New Machine Build- Trying to spec out a servo system for EMC2 & another application concurrently - hard!

[nick mulder]

Hello all,

I have two applications that I'd like to purchase motion control gear for - I'd like to try to get gear that can be used in both applications (there maybe a little adaptation involved in one or more of the cases):

First application:
A 4 axis mill/drill CNC conversion using EMC2 as the controller (the 'loop')

Second application:
A generic 4 axis machine in which the purchased drives can handle being fed simple feed step/dir pulses (from an arbitrary source) with the drives doing their own PID control internally (no more PC attached!)

Consequences I've discovered that will likely need addressing:
-I will likely need some sort of USB or parallel I/O card to free me up of on board parallel port restrictions in EMC2 (I'd prefer not PCI bus) - Mesa gear looks interesting here as it is EMC2 ready
-Once the above point is taken care of its looks like I can have high resolution (incremental) encoders - I'd like them for obvious reasons
-The motor drives would be good if they were able to be hijacked or switched to allow the encoders to go to EMC2 directly (or indirectly) for the CNC, the motors would then run 'dumb'. (If this is impossible within the spec I give then I can run EMC2 (or mach3 even) open loop with the drive running the loop.)
-Assuming the last factor can be addressed I need ALSO to be able to split the encoder stream for the second application, one stream to the drive for its internal PID loop again ('smart' mode), the other split to the arbitrary 'brain' for other purposes (non real time, non control).

Limiting factors:
-I'd prefer brushless servos for the motor, but standard servos are fine also
-COST - I'd like as high torque as I can get (NEMA34 likely?) but don't want to be spending more than around $600~$700 per axis - factor in eventual power supply cost into this also
-I live in single phase 230-240V/50Hz land - thats 10A per circuit ... 2400W max available per circuit

Notes:
I would emphasis the ability to function relatively unhindered or adapted under the second application as more pertinent than the EMC2 CNC application - that can run adapted/converted if need be...
The motors will probably be over spec for the CNC application, excess torque however will be used in the second application.

Does anyone have any suggestions of suppliers I could approach ?

I am in contact with Mesa, Pico systems so far ...

[mactec54]

nick mulder

These would work for you, They will plug & play straight to Mach3 control software, But could work with step/dir output from other software,The drives can be run with +/-10v as well,& soon Dmm will have USB breakout board, instead of the Parallel port

Motion Control Products - DMM Technology

[nick mulder]

Originally Posted by mactec54 These would work for you, They will plug & play straight to Mach3 control software, But could work with step/dir output from other software,The drives can be run with +/-10v as well,& soon Dmm will have USB breakout board, instead of the Parallel port Motion Control Products - DMM Technology

Hi, I was at this site a few days back - noted the absolute encoders however which wont work with EMC2... But there could be a solution there. I have contacted them now - thanks for reminding me of them

[mactec54]

nick mulder

The encoders have nothing to do with EMC2,or the control software,the encoders are taken care of in the drive,when using step/dir signals, the drive only needs to see the step/dir signals through the breakout board from your computer

Here is a video of the Dmm system running, he has many videos to look at, these drives have never been tuned in any way,
just used straight from Dmm

YouTube - cncvids 028.AVI

[nick mulder]

I understand they don't but in my spec I'm interested to see if they can ... Basically trying to make the most of EMC2, or I may as well run Mach3 (?)

There are products offered by Pico System that allow the Gecko 320x to get encoder info into EMC2, It might not run the loop, but the encoder info goes into it so you have a DRO of sorts and EMC2 is aware of the world so to speak...

I found this about the DMM stuff:

DMM drive will not be reviewed due to lack of interest together with some performance details noted in a close read of the specs, notably a very small fixed following error.

(06/01/2009 - Servo Drive Review and Comparison)

The following error is fixed at 128 counts - as I understand it with a perfect drive and PID tune there will be no issues. But then with high CPR encoders this could be problematic... Is the low following error parameter an issue or indeed an indication that it is a good drive ?

[mactec54]

nick mulder

The guy that wrote that about the DMM drives, has never had one, for testing,& made up this story about the following error,( Like a lot of the other information on other drives on his site is incorrect as well,) there is no problem with the 16384 count encoders, the 127 does not mean 127 counts, it is something like 8,192 encoder pulses or 90deg of motor shaft rotation.

The drives are great, & the price you can not beat not even in China, as machine builders there are using them,The drives
breakout board encoders etc are all designed & made in Canada

[nick mulder]

Made it up ?? Why would he do that ? I was linked that review page I think by a mach3 forum user as a good resource...

I guess, its the net after all ...

I'm assuming you own the system, or have used it ?

Can you explain the numbers 14bit absolute, ah hah, yes - ok, half that = 8192 - how does the 128 fit into it ? And where does this info come from ?

interested!

[mactec54]

nick mulder

You can see how the numbers are used in the tuning software, Look in the PDF manual for the drives under tuning & you will see how the numbers are used, & the number is 127 not 128

[Zig]

Nick... maaaatee...

I am doing precisely what You want to do.


Brushles servo receiving step direction signals.
Encoder handled by servo amp.
Cost per axis ( AUD )

Servo motor from Anaheim Automation ( USA) approximately 150AUD
Servo amp fron CNC Teknix ( Australia ) Approximately 150AUD
Encoder ( quadrature ) shaft or linear ..Your choice from Approx AUD 100 to AUD1400

Servo amp connects to the PC serial port to tune up the PID and feed forward coefficients. from there on all it takes is step and direction signals.

Enjoy

[jmelson]

Originally Posted by nick mulder I understand they don't but in my spec I'm interested to see if they can ... Basically trying to make the most of EMC2, or I may as well run Mach3 (?) There are products offered by Pico System that allow the Gecko 320x to get encoder info into EMC2, It might not run the loop, but the encoder info goes into it so you have a DRO of sorts and EMC2 is aware of the world so to speak...

Yes, using my Universal Stepper Controller and Gecko Interface boards, the control loop is closed
within EMC2. Besides the advantages of having configurable following error limits, you also are able to adjust some of the loop tuning parameters that you can't get to on the Gecko drives.
Also, the encoders keep feeding position info to EMC even when the drives are E-stopped, so you don't have to rehome every time you come out of E-stop.

The Stepper Controller board also allows much faster step pulse rates, so that higher encoder resolutions can be used. Since the Gecko drive can handle 250 KHz step pulse rates, why have the software step generation force you to reduce encoder resolution. (Higher resolution almost always translates into smoother motion.)

Jon