Page 411 - Flexible Robotics in Medicine

EndoGoose: a flexible and steerable endoscopic forceps 405

sectional metal wire, providing it with the mechanical properties to maintain the bending
shape and position. Nylon cables are driven through two holes (which are at opposite ends
of each other) on each bead. The driving cables’ proximal ends communicate with actuators
within the control cabinet that houses a motor with gears. When tension is applied to the
left cable, the flexible spine will deflect left (and vice versa). The remaining two holes on
each bead are used to tie all the beads together with two separate cables. This allows the
beads to move as one body, increasing stability during bending.

A distal end is deflectable, with a plurality of bead-like structure and lumens extending
through the edges and a central hole, with at least two driving wires at opposite ends,
penetrating the edges of the beads. The driving wires are pulled to cause the beads to bend
when the steering prototype at the proximal end is operated. Each segment of the gooseneck
corresponds to each other with a spring in between and a string connecting the segment
units together. A control box portion connects to the spring with a sectional wire
(gooseneck) through the lumen to the first end of the flexible rod, enabling the flexible
section to stay in shape after bending. The forceps are designed to be mounted on the
gooseneck with the threads used to close them being threaded through the gooseneck. These
threads are made of nylon and are used for the proof of concept, to prove that the design is
able to open and close with proximal end control.

There are springs interspersed in the bending segment to keep the connector beads away
from each other so that more torque can be created when the cables are pulled. The springs
prevent the beads from being pulled tightly together. Without the springs, the force
transmitted through the cables may be translated into pulling the beads against each other,
creating a static force instead of a motion.
The actively bending section operates based on a cable-driven mechanism. This
essentially means that the bending is achieved through the pulling or pushing action of
cables. In the EndoGoose, the pulling of the nylon cables on one side allows the
connector beads and connector springs to compress together, which then causes the
gooseneck tube to bend toward that side. This pulling action is facilitated by a stepper
motor at the control box that is controlled by a programmed Arduino microcontroller.
Moving the joystick to the left will cause the Arduino tosendasignaltothe stepper
motor that causes it to rotate it in a clockwise direction, which causes the gooseneck tube
to bend to the left as well.

18.2.2 Actively bendable and shape-retaining section

The most prominent and essential feature of the EndoGoose is its actively bendable section.
The core of the actively bendable section is made up of a gooseneck tube. A gooseneck
tube is essentially a typical spring coiled by a metal wire, which results in it being able to