A Toss Up Robot

VEX V5 General Discussion VEX Robot Showcase
#1

Need ideas?

http://www.youtube.com/watch?v=XuigGd5Ooxk

[http://www.youtube.com/watch?v=zMUUYCfGohg

Yes it is inspired by robots used in Gateway. It currently uses 10 motors and fits under 12" and within 15", making it legal for high school and usable as a small college robot. This robot’s focus in a match is stashing buckyballs as quickly as possible.

6 motor internal speed drive
2 motor 5:1 lift
2 motors on roller intakes

To do:
-Big balls (coming soon)
-Descore stash?
-Hang?

I’m sure there are many other people who came up with this exact design, but it can serve as a starting point for teams that are stumped.](http://www.youtube.com/watch?v=zMUUYCfGohg)

#2

What are the 10 motors going towards? You have two on the intake, four on the base and 2 on the arm, right?

Wow, I should have read better. You flat-out told me the answer in the initial post.

#3

We have a 6 motor drive. 2 direct driven, and 1 on the upper sprocket on the drive.

#4

What is that large sprocket there for? Is it essentially another traction wheel?

#5

How tall is it to the bottom of the intake when the arm is up?

#6

The sprocket adds traction which prevents being pushed sideways. It also lets the robot drive over the bump.

The bottom plate of the ramp is exactly at 24" when the arm is up.

#7

How has the six-wheel drive worked on the bump? I saw some other teams with the 6-wheel drive, but it didn’t work very well on the bump.

#8

We don’t actually have a bump yet, but we made a makeshift one out of steel. It gets over it fine because all of the wheels are powered. I don’t think it would work nearly as well if any of the wheels were unpowered.

#9

It literally flies right over it, both forwards and backwards.

#10

Nice. It would make sense too, since it has more contact points on the bump. Do you think you could post a vid?

#11

How did you guys chain all of the wheels together? Looks great, and similar :wink:

A drawing, or CAD, or even a picture with the side of the drive taken off would be nice :slight_smile:

Is your arm steel? Did you use aluminum anywhere?

Thanks Owen and Robert!

#12

When I get home I’ll show you pictures of the drive in here. We actually didn’t CAD, draw or anything. Owen and I just made it up as we went and we decided to keep it :slight_smile: No everything except the base and tower is aluminum. We did that so we have a low COG. It’s worked out pretty well! And good luck this season! We will keep everyone updated on this robot.

-Robert

#13

Also the sprocket makes the traction wheel a little bigger than the omni wheels I think an eighth of an inch to be exact this allows for better turning because not all wheels touch the ground while rotating so there is less friction.

#14

I never understood why anyone would want the drop center wheel configuration. It doesn’t make any sense to me, especially on a 6 wheel drive like this with omnis at the corner. The omnis aren’t going to have nearly any friction when spinning anyway. I’d rather have their forward traction with all 6 firmly on the ground.

#15

We had a drop center drive at Worlds this year, it proved very useful. It was very hard/impossible for people to push us sideways

#16

I thought the 4 inch omni wheel is slightly larger then the 4 inch traction wheel? http://www.vexrobotics.com/276-1489.html

Instead of using the 4 inch diameter wheel with the high traction tread, you guys used the largest sprocket with the high traction tread around it?

#17

Yes. They are not a lot bigger, but they are slightly. All the wheels still touch the ground, but a larger proportion of weight is on the middle. This makes the robot harder to push, and keeps the center of rotation in the middle of the robot. The normal traction wheels are slightly too small as you stated.

#18

Very nice robot guys. I can’t help but think there will be an awful lot of robots that follow this design. I doubt many will be better than this one though. :slight_smile:

The thing is, the ground is not firm and neither are the wheels. Both are quite compressible, meaning the chassis will pitch under acceleration, more so with a load raised up high. We observed obvious wheel lift during skills runs last season. I think that having the centre wheels lowered and driven should help reduce wheel spin under acceleration. I have been wrong before though - it was in 1968.

Cheers, Paul

#19

how high is the back of the of the intake when it is lifted?

#20

Thanks, Paul.
I’m not sure how high it is…probably around 32". Why does it matter?

This robot is now fully big ball compatible. I don’t really want to show how yet to give teams a chance to think for themselves, but I’ll say that it can be modified to work with big balls fairly easily.

That’s all I’ll say for now unless someone has a really good reason for me to post it.