Aperture's "Open" Build Season

Hello VEX Community!!!

As you may have noticed Aperture posts a lot of ideas, concepts, and designs on the forum here. Well we are proud to announce our “open” build season. We will be posting things frequently through our design process for the viewers of the VEX community! We will also be posting our Code once we are finished with that!!!

We would like to make it clear that we are hear to Inspire while pushing the envelop by as much as we can! And if it ends up in winning well that would be nice to! But who knows We’ll just have to see how the battle goes down between the college team won’t we? :wink:

Be expecting lots of updates from Aperture soon! We have lots of concepts that we have come up with recently!

  • Andrew

By open, do you mean you’ll actually be revealing your design as you design it?

Hopefully! We want to start from the bottom up! Kind of like what we have done with the Hand of God so far with the double 4 bar system, Which we have some modifications to do So It’ll be a little bit before that is updated… I have to find the dimensions of the pneumatics clevises because they aren’t in the VEX Cad library on the wiki… :frowning:

I figured that this thread will be the best thread to update everyone on our build season. So updates will be posted here instead of flooding the recent threads with Aperture like crazy (we don’t want you all to hate us after all!)

But I guess I might as well get started for the first “update”

Cody has moved! And is still getting situated! We are working on converging more but its a little bit harder now that he has moved Literally ALL the way across Orlando in relation to my house! :frowning:

But we converged yesterday and spat out ideas for the Hand of God that we needed to talk about since we haven’t for a while.

We discussed many different features that we have both been considering for a while. First on our list was using all 12 motors for the arm giving us maximum power for the control and movement of our arm! However this left us with only one option for the rotation on the arm. Pneumatics! As some of you may have figured out by now I LOVE Pneumatics!!! So much so I came up with many different ways to control this turntable with them. One of these we posted with this picture :


This is a kind of turn table that they use in industry for limited rotation applications. In this case the maximum it will rotate is ~180 degrees. I figured that if the robot were to rotate only that distance the arm can flip in and out as it pleases from each side. However this design served one problem, Means of control was VERY VERY difficult! Stopping the cylinders mid-stoke was something I was not prepared to spend money on to build this robot. So we threw that out Very quickly.

The next approach to turning the arm was a Pneumatic “engine” or crankshaft. We never got to the CAD stage with this one, however the design would have been inspired on another college teams engineering feats with this video:

We wanted to attempt to improve upon this engine to take less air than the current model in the view took. This was a problem because what the video states is that the accumulator got 660 RPM with the tank and well over 1000 with the air tank constantly replenishing it. Now… The VEX website states “45 Strokes from 100 psi to 25 psi” This kind of scared me (yes given thats one tank, Ill do real calculations later when I get all the numbers) Even if we stacked accumulators on the bot we would be using ALOT of air very. VERY. Quickly to even turn the arm. That wasn’t the only problem though, again the control aspect came up and as we thought a previous demo my Dad had done drew inspiration to something quite elegant.

On an RC Jet plane you have quite a bit of forward propulsion… How do you stop this if you ever wanted to get your plane back? Well there is option 1. Let it run out of gas… (not ideal) or option 2. Brakes!

Brakes on some Model RC Jets are actually pneumatic believe it or not! (See why I love them now?) What happens is a special O-ring rides inside the wheels but doesn’t actually touch until the computer tells the system to pump air into the ring. What this does is it expands the ring allowing it to create friction to stop the model aircraft! Now some of you might be asking “How would we do this in VEX?” Well Say hello to my next best friend! Surgical Tubing!!! I had realized that Surgical tubing and Pneumatics tubing had the same OD and they might be able to be interchangeable inside the fittings! (NOTE: This was never tested the idea was thrown our fairly quickly) This would allow us to essentially use the surgical tubing as a brake inside of one of the turntables that we would be using. Again we were worried about being able to control everything simultaneously and the idea was thrown out.

