditional limitations in the
planning and execution of surgical procedures. The use of a continuum robot reduces the
medical costs substantially, improves clinical outcomes, and makes health care delivery more
efficient. Cameras or cutting tools might be attached to the end of the continuum robot or
manipulator. Compared to open surgery, minimally invasive surgery (MIS) reduces the patients’
hospital stay time, blood loss, and brings better postoperative cosmesis [1,2]. Traditional robotic
arms such as PUMA robotic arm and SCARA roboticarmsare usually operatedinopenspaces
[3]. The continuum robots (snake-like robots) have a lot more degrees of freedom (DOFs),
which make it more suitable to be used in constraint places [4 6]. However, because of the
increasing number of DOFs, there is a need for more actuators to actuate the robot, which
causes the size of the robot large and hard to use in confined space [7].

Thus the improvement of the manipulator and flexible manipulator will make the MIS
more accurate and address the working space requirement inside a human body. In order to reduce
the size of the robot, flexible manipulators driven by tendons/wires/cables are always used because
the mechanism will reduce the use of actuators [5,8,9]. The working mechanism of the tendons

Flexible Robotics in Medicine.
DOI: https://doi.org/10.1016/B978-0-12-817595-8.00011-0 249
© 2020 Elsevier Inc. All rights reserved.