Shooter Aiming Methods

[androb4]

I would like to know if anyone is thinking about making a turret or having a variable angle shooter, like last year.

What would be your method of aiming at the goals?

Also, will just lowering the speed of the shooter wheel, decrease the range or trajectory of the frisbee? Has anyone done any testing with this?

[nathan_hui]

Decreasing the speed of the shooter will decrease the range of the frisbee. As to what it will do to the accuracy, that will require testing of a different sort. We initially used a table and a pool noodle to test shooting - different amounts of accelaration cause different ranges

Aiming at the goals will most likely be done via manual aim (the targets are large enough). Auto aim is doable, but may not be of any advantage (you're driving towards the darned thing, might as well take the time to slew the turret). Not sure about range, but then we were thinking of raising the shooter, so there's that too.

[ttldomination]

Originally Posted by androb4

I would like to know if anyone is thinking about making a turret or having a variable angle shooter, like last year.

What would be your method of aiming at the goals?

Also, will just lowering the speed of the shooter wheel, decrease the range or trajectory of the frisbee? Has anyone done any testing with this?

(1) A turret is feasible, but I don't think it's necessary. We're still grappling with the adjustable angle. We're trying to find the sweet angle.

(2) We're determined that if we can do a full-ish auto aim that the driver is comfortable with, then we'll go there. In the mean time, we'll just be looking for that sweet spot for manual aim.

(3) We have done some preliminary testing, and what you have said seems to follow, however, we will do more testing in round two to back up what you have said.

- Sunny G.

[gabrielau23]

Two words:
Photon Cannon

[Mongai]

After dedicating a week of design time to a turret last year and hardly using it, we immediately crossed out that idea. Something along the principles of K.I.S.S. (Keep It Simple Stupid)

[mdrouillard]

We plan in auto to aim the whole robot.

[F22Rapture]

Originally Posted by nathan_hui

Auto aim is doable, but may not be of any advantage (you're driving towards the darned thing, might as well take the time to slew the turret).

Another way to think about it is, "you're writing the autoaim for autonomous anyway, might as well use it for teleop as well"

[Kusha]

The people that are auto aiming:
Do you guys off put vision processing onto something else?

[z_beeblebrox]

I'm thinking of putting vision processing into the operator's brain and combine the best of automatic and manual aiming. Instead of having the computer struggle to identify a target 50' away with different lighting, I want to have the operator look at the camera feed and click the center of the goal. Then, the computer uses that to figure out how much the robot needs to turn and how high to aim the shooter to hit the goal. The output from this will be fed to PID controllers for robot and shooter angles. When the robot has slewed to position and the shooter has spun up to speed, the operator fires a disc and makes corrections if it misses. Then, the operator rapidly fires their remaining 3 discs.

[PhantomPhyxer]

Originally Posted by nathan_hui

Decreasing the speed of the shooter will decrease the range of the frisbee. As to what it will do to the accuracy, that will require testing of a different sort. We initially used a table and a pool noodle to test shooting - different amounts of accelaration cause different ranges

Aiming at the goals will most likely be done via manual aim (the targets are large enough). Auto aim is doable, but may not be of any advantage (you're driving towards the darned thing, might as well take the time to slew the turret). Not sure about range, but then we were thinking of raising the shooter, so there's that too.

I did not know there were other former Tanker on this site. The "Slew" term related to Turrets makes me think there are. I worked on the Bradley Fighting Vehicle several years. We used an aim able Turret last year.

[Anupam Goli]

Originally Posted by F22Rapture

Another way to think about it is, "you're writing the autoaim for autonomous anyway, might as well use it for teleop as well"

But I don't think you HAVE to auto aim for auton. As long as you're contacting the pyramid, you start out in auto right? You could just start aiming straight at the goal and fire. Granted, it's not the best, but hey, whatever works. Also, auto-aim is just sometimes too much to deal with and test. I'd be perfectly happy if we just had a sweet spot and a little camera crosshair that would guarantee that our shots would go in. My theory on auto aim is that you don't absolutely need it unless you're encontering moving targets.

Also, a rotating shooter is probably much more complicated to do for what it's worth. if you've played catalyst, or done some math, the angle of error for these shots is actually pretty high, compared to previous year's games.

[DjScribbles]

My opinion is that controlling the angle vertically will be more important than rotational angle control. We have wide targets, but they aren't tall.

[Anupam Goli]

Originally Posted by DjScribbles

My opinion is that controlling the angle vertically will be more important than rotational angle control. We have wide targets, but they aren't tall.

Using the speed of the shooter and a table of experimented speeds vs distance can also overcome the short goal height.

[Ether]

Check out this post. It's not directly related to shooter aiming, but it does have some useful qualitative observations about shooter wheel speed and slipping:

http://www.chiefdelphi.com/forums/sh...2&postcount=55

[stingray27]

For vision processing, I believe I am going to setup a system that uses vision processing, but at a minimal level. Last year, we wrote some code to attempt and follow the targets at all times. This didn't seem to fit to the game and so this year we are going to revise that method. The labview code for vision targeting from last year is a really good reference for those of you trying to figure it out. The only change you have to make is when determining the aspect ratio subscore, you have to compare it to the targets aspect ratio this year instead of the aspect ratio from last year (18 by 24). I am just going to divide the width and the height and then later use that number to determine what target the camera is currently looking at. I can then throw out the aspect ratio subscore when determining if the camera is looking at a target or not and use the other 3 subscores as the determining factor (convex hull operation score, or the rectangle coverage %, and the vetical and horizontal line scores).

As for actually using the vision information, I believe that we may go with just a single button that activates a vertical alignment of the shooter. Since the target is so wide and just limited in height, the shooter then would line up vertically and then hand over control to the operator. The horizontal alignment would just be from the driver. This allows for just a quick rough alignment of the robot and then the operator would only have to perform quick slight fine tuning.

Any thoughts?