Quote:
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Originally Posted by Kevin Watson
If you really, really want to use a potentiometer, why not use the Bourns 6639S-1-103 which is available at Digi-Key (search for 6639S-1-103-ND). I'd rather use an encoder.
-Kevin |
The 6639S-1-103 Bourns pot is 10K and not available in a 100K. Will adding 90K resistors in series be acceptable to the RC? It seems like we would lose quite a bit of the RC's resolution.
FIRST has promoted the use of sensors the last few years. It seems like many teams are looking for either one of two things here:
1. Some type of encoder/pot to measure steering angle (slow rpm, continuous turn with good resolution ~3°). I like the idea of a continuous pot because it doesn't take up CPU power and takes almost nothing to program, and does not rely on starting postition (absolute). An optical encoder measuring ticks (like a mouse) needs to count not only ticks, but the direction of ticks. PS/2 mice have two optical sensors, and with some programming outside of beginners, these two sensors can measure both position and direction (relative to some starting point).
2. Angular velocity in order to measure speed of shaft rotation, which can then give you the linear distance traveled by the output wheel/belt (C=pi*D).
The
http://www.rec.ri.cmu.edu/education/...tent/index.htm site has some information listed for encoders, but I didn't find where to obtain their encoders and they were not in the Edubot or KOP. Where do we obtain these parts? The sample programs count the number of ticks in a constant direction, but what about when the wheel changes direction or is attached to steering? The sample code does not address this issue.
Sample code from FIRST or Innovation FIRST would help teams to concentrate on building robots. Not all teams have the resource or knowledge to construct additional electronics that use encoders to measure steering angles, angular velocity, etc. which is in turn converted back to an analog signal readable by the RC analog inputs.
Any help from other teams who have knowledge on how to do any of the above would be appreciated!