Shaft Encoders

[wun]

My team has been trying to think of ways to make the drive system more accurate. One of the things we came up with is using shaft encoders to make sure the wheels would be spinning at the right speed (eg: instead of setting the PWM speed to drive, you use the joysticks to set the speed you want the wheel to be rotating at so if both joysticks are full forward, the robot will go straight, regardless of motor inconsistencies).
Has anyone had any luck with these? I have been doing some reading, but I would like to hear what other people have to say.

[Sean Schuff]

Our team used laser cut shaft encoders last year and they worked very well. We had rougly 200 slots cut in the entire 360 degree rotation - probably a little overkill but it did the job. And it kept our robot from drifting due to unmatched motors.

The #1 reason for having encoders - autonomous mode!

Good luck!

Sean

[The Paco]

for several years now we have used hall-effect shaft encoders tied directly to the output shaft of our gearbox and they have not failed us yet. we rely on them heavily in autonomous mode and during normal operation to make the robot drive straight.

a suggestion to make the robot drive straighter and eliminate any joystick inaccuracies may be to write in the code that if the sticks are within 5 or so counts of each other the same output is sent to the speed controllers. PM me if you would like any more details. id be more than happy to help!

[Kevin Watson]

Originally Posted by wun

Has anyone had any luck with these? I have been doing some reading, but I would like to hear what other people have to say.

I wrote some example encoder interface code that might be of interest. You can find it here: http://kevin.org/frc.

-Kevin