The next design saddened me because there was only one measly pneumatic cylinder in the design and this was in our claw! However what this design consist of was the following

1 Motor for the turret
4 393 Motors for the bottom joint on the first stage of the 4-Bar
2 Motors for the second joint of the 4-Bar
2 Motors for the Telescoping Pivot
2 Motors for the Telescoping Extend/Retract
1 Moto for the claw shoulder
and 1 single action cylinder for the tripod claw.

The early phases of this design were posted here:[https://vexforum.com/showpost.php?p=188995&postcount=75

You can see the Double 4-Bar mechanism that would allow us to get both height and length out of the arm allowing us to reach our over all goal of 8 feet.

Don’t worry I’m almost done here!

However when we finally got together and had a meeting we did some mobility analysis of the current design. Trying to see what we could do better. The first thing under the gun was the very first joint of the double 4 bar. We know its going to have ALOT of stress at those points and Im sure there is a gear ratio that will be able to handle it somewhere, However for the sake of design we have decided to not power the entire bottom stage. Heres why.

While the arm is in movement there will be only so many joints moving at once. And movement of multiple joints will create some really fun reverse kinematic problems. Now we figured that once the bottom joint was at its point, it would more than likely stay at that point for the entirety of the match creating problems with motors overheating and all that jazz!!! So, What is our solution?

If you said pneumatics you guess right! And now Im happy again with pneumatics usage!!! We will be putting a total of 4 double acting cylinders onto the first 4-bar. This will allow us to “prop” the first stage off at its 45 degree angle once the match starts. This would get us the most height and distance out of the arm that we can.

Now what happens if this portion of the arm needs to move at all. Well this next part hasn’t been discussed yet but its a relatively new idea. Well. I just thought of it really!

If we were to mount the pistons onto pistons (sounds crazy I know) we would be able to have a larger range of motion out of the arm. Instead of just two positions we could have four combinations of positions the arm could be at at any given time. It could have over extended reach meaning more height or under extended meaning more distance. Might be something interesting to try out for the first stage since its entirely Pneumatic already.

Any CAD’s regarding the first stage will be updated soon! I need to find the clevis dimensions or CAD files to go any further!!! Otherwise I’m going to start making my own (might not be a bad idea…)

Anyway thats all I can think of for now!!!
Its 2 AM and I probably should be heading to bed now…

WOW! Thanks for posting all this! With me being a relative noob to VRC (1 year) this is all really interesting. My team is getting a pneumatics kit in a few weeks, and I know why they excite you. So many uses =).

Mounting pistons on pistons sounds like a good idea to get the proper angle for the double 4 bar. and do you guys have any weight approximations for the arm? I think somewhere Cody said he wanted it under 8 pounds. But yes, it sounds like a nice design. hope everything goes well in the building process :slight_smile:

Now accurate weights yet, have to finish these modifications. However with the bottom stage now being controlled pneumatically we can have that part made from steel :smiley: The Tele arm weighs around 1.5-2 pounds as a stand alone system (I forget really) So the entire arm will probably be around 8-10 but if you are considering the motor controlled parts that will probably be around 5-6.

Then the base will just be crazy heavy as I will post some more stuff as I get further into designing! (have some more crazy ideas ;))

  • Andrew

Judging by your use of pneumatics, I bet you want a pneumatic expanding base. Extra legs that fold out forwards and lock in to stabilize your bot more are good. Our team would use elastics, but I’m sure you wouldn’t mind an extra tank sitting on your base.

Its always a good deal when you can make things from excessive amounts of steel. Im with you on that :smiley:

And you have talked about pneumatics and motors… however, you have not mentioned sensors at all. Have you guys even had any discussions about sensors yet? Or have you simply not mentioned them? (not including Cody’s mention of an IK sensor in some other thread…)

We are considering a few things for sensors. But I want to save that for another post, and I have to also converge with the programmers! :stuck_out_tongue:

I have another one of those irritating design questions for you.

In my team’s brainstorming, we’re aiming all of our design concepts around a single specification: Which goes from start to scoring fastest. We’ve modeled stationary robots, spring loaded arms, motorized arms, different drive bases, all trying to optimize your time.

