Hi,
My name is Mike and I live in the U.K. This is my first experience of discussion forums so please be patient if I am not up to speed on the protocol.
I have followed a few threads on ‘cnczone’ and my interests and aspirations seem to match those expressed by Mr. Davis on his home page at www.homecnc.info.
I have 25 years experience using CNC machines and have recently completed the design and build of my own C.N.C controller. I would like to help unravel the mysteries of motion control for anyone struggling with similar projects, and hopefully develop some cost effective alternatives to some of the more expensive components required to assemble a complete machine.
Enough introduction. The main reason for my post and this tread is to ask a question about the choice between stepper or servo drives. My impression from reading several discussions is that steppers are the popular choice for people converting or building their own equipment. As steppers systems are not usually closed loop and do not report any positional error I do not feel that repeatability is guaranteed, especially with varying loads and speeds. A servo system is fundamentally an error-based system in which the controller waits for a positional error to occur and then applies output power proportionally until the correct position is achieved. An option for those wishing to convert from a stepper to a servo system is to use Gecko Servo Drive Cards.
How do these ‘Gecko Servo Drives’, which receive pulse and direction, input signals, report back to the controller that position is being maintained? If they don’t provided this basic error control facility can they be considered as true servo drives and what advantage is gained over stepper drives?
I look forward to receiving comments and advise from experienced ‘Gecko Drive’ users and also to hearing from anyone who is interested in servo drive controllers.
Regards
Mike