Team 2980's Open Source FIRST BOT

[eedoga]

So we did a bunch of work today and got to drive the robot around a bit. Turns out the window motor overheats pretty quickly running the arm. We are currently using bungie cords, but we might have to use surgical tubing or something else instead. Yesterday we found the big sprocket on the arm was getting pulled out of alignment as it turned the arm. So today we added brackets to keep that from happening. the problem is the arm ballooned out to 28 pounds. We did some major cutting on the brackets and got it down to 26. The brackets are made from 1/4 inch thick aluminum. (all we had left) We will be ordering some 1/8 inch thick aluminum to replace them with.
http://www.youtube.com/watch?v=T-8KXDW74Oc

We also improved the rigidity of the arm mount. The slide mechanism still needs work. We will have to figure out a way to make the wire guides work better, and will probably need to make a roller system that keeps the wires where we want them.

either that or we will come up with something else. I must say I am glad we kept up the schedule we did this year giving us time to beef up the places we need to. We did end up 1 pound over weight. So spent some time cutting things back. The hard part is that that gives us very little room to grow.

This is probably the best shot of what we did to our brackets. It keeps the sprockets lined up nicely, but means we have to redo our safety shield out of cardstock or something. :-)

Right now it is a chopped of arm waiting to happen.

Finally we got started on our cart. After seeing this video we got an idea.
http://www.youtube.com/watch?v=PScY_--XAM4

We came up with this.
There will be two turn tables mounted on each tower, and the robot will sit on a tray mounted between them. We hope that we will be able to tilt the robot on its side while working on it so that we can get to things like wheels and electronics without having to move too much around.

So maybe I will regret signing us up to show off our robot at the bellingham museum of radio and electricity next Saturday...the last Saturday of build season.

What was I thinking!?

Edoga

[DavidGitz]

We are using an arm that weighs (I would guess) around 15 lbs including our gripper that is about 6 feet long total with 2 window motors and a 4.8:1 ratio and 2 heavy duty rubber straps to counter the weight. Our arm takes about 4 seconds to go from the bottom position to vertical. On Saturday we were noticing it was taking longer for the arm to rotate up but thought it was because our gripper was extended out and making it harder to lift, turns out one of the denso couplers had cracked and only one window motor was lifting. It was good to see that one window motor could do the job (barely). Since then we have "upgraded" our denso couplers and they seem to be holding up better (that was the 2nd one we cracked this year).

I haven't watched any video of your robot, so this could be irrevelant but I would make sure to check that the window motors can lift your arm fully extended. Our arm weighs about half yours and we have over twice a gear reduction.

[eedoga]

@ DavidGitz While the total weight of our arm is about 26 pounds that includes the base and other non-articulated parts. It would be asking a lot to try and have the motor move the arm when it is extended. We instead are planning on retracting the arm before rotating it. In fact the only time we should have to extend our arm is in order to reach the top peg.

That said we drove the robot around quite a bit today. We realized that we had the mecanum wheels mounted wrong and swapped them out. The robot handles a lot better thanks to the Chief Delphi community.

The arm seams to work a lot better especially if you don't wave it all over the place. :-) The motor was able to repeatedly move the arm without overheating, though that remains a concern.

Tomorrow we will be presenting the robot to the school board.

We just nominated two students for the Deans List award. While I'm sure what I had to say is the normal stuff to some FIRST participants, In our hearts and minds these two individuals stand out. Here is what I wrote about them.


Deans List Recommendation for Kyle

Kyle is the type of kid who seams to struggle with everything. During our “homework time” kyle is always asking for help with his history or math assignments. When working on the robot Kyle will often ask you to explain how something works several times, or how to cut out a part. As our team has grown from five to fifteen to more than thirty, there have been fewer and fewer jobs for Kyle to do. Yet still Kyle remains a fixture of our team.

There are other people on the team who are better at programming, designing, problem solving, and even fabricating than Kyle. But hands down there is no one with a bigger heart.

