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Homosapien
01-31-2010, 09:51 PM
I am currently studying Robotics and Iíve been lurking around reading up on Robotics. I am working on an industrial Robotic Arm using 7DOF and I have been out of my wits trying to get some help on this. Locally, itís been hard for me to get some help and somehow, I thought I would check out if there were any websites/forums that might be able to help me out so here I am wondering if anyone of you would be kind enough to provide with me some designs in terms of mechanical components?

The motion that I am using is almost the same as a human arm and can hold up 3 kg of things. I want to use electrical actuators and gears, preferably at a low cost and light weight.

As I stated above, I need help on the mechanical design (mechanism) movement of the arm. I would really appreciate it if anyone can help me on this. I seriously have tried getting help elsewhere and Robotics isnít something that is big here Ė not yet, anyway! So here I am Ė trying on a forum!

Many thanks in advance!

jes1510
01-31-2010, 10:15 PM
The problem is the weight that you want to lift. You specify 3kg and want to use cheap actuators. That probably isn't going to happen. Can you give us more information such as a mechanical drawing?

Homosapien
02-01-2010, 12:35 AM
The problem is the weight that you want to lift. You specify 3kg and want to use cheap actuators. That probably isn't going to happen. Can you give us more information such as a mechanical drawing?

Actually I was looking for someone that might be able to help me out with the drawings? A website with basic drawing, perhaps?

badcommandorfilename
02-01-2010, 04:24 AM
Do you need help doing a technical drawing of your arm? Here is a quick guide to 3rd angle projection (http://www.technologystudent.com/designpro/ortho2.htm)(although some places prefer 1st angle).

Or do you need help with the design and specifications for the arm? This is a bit more complex, but if you can distil it down to a few basic questions I'm sure we can help.

First of all, you said you wanted to make a 7DOF arm, and that you want it to be similar to a human arm. Does this mean wrist, elbow and shoulder (plus rotation on those joints)? How many actuators do you actually need? What is the purpose of the arm?

MikeG
02-01-2010, 06:26 AM
Homosapien,

6DOF is the minimum needed to work in 3D space.
When you say like a human arm... like a prosthesis?
Industrial, cheap, and 3kg do not go together.
How long is this arm?
What is the accuracy and margin of error requirement?
How much are you willing to spend on this project?
What is your target controller or control system?

Adrenalynn
02-01-2010, 11:58 AM
Homosapien,

6DOF is the minimum needed to work in 3D space.
When you say like a human arm... like a prosthesis?
Industrial, cheap, and 3kg do not go together.
How long is this arm?
What is the accuracy and margin of error requirement?
How much are you willing to spend on this project?
What is your target controller or control system?

And our names go on the doctorate, right? ;)

MikeG
02-01-2010, 05:01 PM
I thought that went without saying :veryhappy:

zoomkat
02-01-2010, 05:50 PM
I am currently studying Robotics and Iíve been lurking around reading up on Robotics. I am working on an industrial Robotic Arm using 7DOF and I have been out of my wits trying to get some help on this. Locally, itís been hard for me to get some help and somehow, I thought I would check out if there were any websites/forums that might be able to help me out so here I am wondering if anyone of you would be kind enough to provide with me some designs in terms of mechanical components?

The motion that I am using is almost the same as a human arm and can hold up 3 kg of things. I want to use electrical actuators and gears, preferably at a low cost and light weight.

As I stated above, I need help on the mechanical design (mechanism) movement of the arm. I would really appreciate it if anyone can help me on this. I seriously have tried getting help elsewhere and Robotics isnít something that is big here Ė not yet, anyway! So here I am Ė trying on a forum!

Many thanks in advance!

Just as a reality check, if the type of arm you describe were cheap and easy to make, they would already be everywhere. That being said, what you want to do probably can be done, but cheap/easy probably won't be part of the project. You need to give a detailed discription of what the arm is expected to do for any suggestions to be given. Google is your friend to find existing arms that have similar performance to what you want.

Homosapien
02-02-2010, 07:53 AM
Just as a reality check, if the type of arm you describe were cheap and easy to make, they would already be everywhere. That being said, what you want to do probably can be done, but cheap/easy probably won't be part of the project. You need to give a detailed discription of what the arm is expected to do for any suggestions to be given. Google is your friend to find existing arms that have similar performance to what you want.

Cheap as in for me, some people might not see it as cheap, or rather whatever is cheap is expensive for others. Who knows. Google isn't that friendly lately. Thanks.

