On 24 May 2004 03:11:20 -0700, jonsquire2000@hotmail.com (Jon S.)
wrote:
>Thanks for the link. They list a 5.5 ms latency in their datasheets...
>
>Stephen, any idea what kind of latency we should be looking for ? How
>'fast' is epee fencing ?
There are two timing issue in the rules. One is minimum touch time,
and the other is discrimination between "simultaneous" hits which
are more common than one would think. I don't have a copy of the
current rule book and I'm off on a trip tomorrow until the weekend.
You really do need a copy of the FIE rules and someone at your club
will have them. See also
www.fie.ch
www.britishfencing.com
According to my club chairman, Espada will be installing two electric
pistes this year. It seems that lighter portable pistes are becoming
available.
Stephen
--
Stephen Pelc, stephenXXX@INVALID.mpeltd.demon.co.uk
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
web: http://www.mpeltd.demon.co.uk - free VFX Forth downloads
Reply by Jon S.●May 24, 20042004-05-24
Thanks for the link. They list a 5.5 ms latency in their datasheets...
Stephen, any idea what kind of latency we should be looking for ? How
'fast' is epee fencing ?
Stijn
"Jon S." <jonsquire2000@hotmail.com> wrote in message
news:f0ae8fc3.0405190052.2436541@posting.google.com...
<snip>
> I started looking into simple 'car-key' tranceivers. At work i design
> products that use wireless technology (Aerocomm, Maxstream...) for
> serial communication. Altough very reliable, i think these devices
> aren't the way to go with 'ms' timing constraints.
On 19 May 2004 01:52:49 -0700, jonsquire2000@hotmail.com (Jon S.)
wrote:
>Im my club, all adult amateur fencers practice epee.I don't know if
>this is true in general.
At our club (Espada), Tuesday night is mostly epee, and Friday
has some serious foilists. Swash and Buckle and many other London
clubs are mostly foil.
>I still like the idea of designing a non-commercial but reliable one
>weapon(epee) system for recreational use. I don't know how important
>'tip to floor' and 'tip to tip' contact is.I haven't seen a conductive
>floor in amateur fencing.
It's certainly attractive by volume, but it does mean that you can
make NO changes to weapons. Tip to tip contact is rare. Tip to
floor contact is essential only with a conductive piste.
>Does such a 'stripped down' still make sense for an amateur fencer ?
Yes. Don't forget about minimum contact time. If you can figure
out how to deal with the target jackets for foil and sabre, you
will have a three weapon box and should then also be able to deal
with conductive pistes.
I'll happily test units for you.
Stephen
--
Stephen Pelc, stephenXXX@INVALID.mpeltd.demon.co.uk
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
web: http://www.mpeltd.demon.co.uk - free VFX Forth downloads
Reply by Jon S.●May 19, 20042004-05-19
Thanks to all for the constructive reply's.
I already had the impression that designing a reliable, three weapon
device that can be certified for competition will be a hard job
(altough not imposible)
Im my club, all adult amateur fencers practice epee.I don't know if
this is true in general.
(for the non-fencers: epee is considered as being closest to the
original duel, you can be touched everywhere on the body, and the one
who touches first is scoring)
I still like the idea of designing a non-commercial but reliable one
weapon(epee) system for recreational use. I don't know how important
'tip to floor' and 'tip to tip' contact is.I haven't seen a conductive
floor in amateur fencing.
If not, it leaves us with only one switch (normaly open) on each
side.This shouldn't be to dificult to make wireless, even considered
ms timing constraints.
Does such a 'stripped down' still make sense for an amateur fencer ?
And if so, any suggestion for technology to use ?
I started looking into simple 'car-key' tranceivers. At work i design
products that use wireless technology (Aerocomm, Maxstream...) for
serial communication. Altough very reliable, i think these devices
aren't the way to go with 'ms' timing constraints.
Stijn
Reply by Andrew Jackson●May 19, 20042004-05-19
> I'm glad this topic has raised some interest - I'd really like
> to get rid of the spring-loaded spools: I had to retire from
> a competition after one failed and I spent the next morning
> in the hospital emergency department.
I agree entirely! I think that one can have great sympathy with a fish after
going fencing (but then the fishing reel isn't likely to explode into the
fish). Sorry to hear that you did get caught.
Andrew
Reply by Stephen Pelc●May 18, 20042004-05-18
On Tue, 18 May 2004 14:25:57 -0400, rickman <spamgoeshere4@yahoo.com>
wrote:
>I am not sure I understand the wired system. The OP said it uses a
>"switch" in the tip. I had the impression that the tip was one end of
>the switch and a vest worn by the opponent was the other end. When tip
>touched the vest, the circuit was completed. Is this not right? Is
>there a switch in the tip which does not care what it touches?
