Team 3807's "Meh" Build Log!

[Thromgord]

Hello, ladies and gents! I'm Thromgord the Warlord, out of team 3807. While our team's robots are often not quite as good as others on this section of Chief Delphi, I nonetheless want to share our progress with all of you out there.

With that in mind, I'm probably going to post about our build so far. Hey, maybe it will offer ideas to some other teams out there! And, at the very least, some may find it funny.

So, here's what has happened so far.

~~~

Over the course of Saturday, Sunday, and Monday, our team was simply brainstorming ideas about how the robot should work. We drew a bit of inspiration from the official Robot in Three Days build and its Wonderful Clips of Destiny. Here's a video of the Team Indiana build's clips in action, starting at about 1:15. Look at how those clips can clip! Their potential this year is nearly unlimited, though trusted sources tell me that they won't work with pool noodles. Best of all, they're almost embarrassingly simple.

So, after some thought, our team came up with a 'forklift'-style design using a mechanism quite similar to Team Indiana's. Only, instead of placing the forklift on the inside of the robot's frame, it would extend out front. The robot will compensate for having all of that nasty mass ahead of its C.G. by using two omni-wheels at the end of metal rods. This configuration would also allow for an intake mechanism to be placed at the end of said rods, so that totes could be grabbed quickly and efficiently!

The forklift would be capable of carrying multiple totes at once, as well! Once the first tote is grabbed, the forklift would rise up enough to slide in a second tote under the first, then descend straight down until the Clips of Destiny were firmly planted on the lip of that second tote. This could be repeated ad infinitum, creating a stack inside the robot. We're likely going to have some Plexiglas on the sides of this tower, protecting it from harm. The stack could be dropped off as a unit, just as soon as the forklift had lowered itself down all the way, and the robot could drive off into the Mists of Legend. (But hopefully come back in time for the next match. Robot? Robot, where are you?!)

The forklift itself will be propelled up and down by a clever little idea. Our team discovered that a threaded rod with a motor attached to the bottom of it could be used to raise or lower the forklift. This would be achieved by having the rod spin, almost like a screw or bolt spinning into or out of the wrong bit of wood or C-Channel, again. (C'mon, team!) Only instead of having the threaded rod burrow into wood, it just causes a corresponding bit to smoothly translate up and down. Here's a video of that, working on a smaller scale (the fun stuff begins at 1:10). The only thing needed is something to mitigate the small amount of torque produced by this method; two vertical bars of 80/20 should be plenty enough.

This means that we only really have to have one motor on the robot, aside from the normal chassis motors used to drive the wheels. Yet, this simplicity would still allow us to gather totes reliably and create a big stack!

...and there was much rejoicing.

Two days ago, our team made this video of What Our Robot is Going to Do. It did a bit of a better job of explaining these things than I did, it has some pictures, and besides, Gabe had an absolutely stunning Mewtwo hat on that he made himself, which you might want to see. So here's the video link.

Anyways, let me know what you think! Will our robot work gloriously? Do you have your doubts? Will the robot begin bucking violently and then hit a wall really hard, like it did two years ago? (Funny story, that.)

See you in a couple of days! Happy building!

-Thromgord

[Kyle_1881]

Looking good guys!

Some advice on the lifting mechanism. In the past 2 years we have used a "ball screw" for a climber in 2013 and part of out shooter last year. These are meant to do what you described and can lift immense weight with a good gear ratio. Take a look and good luck!

