Team 2980's Open Source FIRST BOT

[eedoga]

Thank you for all of your enlightening posts. We will go over potential solutions with our safety captain, and post what we come up with later in the week.

[Jonzki]

Your Robot looks in great shape and looks like you guys know what you are doing.
Last week we figured we were going to use window motors to power/controll our arm by a sprocket/chain system. Much like the one you have.

The problem is, and my question: How are you powering the window motor? we are using the 2011 KOP window motor and we did not find any connector that fits the connection on the window motor and figured we could just connect cables with fitters and electrical tape around. Then the question about which one is positive and which one is negative?

- team 3481

[jjenkins]

I don't know what 2980 has done, but one of the allowed modifications is to the connector on the window motor. If you like, you can cut away the plastic and solder on more conventional leads (R47D). A little shrink wrap and you should be good to go.

Team 2577 has had good success with crimp-on quick disconnect terminals. Using insulated terminals and a bit of electrical table, we've never had a motor connection come apart during competition. Just make sure that you have a good ratcheting crimp tool.

As to polarity: it is a motor. Test it. Hook it up with clip-on leads on way and see how it spins. The window motors are slow enough to see easily which way they are turning.

[sNeff]

My suggestion: Paint it before you go to competition.

Looks matter, especially if you'd like to compete on Saturday afternoon. Between two bots, identical functionality, one painted and the other not, the painted one gets picked.

Yeah, we're all logically-minded engineers here who want to think we're all making the best decision based solely on technical merits, but--no. Looks matter.

[Nemisis]

Very nice detailed Pictures!! I must say I am very impressed by your excellent use of Autodesk!! Nicely Done!!

[Durham86]

Here is a video link of how our minibot is working. Please leave some positive feedback. Thank you from F.R.E.D team 2883.http://www.youtube.com/watch?v=HZvXsaTXGfI

[eedoga]

Thanks for the kind words.

As for paint, we'll have to wait and see how we are doing on weight and money. I think we will be fine...

Window motor connectors...We cut away the plastic last year and had a motor fail because the connector broke from being stressed. A search through this forum turned up the connectors via mouser.com. You have to get the plugs and the pins separately. They totaled under $2 a piece. (we went to NAPA first and they sold us connectors that didn't fit for $28 a piece...(we returned them only loosing shipping.)

http://www.mouser.com/ProductDetail/...yGCEJfow%3d%3d
http://www.mouser.com/ProductDetail/...dZeQpqSw%3d%3d

We put some 2ton epoxy in the holes in the back of the plugs to keep things from pulling out.

So a few posts back there were questions about safety and our arm motor system. Here is what we came up with.




It is still possible to get a finger caught in there if you try really hard...We used 1/8th inch plexi and a bender to make an open backed cover. we will probably decorate it or something. The plastic protector stuff is still on there so when we peel that off the writing goes with it.

We will definitely be posting detailed tutorials on our electronics and pneumatics systems this weekend for anyone who is interested...

Hope this helps.

Edoga

[Tristan Lall]

You may want to leave the plastic film attached to the acrylic (i.e. polymethylmethylacrylate, known as Plexiglas). It will help keep the pieces together if it gets smashed. You should be able to remove the ink markings with a solvent like isopropanol.

Next time, consider polycarbonate, which is much more impact-resistant.

[2611.Shooter]

just noticed- your arm seems to be fairly far inside the bumper perimeter at it's lowest extension, and I am assuming it's highest as well. at present, it appears as if the arm will only be able to place on the middle, which may pose problems. Or does the tower slide forward, or the arm get longer?

based on post #6

[eedoga]

I will be posting in more detail on the arm tonight. As you currently see the arm it is facing backwards on the robot, and will flip over the top of the tower to the front of the robot. The top section of the arm is mounted on slides and can extend another 18 inches. That puts the gripper at over 9'.

Now the one major problem we have run into is getting hardware into the tiny gap between the two arm rails. We've got it done now, but it was nowhere near ideal.

Edoga

[Durham86]

Here is a short video of our minibot... http://www.youtube.com/watch?v=HZvXsaTXGfI. Check it out and give us some positive feedback. Thank you from F.R.E.D team 2883.

[Nadav Zingerman]

Originally Posted by eedoga

Thanks for the kind words.

As for paint, we'll have to wait and see how we are doing on weight and money. I think we will be fine...

Window motor connectors...We cut away the plastic last year and had a motor fail because the connector broke from being stressed. A search through this forum turned up the connectors via mouser.com. You have to get the plugs and the pins separately. They totaled under $2 a piece. (we went to NAPA first and they sold us connectors that didn't fit for $28 a piece...(we returned them only loosing shipping.)

http://www.mouser.com/ProductDetail/...yGCEJfow%3d%3d
http://www.mouser.com/ProductDetail/...dZeQpqSw%3d%3d

We put some 2ton epoxy in the holes in the back of the plugs to keep things from pulling out.

So a few posts back there were questions about safety and our arm motor system. Here is what we came up with.




It is still possible to get a finger caught in there if you try really hard...We used 1/8th inch plexi and a bender to make an open backed cover. we will probably decorate it or something. The plastic protector stuff is still on there so when we peel that off the writing goes with it.

We will definitely be posting detailed tutorials on our electronics and pneumatics systems this weekend for anyone who is interested...

Hope this helps.

Edoga

I'm glad you decided to do this . It's exactly what I had in mind.

[gopatterson]

what is the height of the bumper

[Brandon_L]

can I ask what kind of gearing you got going on there? Were trying to do something similar with a window motor.

What sized sprockets are those? How many teeth?

Thank you so much for your response

[eedoga]

@gopatterson, We should have our bumpers mounted this weekend. The plan is to have the bumpers sit about 1.5-2 inches off the ground. We will use some 2 inch angle stock to make bumper mounts. I'll post a CAD file of those once I make them. :-)

Hey Brandon, I think the big sprocket is 60 toothed and the small one is somewhere around 30. I would need to count again to get it exact. I think it may be in an earlier post on this thread.

The denso motor was not up to the job on its own. In the original design we were just using pressure to hole the plastic thing onto the front of the motor. But the weight of the arm was pulling the plastic thing out of alignment and then catching the gears. To relieve that we drilled a hole in the front bracket and shoved a plastic pacer through the hole and into the plastic thing on the front of the window washer motor.

The denso motors are not strong enough to turn the arm over on their own. We thought about using counter weights, but didn't have any available. We ended up using bungy cords as counter weights. This way the motor has to work to lower the arm making lifting the arm a lot easier. We need to add the extending mechanism which we should only need to reach the top peg.

http://www.youtube.com/watch?v=v4__hDKGQuU
That is a video. We took the plastic cover off to work on the arm, and filmed it before putting the cover back on.

Hope this helps someone.

Edoga