Re: Firewire

["Bert Eding" <be-at-chello.nl>]

Hi List,

Yes I am back.
Thanks fro reintroducing me Ray.
I'll tell a little more about myself and my work,

My name is Bert Eding, I am 42 years old and I am in the motion-business
since I was 25.  I have done software most of the time.
I have worked with several OSes over the years,
Intel's MTOS kernel, Microware's OS-9, IBM's OS/2, pSOS+ of ISI
and now Microsoft. So unfortunatly I have never really worked with Linux,
nor with any other POSIX compliant OS.

For about 7 Years I have worked on CNC controls, maybe some of You know
the MAHO milling machines from Germany. They have a very good name.
The controls where manugactured by Philips, later Grundig and now
Heidenhain.
I still have good contacts there.

After that I worked with Philips IAS (Industrial Automation Systems)
which became NYQUIST, the company I currently work for.
We control practically anything that moves, from cookie machines to welding
robots.
Unfortunally we are not in the CNC market, which is my hobby.
I have retrofitted my own Mill with the usage of a Nyquist
motion controller. See www.nyquist.com

Nyquist is really Microsoft minded (I am open for any OS).
The real time part of our system, which mainly consist of
fine-interpolators and PID (extended with all kinds of filters)
runs on a Texas DSP. Communication from PC to Motion Control Unit is over
firewire.
We have different types of systems, however the system
that is sold mostly is a  4 axes system. The strong point of Nyquist is
that we are able to control many axes which run all sample synchronous.
This is ideal e.g. in production lines, like in the paper industries, where
many axes must run synchronously.

Ray talks about a sampletime resolution of 0.125 us, probably my fault,
it should be 0.125 ms or 8 Khz, still perfect for servo systems.
Inportand is that there is little delay between sampling of the servo
position
and controller output. Therefore the controller software has this loop
order:
1) Latch measuring system input
2) Calculate new controller output from new setpoint that is precaculated.
3) Perform the output.
4) Calculate new setpoint position for next cycle.
Most of You will probably expect 4) just after 1), this would reduce the
phase margin which can be avoided by this reordering.

About Firewire, it just works and is rapidly getting accepted in industrial
world.
The current firewire uses electrical lines and has a bandwith upto 400
mbit/s.
The next generation is already under development and works optically with
a bandwith of 1.6 Gbit/s.

I think that for our hobby, Firewire is a good choice.
The ISA bus is not existing anymore.
All new printers have a USB connection, so probably next generation PC's
will not have the parallel port anymore.
And many motherboards nowadays do have Firewire.

I am a software GUY, so I can help with code snippets for
the FireWire communication. I would like to see hardware for
us hobbyists that should not cost much more than $100 (material) per
servo-axis.
I would like to see a measuring system interface (S00/S90) with inverse
signals for
cable brake detection, a 12 bit dac and some digital I/O.
By the way a 12 bit DAC is more then sufficient if the output is
Current/Torque
instead of velocity. It also saves a TACHO and makes the servo amplifier
cheaper. I have tested both system in my mill, now I don't use the tacho's
anymore,
I get practically the same results wheter I use my amplifiers in velocity
mode or
torque mode.

It seems that my web page is out at the moment, I will create a new one so
everyone
can see my equipment. I'll inform the list when ready.
Thats all for now.

Regards,
Bert Eding
The Netherlands




----- Original Message -----
From: "Ray Henry" <rehenry-at-up.net>
To: "Multiple recipients of list" <emc-at-nist.gov>
Sent: Monday, January 13, 2003 4:02 PM
Subject: Firewire


>
>
> Hi
>
> I've been in conversation with Bert Eding about some graphical stuff that
> he is using with his EMC.  During that conversation he mentioned some
> things about firewire that I thought the hardware types would find
> fascinating.
>
> Just a bit of background to re-introduce Bert to the rest of the list.
> Bert is a delightful fellow and wonderful cook.  He lives in Eindhoven,
> the Netherlands.  He works for Nyquist, a specialized motion control
> company.  The first page of Nyquist's web presence (www.nyquist.nl) says,
>
> " Nyquist Industrial Control develops and sells Motion Control systems to
> OEM customers who create semiconductor production equipment, special
> robotics and factory automation equipment. Our systems allow these
> machines to make lightning fast movements that are accurate down to the
> nanometer."
>
> Bert's setup is not what a casual user might call a typical EMC.  He has
> fitted a desktop mill with servos and drives them using big dollar
> Nyquist servo drive boards.  Bert uses Firewire to communicate between
> his PC and his drive amps.  When I saw his mill do it's thing, he had
> modified the EMC to run under MS-NT.  He is now using MS-XP.
>
> This led me immediatly to two questions.
>
> 1 - Real-Time and XP?
> 2 - Firewire hardware?
>
> Being an "open source" person,  I'm not really interested in bringing a
> MS version of the EMC to the marketplace but there is lots to learn from
> someone who has worked with them.  It turns out that both questions are
> answered by the use of Nyquist equipment.
>
> > It is currently depending on the Nyquist motion controller.
> > As You know windows is not real-time, or You have to buy
> > the rather expensive VentureCom RTX.
>
> > But the system what I have is different, the PID software runs at
> > the other side of the cable, not in the PC. The PC sends cubic splines
> > to the system.
>
> I believe that the way that Bert gets around the latency of the MS-XP is
> by having the Nyquist system buffer the splines and do the hard real time
> servo loop off the PC in hardware.  This is very similar to the
> approaches that have been taken with USB by projects like the Gecko 2002.
> I believe that is is also very similar to the stuff that Steve Stallings
> showed at NAMES a couple years back.  Enough of that.
>
> I found Bert's comments about firewire to be really interesting.
> Detractors can say, "yea but this guy works for a company that uses
> firewire.  They know how to do it and have the investment already made!"
> Bert says;
>
> > Another problem, I have no hardware, I would like to have hardware
> > based on FireWire. As You know, Nyquist is using the firewire for
> > realtime motion control. It is perfectly realtime, the timer tick on
> > firewire can be set in multiple of 0.125 us, perfect for servo systems.
>
> Now that really got me to thinking.  Matt and several others have
> mentioned 1 ms as the native or best-you-can-expect speed of USB which
> makes for a fairly unreliable communication channel for the kinds of info
> that we need to pass.  This 0.125 us seems like it would really open up
> the connection and allow us to do some interesting things.
>
> > In the Nyquist system, you can connect upto 63 nodes to the firewire.
> > Each node has a DSP and controls 4 axes.  All nodes run up to nano
> > seconds synchrounous with ussage of the 0.125 us timer tick of the
> > firewire.
> <s>
> > Maybe this is also interresting:
> > 1) Firewire boards cost only $25 at the moment.
> > 2) If the PID loop of the software also performs the velocity
> >     loop, and sent torque outputs instead of velocity you can
> >     save a lot on hardware too.
> >     - a 12 bits DAC is more than enough to control torque.
> >     - the servo amplifier can be a lot cheaper,
> >       because the velocity loop is now in software.
>
> Bert has recently subscribed to the list again.  Where my post contains
> errors, he can correct them and fill in details for you.
>
> Ray
>
>
>