RE: [CAD_CAM_EDM_DRO] Re: breakout boards plus - hard choice

Mark Vaughan <mark@...> wrote: Hi Ron




Quote "It would be really nice though if we had simple controls for people to
feedback encoder signal so an allowable error could be mixed with the
federate to control accuracy, you'd then have control over the precision
before you start the job. "
//It's not impossible to do a true closed loop with Mach, it's been debated several times. Now with the advent of the DLL support, it's quite do-able from what I understand.
As Art F said, it's not a 100% guarantee for positional control. No system has that.
The concensus on some of the drawbacks, first and foremost was safety, If the user energizes the control and has a large discrepancy at boot for some reason the machine will take off at full speed to get to commanded position. We did that with the macropump, didn't take long to decide that was unacceptable. I'm sure some changes to the script could have been made i.e. If a compare is too great ignore and alert.
A digital system is more of an exact method of motion command. A system ran within it's capabilities is very reliable and trouble free. There are probably hundreds of thousands of machines that run in an open loop config. They rarely lose position. The board I sell is for folks who want to know when it happens. If a machine is continually losing position, my board won't fix it, it's going to just keep stopping the machine every time it happens. It's like hanging a bell on something thats broken. It's just going to keep ringing.
The main point is that a properly setup and operated digital system will give very good results ran in an open loop. If it's continually losing position, something is wrong with it. No amount of software or hardware add ons is going to fix it. You can make allowances for the problems, but thats really not a fix.

////Ron




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