I’m sure you guys didn’t start work just on the first idea you thought of. What led you to the decisions you’re making? How fast can your pure arm hit the back wall?

I’m looking for some perspective here because I’m never sure if my initial analysis is any good until competition begins.

Good questions (not so much irritating) because you have a valid point.

The nice thing about our arm is that there are 3 joints as you move us the more each joint SHOULD have to do to satisfy the job (one reason why we are using pneumatics for the first joint) The second joint will be powered by motors only because it needs to move further than the pneumatics will allow us to move and it needs to be way more controlled. But like I said the work load increases as we move up. So the last joint on this system (rotation of the telescoping arm) will be doing ALOT of the work. Right now the extension and retraction for the tele arm (in theory) is ~2 seconds with an extended reach of 54 inches at an extreme danger zone. However this does not include manipulator which is being designed for compatibility for 2 objects, but can easily be extended for more. In fact now that I think about it that might be interesting for the preload section of the game… :wink: Ill have follow up post about that idea!

Our first ideas are very crude and you can see a few key differences between the first sketches and what we are actually ending up using. In design im all for passive assist, which is what bothered me about the first sketchs personally. In fact we had come up with thing ungodly complex system of using the pneumatics as gas struts that would be able to over extend and all that jazz, but that was thrown out fairly quickly. This system would had separate air off the main lines so it could keep its pressure.

As you can see that would have been a horrific system to program! and probably not very small. In fact each time we iterate the arm its getting smaller and smaller!

The Arm we have now (without the recent mods) should be something like 7 inches wide I forget really… Something I wasn’t extremely happy about…

I really lost where I was going with this :stuck_out_tongue:

If you have any more questions go ahead and ask

  • Andrew

So I think its about time to throw something up.

Yes this is in a form of a teaser, I figured that we could have some fun guessing what this part is for.


The CAD is a bit sloppy right now so I’m going to clean it up and finish deliberating with Cody with it. :stuck_out_tongue:

Its a metal or lexan part doesn’t material doesn’t really make a big different (however I prefer metal) :stuck_out_tongue:

Bit scatter brained right now so this is all for this post.

  • Andrew

Uh oh, I’m terrible at these. Are the upper holes in the picture wide? So a bolt or shaft can slide in them from side to side? Or is that just a perspective/CAD fail?

If this holes do allow movement then… I still have no idea =)

I can’t actually figure out what it is, but I’m guessing its a part of your intake mechanism. Don’t know what the extra wide holes are for (limited amounts of play?), and why you need square holes on a custom part.

The wide holes are for play in mounting systems a sort of… Tensioner as I’ll call it. I have learned to design things like that into my designs because you never know when it will come in handy (certainly saved me a few times already). You’ll see when I finish up the CAD what I mean.

About the square holes. To be entirely honest I was kind of lazy, But I also wanted to have a “VEX part” kind of look to it. It was just a quick projection from the assembly onto the part so it took me all of like 30 seconds to have the final holes sketched and cut :stuck_out_tongue:

This is actually not an intake mechanism its something a little more elegant

HINT: (has to do with the Hand of God)

I hope that wasn’t to cryptic for you guys.

Promise I’ll have renders up soon :smiley:

  • Andrew

I have no idea still.
By Hand of God, do you mean the whole robot, or the grasping hand on the end in particular (or whatever you are using to manipulate scoring objects)?

Entire robot :slight_smile:

i think its for the double 4bar?
maybe the joint or something

Ding! I had cleaned up the CAD file a bit and made some screenshots!

This is Iteration #2 of the double 4 bar and we are VERY happy with this design and it very well might be what we end up using.

Keep in mind its not 100% complete, The pneumatics on the first stage need to be added yet but thats not to big of a deal (yet). Right now the main mechanics of the arm are shown and what the part is actually used for.





Comments, Questions, and Concerns are always appreciated

  • Andrew