You can also see the white pieces, used to indicate the stop point for judging the accurate stop event.
I wasn't terribly excited by this contest, since I didn't really see much of a challenge in actually building the bot. I expected that most of the complexity would be in the code - the exact opposite of my preferred challenges. After changing my mind several times about whether or not I would even participate, I decided to go ahead and enter.
I had built several prototype units. The two major platforms I explored were differential drives and actual steered units. I had problems making either as fast as I would have liked, but I got the differential drive going faster than the steered platform. So I went with it.
About the only complexity on my bot was a dog clutch that allowed me to lock the two motors together. This was to aid in the accurate stop event, which required the bot to drive down a long straightaway before stopping on a line. I had used my two most evenly matched motors, but even then I had a small speed differential that made straight paths difficult. So I added a micromotor and sliding axle arrangement that allowed the two sides to be locked.
Also, rather than relying on changing compile-time constants for my light sensor threshold values, I added a touch sensor and calibrated the sensor before every contest.
| Build Time: | About 20 hours (including numerous prototype bots) |
| Pieces: | 128 (including 1 RCX, 2 geared motors, 1 micromotor, 1 touch sensor, and 1 light sensor) |
| This image shows the top of the bot. The touch sensor used to trigger calibration is visible on the top of the RCX. The shifter for the dog clutch can be seen just below the 'Run' button under the RCX. | |
| The RCX has been removed. The micromotor used to engage and disengage the clutch is visible. No sensors are employed - the motor just runs for two seconds to engage or disengage the gears. The belt drive slips harmlessly when the shaft reaches the end of its travel. | |
| A bottom view. The two drive motors have 8-tooth gears driving 24-tooth gears on the drive shafts. Those 24-tooth gears, in turn, drive the 24-tooth gears visible farther back in the bot. The clutch shaft is mounted directly above those gears, using two side-by-side 8-tooth gears to lock them together. You can also see the white pieces, used to indicate the stop point for judging the accurate stop event. |
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| The next two pictures show more of the bot disassembled. Now the sliding shaft and shifter mechanism for the clutch is completely visible. | |
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