DIY Servo controller

[ejkoeze]

Servo controller developed in Germany.

Since I have seen a couple of very interesting threads here that I have read with great pleasure and from which I have learned a great deal I thought I’d pass trough some things I have learned elsewhere. On the cncecke.de (German CNC forum) there have been developments that should not be made available to just German reading enthousiasts.

Many of you will have seen the pages made by some Japanese guy that made a simple Servo controller complete with schematic for the driver board and source code for it’s Atmel processor. This project seemed to have a lot of potential and a couple of guys went to work on it. The result is a controller that is able to work with DC Motors with ~200 to 500 CPR encoders and with up to about 3000 RPM.
The controller board can be adapted to drive DC servo’s with power in excess is 1 kW!!!
It has a serial port which can be used to alter PID parameters, debug and finetune the controller. There is a dedicated (DOS) program that can be used for this, that has a little graph showing the position of the servo in realtime (for fine tuning and reducing overshoot). It is controlled with normal Step/Dir signals just like nearly every other Stepper driver. It has a current limiter.

Safety measure include the following.
Daisy chaining controllers to ensure shutdown of all controllers in case a single one has an error. Emergency stop can also be wired to this.
Current limiter
Adjustable position error shutdown (if for some reason the position error exceeds a preset value the controller is shut down.
If the controller hangs the output stage is shut down so no irretic behaviour can occur.

About the amount of power this thing can supply. Yesterday there was a post of a guy that had 1.6kW servo’s attached and while trying to determine the correct PID parameters it started to oscilate. Afterwards his son asked him why the house had vibrated to stangely…. Another has replaced his industrial Haidenhain controllers with these.

The project is not completely open source since the author of the software for the controller keeps the code to himself. However controllers can be bought from him at cost price and the entire project is called beerware. Repay him his costs (2 euro per controller (programmed) and postage and send him a beer or something else usefull (couple of milling bits, centre drills, or whatever) and he’s completely content.
I have built my first controller and I’m impressed.

This can take home cnc’ing to a whole new level. Imaging the amount of power and accuracy this will give your machine not to mention the increase in speed.
At about 40 Euro (~$50) (depending on where you get them) in parts this cannot be called expensive.

Erik Jan
Layout and schematic
Controller software (DOS) and manual (also in English)

Edit: Corrected link.

[jerber]

The first link gives "404 Not found".

[pcroxford]

I got the same eror message when looking for the schematic.
I am very interested though..I checked the rest of the gertrtonic site, but my german is non-existent, and didn't know what to look for.
Help!!

[DennisCNC]

ejkoeze,
Do you have any pics of the controller you built? or a short video of it runing a motor? Is the GBI file the code for the Atmel?

[H500]

I just built a atmega16 based servo. The PID code is actually quite simple to do. I don't have a real servomotor, so I just attached an incremental encoder to a cheap 90vdc motor.

However, it worked surprisingly well when tuned. The motion feels quite stiff, almost like a stepper motor. Unfortunately, the mosfets fried after a day, so I'm troubleshooting it now.

[ejkoeze]

Movie of a small Alu portal mill running servo's controlled by the UHU Servo controller

http://www.pyromantiker.de/servo/MVI_1052.AVI

Photo's of the latest version







Erik Jan

[H500]

Looks good, Erik.

[DennisCNC]

Thats HOT!!!

[ejkoeze]

Call that hot? Look at this

This is when a servo blew up.



For those that cannot read the dials
200VDC and 12,5A (2500W).

Servo blew up since it wasn't made for this amount of power but I have seen guys running a Bridgeport with 1KW servo's on it. This only requires different parts (IGBT) and other diodes in the output stage.

Erik Jan

[Chris D]

WOw, this is fantastic. I checked out the website for this guy, however, I can't figure out how to order the chips (or programming) or whatever it is in order to make these. Did you just send him an email or something to get the chips?

Chris

[jimbo]

Is there a parts list for the board? I did not see one.

[ejkoeze]

You can order the processors at servo@pyromantiker.de
Be prepared to pay first (E2,- per processor + shipping + beer fee)

Partslist at http://people.freenet.de/Mode1/UHU_P...uecklisten.xls

Sorry everything is in German but hey.... would you make something and write the documentation in anything other than English?

Erik Jan