We were wondering what techniques others were using to start their robots in specific field positions. We are finding that simply ‘eyeballing it’ is not accurate enough to hit the center or side pegs in autonomous reliably.
For those of you who competed at week 1 events (or those of you with a plan in mind), how did you align for your autonomous? Was there sufficient time pre-match to start the robot where you wanted? Were there references on the field (ex. driver station walls, diamond plate panel dividers) that you used? Were you able to use the field calibration time to find these references? Were field inconsistencies significant enough to affect your alignment, and, if so, do you think you could have found these through measurement during the field measurement time?
Have you verified that your autonomous mode always goes to the same spot within a few inches? Spending time trying to line up perfectly is a waste of time if your movement has too much variance in it.
We can reliably move to a set position relative to our starting position, but if we start an few inches to the left of our desired start then we will end a few inches to the left of the peg.
The variability between one field and another (and between the two ends of a field) can easily approach the few inches of accuracy/repeatability the OP is looking for.
That is very true; ours were basically the same on both sides, and we refined our auto during competition a lot anyways so it wasn’t an issue for us but it could be for others.
Team 4272 just finished up a week 1 event yesterday with a constant auto gear. When we would set up the robot, we would line the gear up to the center peg and push the robot straight back to the wall. We got our auto gear almost every match by doing this.
I reccomend finding a referance point that is easily allignable, such as a specific part of your robot on a part of tape as well as being aligned against the back of the drivers station walls.
Try using reference points on the robot and the field. Sight down a flat side of your robot and line it with a point on the airship or boiler. Use Fist, Feet, finger type measurements if it is always the same person putting the robot down.
My previous comments apply to the locations of all field elements including the tape, the airship and the walls. You will most likely get better and more consistent results by aiming at a reference point on the airship itself, say the gear peg you are trying to place the gear on.
Using the scoring target itself as a reference point instead of other field elements is a mindset. When we started with FLL many years ago, our mentor asked us a trick question “where is a field element on the field?” The answer is “it is where it is”. This mindset is what leads teams to use strategies such as exploiting the vision targets or mechanical alignment devices (very common in the top level FLL teams).
So, the team i mentor 5547 is travelling to our first event tomorrow. We were wondering when setting up your robot for its start position. the robot can start anywhere against the back wall? Or can you not set up in the opponents retrieval zone or own key? we are trying to get our auton dialed in for side gear deliveries so to cut down on the sharp turns we would start as far out as possible.
At Central valley, the airship distance from the alliance wall varied 5 inches from red to blue. We had to make some edits to the auto code and missed some gears in auto because of it.
You can start in your own key or in the opponents’ retrieval zone, as long as your robot starts in contact with the alliance wall. You only get a foul for being in the opponents’ retrieval zone if you touch an opposing robot who is in that zone, but because crossing into the opponents’ launchpad is a tech foul if you touch an opposing robot, this should never be an issue in autonomous.
Here at 159 we believe in the art of inexactness. We have no way of aligning our robot except for “Does that look right”,“Hmm… Move it over a bit… Yeah, now it looks right”. In all seriousness though, we’re using the vision targets to place our gear in autonomous and so we don’t really have to be all that exact in how we line up our robot. We actually did a test, when running auto on the center lift, the center of our robot could be off the center-line by around 8 inches and still get the gear on.
We line up the inner-face of our side bumper with the very edge of the diamond plate in one of the driver’s station walls. Then we push the robot backwards into the wall to pre-tension the chains for forward movement and to ensure the robot is perpendicular to the wall. It’s probably +/- 0.25" of variance, depending on how tired we are.
Of the times our side peg auton went to the peg (there were issues in 4 matches where it didn’t) it only missed once - the peg tried to spear the very center hole of the gear.
On the Rock City Regional we used our team flag to line the peg with our robot for the middle auto. But for the left and right auto we used the edge of the field as a reference to start.