[asid61]

That kind of screw mechanism is used everywhere in manufacturing. There are lead screws and ball screws for high accuracy linear translation. The former is much cheaper but is less accurate, and has backlash.
McMaster sells cheap leadscrews. The multi-start ones that have 1/4" travel per turn are the cheapest I think.

[Thromgord]

The things that have been said by Kyle_1881 and asid61

I'm pretty sure that our team is going with a single lead screw, on account of its low cost and not-much-worse-than-a-ball-screw capability. I have no earthly idea where our lead screws have been ordered from, but the Build Team has told me that it has been done. So that's nice.

We're going to continue assembling the KoP chassis through Saturday, when it will hopefully be done and running (the Programming Team has already written code, the Electrical Team is working on a nice electrical board, and the Build Team has the chassis more-or-less done, though they're still assembling omni wheels and the like.)

Here's a question for y'all (I'm sure you're more experienced than us): We're considering just having the Forklift extend far enough up to allow a second tote to be slid under the first, instead of having the threaded screw extend all the way up to the full height of the robot. If this was done, the robot could still pick up a full stack of totes, because the Clips of Destiny are really cool (see the original post). The big stack of totes inside the robot could still be given ample protection against falling, as well. However, the shorter-screw assembly could not drop off totes on top of other totes. There is a way around this, and that's to grab the entire stack of existing totes, raise them up and slide another tote underneath, but IMO, this is a bit more risky.

So, your $24,000 question* is:
(*$24,000 will not be given to people with a good answer. Sorry.)

Should the threaded screw extend all the way to the top of the robot, or only go a little over two tote-heights into the air?

Thanks!

[Monochron]

Having used a similar design on our robot last year, I would reccomend using "Acme" threaded rod if you stay with this design. We has issues with the threads getting munched in high load situations, and acme threading makes this much less likely. The threads are trapezoid shaped and show much better wear characteristics when we used them.

Word of warning though, this will be a more expensive solution than what was shown in that video. Acme nuts and rods won't come cheap but you can probably get a reasonable deal if you shop around.

[Thromgord]

Originally Posted by Monochron

Having used a similar design on our robot last year, I would reccomend using "Acme" threaded rod if you stay with this design. We has issues with the threads getting munched in high load situations, and acme threading makes this much less likely. The threads are trapezoid shaped and show much better wear characteristics when we used them.

Word of warning though, this will be a more expensive solution than what was shown in that video. Acme nuts and rods won't come cheap but you can probably get a reasonable deal if you shop around.

The build team has just informed me that we are, indeed, using ACME threaded rod. We've ordered the parts, and we're just waiting for them to arrive.

I'll give y'all a more comprehensive update later today, but as of about 12:45 MST...

>The chassis is BUILT. (yay!)
>The 'practice' electrical board is about 50% done. We'll probably have it done by the end of today. It won't be our final board, but it will be capable of driving the robot around.
>The Solidworks team (of one) is designing the battery mount.
>I'm just sitting around and doing nothing. Perhaps I should get up and help one of the other teams, or get footage for my Week 1 Update.

...and with that, I'm off. See you guys in a bit...

~~~

...oh, and a brief edit: Still looking for your opinions on the eventual length of the threaded screw

[asid61]

Originally Posted by Thromgord

The build team has just informed me that we are, indeed, using ACME threaded rod. We've ordered the parts, and we're just waiting for them to arrive.

I'll give y'all a more comprehensive update later today, but as of about 12:45 MST...

>The chassis is BUILT. (yay!)
>The 'practice' electrical board is about 50% done. We'll probably have it done by the end of today. It won't be our final board, but it will be capable of driving the robot around.
>The Solidworks team (of one) is designing the battery mount.
>I'm just sitting around and doing nothing. Perhaps I should get up and help one of the other teams, or get footage for my Week 1 Update.

...and with that, I'm off. See you guys in a bit...

~~~

...oh, and a brief edit: Still looking for your opinions on the eventual length of the threaded screw

Wow, you guys work fast.
On the length of the leadscrew: that's a fine strategy. However, keep in mind that if you don't start by lifting a can and placing it on a tote, you can't repair your mistake by grabbing a can later.
Also make sure that you can grab the cans off the center area.

[Thromgord]

All right, here's your update! It's only about a day late.

The robot is now drivable. We build the Kit of Parts chassis, but decided to use all omni wheels in lieu of the standard ones, to give a better and more even turning radius. This seems to be working well, with the one exception of the fact that drifts a lot and is slow to stop on waxed floors. But fortunately, our robot shouldn't have to be up on the HDPE very often, and it works well on carpet, so everything seems okay so far.

I'm quite happy that this electrical board won't be the final board that we use, as everything seems to be held in place with exclusively zip ties. I tried to count the zip ties used on the board, but lost track at about 12,668 zip ties. I have no doubt that at least 13,000 were used. Unfortunately, the battery was also held on by zip ties, and thus it sheared them off when the robot crashed into a wall really hard. This is, I believe, the third year when the first thing that we did after creating a chassis was drive it into a wall. Fortunately, the electronics were so thoroughly encased in their zip-ties that nothing was broken or even really budged when the battery slid across the top of the electrical board.

I don't know about our team, sometimes.

We've decided to make the forklift proper out of parts of the VEX chassis. This will provide a solid foundation, and more importantly, it will look really cool. We're going to consider placing Glorified Blocks(TM) on the ends of the forklift, that would be a way of passively picking up garbage bins, as the clips won't quite do the trick.

One thing that's being debated at the moment is whether or not the threaded rod and motor should be located at one end of the chassis, with an arm extending to the opposite end. The forklift would still be able to slide up and down without sagging, due to the placement of some rods or pieces of 80/20 by its sides; it would have special little buttons that would allow it to slide up and down and remain straight. While this would cause a greater strain on the threaded rod, it would keep the center of gravity in a better place, which is definitely something to consider in this year's challenge. Thoughts, anyone?

...oh, and pretty much everyone agreed that the robot should be made to look like our team mascot, a dragon.

You can see all of the progress we've made, including a video of the chassis rolling and drawings of what the thing might end up looking like, in this convenient and short video.

Here it is!

Sorry for the overload of pink... we're very proud of our 'team color' and we're not afraid to show it.

Anyways, see you in about half a week, or maybe sooner if any questions are raised! Bye for now.

-Thromgord

[pilum40]

Great idea for threaded rod. We too are working through the concept using a CIM motor through a Modulox transmission we had in parts (yes, we put it together) to turn the screw. Have y'all tried out this screw yet? We mocked a prototype using one of the IGUS screws, and plastic parts we get from FIRST. We used a window motor simply because the screw we used was out of parts bin and had a "custom-made" (hand fab'd) hub already on it. The window motor was way too slow. What type of motor are you going to use? I'm thinking CIM is way too much in a direct mode but may work ok stepped down a little. What do you think? I like simple because it's less to crap out during competition and my younger students can see success in a shorter amount of time. We are working with a company called Nook to make us a custom threaded rod and support flanges (one for the top...one for the bottom). I still like Robot in 3 Days Team Indiana's approach except we'll use a mechanical (geared) version of the crab claw because our expertise in pneumatics is limited and time is short. When in doubt...gear it out! We too have our base driving in week one and should decide on a plan Tuesday. Can't work today because our school closes early as we are 1/2 mile from the NCAA National Football Championship venue at Jerry Jones' World. Please let me know what you think and drop me news of your team's updates via PM here on CD.
Robot on!!!

Steve Miller
Coach-Team 3355-Purple Vipers (you like Pink? We gots PURPLE!!!)

[Thromgord]

Sure pilum40, I can send you a PM whenever I update this build log. (If anyone else wants to receive a message when this thing updates, send me a PM.) We're probably going to go with 1-2 geared-down CIM motors for the lifter, depending on the amount of torque needed. We've ordered said screws, but they haven't come yet.

I still can't believe that people are actually following this build. I'm actually quite flattered.

...and now, I must apologize to Peter, for he read the build log and thought that it was inaccurate on several counts:

~~~

Dear Peter,

I had no idea that you were reading this thing! It is actually quite unexpected that a member of Team 3807 would be reading Team 3807's build log.

That being said, you were right in the words that you spoke yesterday. Our team likely won't have omni wheels on the front of the robot, or at least that's not currently part of the plan. In addition, the forklift will only extend about two tote-heights in the air, although I thought I made it reasonably clear that the team was mostly decided on that matter. I just wanted to hear what the good people of Chief Delphi had to say about it.

At any rate, I'll try to be a little more accurate in the future. Please keep in mind that I am but a lowly member of the Marketing Team, and thus I may not have the most up-to-date information.

Have a nice day.

-Thromgord

[pilum40]

Outstanding! Please PM me. My team is mostly freshmen and sophomores so we mentors are having to "herd a larger number of cats" this year! It's a great problem to have as sustainability won't be a problem.

Thanks again and let me know about stuff!

Steve Miller
Team 3355 Purple Vipers

[Thromgord]

I'm not going to show any videos today, or really even give much of a build update. I'm not even going to send out PMs. Despite the fact that we're right at the two-week mark, I don't want to do any of this... yet.

Why?

Well, our team next meets on Monday, and we expect to have a fully functional robot that day, capable of driving around and picking up three totes (we'll be able to pick up more, once we have some weight in the back, as well as guard-rails to prevent a tall stack from toppling).

