Installation & Operation
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Figure 4. Your Pioneer 2 Arm safe at home
4. Remove the plastic plug from the robot’s top-plate access port. Just inside, find the
two Arm power and signal connectors. Mate with the signal and power connectors
attached to the Arm. Insert wired harnesses back into the body of the robot and
replace the plastic cap.
Power to the Arm
Main power for the Pioneer 2 Arm is from both your robot’s Main Power and from the Arm
power switch found on the DX/DXE side panel. On the Pioneer 2-AT, the Arm power
switch is built into the back of the backpack.
Your robot’s Main Power switches power to all onboard systems; the Arm power switch
controls power to the Arm’s controller electronics. A software-enabled switch on the
Arm’s controller board provides power to the Arm’s servo motors. For power
conservation and safety reasons, the relay normally is deactivated so that the servo-
driven joints normally are not engaged—all the joints are “limp” and easily rotated and
swiveled manually. When engaged, the servo motors will resist your efforts to move them.
When your software enables
power to the Arm servos, all joints
simultaneously and as quickly as
possible “jump” to their positions
last programmed into the con-
troller. And, if power is removed
from the servos, the Arm will fall
into its mechanically limpest
position.
Since the Arm’s joint positions
cannot be known, they are
assumed by their generic
controller to be in a default
center position. When you apply
power to the servos, the arm
thereby snaps fully extended into
a “salute” nowhere near any
reasonable limp configuration.
This snap-to-salute draws
excessive power and can swing
the joints into nearby objects.
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Arm Safety at Home
Fortunately, on start up or reset, your Pioneer 2 robot’s P2OS-based Arm servers establish
communication and reset the joints to be in a low-energy, folded “home” position.
When limp in that same position, no joint is far from its home position when servo power
gets applied. This way, the snap-to-position jolts characteristic of servo motors when first
powered up are minimized.
Accordingly, when operating the Pioneer 2 Arm, be sure to manually place it in its home
resting position
before
applying power to its servos, and be careful to have it resume its
home position before removing power. Failure to do so may cause damage to the Arm
or to nearby people, animals, and other things.
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Some may argue that this presents a fine opportunity to perfect your robot’s “dope slap” maneuver made
famous by Click and Clack, the Tappet Brothers, on their infamous National Public Radio show, Car Talk©.
