55
Chapter 8
Calibration & Maintenance
Your Adept MobileRobots platform is built to last a lifetime and requires little maintenance.
T
IRE
I
NFLATION
Maintain even tire inflation for proper navigation of your Pioneer 3-AT. We ship with each pneumatic tire inflated to 23
psi. If you change the inflation, remember to adjust the
driftFactor
,
ticksMM,
and
revCount
FLASH values.
C
ALIBRATING
Y
OUR
R
OBOT
Your robot comes with FLASH parameters adjusted for operation on smooth, flat surfaces with its original payload. If
you operate your robot on some different surface and with lighter or heavier loads, you probably will need to recalibrate
many of its operating parameters, such as
driftFactor
,
revCount
,
ticksMM
and the PIDs.
The ARIA
demo
program has two modes to help you do that. In ‘
p
’osition mode,
demo
displays current heading and
position. Press the ‘
r
’ key to reset these to 0 at any time. Press the right or left arrow key to have the robot rotate 90
degrees either clockwise or counterclockwise, respectively. The up and down arrow keys tell the robot to advance
forward or backward one meter, respectively.
ARIA
demo
’s ‘
d
’irect mode lets you change the variety of operating parameters on-the-fly by letting you send an ARCOS
client command number and value to be used during the current session. To replace the default values in FLASH, use
ARCOScf
.
Accordingly, to properly calibrate your robot, first use
ARCOScf
and record and save on disk the current values for the
respective parameters, such as for
driftFactor
and
revCount
. Then connect with the ARIA
demo
and engage
position mode to move the robot. As accurately as possible—a laser-line or pointer is helpful here--measure its actual
motion and position and use
demo
’s direct mode to adjust the reported values for your robot’s current configuration and
operating environment.
Note:
Disable the server-side gyroscope accessory (HasGyro 2) before calibrating driftFactor and
revCount.
Standard Calibrations
Start with
driftFactor
since its value affects both
ticksMM
and
revCount
. Draw a line on the floor parallel to the
robot’s translation travel and drive the robot forward or back at least three meters. Adjust
driftFactor
(command
#89) to minimize the robot’s drift off that line.
Then drive the robot forward or back one or more meters and compare its actual translation distance you accurately
measure with
demo
’s ARCOS-reported distance (x) in millimeters. Adjust
ticksMM
(command #93) so that the numbers
match.
Likewise, rotate your robot and compare your measured rotation angle to the reported heading (
th
). Adjust
revCount
--
the measure of differential encoder ticks to achieve 180-degrees rotation-- accordingly (command #88).
Finally, drive the robot around and adjust its PID, velocity and acceleration values to achieve the desired performance
for the operating configuration.
Gyroscope Calibrations
With the client-side gyroscope (
hasGyro
set to one), ARIA retrieves the rate data and manages it from the client side.
Consequently, you don’t have to disable it when performing calibrations with the ARIA demo program. In fact demo’s
‘p’osition mode displays the gyro versus encoder headings separately for tandem calibration. Adjust the
GyroScaler
value in your robot’s
Aria/params/*.p
params file (
p3dx-sh.p
, for example).
