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Author Topic: 6 axis robot arm thoughts.  (Read 3012 times)

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Offline comet

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6 axis robot arm thoughts.
« on: December 09, 2012, 06:04:50 AM »
Hi, im thinking of building a 6 axis robot arm.using nema 23 425oz steppers.
I am assuming mach3 will control it. Its for trimming vacuum formed plastic parts.
  What im thinking about is using the steppers on 1/2 step mode and bolting 100ppr encoders on the back of them,(giving 400 pulses per rev)
 I would like to do is then manipulate the arm by hand and record the pulses,which could then be somehow turned into machine commands, and replayed as a program.
Is this a goer or a non-starter? any thoughts?
    Tony

Offline ger21

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Re: 6 axis robot arm thoughts.
« Reply #1 on: December 09, 2012, 07:57:58 AM »
1) Mach3 can't do anything with the encoders. It's not a closed loop control.

2) If you plan on direct driving the arm, you probably won't have nearly enough torque. A 1 foot long arm could only support 2 lbs at the end of it with those motors.
Gerry

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Offline comet

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Re: 6 axis robot arm thoughts.
« Reply #2 on: December 09, 2012, 08:13:06 AM »
ger 21,
  no id probably go 4/1 belts all round,plus as i said mach to drive some other system interfaced with the encoders purely for recording the pulses.

Offline BR549

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Re: 6 axis robot arm thoughts.
« Reply #3 on: December 09, 2012, 12:10:07 PM »
First problem is Mach3 will only accept 4 encoders.

You could probably create an encoder reader board then interface it into Mach3 with a plugin and with a LOT of interface programming make it work. BUT you could only move one joint at a time jogging as MACH3 does not have joint kenimatics for world jogging. Mach3 was never designed with rotary joints in mind. It is just a simple CNC machine controller.

Why not just use LinuxCNC(EMC2) it does rotary arm joints for robots AND with kenimatics it can do world jogging in real time.

Just a thought, (;-)TP