Page 293 - Flexible Robotics in Medicine

Flexible robotic platform with multiple-bending tendon-driven mechanism 283

12.4.3 Weight-bearing test

Weight-bearing tests are conducted to provide a general analysis of the stiffness control of
the device while manipulating the flexible tip. Each bending section has a certain mass, and
each section has the capability of carrying weights that are beyond its own weight. The
flexible manipulator is allowed to hang freely in a workspace and allowed to perform
bending at different angles in the direction opposing the gravitational force. The flexible
manipulator is placed with a grid reference, and three trials of measurements were
conducted, measured, and recorded. An average value of the bending angle is then
calculated. A plot of the averaged measured angle against the desired angle is shown in
Fig. 12.11.
There is a linear relationship between the measured angle and the desired angle with a trend
2
line of R value of 0.9993, which indicates that the flexible manipulator platform is able to
translate the desired angles with an acceptable degree of accuracy.
To further validate its weight-bearing abilities, weights of 10 50 g are attached at the tip,
and the device is required to lift the weight to the intended location, as indicated in
Fig. 12.12.

Due to the high degree of independence of each tendon, the device can lift a maximum
weight of 50 g and manipulate the flexible tip with efficiency. This ensures that if the
flexible manipulator is fitted with an end effector such as a gripper, the relative weight of
the gripper will not affect the maneuverability of the flexible arm.

Figure 12.11
The experimental setup of the flexible manipulator is conducted, as shown in Fig. 12.9. The graph
plot of the bending angle versus the desired angle is shown.