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Originally Posted by efoote868
...Probably one of the easiest (and cheapest) to impliment would be the 2 wheel / skid plates.
!*caution*! with the gyro, make sure its rated to a high rotation, when we tried to use that with our robot this year, it messed up because it could only do 80 degrees/sec !/*caution*/!
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I think there are three vesions of the Analog Devices solid state gyro (yaw rate sensor) with different max turn rates, with the highest being 300°/S.
The faster sensor lets you spin your bot quicker with the loop closed, and it will stay 'locked' if your bot is hit, or hits something, and spins at a rate below 300°/S - but neither of these things are show stoppers.
the slowest sensor: 80° / S is a fast enough turn rate for normal driving. If you are spinning your robot 360°/ Second, you are not driving, you are doing a victory spin!
Two things: when the sensor is turned faster than its max rate, it outputs the full scale reading - your control loop will continue to respond with its max output, so the robot does not go berzerk, it acts predictably.
The only shortfall is if you are integrating the sensor to get compass heading, the reading will be wrong if the robot is spun too fast (by an external force). In this case you need a way to reset the heading (if the sensor is being used that way) during a match.
2. If you close the loop on steering with a gryo sensor, I recommend you have a disable switch on the control panel. That way you can drive with the loop closed, giving you very precise steering, and the robot will fight on its on to hold its heading (when something external tries to push it sideways), and then if you want to drive the robot open-loop (victory spins and stuff) you can, with the flip of the switch.
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Ball casters solve this problem nicely (McMaster-Carr #2364T1).
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yes, and ball castors or skid plates take up very little space, which means, you could also have pnuematic feet that extend down, with high friction plates, that can be deployed when you want your robot to
stay where you parked it!.