Last year our team found itself in one heck of a spot. Due to poor design and weight management our robot ended up being 20 pounds over weight. We discovered this when we weighed it the second to last day of the build season. Faced with a terrible choice of loosing our entire pneumatics system including our kicker and arm we decided instead to redesign our robot from scratch. Kyle worked tirelessly cutting brackets, drilling holes, sanding edges and even cleaning the room at the end of the day. While many others on the team were fading off, Kyle stayed until well after midnight.

Its Kyle who is waiting for me when I get to our Saturday and Sunday build sessions. Its Kyle who is asking to use the phone to tell his parents he will be heading home at the end of the night. Its Kyle who keeps track of where I left my coffee and its Kyle who runs to find someone a ratchet, drill bit, or even the rubber mallet. Kyle even takes out the trash. He does all of this with a smile on his face. At the regional last year Kyle spent all of his time trying to find other teams to lend parts to. He seams to love being a part of the team, and having some job that he can call his own, and we love having him.

If this doesn’t sum up the spirit of FIRST, then we don’t know what does.

Mr. Edoga and the rest of the Whidbey Island Wildcats.
Team 2980

Deans List Recommendation for Mary

Mary has been a member of the Oak Harbor Robotics Club (The Whidbey Island Wildcats) since the club first started 3 years ago. When we first started we only had 5 members and we all knew nothing about what we had signed up for. Mary Treis dove in to FIRST without a moments hesitation.

In our first year I received an envelope with a number of badges. One was green and said safety captain. Needless to say I had no idea what any of that was for, so I handed the green badge to Mary without really thinking about it. Mary being the smart girl she is went and looked up what her responsibilities were. Lets just say under her direction we are a much safer team. Mary is there to remind everyone to wear their safety gear.

Over the years our team has undergone “growing pains”. As the team has grown the responsibilities and demands placed on each member, especially the core members have decreased. Mary has gone from being a doer to being a director, and finally to being a leader. While I know she doesn’t always like delegating, Mary has taken on her new role with pride. Recently she commented that she was now a supervisor. If only she knew how important that roll was.

Our team recently acquired 6 brand new members. While they are already showing us how talented they are, they lack basic skills. Mary is always there to guide the new members teaching them the tricks that lead to straight cuts and accurate holes. She seams to know how to keep the new members occupied, and most importantly she keeps us all safe.

Mary is one of the most valued members of our team.

Edoga and the rest of the Whidbey Island Wildcats.
Team 2980

[DavidGitz]

Originally Posted by eedoga

@ DavidGitz While the total weight of our arm is about 26 pounds that includes the base and other non-articulated parts. It would be asking a lot to try and have the motor move the arm when it is extended. We instead are planning on retracting the arm before rotating it. In fact the only time we should have to extend our arm is in order to reach the top peg.

That said we drove the robot around quite a bit today. We realized that we had the mecanum wheels mounted wrong and swapped them out. The robot handles a lot better thanks to the Chief Delphi community.

The arm seams to work a lot better especially if you don't wave it all over the place. :-) The motor was able to repeatedly move the arm without overheating, though that remains a concern.

Ok, that's good to hear. I think the window motors are a great asset, if you are careful with the design and minimize friction/binding as much as possible.

Overheating is a concern to us. Normally we have been using one of the large muffin fans from the KOP on each arm window motor and it keeps them ice cold, even after running for 8 hours non-stop. However today we had to turn our window motors off due to some re-wiring (and putting fence material over the blades so fingers don't go in bad places...) and the window motors over-heated after about 25 minutes of driver practice and wouldn't budge until they cooled down.

[548swimmer]

It looks like you guys can cut weight out of the large sprocket

[jmanela]

Originally Posted by 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!

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.



Edoga

I really don't see much of a problem in the logic itself, however, when I began to program I had all of my code in teleop. You might want to consider compressing some of that code into SubVi's so that it is easier to read. It was fine my first year when there wasn't so much coding, but the second year things got a little crazy and wires were EVERYWHERE so many wires... shudder.

