Heres our odometer. Two sensors reading the reflective CD labels attached to the sprockets. Note the cool pillowblocks we made. They have neat little ridges on the bottom that guide themselves into the tracks in the 80/20
Cool!
Do you have similar sensors on another wheel?
It seems you’d need odometers on at least two wheels (if you are dead reckoning in autonomous mode) to know how much you have turned and how far you’ve gone.
what are you sensing on the wheels?
what is reflecting back?
Looks cool…i’ve seen alot of teams doing this. Why did you do 2 on one wheel? Did you find 1 didn’t work as well?
*Originally posted by oneangrydwarf *
**Why did you do 2 on one wheel? Did you find 1 didn’t work as well? **
I don’t know if this is why team 100 did it, but putting 2 on one wheel 90 degrees out of phase allows you to determine both distance traveled as well as the direction the wheel is turning.
wooo
neato!
Thats pretty cool, looks like you put alot of effort into that. However, why not just use a normal off-the-shelf optical encoder, it would much better resolution and might even be easier to do. It could be included as part of your custom electronics.
*Originally posted by IVIaxor *
**Thats pretty cool, looks like you put alot of effort into that. However, why not just use a normal off-the-shelf optical encoder, it would much better resolution and might even be easier to do. It could be included as part of your custom electronics. **
Many optical encoders are expensive and the number of pulses they can send back to the brain far exceeds the stamp processor. This is just simple way of doing it, similar to an optical mouse.
Actually, it wasnt that hard. You just need to make sure that the reflective sections are aligned and spaced perfectly. The reflective tape stuff is CD labels. We are using the Gyro partnered with this system to do do some pretty neat stuff. Im sure someone can guess what. 
None of this has been tested too much, so we arent sure how its going to work. Our line following has been tested, and works fairly well. With fine tuning, it should be somewhere in the 5-8 second zone to get on the ramp.
Cory
Nice work.
Out of curiosity, are you processing the sensor data with the robot controller or an external circuit?
We thought about using optical encoders of some kind…but eventualy ended up using mechanical rotary encoders…they are cheap and easy to swap out if they get smashed, and really light…We opted for the 4 bit ones which are nice but the grey code conversion was a bit tricky…plus it would be nice if they would send documentation with stuff like this.
Great idea to use CD labels…very cool
Nope, it goes straight to the RC through the digital inputs I believe…it may be the analogs. We dont use a custom circuit
Cory
Thats really nice. It looks cool.
One question though, It is illegal. Last year there could be no reflective tape anywhere on the robot. It is still in effect this year?
We actually used CD’s this year. AOL ones are cheap. We just painted a black non reflective line at 120 degree marks to get 3 (or did they end up with 6?) counts per revolution.
Coupled with the Banner sensors it was a pretty easy set up to do
Really, why do you need two? If it’s linked to the RC, as you say, you already know what direction the motor is going - you’re sending it the data for it’s rotation, after all.
Was there another reason for putting two of them on the wheel, like accuracy?
Will there be some kind of traction control installed?
If one of the wheels starts slipping, power would be transfered to other wheels? That would be cool…
No, its not illegal. I highly doubt a robot will have a powerful enough sensor to lock onto the inside of our robot. That will be impossible since we will have number plates surrounding the sides. To tell the truth, Im not sure why there are two. I am more of a mechanics guy. There will be a type of thing that will tell us if the wheels are not moving, and if they are, we will stop giving current to the motors. Likewise, if we arent moving and the wheels are slipping.
Cory