Page 280 - Flexible Robotics in Medicine

270 Chapter 12

procedures attributed to the purchasing cost of the robotic system as well as its
maintenance. In terms of the robotic technicalities, maneuverability is another crucial issue
[2] as current minimally invasive instruments with manipulators that have four degrees of
freedom (DOFs) would limit the system’s operating space, which limits the operational
capabilities of robot-assisted surgical systems.
This chapter would focus on a preliminary surgical robot that is able to provide sufficient
DOFs such that it does not compromise the functionality of the surgical robot. Secondly,
current robot-assisted systems are undoubtedly expensive due to the technology in actuating
the robot arms. Such actuation involves hydrogels, microactuators, hydraulics, magnetic
rings, etc. [3], which are expensive for fabrication and application in the surgical robots.
Hence, this chapter would like to focus on developing a cheaper alternative in actuating the
robot arm while still upholding its functionality.
The objective of this chapter is to design and fabricate a preliminary working prototype of a
surgical robot platform with a multisection flexible manipulator that can undergo at least two
DOFs per bending section using a tendon-driven actuation mechanism. The flexible
manipulator tip itself is a continuum structure that consists of two bending sections with four
tendon strings attached for each section. Each tendon string is attached to an independent
stepper motor. This concept of connecting each tendon wire to an independent stepper motor
would be advantageous in stiffness control and precision motion control of the flexible
manipulators, as it allows each string to be manipulated independently.

12.2 Design principles and qualifications

12.2.1 Modular design approach

This robotic platform design consists of three main components: the flexible manipulator
module, the motor unit module, and the electronics module. Having a modular design,
which separates these components, enables the prototype to have various applications since
the modules can be manipulated easily to suit these various implementations.

12.2.1.1 Flexible manipulator module
The flexible manipulator of Fig. 12.1 consists of eight major components. The flexible
manipulator module must have the ability to provide forward and backward motion of the
device as well as the constraint. The constraint is a thin, rigid rod that can be inserted into
the central cavity of the flexible manipulator, providing enlarged workspace. The base
holder is used to fix the module onto the base stepper motor, as shown in Fig. 12.2. The
aim of the stabilizer, as shown in Fig. 12.1, is to prevent any rotational effects when the
constraint is moving in the forward and backward direction. The stepper motor attached in
this module is used to drive the constraint.