Mobot 2002

Our entry made it to the ninth gate in the competition, which is where the decision gates are. We didn't code in decision gate navigation because we used 7 ir sensors. These sensors often gave false positives and gave too many errors to accurate navigate the decision gates. Because of our stellar performance, we received 2nd place, losing only to some of my friends, the first undergraduate team to ever complete the course (Congrats Anthony and Alok).

Her is our entry for the mobot 2002 race by Jack Lin and Peter Zhang:

Here are some basic specs:

  • RC car base: Tamiya Super Hornet $80
  • Sensing: 7 * IR sensors from Digikey
  • Computing: Handyboard
  • Code: Interactive C

This page is intended to advise those of you who have never made a mobot so you can learn form our mistakes.

Computing:

A handyboard does a lot of functions for you but is very slow. Its list of goodies includes pwm generators for your servos, motor drivers, and an easy to track lcd display. However, if you really want to do some heavy processing, the motorola processor it uses is far to slow. And ic is really annoying to program in.
Car base:
Don't use a tamiya super hornet. Buy yourself a cheap rc car from radio shack and modify it yourself. The advantage of having the tamiya was its ackerman steering, which was already built and hooked up to a servo. That made turning the mobot easy for us. However, you don't have to find a car with a servo and steering already done, you can easily just use a differential drive robot with a front caster instead. I do recommend ackerman steering though because then you can drive your back wheels at a constant speed to move the mobot and concentrate your processing power on turning. Another problem with using real rc car bases is that rc cars were meant to be fast. Notice the hacked lego gearing down system we implemented onto our mobot. We geared it down 15:1 to get it down to a speed where it could actually follow the line. Rc cars are designed to go 30mph! Its hard to get them to slow down.

Sensing:

We tested numerous ir sensors. For the line, they are all pretty much terrible, although some are better than others. A problem that occurs is that ir sensors give higher readings when there is more light at times, so if the mobot sensors are slightly higher off the ground, the sensors will be skewed. I recommend coughing up the money for anthony's cmucam and doing computer vision. This makes mobot a lot harder, however.




back support.jpg back wheels.jpg cover.jpg
back supp...
5/13/2002
40 kB


back whee...
5/13/2002
40 kB


cover.jpg
5/13/2002
41 kB


entire mobot.jpg extended cover on.jpg extended cover.jpg
entire mo...
5/13/2002
40 kB


extended ...
5/13/2002
40 kB


extended ...
5/13/2002
41 kB


handyboard.jpg jack with mobot.jpg mobot cover and sensors.jpg
handyboar...
5/13/2002
41 kB


jack with...
5/13/2002
40 kB


mobot cov...
5/13/2002
41 kB


overhead view.jpg tools.jpg wheel.jpg
overhead ...
5/13/2002
40 kB


tools.jpg
5/13/2002
41 kB


wheel.jpg
5/13/2002
39 kB


 

 

  Copyright ©2004 Peter Zhang. Page Last Updated on August 25, 2004
Peter Zhang Home