Team 2980's Open Source FIRST BOT

[KleinKid]

Seems super smooth. Thanks for posting all of this it's given my rookie team a lot of help. Our arm design is about twice as long as yours and we wanted to use the window motors very similar to yours. Could you foresee any problems with using two of the window motors on separate sprocket systems nearly identical to yours to power a longer and probably much heavier arm?

Maybe using only one window motor set on a higher gear ratio would do the trick but i'm not certain.

[eedoga]

Last year we ran two window motors coupled together using a PVC pipe. Seamed to work out just fine. Make sure the motors are set to the right polarity and aren't working against eachother. Also be sure to power each motor off of its own speed controller or relay.

I'm really glad we have been able to help you. Why is your arm twice as long? We are using a slide mechanism which we will be mounting on saturday. We should have a tutorial up by sunday night.

PM me and I'll get you my phone number so that I can explain exactly how it all goes together.

Edoga

[KleinKid]

Our arm design has the shoulder joint at a fixed location offset towards the back of the robot. In its starting configuration it should be about 55" long and after extension it should be 64" long. I am looking into using pneumatics for the extension but many members on my team want to use a threaded rod hooked up to one of the banebot motors.


Our material for our arm is 1" aluminum tubing with 1/8" thickness which is a little heavy duty for what were using it for but it's whats left over after we build the frame to support the arm.


Instead of mounting the large sprocket to an axle could we mount our two large sprockets directly on the arm by drilling holes through the sprockets and bolting it directly onto the aluminum tubing?

[Brandon_L]

Just by counting what I can see in the picture, the first sprocket looks like one of those 22 tooth sprockets, and I got around 60 on the other one.

The bungie cords are a wonderful idea! I think that's what I'm missing on ours!

You guys are amazing

[eedoga]

@ Brandon_L
Yeah..the top sprocket is 60 toothed...not sure about the bottom, but 24 sounds right.

@ Klienkid

connecting the sprocket directly to the side of the arm would have created a few different conflicts for us. First off it would make it so that the arm would interact unfavorably with the motor. Second, the chain would rub on the side of the arm, or the inside of the tower making it hard to line everything up. Remember...everything really wants to move so that the chain will bind up or come off with this setup...to be honest I'm a bit worried about the whole thing not working out...guess that is why we have the next few weeks for testing, breaking, and fixing.

You could use a pneumatic piston to extend the arm, but that has its limitations. First off, we are going to have 24 inches of extension. To get that with a piston would add a lot of weight to your arm. The threaded rod idea is cool, but the motor would have to be spinning really fast, or the threads would have to be really shallow in order to be able to extend and retract your arm at a reasonable rate. Now that I think about it, there is that weird threaded rod in the KOP that would work nicely for that...so maybe that is the way to go.

We are most likely going to use another DENSO motor. The idea is you have a round spindle, with 2 ropes or wires wrapped around it. One wire extends down over the end of the arm and then to the back where it attaches to the back of the extension slide, the other goes over the back of the arm and attaches to the front of the extension. Turning the drum winds up one of the strings while un-winding the other so that the slide is pulled forward down the arm. Turning the drum the other direction winds the back string while unwinding the front one, pulling the slide back up the arm. By shortening the arm 24 inches you are lessoning the torque required to rotate the arm around. We will hopefully have a video demonstrating this by late saturday with a tutorial on how to do it on sunday. I may be able to get drawings up by the end of the day tomorrow.

Edoga

[eedoga]

Today was one of those days. Our plan for today was to button down the last few issues with our robot and begin shooting tutorials on how everything worked. Well...Instead we found that we no longer had access to our main cRio. The second cRio that we have needed to be imaged. Needless to say our programmer spent the day chasing gremlins in the system. We did manage to shoot video of how our arm works, and video of a test of our mini-bot, but then I forgot the video camera at work.

So...today we got the backing board for our bumpers cut and mounted...We got the arm extension motor mounted, and we managed to figure out something for our minibot...So while today might have been frustrating, it was a rather productive day.
we ended up moving this to the other end of the arm because it hit the tower frame.
this kind of shows where it would hit the tower.

At the end of the day the network/cRio problems were solved, but by then it was time to go. Our team is meeting again tomorrow...which is another day. Hopefully things will run more smoothly.

The real lesson here is that all teams have their off days. The key thing is to have a good time doing it.

Edoga

[cire]

Originally Posted by KleinKid

Our arm design has the shoulder joint at a fixed location offset towards the back of the robot. In its starting configuration it should be about 55" long and after extension it should be 64" long. I am looking into using pneumatics for the extension but many members on my team want to use a threaded rod hooked up to one of the banebot motors.


