Re: 1918 NC GEARS 2012 Robot
 

Looks awesome guys. Really impressive.

Re: 1918 NC GEARS 2012 Robot
 

We spiraled a V-belt around some PVC and then screwed it in to make the threads on our roller

Re: 1918 NC GEARS 2012 Robot
 

IIRC, we use a single BB P60 for the roller arm at a 64:1 reduction ratio. The extended arm is driven by a pneumatics tube (the orange thing) being powered by the roller claw inside the frame perimeter.

Re: 1918 NC GEARS 2012 Robot
 

How tall is the robot at it's highest point?

Re: 1918 NC GEARS 2012 Robot
 

29" with the arm down, 36" with it up. He's short lol

Re: 1918 NC GEARS 2012 Robot
 

Word has it that we won't see you guys at Traverse again. :(

Re: 1918 NC GEARS 2012 Robot
 

That is correct, unfortunately. We didn't want back to back events, so we switched to Gull Lake instead. Will you guys be at Troy?

Re: 1918 NC GEARS 2012 Robot
 

Nah--Traverse and Wayne (back to back). I'm also not a fan of two consecutive competitions.

In regards to Troy, I'll probably come watch like I always do. It's a tough competition.

Re: 1918 NC GEARS 2012 Robot
 

So on YouTube I noticed some comments regarding Rule R35, which states:

Teams shall display their team number on the Bumpers in four locations at approximately 90° intervals around the perimeter of the Robot. The numerals must be at least 4 in. high, at least ¾ in. in stroke width, and be either white in color or outlined in white. Team numbers must be clearly visible from a distance of not less than 100 ft, so that judges, referees, and announcers can easily identify competing Robots.

The problem being your arm covers the numbers on the front. However, this doesn't say they all have to be visible at all times, so I think its a non issue, but I wanted to make sure to point this out. A simple fix would be to put your team number on the arm. I believe that would be sufficient to block any complaints.

And I am floored by this robot. You guys do it every year and it makes me glad to compete in Michigan so I can see what you guys do. See you at West Michigan and Troy, I'll have to come and snoop around a little bit and cry at the beauty of your robot. :D

Re: 1918 NC GEARS 2012 Robot
 

It is about 36" tall. (edit: already been answered)

The primary roller in the frame and the arm roller in the arm are both powered by the same FP motor. The roller motor/sprocket axis is in line with the arm pivot, so the urethane belt tension doesn't change with arm position. The arm roller does a decent job picking balls out of corners, etc., when the chassis isn't moving too fast, but for open field pickup we generally keep the arm up.

Our alignment is simple, but seems to work well. Mostly its just the drivers eyeballing it. We also use the camera when needed. We don't expect to win any Rockwell Automation Awards.

We have seen the same distance spread due to ball variation that most others have reported, and have taken steps to minimize its magnitude and impact. We did some studies and found that the "sweet spot" for scoring for a given wheel speed combination was quite deep. (We run the bottom wheel wide open and throttle the top wheel to control distance, which improves backspin). Shooting straight on, we could hit about 5/6 from within a distance tolerance of +/- 1 foot from the "ideal" distance thanks to backspin and the backboard. It dropped off to about 1/2 at 2 feet from "ideal". Once we figured this out, we changed our approach. We quit worrying about adjusting wheel speed as a direct function of distance and set up a few standard speeds for shots we expect to be taking often (short, medium, and long, etc.). Now, we just concentrate on the aim (azimuth) and get in the ballpark for distance, something the drivers can judge at a distance or quickly see from the camera. With a bit of practice, they were able to line up and shoot in a couple of seconds. We expect to miss a few, but that is likely to happen anyway because of ball variation. We'll just pick 'em up and shoot again.

We learned a lot about shooters this year (starting from nothing, it didn't take much!). The main thing we learned (thanks to some help from my brother) is that the motor doesn't really power the ball to the target. The kinetic energy in the ball comes from the stored energy in the spinning wheel (flywheel). A bigger motor (or more of them) doesn't throw the ball farther, it just improves the recovery time between shots. What you need is a good flywheel(s) with some decent grip (texture and compression) on the ball. We went from two 775's per wheel to one, and redesigned our wheels.

We chose early on to concentrate on shooting from the key and closer. Not only is the scoring percentage better from up close, but it lets us gear the shooter wheels for faster recovery between shots and keeps us in or near the protected zone. We also made ball collection and ball handling reliability a priority. Collecting from one side and shooting from the other allows for a straight ball flow. We also wanted a very low CG. This approach works well for that.

We saved a few new balls to recalibrate the wheel speeds prior to competition. The new ones go a lot farther than the well used ones.

Special thanks to whoever it was that came up with the trajectory calculator. It was a priceless tool in our design process. We used it to determine ball speed and launch angle, which drove amost every other detail of the ball feeder/shooter.

Edit: I hope the GDC offers their wisdom on the <R35> obscured number issue. This will come up again and again this year and in the future. IMHO, the intent of the rule is met if you can read the numbers while in the starting configuration. People don't come to events to check out the sleek lettering on the bumpers. They come to watch what the robots can do. It would be a bummer if this became a significant design constraint for manipulators. IMHO, putting numbers on the arm wouldn't satisfy a lawyer, either. Numbers get obscured in the course of playing the game by other robots, field elements, etc. I'm neither a lawyer or a GDC member, so I'll deal with whatever happens.

We will miss TC. We have many fond memories and hope to return soon. It just didn't work with our schedule this year.

Re: 1918 NC GEARS 2012 Robot
 

Which calculator? (link?)

Thanks

Re: 1918 NC GEARS 2012 Robot
 

I'll post a link when I find it. One of our students found it.

I believe this is the one - from 2151 "Monty Pythons". Thanks to the "engunneer"

http://engunneer.com/content/blog/fi...ry-spreadsheet

Re: 1918 NC GEARS 2012 Robot
 

I totally agree, that's exactly the way I read the rule. Also, the justification being they want announcers and stuff to be able to see it, so I figure it doesn't need to be visible on all sides all the time. I just wanted to point out what people's concerns might be so you guys are aware. I would hate to see you get attacked because of some stupid little rule.