If " 'nix" were suddenly removed from the world the internet and a whole
bunch of other thing would disappear.
Just to rock the boat: mesa (PCW) has a very nice motion controller for
an FPGA. 50 us cycle time, etc. "ALL" someone has to do is wrap interp
and all the other non-motion stuff around it. Of course it is single
source, etc.
Dave
On 2/11/20 12:05 PM, Chris Albertson wrote:
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
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