But anyway, subvi's are a good way to compress your code and make it easier to read.

[Brandon_L]

Were having a big problem...

We are using two window motors into a small sprocket to a bigger 60 tooth sprocket via chain, similar to what you guys are doing:
http://i187.photobucket.com/albums/x...g/DSCN1408.jpg
(no chain is on in this picture..)

The entire setup works, but the motors like to lock up and when they do we have to put full power on them for them to unlock. The result being the arm slamming into our frame or flying into the air. Motors also tend to heat up a bit when this happens, but nothing extreme. We have two bungee cords down the back as a counterweight.

What did you guys do to prevent it from locking? We don't have a clue

EDIT:
I saw someone mentioning that having a jaguar controlling the arm might be doing something. I don't know if this is true, but we are using two jaguars.

[eedoga]

we recently started running into a similar problem. for us it was an alignment issue. the large sprocket attached to the arm was pulling out of alignment. That was why we added the two large brackets on the side. there is still too much play so we are adding a longer shaft when it comes in on Friday in the hopes that that will solve the problem. check the heck out of your alignment. Also I think when under strain the window motors can sort of bind up internally. It might be that you are overcoming the seasing.

finally I have heared that using some Electronic speed controllers makes the window motors unhappy. we are using a spike relay for each of these motors.

[anyheck]

Originally Posted by Brandon_L

Were having a big problem...


The entire setup works, but the motors like to lock up and when they do we have to put full power on them for them to unlock. The result being the arm slamming into our frame or flying into the air. Motors also tend to heat up a bit when this happens, but nothing extreme. We have two bungee cords down the back as a counterweight.

What did you guys do to prevent it from locking? We don't have a clue

EDIT:
I saw someone mentioning that having a jaguar controlling the arm might be doing something. I don't know if this is true, but we are using two jaguars.

We had a jaguar running our lift mechanism on a window motor and it was locking up as you've described, probably once every few up-down translations. Switched to a Victor and no further problems.

http://www.chiefdelphi.com/forums/sh...ad.php?t=83973

[UltimatJose]

Very nice robot! The offset on the minibot should not be a problem since you all are using mecanum wheels. a team using the ordinary wheels provided in the kit would really have trouble setting up to deploy the minibot. GREAT JOB

[eedoga]

I think build season is finally getting to me. Its 9 on Saturday, and I think I'm going to go to bed. FIRST things FIRST. We spent the day with our robot at the North West Robot Festival. It was really awesome getting feedback from other people, and "showing off the bot.


FIRST Team 2605 was there also. They didn't have their FRC bot, but they did have what looked like a vex bot with them that they let the crowd drive. We even teamed up on a few things.
Here their robot is putting some doughnuts on our minibot deployment tray.

Our robot did slip into demo mode which was annoying.

The shoulder problems we had been having have been fixed and seams to be working well now. We replaced the shaft that tied the right side of the arm to the sprocket with a longer one that extends out through the double bracket on the outside of the arm. (A picture would probably sum this up in half a second, and somehow I forgot to get a close up of the arm.

We did have some strange problems. The gripper solenoid valve stopped working. I think it may be jammed. The light comes on suggesting it has power. We have a spare we will replace it with and I'll blow it out with an airgun on monday. Might also be a kink in the hose...

Our arm extension mechanism also got all sorts of tangled up. The wire is getting caught in some seams in the plastic. I sort of want to come up with a better way to do this. good thing we have 5 weeks before competition.

The mini bot needs more magnets. Things were working really well back in the classroom, but when we got to the festival the minibot wheels slipped up a storm. A part of me wonders if it has to do with temperature. Maybe we should try heating up the wheels before each run...wonder how the officials would feel if we warmed up our pole before each of our matches. :-)

Tomorrow we are going to take the robot to a practice field in Lynnwood. I have the video camera in the truck already so I hope to get some good video...Course we have to fix the arm problems before we can do anything else. :-(

Still...I'm really glad we got as far as we did this year.

Edoga