[mathking]

Originally Posted by brennonbrimhall

Really cool! Thanks for the clarification. Do you guys make your own, scavenge them from old garage doors, or purchase them?

We have both scavenged and purchased them. The first one we ever used from from a parent's garage. It is nice having a sensor you can run out and buy at a local store the Saturday before bagging if you need an extra. One nice thing about garage door sensors is that they tend to come with a lot of attached wire, so it is usually pretty easy to position them inside a robot.

Originally Posted by Racer26

Sensors are great: when they're needed.

Many FRC applications need no sensors at all, or very limited sensors with a very specific purpose.

Sensors used poorly will make a decent robot perform WORSE, not better.

One of the most important things to consider when using sensors in an FRC application is what will happen when your sensor fails.

This is a very important point. One which we try to (and don't always succeed in) take into account with each sensor. You want to make sure that you (A) have a manual override option where appropriate and (B) make sure the the default reaction of the controller when a sensor fails does not disable an important function of your robot.

A quick example of an instructive failure. Last year at Queen City, our ability to shoot autonomously mysteriously failed. The cause was a piece of retro-reflective tape placed wrong side up. As a result the optical sensor could not determine the shooting wheel speed. So the robot just waited the whole autonomous period for the shooter wheel to get up to the correct speed to shoot. The fix was easy. We coded a timer so that after waiting for 1 second without a change in speed from the sensor the robot would just shoot. (For the record, that fix was incorporated in the code at one point before competition, but in making a couple of changes at competition it was accidentally deleted. Because we didn't have wifi access to the code repo no one noticed at first.)