Robotic arm
ratronic
Posts: 1,451
Just wanted to show a arm I made out of the Bioloid beginner kit from http://www.crustcrawler.com/.·I am using Robotbasic from http://www.robotbasic.org/.· This really isn't a completed project (as I have no gripper).·The code is mainly Mike Gebhard's and the interface to the propeller from the PC's USB joystick via rs232 was made real easy by Robotbasic. The AX-12+ are really neat servo's and all four of these are connected with a 3 wire interface. I know it doesn't do much now but I thought I would attach a Youtube video and the code I have so far.
http://www.youtube.com/watch?v=CILzXm80rrI
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D Rat
Dave Ratcliff N6YEE
http://www.youtube.com/watch?v=CILzXm80rrI
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D Rat
Dave Ratcliff N6YEE
Comments
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--Steve
Propalyzer: Propeller PC Logic Analyzer
http://forums.parallax.com/showthread.php?p=788230
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D Rat
Dave Ratcliff N6YEE
I have been wondering lately how hard it would be to make a prop controlled robotic arm.
I was thinking what if you used those really cheap cordless drills that are always on sale
for the motors and made most of the arm using wood. Once painted a dull gray color with
primer it would look the same as a metallic arm and should be very powerful because the
cordless drill motors are very strong.
You would need an h bridge for each motor and some kind of optical encoder thingie to tell
position and speed of the moving parts.
It could be inexpensive and still large and powerful
by an encoder. An encoder controlled system is quite a big challenge. The challenge is the accelarating and deccelarating the motors.
Of course in professional robots it is done exactly this way but with high complex motorcontrols with overlayed position and acceleration
controllers as PID controllers.
It will be easier to use steppermotors or servos. For Servos the basic control routines are already in the obex.
To make it strong with steppermotors you could use a gear build with two wheels and a special kind of chain. I don't know the english word for it
here is a picture
low-cost servos don't have much torque but I have an idea I find interesting:
to move around "heavy" loads the robotarm could have some kind of balancers
this means as soon as a load goes more to the right the balance-weight goes more to the left so the resulting torque in the axle is always minimized
so that a relative small servo can turn it. Next thing to solve is how can the torque be measured ?
some kind of a spring combined with a small switch or an encoder ? Or is this too complicated and just go for bigger RC-servos ?
best regards
Stefan
Post Edited (StefanL38) : 8/9/2009 8:14:13 AM GMT
tubular
This is VERY impressive.....I like the Arm a lot.....cool stuff.
It is also amazing that you did all this and you say that you are
not much of a coder.....
Samuel
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D Rat
Dave Ratcliff N6YEE
Neat video and project. The arm responds really quickly too! My dog would go nuts...
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Whit+
"We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
I thought that since you are so dexterous you might like to
implement one or both of these Simulated arms in this video
http://www.youtube.com/watch?v=AukHmkZqmys&feature=channel_page
I am attaching·below the programs that do the simulations.
As you can see from the video, all you need is to replace the routines that
drive the Graphics to drive a real arm instead....all the math for moving the arms
is already done.
I would love to see at least the 2D one working in REAL instead of just a simulation.
I think you are the MAN to do it.
There was an article about the 3D arm you see in the video in the May 2009 issue of Servo Magazine.
Regards
Samuel
Post Edited (SamMishal) : 8/10/2009 5:13:59 AM GMT
http://www.youtube.com/watch?v=-xU8IUJ8SD4
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D Rat
Dave Ratcliff N6YEE
Nice driving .....a few accidents with the PC.....
When I lived in Madrid, Paris, and London I never owned a car....it was soooo nice to walk everywhere and
take the Metro/Underground and read while sitting in the train....I miss those days....I was healthy then
and now I have to drive everywhere I am FAT..... and also full of fear and hate from listening to Rush and
Hannity et al on the Radio.
Regards
Samuel
·
That is very nice work, and clearly very responsive. I have never built such a device, so this is a question born out of ignorance. Is what looks to be overshoot is caused by the mechanical inertia of the arm elements or the properties of the joystick? If you force the arm to go through a mathematical sequence (no joystick) would it overshoot as well?
Nicely done!
Cheers!
Paul Rowntree
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D Rat
Dave Ratcliff N6YEE