Elm Dc Servo Controller???

[smartgsm]

i found in google this page:

http://elm-chan.org/works/smc/report_e.html


In my first view is very interesting.
Specially on page is all: shecmatic and SOURCE code.

Does anybody try this project?

Br
Greg

[patndel]

Originally Posted by smartgsm i found in google this page: http://elm-chan.org/works/smc/report_e.html In my first view is very interesting. Specially on page is all: shecmatic and SOURCE code. Does anybody try this project? Br Greg

Hi Greg,

I've seen this, and planning to go ahead and build atleast one for the learning value. I'm at a bit of a disadvantage at the moment, not knowing assembler or C for the AVR but more than keen to learn.

I plan sticking with the AT90S2313 AVR, which I already have (I purchased a dev board from www.futurlec.com). I'm at the "Hello World" stage, managing to blink an LED.

As for the drive section, I'm looking at using a single IRF540 per leg of the H bridge generally as per the OSMC bridge, and incorporating the same protection, and driven by a HIP4081 FET driver.

I'm by know means an electronics whiz, I can follow a schematic, and read specs, and solder. Designing from scratch really is beyond me.

I understand that the ELM SMC3 is some what limited and has no current feedback, other than calculated which may not be ideal.

My interest in this is to eventually build 3 servo drivers for a converted X3 milling machine. For the moment, it will be run with stepper motors and a xylotex microstep drive.

If anyone else is interested, or made some advances, I would love to hear about it.

Pat

[mcm_xyz]

Hello.

I have made 3 boards of ELM Controller and put them on a giant machine... And they work just fine. I have compiled the software using AVRStudio and made almost no modifications to the software.
I have made some modifications to the board but only on the High power driver part. (The H Bridge)
The whole thing works flowless. It's a very cheap thing to try, easy to build and works perfect with TurboCNC.

As a note I must add that you will have to tune up the parameters of the servo with respect to the motors driven and the load involved...

My best to CHAN!

[patndel]

Hi mcm,

That's great to hear that you got the boards up and running. I think the ELM controller design is by far the simplest and cheapest open source alternative for those who would like to move up to servo control for their CNC machines.

What capacity does your H bridge have? Did you etch your own boards, or were they commercially etched?

I have the H bridge portion of the board drawn up, but everything has been put on hold until I can get enough free time to finally complete the mechanical conversion of my X3 mill. I have the X and Y axis complete, just need to finish off the Z axis (install the ball screw, nut, and thrust bearings)

Have you got any pics of your completed boards?

Sorry for the ramble of questions, but I was actually going to order 3 gecko drives, but your post has inspired me to re-think it.

Pat

[mcm_xyz]

Hello

Sorry but I do not have any pictures to show. I'll try to make some this weekend and post them.
My H bridges are also home made. (I'll have to tell you that my Servo Motors are home made too ... Extremly low budget... But they also work pretty great...
The H Bridges have to handle 20Amps on 12Volts. Not too much but not little also... At least when the engines are on heavy load the current can grow a lot...
Unfortunatelly I can not found the link now but I'll post it as soon as I reach home.

Anyway... It's amazing what you can do with a broken mouse a 10$ normal DC engine and 10$ of electronics... I can not really understand why servo engines are so expensive...

Best regards

[mcm_xyz]

PS...
The pcbs are made using test pcbs... The ones with a lot of holes... Not the best solution but I was too lasy to design some... I am now working on some pcb's design and I'll be happy to post them when ready...

Mike

[rippersoft]

MCM_XYZ,

I'd be very interested to see what you did for making your own servos with feedback. The mouse idea is very interesting. I would guess that it has all of the position circuitry you need. How did you hook it up mechanically?

RipperSoftware

[mcm_xyz]

I'll post some pictures of the motors too... It's really simple... You will have to make a hole in the back shaft of the motor... Place the mouse wheel in that hole... You will have to make the hole as straight and centered as possible... This could be pretty tricky... Afer that find a way to place the pototransistor and photodiode near the mose wheel in the same position as they stayed in the mouse... One more resistor is needed to limit the voltage on the phototransistor and the quadrature encoder is ready... you might need to boost the output signal width a schmidtt trigger...

I'll show you later...

[sdantonio]

Originally Posted by mcm_xyz PS... The pcbs are made using test pcbs... The ones with a lot of holes... Not the best solution but I was too lasy to design some... I am now working on some pcb's design and I'll be happy to post them when ready... Mike

Hi Mike,

Thank you in advance. Being totally an electronic bafoon (though the girlfriend seems to think I know what I'm doing electronically... how easily their fooled) PCB's would help greatly. I was going to ask if anyone would take the time to make some board designes and post them.

Steven

[mcm_xyz]

Here are some pictures as promised...
2 pictures of the boards and 3 of the motors.
Sorry for the quality but I do not have a camera.

[sdantonio]

Now I hope this isn't to much of a dumb question, but having never worked with servo's before, can I keep using the same software?

In my case Rhino3D as my CAD
RhinoCAM as my program to generate gcode
Mach3 as my gcode interpreter and step-pulse generator.

Steven

[mcm_xyz]

The first two will work for sure...
I have never tried Mach3 but if it is step / dir based and outputs on LPT it will work too.

Mike