[FTC]: NEW ROBOT DESIGNS!
 

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.

Re: [FTC]: NEW ROBOT DESIGNS!
 

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

Re: [FTC]: NEW ROBOT DESIGNS!
 

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.

Re: [FTC]: NEW ROBOT DESIGNS!
 

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.

Re: [FTC]: NEW ROBOT DESIGNS!
 

How thick is that bottom plate?

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

Very impressive so far.

Re: [FTC]: NEW ROBOT DESIGNS!
 

Looks like 1/8 and. Heavy.

Re: [FTC]: NEW ROBOT DESIGNS!
 

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

Re: [FTC]: NEW ROBOT DESIGNS!
 

Are the 80/20 90* brackets legal?

Re: [FTC]: NEW ROBOT DESIGNS!
 

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

Re: [FTC]: NEW ROBOT DESIGNS!
 

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.

Re: [FTC]: NEW ROBOT DESIGNS!
 

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

...what a ridiculous interpretation...

Re: [FTC]: NEW ROBOT DESIGNS!
 

More recent PICs

Front view:


Rear view:


Conveyor off:

Re: [FTC]: NEW ROBOT DESIGNS!
 

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.

Attachment 13208
Can you smell what I'm cooking?

Re: [FTC]: NEW ROBOT DESIGNS!
 

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?

Re: [FTC]: NEW ROBOT DESIGNS!
 

Very inspirational posts to this thread showing pushing the limit with the new materials allowances.

I see FTC moving more to a manufacture and design competition for some teams with the new rule changes. I am the team lead for our overall program and do not get much time to work with the FTC program. I am excited to see the new designs such as your team(s) have posted in this thread. Hopefully we will see more teams post pictures and designs. I feel that is one of the unique features/strengths of FRC.

Just wondering how you are moving your elevator? I notice what looks to be pulleys, will it be actuated by a series of pulleys? If so, what thread/cord are you using?

Norman

Re: [FTC]: NEW ROBOT DESIGNS!
 

Hi all,
We are rookie Team this year in St. Louis, seems the shoulder/Arm/Wrist is popular. we have that basic design but are having serious stability issues, Tip over danger, motor torque and other challenges. the U-Channels are just too heavy. is it true that if your bot tips in competition, the referee will set you back up?

what areas of the competition are you focusing on?

We jumped right into getting rings on pegs. I was suggesting a bull dozer approach. if time is running out, easy points could be earned by pulling all rings to the floor and sweep them to the center board.

what other quick and dirty point gains would you suggest for Rookies?

Re: [FTC]: NEW ROBOT DESIGNS!
 

I agree that the new direction of FTC for allowing use of additional materials will be good for the program, and it will help to better train the younger students on the kind of fabrication skills and creative design thinking that will directly carry over to the into the FRC program.

We are lifting our elevator for a maximum travel of 28" using some no stretch, 600 lb. test, kevlar cord in 3/32" size -100 ft for $16 at this source:

http://www.qualitynylonrope.com/mm5/merchant.mvc?3/32

We will use two 3" or 4" Tetrix wheel hubs (rubber removed) as our cord winder "drums", and the cord will wrap 3.5 or 2.5 times around these nylon wheel hubs.

The cord will feed both on & off each of the winder drums in two directions, one end will pull for lifting and the other end, when winder drum reverses, will pull for lowering, since there is a fair amount of friction with the slides we are using.

-Dick Ledford

Re: [FTC]: NEW ROBOT DESIGNS!
 

With our 1.5" lift platform maxed out to nearly 18" on width, we were barely able to fit in the cube at the 1st competition.
Our motor/wheel spider modules do slide in or out by loosening just three tee slot screws, so, fine tuning them for maximum size is fairly easy.

With the limited 30 pt. score boost that an only 1" lift can give, compared to getting another row bonus or two during the end game, we have decided to remove the lift platform. Unless we can rebuild another lift in a more compact and less defendable way, that can quickly raise our partners at least 10+ inches, we feel that end game time would be better invested in scoring rings for more row bonuses.

