Friday, April 11, 2008

Greetings from Hartford

We just got to Hartford. The competition starts tomorrow! Well, technically tomorrow (Saturday) is for registration, practice and qualifying for the actual competition on Sunday but honestly Saturday is when all the fun is since that is when you meet other builders and see what they have done. On Sunday everyone is more concerned with the competition itself so there is less socializing.

I think I am in pretty good shape. Since my last post I have worked on improving the candle seeking and also added some code to re-find the candle when it looses sight of it. I also have it finding the "baby" fairly well however it is really sensitive as to the hight of the light bulb they use to simulate body heat. They do not specify how high off the ground it is but they do have a picture which I used to estimate it. Hopefully I can practice with the real thing some tomorrow.

I worked on it every evening this week also except last night (didn't get home from work until after 9:00). Most of this week has been working on some reliability code for recognizing when it is stuck. Last year I used wheel rpm to determine if the robot is stuck but this year I have tried a new method of watching the distance sensors. If it doesn't see enough variability in the distance sensors it assumes it is stuck and backs up a bit. From experimenting this seems to work well.

I also worked on some "intelligent" navigation code. OK, it isn't all that intelligent but should be an improvement over what I had last year. Last year it simply followed one wall for a while, then switched to the other wall. I found that it often picked a very inopportune time to switch so I have improved this a bit. First it only switches which wall to follow when in a hall. I realized last year that if it switches when in a room it is just going to go out the same way it came in and retrace the same steps. The other change is instead of switching after a specified amount of time it is watching the wheel distance sensors. If one wheel has turned considerably more distance than the other it thinks it might be in a loop. I set the threshold on this so it actually goes through the loop just over 2 times before it does this so it shouldn't do it too soon. I may tweak this setting some tomorrow as I experiment in the real maze.

The maze we get to practice in will not be the same layout as the competition but it should allow me to see how my code changes should work out in general. I plan on having Jane shoot some video as I run it through some simulated runs. I just realized I forgot my firewire cable so I won't be able to upload video until I get home but I do plan on posting some video of it on youtube or some place like that.

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