[Thad House]

Originally Posted by EDesbiens

What would you guys use to know the position of the robot on the field at all time? And do you know any not drifting gyro?

This is something that's actually very difficult to do.

Pretty much any gyro within FRC budget is going to drift, at least a little bit. Things like the NavX, or 2 gyros stacked on top of each other upside down can help, but since a gyro is a rate sensor, getting angle requires integration, and any integral error just adds up and compounds, which is actually what creates the drift. A compass could work if the motors didn't create so much interference, but with FRC robots compass's are not reliable enough.

Position is difficult as well. Things like encoders on drive wheels can give a start to position, but since you need a gyro to detect angle, you still get error, plus if your wheel's slip everything goes bad fast. You could use a non driven wheel to measure, but those can slip too, and you still have the gyro error.

The only good options that would be within FRC price ranges would be something like a FIRST provided HD camera above the field, that teams could use to track their robots. But with current items, getting 100% accurate position and angle of the robot throughout an entire match is not easy, and I would say its not possible within the current budget and DS rule limits.