FIRST Team 2980's 2012 Open Source Robot

[eedoga]

Hey all,

Team 2980 is once again going to post everything we come up with. We receive a ton of help from the FIRST and Chief Delphi community and want to give back as much as possible.

Our team goes uses the first week for prototyping and design. At the end of the first week we share our designs with the greater community and have them select the design that we will finalize and build. This years plan is to build a robot capable of dumping into the second row, and shooting from the safe zone at the top of the key. From there we hope to shoot for the top and middle row.



We'll try to post some more detailed shots as we finalize the design today and Monday.

Key things and ideas:

We want to use a belt driven ball harvester to convey balls from the floor to the hopper/dump bucket.

We designed the drive train with a dropped mecanum set up using 4 powered traction wheels 2 inches off the ground that lift the robot up so that the mecanum wheels are slightly protected for driving over the bump.

We want to have a pole slapping mechanism for pushing down the Bridge for the end game.

Issues:

The magical dumping ball hopper...

So making a box that can dump seams easy...trap door in the bottom to let balls in but not out, open top for pouring balls out... use a piston to lift the and tilt the box to just over 90 degrees pouring the balls out into the hoop...Uses gravety...easy peasy.

cannon hopper...Balls come up through the bottom trap door, then a piston pushes them forward in loading them into the cannon...Piston retracts letting another ball light up to be fired...also seams relatively simple...

Now we need to combine those two things into one thing...

Aiming...

The community really wants us to use either a camera/ultra sonic detector combo, or mount the kinect on our robot.

Using the ultra sonic sensor mounted on the cannon... The sensor measures the distance to the wall and regulates the speed of the spinning wheels in order to get the ball to go the right distance based on the desired target height...

The camera would be used to detect the reflective square above the hoop, or for our driver to use to line up shots.

Thinking of using a piece of plastic mounted in front of the camera to calculate the range to the target.

Ok...so those are at least some of our ideas...

Team 2980

[eedoga]

We're having a sad day and could use some advice...

We were planning on using the fisher price motors with the planetary gear box mounted to them in order to power our ball cannon...

Given that they are out of stock, and We're not holding our breath on them being back in stock any time soon...We are going to need another plan.

This is something we have very little experience with. Any ideas?

[Cynette]

Which Fisher Price Motor were you hoping to use? And how many?

[eedoga]

its not the motor...9013...its the planetary gear box that seams to be the problem. We have two of the 9013s...just no planetary gear boxes.

Sort of hoping they will either come back in stock or someone will have two that they are not using.

I guess...lesson learned...we'll buy a ton of stuff in the off season just in case for next year.

We may go with the AM gearhead motors...

So we are doing some math to try and figure this one out...

We want the ball moving at up to 27 fps when it leaves our shooter...

So...we figure if 50 percent of the wheel speed goes into the ball as it passes through the shooter...

so rotating 8 inch diameter wheels 3 times a second? so basically we would have to have the wheel spin 4 times as fast as the motors?

my brain hurts at this point...

[Jonathan Norris]

Originally Posted by eedoga

its not the motor...9013...its the planetary gear box that seams to be the problem. We have two of the 9013s...just no planetary gear boxes.

Sort of hoping they will either come back in stock or someone will have two that they are not using.

I guess...lesson learned...we'll buy a ton of stuff in the off season just in case for next year.

We may go with the AM gearhead motors...

So we are doing some math to try and figure this one out...

We want the ball moving at up to 27 fps when it leaves our shooter...

So...we figure if 50 percent of the wheel speed goes into the ball as it passes through the shooter...

so rotating 8 inch diameter wheels 3 times a second? so basically we would have to have the wheel spin 4 times as fast as the motors?

my brain hurts at this point...

Here is another option, take the first stage (or two, depending on what ratio you want) of plastic gears out of the big plastic FP Gearbox, and you can build a very simply gearbox from those gears. A couple shafts, some bearings, 1/8" Aluminum plates, a little milling and BOOM! FP Gearbox.

[eedoga]

BOOM! FP Gearbox.

Yeah...that is another option we are looking at. We'll post the solution once we come up with it...

[IndySam]

Don't worry the planetaries will be back in stock. You could also use a Cim-sim.

[pmangels17]

Originally Posted by eedoga

We're having a sad day and could use some advice...

We were planning on using the fisher price motors with the planetary gear box mounted to them in order to power our ball cannon...

Given that they are out of stock, and We're not holding our breath on them being back in stock any time soon...We are going to need another plan.

This is something we have very little experience with. Any ideas?

