How would you build this?

[DIYedInTheWool]

Hi. This is my first post. I've been reading this forum for a while now and have had a lot of fun learning about DIY construction of CNC platforms.

My question is, what kind of motor drivers and software (or programming language, etc.) would you use if you were designing a really complex CNC robot. For example, with multiple gantries to keep track of, maybe an arm to pick things up, probably several relays, probably tens of motors total?

In other words, how would you build this:

YouTube- Automated Lab Robot in Action

I'm in the planning phase of my first project--just a little CNC dremel setup to get my feet wet and, I'm sure, learn from mistakes i'll make in the mechanical construction. I think I have it more or less figured out how get up and running with Mach 3 and the right driver boards, etc. But, before I buy anything. I wanted to see what you guys had to say about scalability. I'd like to interface with the steppers in my "toy" project in a way that can be scaled up to more complex robotics, even if it's more work.

I have quite a bit of programming experience, but have not done much in the way of driver development or low level hardware interfacing. I have some electronics experience. Any comment or insight would be much appreciated.

[WayneHill]

Welcome to the Zone!

First off, the video is a great example of what many of us would like to achieve. It is an advanced Phd level of robtics.

Learning is what it is all about here.

Starting with an easy small project is a great way to learn.

There are lots of folks here willing to help you on your journey.

Wayne
'-------------------
If I learned from my mistakes, Then I must be the smartest person in the world.

[cyclestart]

A couple of years ago an interesting system was being assembled in my workplace. The raw materials were a roll of paper and a stack of covers. From these it manufactured and boxed books, completely automated. The speed was amazing. The interesting part was it was a coordinated system but came from 3 different manufacturers. The magic of PLCs ? Where was your question 2 years ago ?

imho Mach3 is a waste of time for for where you're heading. Linuxcnc ? Probably not the answer either but at least it's more flexible and open source.

A related question came up on another forum
http://www.cnczone.com/vb...mation-206575/

[cyclestart]

Thinking of the book machine, the systems components didn't need to be aware of each other. It was done with sensors.

[DIYedInTheWool]

Thanks WayneHill, I've already learned a lot here.

I thought I would add that I work with these lab robots, they cost as much as a house, and that you interface with them through proprietary software. Most fundamentally, though, they are the same as automated machine tools in that they just require well coordinated control of a bunch of steppers or servos, and x,y,z linear motion. I think I might be able to DIY one.

That's not my only interest in being here. I'm also looking forward to eventually building a nice CNC router for home.

But would you run that many motors in complex robotic operations by generating g code? I read in the Mach 3 docs that it's limited to 2 parallel ports. I don't fully understand what practical limits that puts on the number of motors you can control. It seems like I would want to write my own software that sends commands directly to the hardware. Would I have to learn to write drivers? Should I involve Arduinos or some other microcontroller?

I'm looking into LinuxCNC and that other thread is actually really helpful.

[WayneHill]

Check out Automation Direct for some ideas on PLC.

http://www.automationdirect.com

[DeadTom]

Originally Posted by DIYedInTheWool I read in the Mach 3 docs that it's limited to 2 parallel ports. I don't fully understand what practical limits that puts on the number of motors you can control.

DIYITW,
Mach 3 will control 6 axis per port so with 2 ports theorectically you will have 12 DOF (Degrees Of Freedom). I cannot see the video at work so I do not know how many DOFs the robot has.
On average the small humanoid robots have 18 DOFs, some more some less. Check out www.botmag.com for more information they have alot of links different controller manufacturers and software to control the robots.
DT

[ger21]

Originally Posted by DeadTom DIYITW, Mach 3 will control 6 axis per port so with 2 ports theorectically you will have 12 DOF (Degrees Of Freedom).

No, Mach3 can control 6 axis total + 1 step/dir spindle.

[DeadTom]

Thanks for clarifying that Gerry

[RomanLini]

If you're a good programmer you have the hard part licked.

Just build all the mechaincal assemblies as separate units and then connect everything up to a PC and just write the software to run it all in real time. That's pretty much how I work my CNC and automation projects.

And no you probably wouldn't bother with g-code when you can write your own data standard quickly and easily. G-code is extremely clunky for the type of automation you are talking about.

[DIYedInTheWool]

Originally Posted by RomanLini Just build all the mechaincal assemblies as separate units and then connect everything up to a PC and just write the software to run it all in real time. That's pretty much how I work my CNC and automation projects.

It sounds like you're a guy I need to talk to then. I'd like to hear more about your software and how you connect to your PC. For example I found this:

http://electronics-diy.com/electroni...per_motors.php

Which ICs do you use? And what programming language/libraries/commands do you use to send the signals to the parallel port?

[PaulRowntree]

Mach3 can handle 6 axes, EMC2 up to 8 I believe.

This type of automation is a bit different from CNC's since it looks to require more coordination and feedback, whereas most CNC systems are dominated by GOTO and MOVETO type instructions. Is this correct?
Cheers!