Page 434 - Sensing, Intelligence, Motion : How Robots and Humans Move in an Unstructured World

EXAMPLES 409

the fact that each module includes all the control electronics its own operation
requires, makes for a universal module design. Covering the whole arm amounts
to tiling it with such modules, perhaps with some modules cut to size for better
coverage. The skin resolution (distance between neighboring sensors on a mod-
ule) is 2.5 cm, twice as good as that of the earlier skin shown in Figure 8.6.
Consequently, the skin has about 1200 sensors. Modules are electrically con-
nected with each other by special connectors built into all four sides of each
module. The skin’s material base is again Kapton, but it is slightly different
from the type used in Figure 8.6. The arm used in this system is a Hitachi P60
industrial arm manipulator.
One such sensor module is shown in Figure 8.8. Unlike the skin shown in
Figure 8.6, surface mounting technology was used for the skin component instal-
lation. Combined with smaller components available at the time, the skin has
about 2-mm maximum thickness, three times less than in the skin of Figure 8.6.
Black dots in the figure are sensor detectors.
Both of the described systems went through a variety of tests using the software
packages based on motion planning algorithms discussed in prior chapters. A
good number of tests covered these three settings:

1. Tests with a Fully Autonomous Operation of the Robot Arm Manipulator.
Typically the arm would be requested to go from some position A to a posi-
tion B, while automatically avoiding collisions with previously unknown
obstacles that it encounters on its way.
2. Tests with Teleoperation. In real time the operator shows the arm a rough
idea of the desired trajectory, moving a master arm quickly and without
any account for possible obstacles, and the main (slave) arm is expected to

Figure 8.8 A single sensor module, one of those used in the skin on Figure 8.7. The
module is 23 by 23 cm in size and includes 8 by 8 = 64 infrared sensor pairs, spaced at
2.5 cm between neighboring sensors.