Our material for our arm is 1" aluminum tubing with 1/8" thickness which is a little heavy duty for what were using it for but it's whats left over after we build the frame to support the arm.


Instead of mounting the large sprocket to an axle could we mount our two large sprockets directly on the arm by drilling holes through the sprockets and bolting it directly onto the aluminum tubing?

We used 2 window motors with 2 60t sprockets in 2007. everything was on a shaft but the arm was bolted directly to the sprockets with little spacers between them so the chain did not run into the arm. It worked pretty well, but our programmers found it hard to get our arm hold to get to move to the targeted position because it was so massive and the window motors are either on or off, no fine position movement. In the end it worked pretty well though, using surgical tubing as a counter weight.

Heres some video of it in action: http://www.youtube.com/watch?v=Ak954iBVwKg

[eedoga]

@ Cire. That arm is absolutely awe inspiring. I want our team to watch that video. I especially like the fact that you controlled it using a miniarm at your driver station. Seriously cool.

This weekend has been both good and bad for us here at 2980. On wednesday we drive the robot around. On Saturday morning...Nothing. Here is what happens. The driver station classmate says that the cRio has code. The jaguar lights go solid amber. We move the joysticks and nothing.

At this point we are concluding that it is the classmate PC. Everything else has been replaced or re-imaged. We are hoping to be up and running again in the next few days. That way we can finally shoot our electronics and programming tutorials.

We did get some other things worked out and finished.

We re did some of the welds on our frame, and welded up a practice frame.


We also took our main robot apart and cleaned it up a bit.



Here is a way to use surgical tubing to make sure your bolt heads are safe to be around. In this case these two are on the side of a linear bearing that will move back and forth. We also put them on bolts that extend into blind parts of the frame where people may put their hands. This makes it so that you can't catch your skin on the bolt and cut yourself.

We also shot a few videos explaining how different things work.

Jenn explains the pneumatics system

Clamps explains the arm

Oprah explains the mini-bot

You know your coming down the wire when you go into a hardware store and walk out with only 1 screw and 3 feet of wire.

Thanks,

Edoga

[Chris is me]

I love what you've done with the Jaguars, mounting them to the "empty" parts of the Toughbox. What a great way to save space!

[AndyTham]

The arm looks identical to ours here at team 2625 and we are sortof struggling with the code, would you be able to send it to us please? email: david@prowebdev.ca or daoud93@live.com

[Dr Theta]

It looks great! I finally got time to read through this thread and I am impressed, good job.

By the way the use of the term "babybot launcher" made me laugh my head off... I had some of the strangest images pop in my head.

[eedoga]

@ TEAM 2980 Programmers. This post includes EDOGA CODE. You probably shouldn't look at it because Im taking you through this process step by step...Also...I don't know if it will work. so...DON'T LOOK!

@ AndyTham

I'm sort of sorry. I think I already posted this, but...Our team suffered a setback a week ago today. A student on the team made some changes in the way in which things were set up without consulting other members of the team, and then didn't come to any meetings for almost a week. This created a sort of melt down of chain events in our electronics where we could not for the life of us figure out what was done, so instead of progressing our project was completely stalled until today. We are finally where we were a week ago. I put together some code that might work. Given that I am a mentor I am taking several students through programming our robot. They just finished getting the controls to work with the drive train, and will be adding the arm controls tomorrow.


Disclaimer - This is untested code!!!!! I am running on very little sleep given that our team meets 7 days a week and as lead mentor I am there all the time!!!!! Look this over before you use any part of it.

What I made can be downloaded here. It includes what I hope to be control for the arm.

the begin.vi that I came up with didn't fit in one screen capture.



Here is the teleop code I came up with.


I hope this helps. Also, I am guiding our programmers through this process. They aren't this far yet. If anyone sees anything that is wrong with this code please post what changes need to be made.

@ Dr. Theta

Thanks for the kind words. We just hope we are helping someone out there...especially the rookies!

Edoga

[eedoga]

For anyone looking at using any part of our code. The button to victor controls are wrong. Just thought I would pass that on. The values the buttons trigger are not right so the arm goes forward, but does not stop. Easy solution is to swap out the victor for a spike relay. In actuality that makes more sense anyway because the button solution was really either on or off anyway.

The compressor code is working just fine as is the code for extending and retracting the arm. Driving even seams to be working properly. The robot wasn't on the ground so I am not totally sure.

Good luck to you all.

