I was wondering if it will be possible to use the banner sensors(from last year) as encoders on slow moving assemblies such as arms. This could be done by putting white and black stripes on a sprocket and than keep track of the changing stripes to calculate the relative position of the arm.
Tell me if you think this is possible, also please tell me if this would be leagal to use previous year’s banner sensors.
Why wouldn’t you just use a potentiometer? I don’t think an arm would move so fast or so many revolutions. I see an arm as moving at a maximum of 1 revolution at a macimum of 1 rev per second. So wouldn’t a pot work for this?
Absolutely possible.
Check the flowchart for legality… I think yes…
yea a potentiometer would be perfect for your use. Cheap Digital encoders work extreamly well. Team 115 and also 254 used one last year to prevent the arm up and motors from backdriving.
u r right, would any one recomment a specific potentiometer. I knwo that potentiometers are pretty standard and are used as variable resistance in a circuit, however i am thinking to control the arm using a knob(potentionmeter) and i think ur idea will really suite my ambitions. Thanks, but just out of curiosity would the banner sensor be able to perform these tasks?
As for a manufacturer they are all about (I said about) equal
Things you need to consider/look for
will you be moving more than about 250 degrees? if that is a yes then you don’t want a regular 1 turn.(they don’t actually go 1 full turn) You want a multi turn Pot.(think of how older radios have a volume control, you spin for a while and then they hit a stop) we normally use 3 turn 10K pots for things that we need to track for about 1 full rotation (like an arm)
you would prefer a 100k but I never have found a 3 turn 100k Pot.
Make sure you use a linear pot, not an audio one. the audio stuff is logrithmic and will not track at all how you want.
If you can use a regular 1 turn then get a 100k.
You’ll read the positions as an analog signal, 8 bit 0-255. the nice part of this over the Banner sensor idea is that the robot will ‘know’ where the arm is at power up. The Banners would not be able to do this.
Hope this helps.
Look at Mouser or Digikey for the multi turns. Radio shack or Fry’s should have linear 1 turns
For the baner sensor and black lines to do it, 'm thinking you would either need it on a very fast part of the arm (like the motor before the gear or sprocket reduction) or you would need lots of very thin lines, but I’m not sure how “thin” of a line the baner can detect reliably.