Take the case for foil. The target area is the "trunk" of a human
and is covered by a conductive vest. Note that fencing is an
"explosive" sport, and humans sweat - I certainly drip and have
to wear a headband. The outside of the vest can be damp. In order
to prevent very light touches causing a score, the switch in the
tip of the foil must open (normally closed). The weight required
to open this switch is tested in competition. One side of this
switch is the foil itself, which is normally ground. Sabre is
similar, and in epee the target is the whole body, there is no
conductive vest and the switch is normally open.
In competition fencing the piste (floor) is copper mesh, usually
a paper-making by-product. The tip of the weapon can touch
the other tip
ground (piste/weapon)
target area (vest)
non-target area
The switch can be closed or open. The problem area with a wireless
system is in discriminating these regions reliably, while
maintaining good timing discrimination. Fencing is fast
enough that discrimination and decision must occur within
a few milliseconds, and bias from one side to another must
not occur - fencers *will* notice it.
I'm glad this topic has raised some interest - I'd really like
to get rid of the spring-loaded spools: I had to retire from
a competition after one failed and I spent the next morning
in the hospital emergency department.
Stephen
--
Stephen Pelc, stephenXXX@INVALID.mpeltd.demon.co.uk
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
web: http://www.mpeltd.demon.co.uk - free VFX Forth downloads
Reply by Andrew Jackson●May 18, 20042004-05-18
> I am not sure I understand the wired system. The OP said it uses a
> "switch" in the tip. I had the impression that the tip was one end of
> the switch and a vest worn by the opponent was the other end. When tip
> touched the vest, the circuit was completed. Is this not right? Is
> there a switch in the tip which does not care what it touches?
It depends which weapon you are using. For a foil you do have a conductive
vest but if you use an epee then the tip *is* a switch. The three wires
allow you to distinguish (1) a hit, (2) a coquile** hit and (3) a floor hit
(if you have a mat). ** - guard.
Andrew
Reply by CBFalconer●May 18, 20042004-05-18
rickman wrote:
>
... snip ...
>
> I am not sure I understand the wired system. The OP said it uses
> a "switch" in the tip. I had the impression that the tip was one
> end of the switch and a vest worn by the opponent was the other
> end. When tip touched the vest, the circuit was completed. Is
> this not right? Is there a switch in the tip which does not care
> what it touches?
I believe you must be right about the tip being a contact. IIRC a
'hit' is only valid on certain areas, and that can be controlled
by the conductivity of clothing areas. All this is very simply
controlled by wires and current flow. Once you eliminate the
wires the complications are going to abound. KISS.
--
Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home.att.net> USE worldnet address!
Reply by rickman●May 18, 20042004-05-18
Stephen Pelc wrote:
>
> On 14 May 2004 12:03:41 -0700, jonsquire2000@hotmail.com (Jon S.)
> wrote:
>
> >My first reaction was offcoarse: why don't we do this wireless ? Ofter
> >some searches a learned that such systems exist, but that they are not
> >very reliable and are very expensive.
> At senior and international level these systems also have to be
> shown to be secure, and to work on multiple parallel pistes in the
> same room.
>
> Other problems you have to contend with are things like tip to
> tip contact, and tip to piste contact. Note also that in epee
> scoring you also have to cope with the simultaneous hit
> discrimination, which is of the order of 40ms as far as I
> remember, but I don't have the current rule book.
>
> Try doing a wired system first, and then you'll begin to see
> the problems. I built an all CMOS scoring box many years ago,
> and contact wetting was a real problem that the then current
> relay systems just did not suffer from.
>
> Although wiring and spools are currently heavy and unreliable,
> they have the advantage that the cost is usually born by the clubs,
> rather than by individual fencers, and small radio units will
> inevitably "walk".
>
> Don't let me put you off, but the *system* problems are non
> trivial. We'll all cheer when you find a repeatable solution
> at a reasonable price.
I am not sure I understand the wired system. The OP said it uses a
"switch" in the tip. I had the impression that the tip was one end of
the switch and a vest worn by the opponent was the other end. When tip
touched the vest, the circuit was completed. Is this not right? Is
there a switch in the tip which does not care what it touches?
I believe I could develop a wireless system that would meet all the
reqirements you have stated. I have seen systems for detecting touch by
using conducted low end RF (>100 kHz). Very little energy is needed and
the frequency can be tuned so that you and your opponent are
distinguishable. The problem of "simultaneous" hits can be resolved by
shutting down your touch oscillator when a touch is detected. Then your
opponent can not detect a touch until you remove your tip. A circuit
should be able to resolve to much better than 40 ms. A very simple
wireless interface (or as complex as security needs) can be used to
indicate a touch to the scoring equipment.
--
Rick "rickman" Collins
rick.collins@XYarius.com
Ignore the reply address. To email me use the above address with the XY
removed.
Arius - A Signal Processing Solutions Company
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