Team 951C's Summer Toss Up Reveals

Or it could be as simple as a shallow V-shaped bottom plate, which centers the balls in your robot after they’ve been intaked.

Yeah, that’s what I meant. Was that not clear? Sorry.

I think we were picturing two different things, both of which would work. You could take the lexan plate of a “NZ design,” and taper the side walls, funneling the balls towards the center as they are pushed backwards. Or, you could put a ~30 degree bend in it lengthwise down the center of the robot, forming a plate with sloped edges which will naturally center the balls due to gravity.

hmmm i like both ideas but I think the best is probably the 30 degree angle with the metal bent length wise because it would be easier to output for scoring… an adjustment to that could be making it a _/ shaped intake which will glide easier on the bump and the mat.

Uploading a video of the robot in action in about an hour :slight_smile: I hope you guys like it…

I can’t wait to see it! I love when teams upload videos!

I think everyone thinks “Oh balls!” and then “Oh, Gateway had balls! We must do side rollers!” Whereas in actual fact top rollers handled the balls just fine :stuck_out_tongue: side rollers were good and do work with the balls too though, I will admit. But the beauty of spherical objects is that most intakes WILL work with them. Side rollers, top rollers, side tracks, claws, scoops - they all could work.

As for the chassis, I like it! :smiley: Good luck and I hope you get the full robot on it and working :slight_smile: crazy chassis are cool.


i can see method in your madness. Like others have noted, your high elevation of the drivetrain will be good at getting over the bump. It’ll also be good at getting under the barrier and reaching the hanging bar. However, your choice of omni wheels (from what i can see from the photo) will leave your robot easy to push around. Also, if you decide to power your wheels in opposite directions to stand up, you could get a faster lift by covering more distance than most robots. While crouching through, you lose turning ability due to your length(at least from what i can tell your robot is long). Not only that it adds to driver complexity and engineering complexity, another thing that cautions me is that the legs don’t look limited. They aren’t cantilevered, but i didn’t see, any mechanical joints or stoppers which reinforces against pushing.

If you can, i would swap the wheels for mecanum wheels so you gain holonomic capabilities and more traction. It’ll be a lot easier than adding high traction wheels or swapping your wheels for high traction. This will also grant you motor control over your robot if you choose to use your drivetrain motors as a lift system as well. I would also suggest making the front of your robot one of the sides if you do decide to go holonomic. That way, your drivers don’t have an awkward time driving and you have the ability to choke out other robots when scoring on goals. Also, i would place a brace across your wheels. Not only will it solidify your base, it will protect your motors. Also, i would add those wheel locks as other people discussed on past threads.

Thanks Draco the Dragon :slight_smile: basically just predicted the video XD haha What I discussed in the video that is uploading to youtube is that I need to switch out the omniwheels w/ mecanum so they create more traction on the floor because right now it can push itself back up but it can only do it on carpet :stuck_out_tongue: Now I don’t know what the wheel stoppers are that everyone is talking about. And there are restrictions for the wheels. Ill post a pic soon. It’s basically a long screw with a lock bolt on it :smiley: haha ingenuity at its finest hahaha Now I am having some problems with trying to keep the motor screws tight. The motors I am using are 393’s and they jolt the bar attached to it pretty roughly…

Video should be up in a few minutes guys :slight_smile:


Here you guys go :slight_smile: Please share! I would love to see if everyone attempted this design!

haha excellent and ingenious drive design!
just read the entire thread from the beginning just now from the first time, and boy! did you prove those haters in the first few posts wrong!
keep up the good work!

Cool system! Definitely has potential. More weight from your manipulator will help it gain traction. If it still takes excessive force to push itself up, consider limiting the wheel motion a bit more, so that they don’t lie quite as flat (It’s hard to tell in your video, but the transmission angle looks very close to zero at the moment). This will produce a better transmission angle between wheel arm and chassis. You could also switch to pneumatic actuation, which would allow you to use this system to double as a low hang with no additional moving parts.

Reminds me of projext drive

Heh. I thought about doing a similar thing to this however my team was too worried about complexity.

