Team 1064B Robot Reveal

VEX V5 General Discussion VEX Robot Showcase
#1

Howdy, my name is Jade Krivanek, from vex team 1064B. We are a high school team located in Omaha, Nebraska, from Omaha North High School. I’ve finally convinced my team to let me do a reveal of our robot, and I’m hoping that there will be some helpful criticism as a result of this :slight_smile:

To being, pictures!
http://imgur.com/a/JBJdX

Condensed in an album format, i did my best to get pictures of the drive, lift and claw. Unfortunately, I don’t have a drive photo from beneath and a photo of the lift fully extended.

The robot’s lift is a basically a double four bar system, with a capability of reaching ~50 inches in height when fully raised. The first two bars are configured as a standard four bar, and powered at a 1:10 torque gear ratio by three 393 motors. The second set of bars or the other four bar is chain driven and can have its maximal height adjusted by “resetting” the chain. What we did to align it was lift the first two bars up a bit, then lift the second bars slightly above that then lock it in place. The weight from the claw caused the second set of bars to droop slightly, so we compensated for that with elastics and setting it higher than necessary.

teams thoughts on the lift - it was interesting to do a lift that we hadn’t seen before, but we are planning to not continue to use it. It had issues with the second stage or set of bars getting knocked down a notch when it had something stopping it from lifting vertically, and that prevented us from scoring on the 30 inch goal in our final semifinal match in our last tournament.

The intake was a claw driving at a 1:5 torque gear ratio by two 293 motors. It was pretty average, and had no major issues with performance, but after seeing other teams using a intake roller system, we are planning to switch to that to more easily store objects and pick them up. I personally don’t think that claws are the way to go for this years game due to the lack of a descoring rule.

The drive is fairly basic by our standards, but was what we needed after going from HS chain loop to HS chain loop with different configurations. It’s a 7:5 speed ratio powered by four 293 motors. There are six wheels on the drive, two omnis on each side at the front and the back for easier turning and more grip, and then one standard wheel in the center to keep us from being pushed to the side.

Questions and criticism will be appreciated greatly! :slight_smile:

#2

as the first person i am obligated to say
great robot nice six bar and thank you for reveal

now for the **** you actually want
how many game objects can you hold i am assuming 1 but i am really curious about the stacks of 2 if you could successfully hold those 2
how long does it take to lift to max height or at least to score in the top goal

biggest critism
that 6 bar looks really angels why is this

#3

Does your standard wheel in the center touch the ground? Those are about a mm smaller than the omni wheels and when we put them on my robot they did not touch the ground. I think JVN or possibly some one else suggested putting zip ties inside of the wheel covering, outside of the wheel rim to make it touch the ground when used in a 6wd.

If they do touch the ground did you drill out the hole slightly to lower the wheel?

Are you going to switch to a 6bar or the ‘2 bar with chain to keep same orientation’ (not the proper name, not sure of it)?

#4

I would like to emphathise that it was not actually a six bar - it was **two **four bars. It had some trouble holding the stacks of two early on in the day during robot skills, but that was closed before the matches had begun, and we never really encountered a situation where we had to pick up the stacks. Capacity was the primary flaw of our intake.

A lot of the angling on our lift was from the weight of the claw. We attempted to supplement this with elastics, but this wasn’t totally successful. The angle of the arm with weight on it. was fine though for reaching 30 inches because when it had no weight on it, the arm was capable of reaching 50 inches.

#5

We had no issues with it not touching the ground on the foam tiles, they do dig in a bit. There were no modifications to either the wheel or the metal.

#6

So… Wait…

Its two four bars, one of them driven by chain from the other, correct? Pretty cool idea, but I don’t know how practical it is compared to a 6 bar. Also, why is the second four bar angled down so much compared to the first?

The claw reminds me of the robot I built at the start of this season.

Would you consider this robot “fast” when compared to others at the competitions you’ve competed in? (I know thats a vague question :p)

#7

We didn’t break any speed records, but we weren’t slow. Based on the weight of our robot (mostly aluminum, 12~ pounds) we could have probably geared it up more, but no need to risk it.

The bar wasn’t set parallel, for it to sit parallel to the other two bars it wouldn’t have fit in the 18 inch box.

It really wasn’t that viable, but it was fun to do something different and experiment with it.

#8

Love the double 4 bars!
Too bad they aren’t independently controlled, as then you would easily be able to reach across the fence to score in the others mid-goal.

My idea of a VRCC bot would be similar to this, but with double claws, so it could pick up a stack in each claw, and then drop the bottom object without yet dropping the top.

It would be interesting to come up with some tension/chain/elastic, such that the same tension that is needed to support the 2nd arm is reused to support the 1st arm.
Or get the equations to balance WORK as well as TORQUE.

I would have expected vexmat or vexfoam to be needed on the claw gripping surfaces.
Did you have any slippage issues?

#9

Before you decided to stop using that lift system, did you consider using an 8 bar linkage? It would work the same way as what you have, but without the issues caused by the chain.

#10

Mind… Blown… Now this I must see :D.

#11

https://vexforum.com/gallery/showimage.php?i=5401&catid=searchresults&searchid=696946

#12

We were actually able to score across the field in the other teams 20 inch goal without a problem, it sat pretty much perfectly on their goal when we drove up to our goal.

The claw did have some issues, but the rubber band “net” managed to work fine. The vex mat would have probably increased the performance, but there weren’t any major issues.

@Vex Mundi, do you mean something like this picture?

With two vertical bars rather than just one?
If so, that is what we are currently testing, and seems to be working well :slight_smile:

#13

Thats not really an 8 bar as such, because it uses gears to drive the second set. An 8 bar would look like the picture above this post (I think).

#14

I would recommend using a common six-bar linkage in your situation, it would be much easier and efficient than a dual parallel link.

AURA has made a very good tutorial over at http://www.aura.org.nz/archives/672.

#15

I would have thought an 8 bar linkage would be something like what I made (very professionally, mind the high quality ;)) in paint below.

https://vexforum.com/attachment.php?attachmentid=5041&stc=1&d=1321511839

~George
8 bar.jpg

#16

look at it sideways, its just a scissor lift :slight_smile:

#17

Yes, something like that. Of course, this is just the same as what Jij posted above, except with a couple of redundant joints and longer metal pieces (which I suppose could potentially make it more stable).

#18

Yeah, it really is just like a sideways scissor lift.
do you give paint lessons Jij? I am impressed :stuck_out_tongue:
It looks like the same thing but with another set of joints.

So far with just throwing the bars together we were getting about 33 inches, and I’m sure that that height could be improved.

As for six bars, our experience with them so far this year hasn’t been negative, and they are certainly a viable option to fall back on, but experimenting with different lifts is more fun!

#19

Great robot! I hope we could team up sometime! :wink:

#20

Sadly, not at this stage :stuck_out_tongue: