VEX Robotics

[bobafettacheese]

Last year, my high school started a robotics program and a team led by one of my good friends won a Worlds event. This sparked my interest in robotics, so I joined the team at the beginning of this year. After a few introduction meetings, we finally got to get started on building an actual competition robot. I'm approaching this the same way I do Lego and Minecraft most of the time- no guide, no instructions (not that there are any for VEX, the whole point is to build your own robot I guess), no prior experience, just putting pieces together and seeing what happens. So far, I haven't blown up anything, but we'll see how long that lasts

Just wanted to put up a little progress log, almost a FMB for the little robot- well, I say little, but it's rather big and heavy. The max dimensions are 18"x18"x18", and I've had to redesign to fit the requirements several times already.

Without further ado, I present:
50% of the Time, It Works Every Time
http://imgur.com/a/yBl4u
The team name was too long to fit on Competition Rosters, so we used the acronym 50PotTIWET.

This is what I've got after a few hours of going in during homeroom/lunch and whatnot, just a chassis and part of the loader so far, but hopefully it'll look cooler later. The yellow ball in the background in the second and third pictures is part of this year's game- to shoot those balls into nets, similar to basketball but with robots.

Here's some a link if you want to learn more about VEX:
http://www.vexrobotics.com/vexedr/competition

This explains this year's game better than I can:
https://www.youtube.com/watch?v=A8daR6qBw3M

If I remember, I'll take more pictures and post them here as 50PotTIWET progresses.

 

[Tsar_Maple]

Dude this is sweet! Always cool seeing friends do new things!

Hope it goes well

 

[bobafettacheese]

Thanks Maple! Just a mini-update today, haven't been able to work on it quite as much as usual lately due to sports and FBLA meetings.

Here're the photos for this update: http://imgur.com/a/5tMBX

The first picture is just showing the dumb little team poster I threw together in about 5 minutes during homeroom last week. Lots of inside jokes between me and my friend that's building the robot with me.

I added the chain to connect the fifth motor to the axle that spins the ball intake at the front of the bot (second picture). Fun fact: the longest axles we had were a good 5" shorter than I needed, so I had to use some good ol'-fashioned tape and a couple axle couplers to make the darn thing work. I can already tell that if anything falls apart during a competition, this will be it.

The third picture shows our Flywheel Mk. 1. As I'm writing this, the flywheel is completely dismantled- the wheels were too low and close together, so they squeezed the ball too much and stalled the engines. Gear ratios blow my mind.

The final picture is just showing the current state of the entire robot thus far. I took this right before I left class today. The top left bumper rail probably won't be hanging down like that on the finished product- I didn't have time to put a second screw on to hold it in place. You can also see in this pic the little gray box (called a Cortex) in the middle of the robot with all the red wires coming out of it- that's the brains of the robot- and the blue cube behind it is the battery pack. Right now they just have to drag on the ground whenever I test it, but I'll be building a little platform for the Cortex and battery to sit on in the near future.

I also took video of 50PotTIWET's first successful drive test with all 5 motors running! I made a YouTube channel to archive all the videos I take of the robot. Here's the link to the video mentioned above: https://youtu.be/lShyOec8scs. I'll try to record some cool things (if we ever have cool things to record) and put them up there.

Until next time, stay gold, Ponyboy.

 

[Electric_Current]

omg i was reading this post and saw the last line of the post... i almost cried XD

 

[bobafettacheese]

Well... time for another update! I meant to post this Saturday afternoon, but I got a little busy so I'm posting it at 12:05 AM now. If anything doesn't make sense in this post, it's because I'm half asleep. This'll be a rather large update, I got quite a bit of work done on good ol' 50PotTIWET on Friday. Enjoy!

This update's pictures: http://imgur.com/a/morKk (lol, mork *unrelated video* https://www.youtube.com/watch?v=QBP-CScCPyc)

The first picture shows the arena for this year's competition. Ignore the red and blue cubes, those are from last year's game and were being used as a little obstacle course to test our driving skills. The two large red and blue nets are basically basketball hoops for robots- we have to shoot balls-- seen in last update's photos and a couple times in some of this week's too-- into those net/hoops. The 2 red and 2 blue tiles are the starting areas for robots- there are a total of 4 robots in the game area at the same time, two on the red team and two on the blue. However, the people that you're teamed up with for each match aren't necessarily people from your school, they're just whoever picked you (or whoever you picked) before the match, somewhat similar to an NFL draft I guess.

Next I have a picture of the coolest looking wheel I've ever seen, and also the most complicated. These wheels are called "mecanum wheels" ("meh-kuh-numb"? "mee-cah-noom"? No idea how to pronounce it), and they allow the robot they're on to strafe instead of having to turn like a tank, moving one side forward and one side back. I was going to try to put these on 50PotTIWET, but after I discovered that it would require me taking apart the entire chassis and basically starting over, I changed my mind. They're still really cool wheels though, and I might try to use them to build a little robot just for fun.

The third image shows the c-ramp that the balls travel up after going through the intake, you'll see how that fits into the robot as a whole in later images.

After the ramp, there's my hand holding what looks like a tank tread. Originally we were going to use this to make a vertical conveyor belt for the ball to be transferred from the intake to the flywheel, but that design got scrapped once I came up with the c-ramp concept. I still might use a smaller piece of this conveyor near the flywheel, but I'm not sure yet.
{1/2}

 

[bobafettacheese]

Up next is a picture of what the robot looked like when I started working on it on Friday. The [SUP]hombr

 

[bobafettacheese]

Ok, I'm having serious trouble with the forum... lol. When I try to copy/paste the next section of my update into here, it looks fine, but when I click post it just posts the message above I've got a whole bunch more typed up about this update that I want to post. Help?

 

[mk59apr]

I've had that problem before as well, it seems like the posting box will only accept so much at a time.

You might try breaking up your posts, or breaking up your block of writing into smaller pieces and pasting gradually...

btw, when this robot is done you should build it in minecraft..

 

[bobafettacheese]

Hahahaa, we'll see about that in-game build- it's taking pretty long to do irl, lol.

Gonna try to post the update in smaller chunks now:

Up next is a picture of what the robot looked like when I started working on it on Friday. The [SUP]hombr

edit: wut. It seems like anything I type is fine, but copying and pasting from the word doc makes it display the same message

I seem to have found my problem.. I was trying to use a Spanish "e" (with an accent above it) and the forum really does not like that. Lesson learned.

{2/3}
Up next is a picture of what the robot looked like when I started working on it on Friday. The [SUP]hombre loco[/SUP] in the background is my friend who got me into Robotics in the first place (and who won some Worlds event last year). You can kind of see how the c-ramp fits in right behind the intake, so as soon as the wheels spin the ball into the robot, it gets carried away to the flywheel- at least, that's what I hope will happen.

The next picture shows my original plan- I was going to have a wheel spinning inside the c-ramp so that after the ball entered the robot, the wheel would grab it and send it up the ramp into the flywheel. This would have worked [SUB](if it weren't for you meddling kids and your dog)[/SUB], but the height restriction of 18" didn't give me enough space. Plus, the wheel for the c-ramp would have been hitting the wheel for the flywheel, so it wouldn't have worked. You can also see that the back of the robot (on the right side in this photo) now has a nice little platform to store the Cortex. There is a compartment that I hand-designed out of some scrap we had laying around that holds the battery nicely below it as well, but I forgot to take a picture of that. I'll put that in the next update, if I remember.

After that, there's a picture of the Flywheel Mk. II. This time, it only has one wheel, and so the balls will be rolled over it instead of through a gauntlet of two wheels. We decided to go with this design after seeing a couple of robots on the VEXforum with a similar design, and because when using two motors, the battery level, internal gearing, and even just how worn the gears are can affect how fast the wheels spin, and so having a dual wheel flywheel could technically be less accurate later in the match when our battery starts to wear out compared to a one-wheel flywheel that doesn't have to worry about things like varying battery levels. You can see tape on one of the axles, that's because I had to connect two smaller axles to make one long enough to work with the design.

The next picture just shows the size of the new flywheel compared to the balls that it will be shooting. You can see that the plates on one side of the flywheel are much longer than the other side- that's due to how we were going to install the flywheel on the robot. At first I was going to have the gears stand vertically, but on the right side of the robot there's already a motor that takes up space where that plate would go. Thus, we made the right side of the flywheel using shorter plates. However, we are no longer orientating the flywheel vertically- after I tested it, the screws and bolts sticking out between the plates where the balls would roll actually prevent the balls from getting through, so we had to come up with a different way to install the flywheel (which you'll see in a later picture).

This next picture looks very similar to the previous one, but there are a few important details that were changed. First, I got a longer axle from the Robotics coach/advisor/teacher, so I took apart the taped one and replaced it with the new axle. Second, I moved the two little pipe-lookin' things from the longer side to the shorter side (in the previous image they are on the top right part of the flywheel, now they're on the bottom left). These two small pieces are very important- before I put these on, the gears on the flywheel would absolutely not budge. We didn't know what was wrong with them until I figured out that the gears wouldn't spin unless both plates they were attached to were angled at the exact same degree, so these little pipes are basically just there to keep the plates from turning away from each other.