Homosapien
02-02-2010, 07:55 AM
Do you need help doing a technical drawing of your arm? Here is a quick guide to 3rd angle projection (http://www.technologystudent.com/designpro/ortho2.htm)(although some places prefer 1st angle).

Or do you need help with the design and specifications for the arm? This is a bit more complex, but if you can distil it down to a few basic questions I'm sure we can help.

First of all, you said you wanted to make a 7DOF arm, and that you want it to be similar to a human arm. Does this mean wrist, elbow and shoulder (plus rotation on those joints)? How many actuators do you actually need? What is the purpose of the arm?

Thank you so much, badcommand for the link. I will give it a looksy soon. Yes, I need help with the design ... but at the moment, am stuck with something else so will get back to you on the details. Thank you again!


Homosapien,

6DOF is the minimum needed to work in 3D space.
When you say like a human arm... like a prosthesis?
Industrial, cheap, and 3kg do not go together.
How long is this arm?
What is the accuracy and margin of error requirement?
How much are you willing to spend on this project?
What is your target controller or control system?

Hi Mike G, yes something like that. As I stated above, I have something going on right now so won't be able to type more :( Will get back to you guys soon! Thank you so much for the offer to help!


And our names go on the doctorate, right? ;)

Lol :p Deffo!

Homosapien
02-02-2010, 10:39 AM
Okay, getting back to this. I'd like some help on the technical drawing of the arm. It is similar to the human arm - shoulder, elbow and wrist. The robot will, of course, be bigger than the arm which we will get into later on. Also, any help on the mechanism of the arm (body, gears) would be appreciated. For example : how to put the gears together in the body (am not sure of the shape of the body - yet). I tried to find some drawings but to no avail. Even anything close to what I want is not available. The material used would be aluminium. I plan to build this robotic arm as small as a human arm. As for the rotation, yes I will need help on that too. Actuators I am looking into to be used would be 6 - 7 actuators. The purpose of the arm is to hold a weight of 2kg - 3kg, if possible.

Grasper can be used as well and another purpose would be welding (among other things) but as for now, I'm concentrating on it to be able to hold the mentioned weights. I am hoping to start of with the designs first and get into the rest of it later on. In other words, I'm working on a prototype.

As for the shoulder, I'm looking into 3 DOF, 2 DOF for the elbow and grasper - maybe 2 DOF or even more? This prototype will be put in a university lab. As for the length of the arm, for the things I want for the arm - 22cm from shoulder down to the elbow and from elbow down to the wrist - 25cm. I know it would not be cheap but I'm pretty sure somehow, there is a way to work on that? Even if it could hold up up to 1/2kg, would be good enough. Any suggestions on this would be greatly appreciated.

Is this impossible? :(

JonHylands
02-02-2010, 10:49 AM
to give an example, an RX-64 servo (800 oz-in) can lift and hold a full can of soda with a 30cm arm, for at least 10-15 minutes.


http://www.youtube.com/watch?v=2nu9BYpMrwY

I don't show the whole test, but I ran it for something like 15 minutes without having the servo overheat.

A full can of soda weighs in at something like 450 grams, I believe.

The RX-64 servo in question costs $285.

You could probably build an arm like that using stepper-driven linear actuators, and it wouldn't even have to cost an arm and a leg (groan).

- Jon

Adrenalynn
02-02-2010, 11:28 AM
Cheap as in for me, some people might not see it as cheap, or rather whatever is cheap is expensive for others. Who knows. Google isn't that friendly lately. Thanks.

This is only 2KG, but it seems super cheap to me, so approaching free for you!

http://cgi.ebay.com/Mitsubishi-Movemaster-Industrial-Robot-Arm-RV-M2_W0QQitemZ170384403559QQcmdZViewItemQQptZBI_Robo tics?hash=item27abb3ac67

darkback2
02-02-2010, 12:02 PM
Am I currect in thinking that this is a torque problem? or is this an IK problem? As for the design of the arm, if you know the necessary reach of the arm, then can't you figure out the lengths of the arm segments? Lets start there...Then we can figure out the necessary torque...that will start everyone off in the right direction.

Here is the link to the dynamixel servos page. I'm not sure if this is at all helpful...
http://www.trossenrobotics.com/c/robotis-dynamixel-robot-servos.aspx

Depending on the length of each arm you may need to double up servos at the shoulders and such.

The dynamixel servos have specialized brackets that come with them which make setting things up really easy. You could start out with a small scale model using AX-12s, and then once you have a feel for it stepping up to the big boys won't be too hard.

A firm number for a budget will also make it easier for us to help you out.

Finally check out the tutorial on robotic arms...not sure if it is too basic for you.

Hope this helps.

DB