Moving to a point between lights with autonomous

[Tom Line]

There are dozens of ways that would work, with varying degrees of success.

You could use blob size to determine your angle to the front of the light. (Yes, yes you can. We've done it.)
You could track multiple lights with a single camera simultaneously.
You can track multiple lights with a single camera by switch back and forth between them.
You could track one light while dead reckoning. With 2 positions and distance measures to the same light, along with the distance of traveling, and angle from the light you can triangulate with reasonably good accuracy.
You can drive the arc of a specific distance of the light until you lose the camera tracking. This is very repeatable (you move along at the same distance from the light until you pass the "event horizon" of the light).

Basically, to be able to score on any post in auton, you MUST have a way of determining your position relative to the racks.

To be able to score only on the spiders under the lights is significantly easier, and I suspect you'll see far more of this in the early competitions.

The neat part about this whole thing is that while I've given you a good number of ways to do what you want - I haven't told you how we're going to do it

[Donut]

Originally Posted by Tom Line

To be able to score only on the spiders under the lights is significantly easier, and I suspect you'll see far more of this in the early competitions.

Indeed it is, and I know our team is going that route. We looked at trying to score on in between legs early on, but decided it really wasn't worth it unless we had alot of extra time to work on that.

Have you gotten autonomous to work for a spider leg directly under a light yet (the full autonomous mode, not just tracking it)? If you haven't, I recommend you do that first and not worry about dual-light tracking.

[kaszeta]

Originally Posted by Donut

Indeed it is, and I know our team is going that route. We looked at trying to score on in between legs early on, but decided it really wasn't worth it unless we had alot of extra time to work on that.

We're counting on filling in the gaps between the other teams going for the ones under the lights...

[ebowla]

Yea, Donut has a point. Our team started this year and I do most of the programming. I haven't been able to figure out a way to pin down the spot between lights due to the movement of the rack with a camera and encoders, but I can get a tube on any spot under lights, thats 12 spots we can get. So even if you can only get the ones under the lights, it doesn't mean that you're at that big of an disadvantage. (although if your team can get 3 keepers in a row horizontally you are in pretty good shape)

[CircularLogic]

Disclaimer: I do not have a robot, nor have I seen a robot the entire season (stupid graduating High School to go to college). However I have been thinking about this for quite some time.

Note: I fully thought it out around kick off. This is what I remember. Hopefully it can get you thinking in a good direction.


The first thing you need to have planned for in your autonomous is knowing your starting position, because that will make a difference later on.

When the autonomous period starts, have your camera track the closest light. Figuring out which light is the closest should be able to do be done relatively easily based off of the fact that you know all cameras are a constant distance apart. Then simply do an an angle check of the pan on the camera. If its too great, tell the camera to search the other way.

Now, once you have that target, you can make some reasonable estimates about the position of the off-light row. Using trig (specifically the law of cosines) you should be able to calculate the distance you need to adjust your robot in the X axis direction. That requires some ability to make reasonably accurate turns and movements (if you dont have some type of closed loop system, I would say go with the slowest viable speed to make those movements). Once you are aligned in the X direction, deploy your mechanism and drive forward the estimated distance that will get the ringer on the spider. I realize that you will be approaching the spider at an angle, but worst case scenario is about a 45 degree approach to it, which most arm designs should be able to handle.


Its not the best way. Its probably not fully thought out. It absolutely isnt tested. But the the thing it has going for it is that the math will work. There are a number of known things about the field when you first start the match, you have to use those to your advantage. It involved a lot of angle calculations. It involves creating lots of triangles to figure out distance accurately. When looking to make those triangles, remember a couple of things. Your robot will always be approximately the same distance away from the rack regardless of orientation but dependent on starting position.

The straight line distance is between spiders is a very useful thing for creating triangles.


Good luck.

[1768]

Our team can (probably) score between lights. I made a rom table of trig values and used that to approximate where each light is. Knowing two lights and their relative positions to each other, it can find the center of the rack and angle of rotation, and therefore where leg #3 is. Of course, this is still untested.