[FTC]: NEW ROBOT DESIGNS!

[FTC-4077]

Since it's been a little quiet around here lately, I wanted to get a feel for how teams are doing with their designs so far and if anyone's come up/seen something pretty neat.

We had a scissor lift on our first design because we thought that if we deployed the lift backwards and made it act as a counterweight, then our robot would flip onto its back. This means that if we hooked onto a robot in the front, they would end up on top of us. It ended up being too heavy and we dumped it.

Now, we have a simple 50pt ramp that we're attempting to expand and go higher, but we wanted to see if anyone has better thoughts or actually has gotten a "lifter" to work?

Thanks.

[FTC-4077]

Alrighty, well there goes my last attempt at starting a conversation.

[smcmahon]

Happy Monday MASH. Just saw this post. Hopefully I can get some of our team members in here to comment, but to get things rolling:

We're looking at a classic should-elbow-wrist arm, powered by some Tetrix motors and chain/sprockets. The ring gripper is still being designed, but we're hoping to have at least a basic motorized version of it up and running for the Western PA FTC scrimmage here at CalU on November 17. As of now, our only registered qualifier is the W.PA one in February at Robert Morris. [Hope to see ya'll there again this year!]

We haven't put much thought into lifting other robots yet, but we're trying to keep as flat a bottom as we can if anyone wants to try to fork-lift us, haha. We should also, hopefully, be able to drive up onto a ramp-bot too, as you're describing. How *wide* is your ramp? We're pretty close to full legal width now, over 16" alredy with no guards on yet.

[RRLedford]

Here ya go with some juicy material to chew on. Hopefully it makes up in quality, for the lack of quantity of reply posts here in the thread so far.

We have build what is likely to be one of the most robust, 3-wheeled Kiwi drives ever seen at FTC competition.
With the new rules allowing sturdier materials in greater variety, we designed some super compact, linearly aligned motor-wheel modules, assembled along a joined pair of slotted AL framing pieces. The clearances are all engineered to be very close.
The omni-wheels are chain driven via direct mounted sprockets, and they free spin on fixed, case hardened (no-flat) axles. The drive sprockets are isolated on their own shafts with double bearing support via Tetrix sleeve bearings set in a one-unit doubled/nested Tetrix "channel block". This scheme prevents any chain tension shaft-bending torque from transferring onto the motor's shaft.

The motor is coupled to the sprocket drive shaft via a urethane rubber flexible coupling that handles any minor misalignment of the shafts, and isolates the motor from any loading, other than rotational torque. Motor shafts are set to bottom dead center in the clamps, and the clamps are then shimmed up slightly to the Tetrix sleeve bearing module centerline heights.

All of the driven (wheel) sprockets and the drive shaft sprockets have bearing support immediately adjacent to them, with absolute minimum axle/shaft overhang, to minimize the bending forces on the axles/shafts from chain tension and impacts.

We are currently at one-to-one on the sprocket ratio, but may go to 1.5 to 1 as we gain confidence with our driving skills. Each of the three drive/wheel modules are completely removable by just loosening three slot T-nut screws, unplugging the motor and encoder, and sliding the framing piece radially from the bot. We have a 4th module ready to go if there is any problem.

We handle rings with two gripper modules mounted adjacent on a horizontal conveyor belt. The conveyor is sandwiched between two vertical elevator assemblies that extend up to 28" from initial level 1 height. The conveyor pushes the grippers past the sides of the rings and they snap into flexible plastic U-shaped channels in a little over 1 second. Reversing the conveyor takes them off the dispenser and to the rear of the bot in another 1-2 seconds

With the front of the bot pushing against the scoring rack PVC pipe base bar, we can move laterally along it to align with scoring columns (Kiwi drive).
Our conveyor sits below the level 1 scoring pegs, and nothing will hit the pegs or hanging rings as we move laterally.

