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Originally Posted by MichalSkiba
First off, a question about the uber-accurate Wildstang Positioning System (WSP perhaps?):
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It was WPS originally, but we ended up dubbing it StangPS
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How were you able to account for wheel slipping?
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Very good question. Our system had no slippage detection/correction. (read on...)
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This would occur when your robot would be pushed (while wheels were locked) or sliding down the ramp (for example).
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It was more of a problem on the ice (HDPE) and performing turns on the ramp.
Like Mike said in a previous post, we didn't need a whole lot of precision. If we wanted to ram a stack (whether freestanding or the group on the ramp), we just had to make sure that the stack ended up in front of our robot.
Our wheel slippage (in normal situations) was
* minimal on the carpet in normal situations
* slight climbing the ramp
* measurable on the ice (HDPE)
* negligable descending the ramp
Therefore, we didn't design programs that spent significant time on the ice. Our double-hit program (hit the left side of the stack, come back, hit the right side of the stack) consistently cleared a good portion of the bins, but was slightly inconsistent due to the slippage on the ramp.
In situations where we came head-to-head with another robot, there was a good chance that we deflected during the collision and recorrected our heading to squeeze past and continue on. If is was the type of collision that stopped us dead in our tracks, that was a different story. Luckilly, those types happened on the ice which allowed our wheels to slip and not burn motors.
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I'd immagine that such 'small' inaccuracies could addup to more then +/- 1-inch by the end of the match.
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You are correct in saying that the inaccuracies would add up, but after the 15 seconds were up, the knowing our position wasn't extremely important. Had it been, we would have probably considered determining the slippage and corrected.