Our forklift is built, with the exception of the Clips of Destiny, which will be added on soon. The bit that raises and lowers the forklift is pretty much complete; it just needs to be assembled. The 'final' electrical board is 95% done; we've decided to try for a vertically mounted board with plenty of protection against falling totes.

I don't wanna jinx it, but we might have several weeks to perfect our robot. That would be absolutely unprecedented for our team. I'm really hoping that it happens.

See you in two days or so, for a "real" update.

-Thromgord

[Grey Mann]

Damndamndamn... We are stilling CADing our robot as of the last meeting I went to yesterday... At this rate we should have a robot by around June by my estimate..

[Thromgord]

Hi everyone!

Sorry for not updating earlier. These things are time-consuming to write, and I'm quite busy, both within the team and in other matters as well.

So, here's what's happened since I last posted:

>We've made some progress on the forklift. It is now capable of raising and lowering quite nicely; I'd say that it has about 100 pounds of force to it, which is more than enough. The Clips of Destiny still aren't done: we made some and attached them, but they were too stiff to pick up a bin from above. Other than that, though, the forklift is complete and lookin' good, man!
>The final electrical board is 100% done, mounted vertically, and it works. Or at least I assume that it works: While I can't tell a PWM cable from a Talon, I know that there are loads of happy blinky lights when things are turned on, and that the robot moves and raises and lowers the forklift when we tell it to.
>The electrical team has also been busy mounting sensors to the robot. As of now, it has a camera, a little gyroscope/accelerometer thing, and some magnetic sensors that tell us how high the forklift is. They're looking to add even more sensors, but we're trying to restrain them by force. (To give you a sense of how unique all of this is, last year's robot had a single camera, and even that didn't work too well.)
>We built a little ramp for the robot to drive over, and it drove over the thing quite nicely. So we should be able to drive to the top of the Scoring Platform with no difficulty. Those 6" wheels give the robot plenty of clearance.

That's pretty much it, for now! I wish that we had more to report.

I'll probably edit this post with a picture or a build video... so check back soon

-Thromgord

[Thromgord]

Well, we're just about done.

I wish I could say that this thing was updated nearly often enough, but it wasn't. Maybe next year (when we also have more credibility under our belt by NOT getting second-to-last place at Regionals the previous year.)

This robot is so good, we're probably not going to end up in second-to-last place at regionals!

Its features:

A Passive Aligner, for when you just want to ram into a tote until it's in the right spot for your robot to pick it up!

We built the Passive Aligner in about an hour. It's basically just two long sticks that are attached to the main robot by a bolt and some surgical tubing. Despite their simplicity, they seem to work almost magically. Previously inept team members (me) can now pick up bins with relative ease!

A Non-Unique Forklift, capable of not only picking up stacks of up to six totes, but also able to lift bins!*
*Bin-lifter will probably be done in a day or two.

I'm actually very proud of our forklift. At this point, we could probably carry around a team member of average size and weight without the robot tipping. It has a special attachment to lift bins, and the clips we're using seem to do a nice job of carrying 4 totes reliably (we should be able to get up to 6 with a clip replacement and some guards on the sides of the forklift.)

A Vertical-Mounted Electrical Board!

Because why not. It's wonderful to see all of the twinkly lights, and it also puts the on/off switch in a very convenient location, so that if the robot suddenly begins driving off at full speed, we can chase it down and stop it! (This actually happened three years ago.)

A Reasonable Center of Gravity! Because tipping is bad.

Our robot is only about three feet high (without guardrails) and weighs in at about eighty pounds. In other words, it's a scrawny little thing... and yet it can pick up tote stacks that weigh more than half of what it does.

It's capable of making Coopertition stacks, though only barely! It's quite simple and difficult to break! With some properly placed decals, it will be so beautiful, it will cause the opposing team to cry and drop their tote stacks!

I can't believe that there's still a week to go before the Week-Zero Scrimmage! It'll be held on Valentine's Day here in Colorado (how romantic), and there's no better color for Valentine's Day than good ol' eye-rattling pink!

Oh, and here's a video of the robot. Because a video is worth 30,000 words a second.

Let me know what you think! Thanks for any feedback.

-Thromgord