Page 262 - Flexible Robotics in Medicine

Comparative mechanical analysis for flexible bending manipulators 251
Table 11.1: Comparison of selected flexible robot/manipulators.

Robots/flexible
manipulators in
the current Degrees of
market Size Actuation method freedom Pros and cons
Da Vinci robot, A variety of The system seamlessly Multiple It has been clinically
Intuitive Surgical EndoWrist translates the surgeon’s DOFs applied in many surgical
Inc. [6,11] instruments with hand, wrist, and finger specialties, such as
different sizes movements into precise, urological, cardiothoracic,
real-time movements of gynecological, and head
surgical instruments and neck surgery
(multiple actuators)
HiQ hand 5 mm The hand instruments are 3 DOFs of The reusable design
instruments curved to offer surgeons translation features independent jaw
provided by the ability to triangulate rotation, versatile shafts
Olympus [12] and avoid crossed for the left or right hand,
instruments in the and low-profile handle
abdomen. design for ideal
ergonomics.
OctArm, inspired 45 mm diameter Multiple actuators control Multiple Reduced sweeping area
by biological the robot to operate to the DOFs and have ample working
examples desired position directly. space. Too large to
[13 16] operate inside the human
body
Highly 12 mm diameter Tendon actuation. Three 3 DOFs of Switching the mode of
articulated tendons are actuating the translation limp and stiff for both
robotic probe outer shell. One tendon is inner and outer concentric
(HARP) [17] actuating the inner shell. tubes achieved its link by
Tendons are actuated by link motion, which is slow.
the individual motor.
IPMC worm-like Parameter Each thin strip of IPMC 1 DOF of The robot moves in
robot [22] 25mm 3 5mm 3 2mm acts as an individual translation undulatory locomotion.
actuator The average speed of
0.14 mm/s is achieved.
IPMC, ionic polymer-metal composite.

designs, including the difference in support and guidance hole. One of the designs using
numerous vertebras and constraint tube to operate [18,20]. There are one elastic tube and several
vertebras acting as a backbone. As shown in Fig. 11.1, there are holes on the vertebras to provide
guidance [18],asshown in Fig. 11.1. However, because all the vertebras are tightly connected,
there will be friction between the vertebras that will affect the performance of the manipulator.
There are other designs using a one-piece tube acting as a backbone and holes in the wall
of the tube to provide guidance for the wire to go through [4,21]. However, these designs
have a high requirement of the material of the tube because it needs to provide support at
the same time to be able to bend. Drilling holes in the wall make it harder to manufacture.