It turned out that even with near 18" of width and a not so steep slope, most partners still had trouble driving up the ramp, and defending our lift by merely blocking access to a lift mechanism proved to be much easier to do, than it was to overcome, especially once the lift platform was deployed (too hard to maneuver much around blocker with protruding platform).

-Dick Ledford

Re: [FTC]: NEW ROBOT DESIGNS!
 

our robot tell me what you think?

Re: [FTC]: NEW ROBOT DESIGNS!
 

our robot, tell me what you think?

Re: [FTC]: NEW ROBOT DESIGNS!
 

More recent PICs.

Electronics removed.
Elevator set up for only up to level two testing (currently 15" limited).
Scissors wire carrier.




We have determined that by lowering our aluminum platform 1" (raising wheel modules actually => relative to platform), we can reach level three on scoring rack with the only two stages of our elevator and thus avoid having to penetrate the plate with any holes for our other (longer) elevator columns - YEAH!

-Dick Ledford

Re: [FTC]: NEW ROBOT DESIGNS!
 

Very inspiring photos and images. I like the use of materials other than the tetrix such as the 80/20. Do you have experience with using 80/20 previously? Do you utilize CAD in your designing?

What is the weight of your robot?

Thanks again,

Norman

Re: [FTC]: NEW ROBOT DESIGNS!
 

Norman, thanks for the encouraging feedback.

We are not currently using CAD but our freshman are finally taking on the task of learning it. I do not do CAD myself, but will pick it up as the freshman progress.

Since we do both FTC and FRC, we do have a few years of 80/20 experience, but this year is the first one using their linear motion items. The key to success with 80.20 is in mastering all the ways to use non-standard fasteners and hole drilling to make strong joints and connections, Gusset plates in corners are also essential for the larger FRC robots.

We have reached the stage where we know how to maximize our designs to take advantage of the inherent flexibility that the slots allow, as far as fine tuning and repositioning our structure and the mounting of our modules. Our elevator and gripper module have 3-axis repositioning by just loosening slot screws. Our complete motor/wheel modules just slide out radially by loosening 3 slot screws on each. With the small amount of man hours our team can muster, there is no way we could do a robot with this level of design without using the 80/20 type of system.

With three years using 80/20 we now have a huge inventory of related standard and specialized fasteners. This year I discovered that we can adapt their 10-32 slot nuts to work in both the 20mm and the 1" size frame.
Since we tend to buy longer fully threaded screws (flat & button head socket screws) and then dremel cut them to the specific needed lengths this has helped a lot. Cutting 1/4" and 6mm screws with the dremel is tedious.
I cannot overemphasize the importance of a large and varied inventory of fasteners when working with the 80/20 framing system.

We only just got the fully assembled robot together yesterday and I have not had a chance to weigh it, At our unofficial Illinois competition today I will try to find a scale, check it and then post here. We are in the vicinity of 40 pounds by my estimate.

-Dick Ledford

Re: [FTC]: NEW ROBOT DESIGNS!
 

With electronics and bumpers/guards, plus 5 pieces of slotted channel as ballast on right front corner, we tip the scales at just over 35 LBS.

We made it through our 1st unofficial competition with no real mechanical failures, only tuning issues.
Our electronics were troublesome, though considering how last minute they were completed, not that bad.
OH, and we were able to score on the 2nd level, as planned, but our driving is stily not very good.







-Dick Ledford

Re: [FTC]: NEW ROBOT DESIGNS!
 

Here is a link to a video of our FTC bot in action. This was from the finals at the Kentwood qualifier. http://www.facebook.com/#!/photo.php?v=538191479525268&set=vb.100000032622989 &type=2&theater

We removed the rings during autonomous and then picked them up from the floor.

Re: [FTC]: NEW ROBOT DESIGNS!
 