We had the same issue with andymark being out of stock on our drive gearboxes, but they should be in by the bext three days

as for your problems., i have seen some teams using the transmissions, not the motors, off of power drills. double check the rules on this but i think the transmissions off of a drill are legal. double check this though.

also, your robot looks a bit top heavy, and excessively tall. maybe consider a shorter superstructure. like this you will probably fall as you cross the bump. also, i dont see another option to lower the ramp. maybe consider moving elements for a lower center of gravity

that being said, you are probably further ahead than we are, but by this weekend we should be back on track. the shooter looks great, and i applaud all teams who are successfully using mechanums, as nobody on my team agrees to use them.

all in all, design looks great, nice to see teams doing robots in full CAD early on. Good Luck to you.

[eedoga]

@ Pmangels17...Funny you should say something about teams doing everything fully in cad...never modeled our bridge lowering device...because of that we had to make some structural changes to be able to add it.

We too are worried about weight distribution. We are going to mount our battery really low in the ANDY MARK frame, and we may loose the whole 2 inch drop because of weight issues which would lower our robot slightly. Our plan for the bumps is to go over them carefully, but you might be right about it being a tipping hazard. hopefully we won't end up on our backs more than anything else, and super hopefully we won't tip over and block the bridge from our alliance team members. We should be moving around by the end of the week, so we'll have a better idea about what our robot can do. Last minute redesigns are not entirely out of the question, though we should probably avoid that as much as possible.

We also moved the pivot point for the hopper down by 12 inches. This makes it so that we are resigned to dumping in the bottom hoop. Having a lift and tilt mechanism was just not feasible given our weight constrains. Our robot will probably end up being a "jack of all trades" as it were...At least that is what we are hoping for.

We should have updated pics and video this weekend.

Edoga

[eedoga]

For starters...a short video.


This weekend was incredibly frustrating, but to be honest we got a number of big problems solved.

Cameron managed to fix all of the problems we were having with our box. The balls go in, and don't come out until we want them to...But...when we want them to they come out smoothly.

The top roller of our ball harvester is mounted and happy.

The bottom roller is being persnickety, but we will clean up the mounting brackets and the sprocket mount and that should be ok.

Our drive train is assembled and needs to be chained, but that should go smoothly.

Our frame was pretty much done, but a rushed weld broke making it impossible to marry the frame and the drive train.

We tested our shooter for the first time (I know...we are late to the party.) Not getting nearly the distance of other teams, (didn't really expect to) Our current set up doesn't really compress the ball at all. We are planning on adding a pinch point above the wheels so that the ball gets compressed just a bit. We are hoping that that will increase our distance enough to make us somewhat effective.

our current set up using a CIM-sim connected to two fisher price motors. We started out with a 60 tooth sprocket on our shooter, and moved down to something closer to 1.5 : 1...I'll have to get an exact count and some detailed pictures tomorrow.

Also, I think detailed pictures of our hopper are in order.

I guess I was really hoping to be farther along at this point...Oh well...

Edoga

[aeniug2]

Looks nice. My team is considering something similar. I know they started to mock something up down in the shop, but I had to miss it for pep band.

[eedoga]

This is our shooter. One of the fisher price motors is missing because we have to make a run to the hardware store to find new mounting screws. While the chain was mounted about a minute before this picture was taken, we pulled it off because one of the fisher price motors had worked its way loose and the screw was missing...Guess it is time for some thread locker blue.



This is our base. We might have to add a metal plate to the front to keep the frame from toeing in, which would be a nightmare. The upper frame bolts to it and has gussets to stiffen up the chassis. On this one we will have to wait and see what modifications are needed.

We still need to add chains...We spent the better part of Sunday and again today cutting spacers to line the wheels up so the chains won't be stressed. Then we ran out of half and master links...

We are also redoing our ball harvester rollers...Couldn't seam to keep the chain on.

I'll try to take some detailed picks of our hopper during tomorrow's build session.

[eedoga]

I went to weigh the robot and was sad to see that I had lost some weight. :-p As it stands now we are at about 100 pounds. We still need to add a couple things, but I think we will be fine on that front. I am in love with autodesk inventor. I'm sure Solid Works is just fine, but I am now familiar enough with autodesk that I can work pretty quickly. We even have a few team members who are getting good at it also! makes me happy.

[aeniug2]

wow. That looks really nice. We are just starting work trying to install our ball manipulation stuff, which might be a bit of a challenge due to our lack of CAD. A couple of us have a bit of experience with it, be we are kept busy with more urgent things...

A quick question: I notice you left those little bits of the (front?) of your frame on (the ones pointing inward) when you opened it up. Any specific reason for that? We cut ours off flush with the wheel well area, I was told by another team member that ours should be OK according to the rules...

[eedoga]

@ Aeniug2...You should be fine. We just figured since our bumper backing had to be 8 inches having the frame behind it wouldn't hurt. Based on my interpretation of the rules you should be fine provided the bit of bumper backing doesn't stick past the frame by more than one inch...
We too are at the ball manipulator bit. Our polychord belting arrived at our local parts shop today so I can pick it up tomorrow...Then once we have the motor stuff all figured out we should be rocking and rolling... At least that is the idea.