pic: The real robot - Week One work


This is the status of our FRC 2008 robot from week one. There is an extra pulley on the left tire which has been removed. The belting is Eagle Orange 85. We’ve seen it used by the Robonauts FRC 118. We’ll give it a full test in the shop next week after we get a program loaded into the chassis and run it around with some extra weight added. AndyMark super-shifter with IFI traction wheels 6" OD x 1" wide.

GAH!! We are still in the design/prototype phase! Awesome :smiley:

Have you guys thought about the side load on that drive shaft? I do not know much about the super shifters but looks it you should have a bearing block on that thing. :slight_smile:

thanks, Vivek

p.s. did I mention the orange belting looks cool?

will that stuff change shape or turn brittle when it gets cold?

Is that 4 wheel drive? How are you guys gonna steer it? tank?

Looks nice! That looks like a really really short robot…or maybe it’s a wide bot…looking forward to seeing it at LSR!

Nice SuperShifter mounts!

It is a wide robot so the front to rear is short. It is four wheel drive / tank steer. I do not know the thermal properties of the belting but I don’t think that we have a reason to be concerned. It was nice to find the small angle plate for the AM toughbox in the kit as the AM supershifter has the same hole pattern. We needed an additional support so this idea came to mind. We’ll look on Monday to see if we can move the plate to the inside of the transmission so that we can more easily get a second cross-brace on there and have a better support for the rest of our electronics package.

View basic product specs for the polyurethane belting.

Looking at the specs specifically for temperature data, I can now say that we should be fine as long as we don’t attend a regional in the artic circle :slight_smile:
-22ºF to +150ºF
-30ºC to +66ºC

If each wheel was drive by a belt from the trans, then a belt failure would not shut down a side. Right now if you lost the belt from the trans to the first wheel, your robot would be stuck spinning in a circle.

cool, the orange belt is sweet…it looks kind of like elastic!? BTW your left wheel should you a bearing block or something because it’s tilted

Looks good so far…

A couple suggestions:

  1. Extend the shaft of your drive pulley and put a pillow block on the other side. Even though there are two supports in the gear box, you will be putting a lot of side shearing loads onto that axle.

  2. Tension: Maybe you want to have a spring loaded tensioner to make sure you have good contact with those belts at all times.

  3. Once you have the kit-bot frame set to go, maybe you should weld the pieces together. I would hate to see a bolt or two come loose during the competition.

Good work!

Thanks for the many suggestions. By far the coolest thing that we have found with a week’s worth of play with this urethane belting is that no tensioning system is needed at all. The elasticity and friction between the belt and the UHMW pulley is terrific. Even when the belt looks slack, it grips the pulley and does not slip. We’ll look at the side load issue and may go to the two belts from the drive shaft going to a single wheel as a fail safe idea. Since the belt is under constant tension, is that making the side loads more of an issue then in previous years when we ran the Kitbot and transmissions in very much the same configuration with ansi #35 rollerchain?

any trouble with that stuff slipping?
How thick is it?
What material does it ride on?

There don’t appear to be any as of yet. We’ll be giving it a full test this week. It is extremely grippy with the plastic pulleys. The spec sheet linked above quotes friction coeficients for steel as well. This is ‘v’ belt @ 0.500 width on outside. The belt actually rides on the sides as it doesn’t seat on the I.D. of the pulley. This means there are two surfaces gripping instead of one.

Complete robot after week six.

Well the real test on this system came in Katy, Texas during the LoneStar regional competition. They gave us fits all weekend long. During hard stops the belts would jump off the pulleys. We increased the tension and even added a flange on the side of the pulley, none of which eliminated the problem. It was very frustrating as we had driven the robot hard on the test field in the shop but nothing matches the punishment of competition. After we were eliminated in the quarterfinals in Texas we began the switch over to #35 ANSI rollerchain and sprockets and never had a problem again with the drive-train. This allowed us to put in a dead-reckoning / closed-loop hybrid mode which could clear 2 - 3 lines depending upon robot traffic.


I thought you guys were on to something here, with a new, lighter alternative to roller chain.

Although things did not work as well as you wished, we all should thank you for making this effort and keeping the CD community informed about it.

Andy Baker