I like how all the rings shoot all the way down the slides to get nearer the platform, but still do not roll away in every direction. Floor pickup seems easier too, especially one at a time.

The elevator seems quite fast and the short arm reach seems just enough for coming in to score from different angles, often avoiding the wood edge.

If you can only further upgrade the gripper to pick up two at a time and then individually score them, this could really become a very high scoring bot.

-Dick Ledford

Re: [FTC]: NEW ROBOT DESIGNS!
 

What materials did you guys use for the elevator? Do you have any pictures?

Re: [FTC]: NEW ROBOT DESIGNS!
 

The main elevator segments are Igus slides (shortened) from the FRC kop. There are three of them, but two are fastened back to back to get sliders on both sides of the subassembly. The sliders on the back of the first stage are attached to the frame, and the sliders on the front of the first stage are attached to stage 2. The lift mechanism is cascading cables. I don't have a great picture that shows how the elevator works. Here is something:
http://www.facebook.com/#!/photo.php?fbid=533218163374240&set=o.4476507419464 38&type=1&theater

Re: [FTC]: NEW ROBOT DESIGNS!
 

I like the way that your robot worked, but we ran into a problem at competition when a sister team tried a similar design and similar autonomous routine.

Your robot may have been in violation of the possession rule <GR2>. Forum entry 12 in game rules and game play seems to match your situation and seems to indicate that you should have received multiple 10-point penalties. Was there any discussion by the refs?

In our case, we had to change our autonomous and teleop so that the rings were never on the robot, despite them sliding off immediately, but of course they didn't get as close to the pegs and sometimes rolled quite far when we did not give them a ramp.

Re: [FTC]: NEW ROBOT DESIGNS!
 

We did look into it and discuss it with the referees. They didn't have a problem with it because it always passed the "do the rings stay with the robot when you back up" test (they don't). The rings may fall down the robot or get herded en masse, but the only one in our possession is the one in the gripper.

Re: [FTC]: NEW ROBOT DESIGNS!
 

We tried the argument, but that is where the forum entry came into play, since the ring's weight is supported by the robot and moving the robot back quickly, would have the effect of moving the ring back with the robot while it is on the slide, however briefly. We just changed our approach when they said no.

I might suggest getting an official ruling on it in the forum (and be as specific as you can so that you can show it to a ref) to protect yourself, because some refs will rule it illegal and some obviously won't. You would hate to advance, then be told your robot was illegal and rack up 80 penalty points. We did not do well when we had to change our approach at the tournament.

Good luck.

Re: [FTC]: NEW ROBOT DESIGNS!
 

The FTC game manual, Section 1.5, uses the "back up" example in the definition of "possession". There is a Q&A entry about possession, and the answer just points back to section 1.5 of the game manual. Unless the rings came to a stop on robot and moved with the chassis, it doesn't meet the definition of possession. As for team 6043, our season is done. In Michigan, the only teams that make it to the Championship are the Inspire Award winners. Our alliance partner 5385 earned that award and will represent our state well.

Re: [FTC]: NEW ROBOT DESIGNS!
 

In past possession definition clarifications, if game elements would immediately separate from the robot by just its spinning motion, one way or another, this was declared an non-posession scenario.

I do agree though that an official ruling should be requested in this case, and I expect that it will be favorable.

-Dick Ledford

Re: [FTC]: NEW ROBOT DESIGNS!
 

Thank you for posting all of the great robot pictures. I have really appreciated seeing all of the great ideas. My team is rookie team from Alberta, Canada, and we have tried to make a simple and effective robot that has several strategy options for tournaments. Our robot is a six wheeled slide-drive-like robot with a three segment cascading forklift that raises an arm with two joints which holds two rings and can reach all three rack heights. Our robot also has a four segment ramp which can be released to allow other robots to climb onto our robot for the end-game. We will be competing Saturday, January 12 at the Canadian Championship.

We have a video of our build season, with more of our robot coming soon, on our YouTube channel: https://www.youtube.com/user/swatbotsrobotics