Edoga

[soxfan269]

Originally Posted by eedoga

Things are going so smoothly I'm starting to get scared. We drove our robot today. It took a little figuring out, and some polarity switching at the motors, but we drove our robot today...And not even as a last minute thing, we drove it before we broke for lunch. Not only did we drive it then, but we got to drive it a bit after. Our driver said "I am amazed that it drives so smoothly." We've never had that happen before. We also finished welding the tower, and the arm, and got up to the first arm segment roughed in. We even got to clean the classroom up. :-)

Ok...So some pictures.

In this pick the second arm segment is just stuck in. We still haven't mounted the linear bearings that will allow it to slide back and forth. We also haven't plummed or wired the piston, or mounted the cable organizers that will allow the arm to move back and forth without ripping the wires out.


This is a much better indicator of our actual progress. We may paint the base purple and the arm gold (our school colors) but I sort of doubt that that will happen before the competition. We may do it after the competition to help raise money and awareness for next year.


This shows a close up of how the arm rotation is going to work. The window washer motor is mounted below in back. The sprocket has two holes drilled and tapped to 1/4 * 20. We used the shaft from the gearbox that came with this years kit linked to the large sprocket on the other side. Some 1/2 inch inside diameter bearings complete it all so that power can be transferred from the 60 toothed gear to the arm. The gear ratio between the windshield wiper motor and the large gear is 1:2, so I'm hoping the motor will be able to turn the arm, while retaining a reasonable turning rate. If that fails, plan B is to add a second windshield wiper motor on the other side and tie the two together.


Here is a close up of our electronics bay. We are still trying to kill the spaghetti monster lurking in there. you can also see the Pneumatics which are coming along nicely. We are using two smaller tanks, and the bigger tank that came with this years kit of parts. We figure filling the 20 inch * 2 piston we are using to deploy the minibot will use up most of the stored air even though its on the low power side of the system.


Here you can see the relief valve and power switch which are both accessible without reaching in the way of any moving parts, or anything sharp. We are a bit concerned about the gauge that is mounted on the top of the frame rail might get hit by something if another team carelessly hits it, but hopefully not.

We weighed the base, and it was only 89 pounds with everything except the tower, arm, and battery. (Battery isn't included in the weight limit). The tower weighed in at about 5, and the arm was only about 8 total, so we are actually looking at coming in right around the perfect weight. (Again, something that has never happened to us before.)

We still have a lot of work to do, our minibot is still a figment of our imagination. We also have to finish up the arm extension, and then do a final tear down, prep, and rebuild where we use locktite on all the nuts, and make sure everything is where it should be. All in all, a great day for 2980!

I realize this is a long delayed response... but I would advise you to put your router (radio) on a higher location on the robot. It will increase its range. Keeping it down with the rest of the electronics could also have a potential to cause interference. I hope this is helpful to your team

[eedoga]

@ soxfan269

While we haven't had any issues, and have even been able to drive the robot at a relatively great distance, that is an important thing to consider, so thank you for pointing it out. I'm not sure if we will move our radio at this point, but we definitely need to keep an eye on that. (one student in the club was able to pick up the wifi signal from another building on campus.)

Today was supposed to be our first testing day. Things are moving, don't get me wrong, we just want them moving faster and farther.

So...today we buttoned down the wiring, fixed some things in the teleop code, (the button control of the victor was wrong, so we swaped it out for a relay and got that all running). We realized we had a problem with our babybot extender. We were using a 20 inch piston figuring on loosing 4 inches to our linear bearings. What we forgot to take into account were the bumpers and the stop that keeps the bearings from sliding off of the back of the track. So we were really only getting 15 inches of travel, which with the inset of the babybot track meant our minibot would not hit the pole. So we started out by swapping out the 20 inch piston for a 24 inch piston.

We also had to wire our solenoids and light sensors, and mount our camera.

With that done we went on to actually get our bumpers done and mounted. This year we decided to make the red bumpers and then make a blue slip cover.

We start out making a "sock" that contains the pool noodles and backer board.



Then we sew together a slip cover that is creased on top so that it can't slip down, with elastic in the corners around the bottom. We will probably add some velcro tomorrow.

Ricky-Bobby tried to teach Cat how to sew. (he is actually much better at it than she is. :-)


Here is the gripper. We added surgical tubing to give it a bit more bite. I'm not the happiest with the geometry of the whole thing, I would prefer if it opened up wider and was more level at ground level.

So the arm sort of had a melt down today. The tension on the chain is pulling the sprockets out of alignment. I came up with a fix tonight. 2 really big brackets that hold both the Denso motor and the big sprocket in alignment.

That might make it more difficult to mount the plexiglass safety shield, but we will figure something out.

Should have more pics and video tomorrow. Were coming down the wire.

Edoga