UTD AUV Team - Status
Tuesday, July 25, 2006
  Vision, Sonar, and Compass
Sunday night, I swam laps with the sub for about an hour, and it only ever lost the line three times. Whenever it did that, though, it always picked up the adjacent one successfully. At the same time, Wes and Ian were unsuccessfully fighting with the sonar boards trying to read the time differential between two channels. Once they get that worked out, it looks like the sonar will be working properly.

The compass has also started reporting bad values, and we haven't been able to fix it yet. If the values were consistent, then we could probably use the compass, but at reduced effectiveness. The compass seems to have several different transfer functions and there is no way for us to know which one it is using this time. We also don't know if the problem is the compass reporting the value incorrectly or the AVR reading it incorrectly.

I was at the pool for about three hours yesterday, and discovered that the handheld PC that was loaned to us doesn't have a daylight-readable display, so it is mostly useless in the Texas sun. In the evenings, however, it is quite invaluable. I did some work on the compass yesterday, and it seems to be better. Unfortunately, that does not necessarily mean "useful". I also had trouble getting the vision system to recognize the test bins, but I believe that is because the pool is so shallow that it could never get the entire bin in frame at the same time.

Today's adgenda (for me) at the pool is:
  1. Get the sub travelling straight by any means necessary. This probably means using the IMU's rate gyro to control our yaw speed to 0, independent of our heading.
  2. Train the vision system on our test course elements in daylight. See how long it takes and how dificult it is with a washed-out screen.
  3. Follow the orange pipe. This should just work, but it will be the first time the sub has followed a non-straight line.
  4. Identify a bin in the camera frame. If necessary, use a surrogate bin that is a smaller target due to the shallowness of the pool.
  5. Get the bin-seeking control system working.
  6. Follow the orange pipe to a bin and stop at the bin instead of continuing along the line.
  7. When sufficiently centered over a bin, dive to the bottom, remaining centered over the bin.
  8. Drop markers on the bin.
  9. Automatically abort the vision system when we have no more markers to drop.

I probably won't get all of this done today, but I will try. Once all of these steps happen, the vision system will be completely working, and we will be able to make it through the validation gate (and hopefully hit the docking station in the process). It also sounds like sonar is coming along nicely, so we should have a real contender here in a few days. Now the real question is whether "a few days" is before or after the competition.
 
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Tuesday, July 25, 2006
12:02   Vision, Sonar, and Compass
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