Robot in 3 Days Reveal (FRC inspired)

We proudly present our robot in 3 days, Lebron James Pearman:

https://www.youtube.com/watch?v=aInhRRiSF7E&feature=youtu.be

Cameron (team 62) and I decided to bring the FRC ri3d to VEX. We documented the whole process and are still working on putting it all together, so it will be posted in the next few days for those who are interested.

Specs:

11.5 lbs

Drive:
6 motor 1:2 (turbo with 3.25" wheels)
Pneumatic brake

Shooter:
2 motor custom lexan nautilus “pinball” shooter and pneumatic shot power control system. Takes just over 1 second per shot.

Intake:
1 motor chain conveyor

Tilt:
1 motor worm screw linear actuator powered

1 Like

This is a very interesting robot! I am glad to see that people are considering using a brake system this year and a pinball-like launching system!

I’m currently having to take apart a whole dr6b lift, because we weren’t allowed to until we had our robotics camp. All I could do was make prototypes of random stuff since the end of April. Hopefully I’ll be able to do a reveal before the end of next week!

I like the launching system, it’s fast, efficient, and looks cool!
Also, A+ on the 118!

Super pumped to compete against this in a few months!

We should make early season reveal a tradition. We really should.

This thing blew my mind. It did. While I was burning my brain designing some heavy power flywheel system that uses the base’s power, this thing nails launching with perfect accuracy + 2 motors.

However I am worried about the methods you guys use to maintain the elasticity of the rubber bands. But you guys are team 62 – I’m sure you guys can do neat things to make that happen.

Awesome awesome reveal!!! Love it.

I hope this will inspire teams to actually adopt the ri3d challenge next season. Not a bad build though

By any chance, have you tried turbo with 4" wheels? how did that go?

Their pneumatics is just for the brake, I think. It appears that the tension and release are purely done with the 2 motor powered slipping mechanism.

Martin is mainly correct. So you can see the piston if you start here

The piston controls the power mode and so it only requires actuation if you want to switch between long shot mode and close shot mode. This combined with the angle control allows for varying field locations.

The actual firing does not require air and they could do close shots at 0 psi for as long as the battery has enough power to wind back the rubberbands. If the battery was extremely dead each shot would take longer to recharge BUT would be the same shot as full charged battery compared to a flywheel which would be drastically different.

The shooter is powered and released by the motors and cams, but there is also a piston used to control the power of the shot. In order to get full field shots, to shoot from right in front of the goal you would need to shoot almost vertically and hope it makes it. The piston moves the stops on the shooter back and forth to get different contact on the ball for a strong shot and a close shot.
There will be more detailed information about every part of the robot when we post the videos of the building and design process.

We didn’t have time for elevating, but there is plenty of space to add something to this robot.

Thank you! Despite its looks, both Aaron and I agreed that it was one of the most challenging robots to design and build.

We use military grade rubber bands by a company called “Allience rubber bands” that have proved their constancy over the Skyrise season. Data I collected on them show that, if they are fully stretched, after around 3 days they start to slightly drop in elasticity. All of this can change depending on how you stretch them and for how long. The plan to cope with this is to replace the rubber bands before each competition.

Yes we did, it was actually the design we had in mind going in to the ri3d. We spent more time designing and testing a flywheel design than we did on the cam shooter, however we decided to try something else because… A: We did not like how much power the flywheel consumed. B: It was not accurate enough to our likings unless you made the flywheel 3 motors and put a lot of back spin on the ball. (We wanted a 2 motor shooter) C: VEX parts are not made to spin at over 1000rpm, possibly causing bearing failures. D:The whole point of ri3d is to inspire other teams, so making a different design could get them thinking a little more. I will go into detail of all of this more and our exact thinking in the documentary video of the ri3d that I am currently making.

The pneumatics power both the brake and the shot power control system. If you watch the video closely, you can see that some of our shots are much shorter than the others, this is because the shot power control system is engaged. I will explain how this works in the documentary video.

That was one of the things on our to do list that we never got to because of the 3 day limit. It should be noted that there is space for a ramp over the cortex, and that the drive base is designed to be able to drive up a parter’s ramp.

Yup, the shape of the nautilus gear allows the cam to be pulled back and fired all without any releasing mechanism.

I’m sorry, but I still don’t understand how the release mechanism works. Will you be clarifying that in your next video as well? Thanks.

Here is a closeup

The release is caused by the drop off cam

see this:

Sorry, I wasn’t referring to a flywheel with a 4" wheel. I meant 4" wheels on the 6 motor drivetrain. Theoretically, with turbos it would be equivalent to a 4 motor drive with high speed gearing with the same wheels, and I’ve seen a team do it in skyrise, but I would like to know if you noticed anything from your experience if you’ve done it.

The red thing is exactly like the lexan cut out. The black peg in 148 is the same as the white and black spacer set up. As the wheel pulls further, it stretches the slingshot back, then as the wheel dips down into the crevice, it creates a space for peg to shoot the sling out

There is no separate release mechanism. The motors just spin continuously and it winds up and then slips off the end of the cam.

There is even a VEX Cam with a nice explanation video.

I assume the Cam Cam was chosen partially because of access to the parts and partially because they wanted something they could control the size of.

Great Robot, the launcher is really Amazing, I remember seeing a similar FRC robot that launches basketballs, how thick is the polycarbonate?


Nestor Ribero
formerly Masters 4423C

No need to be sorry! Everyone else pretty much explained it, however, if you still don’t get it, I can clarify.

Sure! here is the company: http://www.rubberband.com/ and here is the link to the exact rubber bands that I use: [

Thank you! The poly carb on one of the nautilus gears is made up of 2, 1/16" pieces bolted together.

](http://www.amazon.com/Alliance-Sterling-Rubber-Band-Approximately/dp/B008X0A0Q8/ref=pd_sim_229_1?ie=UTF8&refRID=03Z8E94K3R2SHSX5VZS4)

This is VEX forum convention of naming base gear ratio. We call high torque motor (100 rpm gears but actually free speed 110 rpm) directly driving 4 inch diameter wheels (VEX traditional big omni wheels) the 1:1 ratio because before 393 motors populated, this was the most common gear ratio.

Based off of that, only swapping the internal gears to 160 rpm gears is called 1:1.6 gear ratio. Which is a very popular choice nowadays.

Keeping everything in 1:1 gearing but externally use a 5:3 speed gearing produces 1:1.667 gear ratio, which is basically the same as 1:1.6. More often appears in two speed transmission.

If you swap for 3.25 inch diameter wheels, you are covering less ground every spin, thus you slow down. Using 3.25 inch diameter wheels with 240 rpm internal gearing will give you a combined gearing of 1:2 speed gearing, meaning it is 2 times faster than the “standard gearing” described above.

Hope this clears things out. I think we have a chart describing how we name base gear ratios somewhere. Or I’ll make one.

That makes much more sense. Teams should do this. Use every single square inch of your polycarbonate.

Very nicely done! Three days… IMPRESSIVE!

Jason

I still don’t see how

unless he is talking about torque, which I understand. The speeds would be much different.