Page 221 - Hacking Roomba

202 Part II — Fun Things to Do

Listing 10-4 Continued

Process p = Runtime.getRuntime().exec(radioCmd);
p.waitFor();
} catch(Exception e) { println(“exception:”+e); }
}
void parseRoombaSensors() {
if( alarm ) {
if( roombacomm.bumpLeft() &&
roombacomm.bumpRight() ) { // snooze
wakeupDate.setTime(wakeupDate.getTime()+snoozeSecs*1000
);
println(“snooze until “+wakeupDate);
alarm = false;
}
else if( roombacomm.wheelDropLeft() &&
roombacomm.wheelDropRight() &&
roombacomm.wheelDropCenter() &&
roombacomm.powerButton() ) {
println(“alarm off! (until tomorrow)”);
wakeupDate.setTime(wakeupDate.getTime() +
(60*60*24)*1000);
alarm = false;
}
}
if( roombacomm.cleanButton() )
runRadioCmd();
}

Summary

Even though the Roomba’s sensors are primitive, they can be put to some interesting uses.
These uses need not be vacuum-related or even robotics-related. The cliff sensors are one of
the best examples of this, becoming non-contact proximity sensors for hands or other movable
objects when Roomba is turned upside down. While upside down, the wheeldrop sensors become
buttons to trigger actions. You could even turn the wheels when upside down and register the
movement as a variable function.
By combining the sensors into more complex aggregations, you can create a novel way to meas-
ure something Roomba normally cannot measure. Combining cliff and wheeldrop sensors gives
a sense of tilt, but you can imagine other combinations as well. Perhaps a combination of but-
tons and driving motor over-current sensor could make a weight sensor and turn Roomba into
a scale. Or using the distance and angle sensors and a little calibration could yield a Roomba
yardstick. Try making Roomba a DJ input device and “scratch” audio files with it by rotating it
back and forth like a record. The number of possible sensor combinations is huge and many of
them produce useful results. Even those that produce non-optimal results are fun and instructive.