Looking at your video, your biggest problem is coming from crouching too low. You lose all your support from elastic which causes your drive to stick up and now the vector forces are pushing against the metal, making torque very bad. Of course you can limit how much you crouch, but according to the grass view, traction is also a nice feature. To increase your frictional force, you can try adding deadweight to the robot. You can also try increasing your surface area. Theoretically, it doesn’t do anything except add weight, but practically surface area increases your coefficient of friction. Another thing you can try is changing the angle of your elastic like 599D. Make your angle extremely low when the robot is compressed, and make the angle close to 90 when the robot is expanded.

Haha thanks Murdomeek! There was definitely a change in tone when things were explained! Heck, I would have been a little skeptical too if a Noob thought he knew everything! hahaha jk

Yeah Joe I was definitely thinking of using Pneumatics to either help the wheels retract or push off of the ground so the rubber bands could take over. I may have some double action pistons push off the ground so the rubber bands can do their job.

I just ordered the Mecanum wheels because I know for sure those are something I need! To be able to hover over the bump quickly would be a HUGE advantage!

I really appreciate everyone’s feed back from the beginning! Keep it coming! haha

Just a small thing to note. The VEX tiles are mostly flat, as I’m sure you’re aware. I’m going to hazzard a guess that they won’t give you more grip. However, Mecanum would give you a heck of a lot more grip. You are absolutely right, there. You’ll probably have to make your wheel holders wider, though.

If you want to have a control setup that might work, try making a program where if you push, say, up on the right numberpad it will either push all of the wheels out, or down pulls them all in. Then just use the Joysticks for holonomic drive like you’re planning.

This is a very nice idea. Thanks for the proof of concept video.

From my very, VERY poor understanding of Physics, I believe this is basically incorrect. Or am I mistaken?

Draco that first robot made me have to change my pants! XD haha jk DUDE that was awesome! Kudos to that team! It looks like they did the X drive with pneumatic powered wheel that could contract and expand? that was cool but not something for Toss Up. I wish I could have seen that robot in action in Sack attack!

And I was thinking the extra weight from the lift should help it get more frictional force on the ground but it will also create more stress on the joints like you said…
I may change the angle at which it compresses to but that will add height to the base which might not leave me any room for the lift.

Now everyone! I am definitely pondering the idea of a scissor lift with the
_/ shaped intake for the Bucky balls. It may not be huge cuz we can only hold three at a time but I am thinking of a prototype for a dual Big ball claw for both ends of the scissor lift. That would give me the ability to hold possibly two Big Balls and three Bucky balls which would be a fairly decent advantage for something like the autonomous program… Tell me what you think! I’ll get working on some prototypes that are pneumatic powered and just motor powered…

While it’s true that CoF isn’t 100% independant of surface area practically speaking, the effects that cause this are minimized on surfaces like the VRC field, and at the scale of VEX robots. I guarantee that a change of trasmission angle of even a few degrees will be a much better solution than the monumental lengths you would have to go to to improve CoF through surface area to an appreciable degree.

Although Pneumatics could work, I wouldn’t use them if you don’t plan to use them to help with hanging. Tweaking the transmission angle would save you tons of weight if you can keep the system elastic only.

I don’t think anyone was skeptical of you being a newbie, the skepticism was due to there only being one picture that did not clearly illustrate the function of your design. I definitely think it’s a cool drive and I hope it works glitch free for you. I don’t personally see anything that makes it so complex that it gives you problems aside from maybe being a bit to heavy to hang, but that’s just an observation that may be way off. I think you are off to a great start if you can design an intake and lift that integrates well with the base.

Thanks for the Confirmation Joe :slight_smile: I will go with changing the angle of the collapsed mode which is literally two turns of a screw. Thanks again Joe!

I’m of the opinion that a scissor lift should only be used if you absolutely need the near flat compressed position, and can’t see a good reason you’d need that with your collapsing drive system. There are a lot of more efficient ways to create a linear lift if that’s your goal, continuous/cascading rigging elevator for example, or any number of linkage systems. My instincts say that two separate big ball manipulators will take up more space/weight/motors than you can afford to, but by all means, experiment.