26-02-2003 11:19

David Brinza

Light sensor odometer

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.

26-02-2003 11:25

Josh Hambright

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?

26-02-2003 11:35

Dave Flowerday

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.

26-02-2003 11:55

Josh Hambright

wooo
neato!

26-02-2003 12:00

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.

26-02-2003 12:47

Bduggan04

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.

26-02-2003 13:37

Cory

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

26-02-2003 14:28

Dave Scheck

Nice work.

Out of curiosity, are you processing the sensor data with the robot controller or an external circuit?

26-02-2003 14:58

Josh Hambright

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

26-02-2003 14:59

Cory

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

26-02-2003 15:07

Kyle Fenton

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?

26-02-2003 16:28

EStokely

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

26-02-2003 17:01

Gui Cavalcanti

Quick question

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?

26-02-2003 17:23

AJ Quick

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..

26-02-2003 19:01

Cory

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