Author Topic: robotic arm (Read 5199 times)

junior000 · « **on:** August 01, 2008, 06:53:34 AM »

hi ppl,

i am planning on building a robotic arm with four degrees of freedom(four joints).

do you think its better to go with dc motors or servos?

and for the body i am thinking of using wood(instead of aluminium).so is it ok to go with wood?

airman00 · « **Reply #1 on:** August 01, 2008, 02:21:27 PM »

how big of an arm, what kind of payload, we need more details!

junior000 · « **Reply #2 on:** August 01, 2008, 10:02:34 PM »

the length b'n two joints is 15 cm -20 cm(link length)

the main objective of the gripper(of the arm) is to lift an 10x10x10 cm cube weighing 50gm

Trumpkin · « **Reply #3 on:** August 03, 2008, 08:12:00 PM »

I think you should use servos.

Centaur · « **Reply #4 on:** August 04, 2008, 08:52:20 PM »

servos are way easier, both making mechanical connections and programming, and you can find some monsters with tons of torque if you really need it.

If all else fails, you could use motors at the base and servos near the gripper where you'll need less torque.

sonictj · « **Reply #5 on:** August 15, 2008, 12:48:00 AM »

These are the pros and con I can think of at the moment. Steppers would also work but they are more difficult to interface.

servos:

pros

require no motor driver
require only one i/o pin
relatively inexpensive

cons

somewhat limited amount of rotation

DC motors

pros
powerful
inexpensive
fast

cons
require encoding for precision motion
require a motor driver

I would recommend servos.

Admin · « **Reply #6 on:** August 20, 2008, 05:46:39 PM »

Well, don't use the more expensive Hitec servos . . . they kept burning out on me on my ERP. Others reported similar problems. I'm moving to Futaba soon.

Magnus · « **Reply #7 on:** August 20, 2009, 07:45:17 PM »

Goto www.ServoCity.com. They have some really powerful servos with gearboxes. Kind of expensive though.

Razor Concepts · « **Reply #8 on:** August 20, 2009, 11:57:34 PM »

Don't buy servos from ServoCity, they charge crazy prices. Towerhobbies, Horizon hobby, ebay, etc.

sonictj · « **Reply #9 on:** August 21, 2009, 12:09:41 AM »

Quote

Don't buy servos from ServoCity, they charge crazy prices. Towerhobbies, Horizon hobby, ebay, etc.

If you don't buy from them at least check out their product summaries. They have more information about their products than most servo retailers. I don't think their prices are that out of whack. It depends on the particular item. It always pays to shop around before any purchase regardless.

Trumpkin · « **Reply #10 on:** August 21, 2009, 02:12:41 PM »

read the timestamp

Admin · « **Reply #11 on:** August 21, 2009, 02:24:21 PM »

servocity has decent prices. I still shop around though, as servo prices for all the retailers fluctuate a lot.

matt liao · « **Reply #12 on:** August 25, 2009, 12:03:25 AM »

I designed smart arm!

gaurav.p · « **Reply #13 on:** August 25, 2009, 07:04:57 AM »

servos would be better in this and i prefer tower hobbies or dealextreme(free shipping)
nice cad image

Joker94 · « **Reply #14 on:** August 25, 2009, 06:07:08 PM »

i Would go with servos for eas of use and you can get some relly high powered servos. If your are on a tight budget i would go with motors as they are inexpensive.

SmAsH · « **Reply #15 on:** August 26, 2009, 12:06:30 AM »

for an arm you will most likely want servos...
just because they have position feedback, gearbox etc...

Razor Concepts · « **Reply #16 on:** August 26, 2009, 12:11:01 AM »

Servos dont have position feedback, you don't actually know where the arm is. You just hope the servo is working correctly when you tell it to go to a position

airman00 · « **Reply #17 on:** August 26, 2009, 07:25:00 AM »

I've seen a wire being run to the servo's internal pot so you can get position feedback with a little modification.

wil.hamilton · « **Reply #18 on:** August 27, 2009, 05:23:14 PM »

you can get digital servos, which i'm fairly certain have position feedback, your run of the mill servo is not a "digital" servo

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Author Topic: robotic arm (Read 5199 times)

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