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 Post subject: Manipulator arm general
PostPosted: Nov 22nd, 2010, 9:18 am 
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Joined: Nov 22nd, 2010, 9:01 am
Posts: 4
Hello! I am an Engineer student from Norway who is building an ROV for my last main project. (Appologize in advance for my poor English)

Got a few questions for the wize and inlightened.

As I have read, pneumatic manipulator arm is the best sulution for ROV? I want a bit "grip" in the arm so maby this is the best sulution?

Have read that some arms is controlled by servos, and simple rod conection? maby simple is best?

What dou YOU think? :)


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PostPosted: Nov 22nd, 2010, 11:37 am 
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Joined: Nov 8th, 2010, 10:25 pm
Posts: 343
Location: Connecticut
I use a simple geared motor and block setup to move the gripper fingers on my manipulators but the gripping force isn't that great. If you need a lot of gripping force pneumatic might be the way to go.

The only thing you have to keep in mind is the Manipulator is only as good as the Rov it is attached too. If you try to pick up to large of an object it may throw the balance of your Rov off, or if you don't powerful thrusters you won't be able to move the object anyway.

-Steve


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PostPosted: Nov 22nd, 2010, 1:33 pm 
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Joined: Nov 22nd, 2010, 9:01 am
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Thanx Steve, that were my thaugts also, nice to get confirmation:) My rov will be a bit heavy with a counter ballance tank to get som extra lift when the waight on the arm get high. But i think i'll go with pneumatic. But if someone got a better idea im listening!


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PostPosted: Nov 24th, 2010, 12:59 am 
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Joined: Nov 13th, 2010, 3:40 am
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Location: Kauai, Hawaii
Hi SubSea ~ welcome to this forum. You should not worry. Your English is easily understandable.

I'd be very interested to learn more about pneumatic manipulators. Can you forward any links that explain and show it? Are there good sources for the equipment? Are there complete small scale systems available?

Thanks in advance. --Pilikia


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PostPosted: Mar 1st, 2011, 2:42 am 
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Joined: Feb 17th, 2011, 8:47 am
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can any one show how to build a arm. cause i'm cracking my head how to build one hear. how to seal it and make it aterproof. or is there any arm selling outside which is waterproof.


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PostPosted: Mar 26th, 2011, 7:09 pm 
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Joined: Feb 13th, 2011, 9:27 pm
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Location: Pennsylvania
Yes, I have wondered a lot about this subject. Is there anyone out there who has built an arm with a lot of joints, so that the ROV can settle down and then pick up the object, versus trying to grab the object with the manipulator by manuvering the ROV?

Thanks a lot for all you guys' help and support :)


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PostPosted: Mar 30th, 2011, 9:56 am 
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Joined: Nov 8th, 2010, 10:25 pm
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Location: Connecticut
I think the more joints you add the more complicated things are going to get. Another thing to remember is if you set the Rov down on the bottom (depending on conditions) you are more then likely to kick up slit or bottom debris which can obscure your camera view)

Here's a couple of basic examples of how to make a simple manipulator arm.

http://www.homebuiltrovs.com/stingermanipulator.html

http://www.homebuiltrovs.com/seafoxretr ... lator.html

I use a simple geared motor in a PVC housing and seal the shaft exit with a small motorcycle oil seal. There are some simple toy robotic arms out there that people have been known to convert for single function manipulators such as something along these lines...

arm1.jpg
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arm2.jpg
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Another thing to keep in mind is the manipulator is only as good as the Rov it's attached to. If your Rov is to small or under powered you won't be able to pick up to large of an object anyway.

Hope that gets you pointed in the right direction.

-Steve


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PostPosted: Jun 15th, 2011, 2:22 pm 
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Joined: May 31st, 2011, 2:55 am
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Another approach you can take to constructing manipulators is to use an already sealed motor (bilge pump) and use "wet" mechanical reductions to slow it down. You don't have to worry about sealing anything with this approach, but the manipulator can get pretty bulky.

Here are two examples that we've made. The one on the yellow ROV uses a lead screw directly attached to the motor shaft to run a linkage. The lead screw in this case is actually a long threaded rod. Given the small motor we used, this gripper didn't have a lot of clamping force and sometimes got stuck. It's not a very smooth mechanism, but it works.

The claw on the red ROV has an extra degree of freedom; it can rotate as well as grip. Two bilge pump motors drive it, each attached to a worm gear that turns one of the green gears. The small green gear acts as a winch and pulls the fishing line in, while the other bigger gear is used to rotate the claw. It has a surprising amount of gripping force... we measured it with a small scale to be approximately 40 newtons.

-Steven


Attachments:
File comment: Simple gripper on 'notBob'
Claw_notbob.jpg
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File comment: Gripper on 'Babs' with two degrees of freedom
Claw_Babs.jpg
[ Viewed 2918 times ]
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