Quote:
Originally Posted by Knufire
Remember that you're trying to measure absolute position here (the exact angle of the arm). Incremental encoders (which are most of what has been mentioned in this thread so far) measure relative postion (how much the angle of the arm has changed since the robot turned on). There are a few different solutions.
If you want to use an incremental encoder, you'll need a second sensor to tell you where "zero" (or any reference point) is. I've found the hall effect sensors from WCP made by 971 work great for this pupose. It's a little circuit board that returns a true/false based on whether there's a magnet in front of it; you attach a magnet to the arm and place the sensor board where it will trigger at a known arm angle. Now you know how much the arm angle has changed from that known position.
An alternative solution is to use an absolute encoder or potentiometer, that will tell you absolute postion. One option for this are the VP Encoder Stage (this is actually the SRX Mag Encoder mounted into a plastic block the same shape as a VP stage). You'll need a Talon SRX to interface with this sensor. If you don't want to use an SRX, one of my personal favorites is the US Digital MA3: http://www.andymark.com/product-p/am-2899.htm. |
Thanks so much! That encoder might just be what my team needs.