You care where the loop are because if they are in your PC you need a special PC with a special OS. But look at how most 3D printers work. They are just like 4 axis milling machines, typically using 4 stepper motors and no one needs a special PC or OS to make prints. In all cases the designers have pushed all the real-time function out to a $2 chip.
Back when LinuxCNC was first designed, decades ago there were no $2 chips that could work. But today the $2 chip is more powerful than the entire PC was back in the day. Doing the work on the PC under Linux was a cost cutting measure but today it dramatically raises the cost because of the difficulty of interfacing a PC to a milling machine. And the need for a special PC and OS has dramatically reduced the widespread use of LinuxCNC. Linux is popular in the world if it is hidden. Look at Android phones. Everyone uses them but no one needs to learn how to recompile a kernel on their phone. They "just work". Linux has become the #1 OS but only because it is hidden from users. Another example of real-time motion control software "done right" is Cleanflight or BetaFlight (both are nearly the same) This software controls the motor in a drone. The control loops run at 2 to 8 KHz and the software can be configured to run on all kinds of different hardware then downloaded to the flash ROM on a chip. What is impressive is that this configuration process is way-easy even for those who know nothing about computers and software. It is entirely done inside a graphical web browser. Users can set which serial ports do what functions and select protocols anyhow the videos setup. All using Chrome. Cleanflight is a model of how this can be done. It is all open sourced. That said, when some thing works few people are motivated to replace it. On Tue, Feb 11, 2020 at 5:17 AM Les Newell <les.new...@fastmail.co.uk> wrote: > > What I really > > meant was that with a printer, all the critical timing happens in the > > printer. There are no servo-loops on the PC and you don't need a > real-time > > OS to print to paper. > > Who cares where the servo loops or trajectory planning are? When the end > user presses a button to move the machine they don't care how it is > implemented. They only care that it works. Running a machine takes CPU > cycles. You can either use the CPU in your PC or an external one. What > difference does it make? > > Think of your printer example. Do you know or care how much processing > is done in the PC? For example the driver may convert your print page to > PostScript and send that to the printer. The printer then renders that > PostScript to an image of the page. Alternatively the driver may render > the print to a bitmap image of the page and send that to the printer. > The only real difference is in where the processing is done. To the end > user the experience is exactly the same. > > Les > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
