Controls Upgrading Idea

My control is an Anilam Crusader II but this could work on other Servo control systems.
A few years back I saw a Microcontroller chip on the internet that allowed
you to use step and direction with a servo. It worked by mixing the encoder feedback with step and direction. The chip would go between the encoder and the motor, a step command would make the controller think that the encoder incremented when it didn't. The controller would then correct for this and step the motor back to the commanded position. Basically, the controller would be trying to hold the servo motors still and the step and direction inputs would be electronically moving the encoder signal.
Anyway, my thought is to buy the connectors and cables to intercept the encoder signal. Have a PC with running software with step and direction outputs to control my mill while my Anilam Crusader II is trying to hold the axis's still. Since my Controller still works, this would be a much cheaper path to go than using a servo motion control board in the PC. I visited the website that used to sell the PIC microcontroller that was programmed for this type of application, it is no longer listed. I could program these chips myself for this application.
Anyone else interested in tinkering with this kind of stuff? (Upgrading older controls to PC Control)
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RogerN wrote:

Yeesh, that is really going around the long way. What happens when the Anilam finally croaks? Why not replace all the obsolete hardware with new stuff that you can replace or repair if you have trouble with it? Gecko makes a servo drive smaller than a pack of cards that does it all. I also make a servo drive and controller that replaces it all. See http://pico-systems.com/univpwm.html for more info. If you have analog-input servo amps that are in good condition, I have another product that will control them. I have been running my Bridgeport on a PC control for 7 years, now, and am glad I dumped the old hardware.
Jon
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The Anilam still works but needs a keypad ($600), I can load programs from my laptop and run them but direct program entry is limited(1 column of keys are out). If I'm going to spend that much, I would prefer to spend it on upgrading to a PC based control. I don't think the Gecko drives will do exactly what I need. My servo loop is closed twice, once in velocity mode and also for table position using the linear encoders. I can have backlash in my system and it is still stable. If you were to remove the motor encoder feedback from the Gecko or Pico-Systems, and replace it with linear encoder feedback from the table, would it be stable if there were a few thousandths backlash?
I'm slowly trying to work on an EMC system. I thought perhaps I could get it working with step and direction for now and upgrade to a servo control board later.
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