Specifications & Controls
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Figure 8. Pioneer 3 SONAR array
On all models except those outfitted with the docking-charging system, a hinged rear door gives you easy access to the
batteries, which you may quickly hot-swap to refresh any of up to three batteries.
Nose
The nose is where we put the onboard PC. The nose is readily removable for access: Simply remove two screws from
underneath the front SONAR array. A third screw holds the nose to the bottom of the AT’s body. The DX nose is hinged
at the bottom.
Once the mounting screws are removed, simply pull the nose away from the body.
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This provides a quick and easy way
to get to the accessory boards and disk drive of the onboard PC, as well as to the SONAR gain adjustment for the front
SONAR array. The nose also is an ideal place for you to attach your own custom accessories and sensors.
Access Panels
All DX’s come with a removable right-side panel through which you may install accessory connectors and controls. A
special side panel comes with the onboard PC option, for example, which provides connectors for a monitor, keyboard,
mouse and 10Base-T Ethernet, as well as the means to reset and switch power for the onboard computer.
AT’s come with a single access panel in the deck. Fastened down with finger-tight screws, the User Control Panel and
onboard computer controls are accessible beneath the hinged door.
All models come with an access port near the center of the deck through which to run cables to the internal
components.
SONAR
Natively, ARCOS-based robots support up to four SONAR arrays, each with up to eight transducers that provide object
detection and range information for collision avoidance, features recognition, localization, and navigation. The SONAR
positions in all Pioneer 3 SONAR arrays are fixed: one on each side, and six facing outward at 20-degree intervals.
Together, fore and aft SONAR arrays provide 360 degrees of nearly seamless sensing for the platform.
Multiplexed Operation
Each SONAR array’s transducers are multiplexed: Only one disc per array is active at a time, but all four arrays fire one
transducer simultaneously. The SONAR ranging acquisition rate is adjustable, normally set to 25 Hz (40 milliseconds
per transducer per array). Sensitivity ranges from 10 centimeters (six inches) to five meters, depending on the ranging
rate. You may control the SONAR’s firing pattern through software, too; the default is left-to-right in sequence for each
array. See the
ARCOS
Chapters 6 and 7 for details.
Sensitivity Adjustment
The driver electronics for each array is calibrated at the factory. However, you may adjust the array’s sensitivity and
range to accommodate differing operating environments. The SONAR
gain control is on the underside of the SONAR driver board, which is
attached to the floor of each SONAR module.
SONAR sensitivity adjustment controls are accessible directly, although
you may need to remove the Gripper to access the front SONAR, if you
have that accessory attached. For the front SONAR, for instance, locate
a hole near the front underside of the array through which you can see
the cap of the SONAR-gain adjustment potentiometer. Using a small flat-
bladed screwdriver, turn the gain control counterclockwise to make the
SONAR less sensitive to external noise and false echoes.
Low SONAR-gain settings reduce the robot’s ability to see small objects.
Under some circumstances, that is desirable. For instance, attenuate
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With older Pioneer 2 models, you also needed to remove the Gripper before removing the nose. With P3 models, the robot’s nose and Gripper come
off together, so you only need to remove the nose mounting screws.