Once we have column alignment established, the conveyor pushes the rings forward onto the scoring peg. We can score one or two rings on a peg in under 2 seconds

If we raise the elevator to level 2 or 3, we can still move laterally between the columns without hitting pegs or rings, since the conveyor remains just below them at each level, and since the elevator columns are set far enough back, near the rear of the bot.

We are just starting to practice driving and scoring this week. Our qualifying competition is this coming Sat. We are using shorter elevator columns that only allow reaching level 2 for qualifying, and will upgrade them for longer ones for the state competition. We spent so much time on the drive setup, we fell behind on our build schedule for the other modules, but we are starting to catch up now.

[TRWSHSHLX]

How thick is that bottom plate?

And as of right now, how heavy is the robot?

Very impressive so far.

[Andrew Remmers]

Originally Posted by TRWSHSHLX

How thick is that bottom plate?

And as of right now, how heavy is the robot?

Very impressive so far.

Looks like 1/8 and. Heavy.

[RRLedford]

Originally Posted by TRWSHSHLX

How thick is that bottom plate?

And as of right now, how heavy is the robot?

Very impressive so far.

It is heavy - haven't weighed it yet. Next day or two.
Plate is 2024 aluminum at ~.200"
Weight reduction will no doubt come into play soon, but now it is just all about making things work.

We will be cutting rectangular holes for the full height (17.25") elevator column sets to pass through to get them starting closer to the floor and to max. out their extension within the 18" size limit. This is the only way we could reach up 26" with 2-stage extension. We are already pushing the limit with minimum overlap of the slides on the columns, and may have some wobble issues to solve at level 3. More weight reduction holes will no doubt follow.

We already had a lot of 20mm and 1"/25mm slotted framing material on hand, but, unfortunately, there are no linear slide modules for the 20mm. We are looking at using the elevator for both scoring @ level 2/3 and robot lifting, since adding more structur for a separate robot lift is out of the question weight wise.

We are seeing some traction benefit though, with the omni-wheels, from being heavy.

-Dick Ledford FTC 3507 Robo Theosis

[Madison]

Are the 80/20 90* brackets legal?

[Nemo]

Originally Posted by Madison

Are the 80/20 90* brackets legal?

Yes. After initially ruling them illegal, they went back and changed their minds.

[Andrew Rudolph]

Very impressive bot! I'm excited to see teams not just staying with Tetrix and branching out to new building techniques.

Originally Posted by Nemo

Yes. After initially ruling them illegal, they went back and changed their minds.

http://ftcforum.usfirst.org/showthre...ull=1#post3683

There is one of the official posts in the forum.

[Madison]

Originally Posted by Andrew Rudolph

Very impressive bot! I'm excited to see teams not just staying with Tetrix and branching out to new building techniques.




http://ftcforum.usfirst.org/showthre...ull=1#post3683

There is one of the official posts in the forum.

Thanks. In what manner can those be considered a linear slide? Am I misreading this rule:

<R02> In addition to the TETRIX, LEGO, and/or MATRIX components, teams may use additional materials
to construct their robots providing they meet the following constraints:
a. Commercial Off The Shelf (COTS) assemblies are not permitted with the exception of the following:
1. Linear Slides.
2. Non-motorized Turntables and Lazy Susans.
3. Lead Screws and threaded rod plus compatible nuts.
4. Servo blocks (e.g. ServoCity Part # SB608SH and SB609SH).
5. #25 chain and compatible connector links and half-links.

...what a ridiculous interpretation...

[RRLedford]

More recent PICs

Front view:


Rear view:


Conveyor off:

[Garrison P]

The team that I am mentoring is also doing a forklift style design. Yours looks great, but I have one question;

Did you guys make those pullys? If not I am pretty sure those wont be allowed as they are not specifically mentioned in R02.

Other than that, it looks great.

[JohnFogarty]

Can you smell what I'm cooking?

[Andrew Schuetze]

very interested in this design and use of new materials. What I can't tell at all from the many great pictures is will this fit in the sizing cube?