 

[bobafettacheese]

{3/3}

After that, there's yet another view of the flywheel, giving you a better look at the silver pipes. The left side of the flywheel in this image is the side with the longer plates, and I'm going to have to take it completely apart to change out the longer plates for shorter ones so that the flywheel doesn't stick out of the front of the robot and break the 18" restriction.

Second to last, this is how the flywheel will be installed into the robot once all the rest of the framework is in place. This orientation allows the flywheel to function as both the c-ramp wheel and the launcher wheel at the same time. I don't know if it will be efficient enough to only be able to really hold one ball at a time (some robots I've seen can hold up to 4), but I guess we'll just have to find out.

Last but not least is just another viewing angle for my original [SUB](scrapped)[/SUB] design for the c-ramp wheel. It would've been cool if it would've worked, but oh well.

Wow.. I've been typing this for 40 minutes (edit: 2 days) now. This is the longest forum post by far that I've ever made..
Anyways, that's all I've got for this robot update. Again, I apologize if none of this makes sense, it's super late and I'm super super tired. Until next time, stay fresh and adios <3

 

[bobafettacheese]

Big update coming tomorrow night! Tomorrow's the first official meet of the 2015 season. It's really just a scrimmage, but it'll be the first time ever taking 50PotTIWET into battle*! I'll try and record some video of the matches, or at least just grab the footage from the Journalism camera (I'm on the Journalism team at school too.. recording for the weekly news video while driving the robot should be fun )



*not really battle, more like friendly competition I guess

 

[bobafettacheese]

Well, apparently when I say "tomorrow night" I mean "almost a week from now". Sorry Been really busy helping move the YMCA in town from a really old building to a really new building. Lots of fun. Anyways, here's the belated update:

Pictures: http://imgur.com/a/YVla1

The first three pictures are just showing some of the wiring that makes the robot run. This is only about half of the cords that were hooked up by the time the first version of 50PotTIWET was finished, and keeping them all organized was a pain. I labeled each cord and motor pair with a number that corresponded with the port it plugged into on the Cortex to keep everything straight. All of these labels are going to change, though- more on that later.

Next is a picture of 50PotTIWET inside the arena for its first match ever. The blue tiles are where one alliance/team starts, and on the adjacent corner there are two red tiles for the other team to put their robots at the beginning of the match. Going in, my hopes were high- mainly because I had never gotten to test 50PotTIWET before putting it into the match- I literally finished the flywheel and stuck it on less than a minute before the match started. My teammate was programming 50PotTIWET in the car on the way to the tournament *no procrastination at all*

Next, you can see 4 robots (50PotTIWET is the bottom right one) in the arena- all four of these were from teams from my school. It was cool getting to see everyone's work pay off (or not pay off, if you're talking about our robot). Fun fact: I wasn't driving during this match, and my teammate that was decided to not turn to avoid a collision at the start of the match- in the image, the bottom left robot (the smallest one) has a lift that scoops up the balls. You'll notice that the lift is bent at almost a 45

 

[bobafettacheese]

degree angle from where it's supposed to be- that's the result of the crash. Needless to say, they were not quite happy with my teammate. The big, terminator-looking robot in the top right is the one built by my friend that got me interested in robotics. Everyone but him jokingly calls it "School Budget" because he used almost half of the parts we have

Next is 50PotTIWET after the tournament. As you can see, several things are missing. The flywheel is gone, the intake is gone, [SUB]my mind is gone[/SUB]. We quickly found out that our flywheel overheats after about 20 seconds of running at the minimum speed needed to shoot a ball. I literally got a max of one shot off per match before the motors would overheat and the flywheel would just stop working. Also, if the flywheel wasn't already spinning at top speed when the intake grabbed a ball, the whole system would just jam and we were dead in the water. It drove fine, but unfortunately didn't do much besides that. When I did get a shot off, it worked wonderfully- it just didn't work enough. I told the robotics sponsor that we were changing it's name to "10% of the time, it works every time" because 50% was too high. We also call it "Scrap Iron" because nearly a third of it was made using old metal from previous years.

The last two pictures were taken the day after the tournament. This is 1/2 of the new design I'm testing out for 50PotTIWET- a dual wheel flywheel with a different intake. I might still put that big wheel in the c-ramp, but this time it will only be for loading the balls into the flywheel instead of loading and shooting them. This should reduce stress on the motors enough to prevent them from overheating in 20 seconds.. I hope.

I took a couple videos, I'll try to upload them to the channel when I have time. Sorry this was almost a week late, like I said I've been a lot busier than I expected with the moving project at the Y. Anyways, until next time, in the words of Abraham Lincoln*, "Be excellent to each other. And... PARTY ON, DUDES!"

*Well, Bill and Ted's Excellent Adventure anyways.