I've been putting together a few ideas with respect to creating a low cost wireless fencing solution. As most of us are aware, the constant setting-up & tearing-down of wired systems is a real deterent for clubs that don't have dedicated gyms. I noticed a few threads in this forum on this subject by not much detail on what is currently available, how the systems may work, or how to design one.
The one system I had an opportunity to disect is the HitMate http://www.hitmate.co.uk/index.shtml Currently, the design only supports Epee; claiming the Foil version is still under development. Personally, I think the HitMate solution is way too expensive for only 1 weapon support ($400), and is not all that reliable based on some trials undertaken by our club. The closest thing I can compare it to is a wireless doorbell system which can be purchased at your local hardware store for less than $50. The marketing folks did right however by picking nice looking boxes.
For those familiar with the technical challenges, coming up with a wireless solution is a relatively simple task for Epee. It is much more complicated for foil & sabre due to the fact that there is no close circuit or signal return path common to both sides. Previous designs relied on single-ended signal detection techniques; i.e. tone detection, etc, which was often too slow or unreliable.
If anyone has any ideas on what would be the proper approach to take on this I'm all ears. I'll be putting together of list of my own which I will post in the next few days.
We're all waiting for the confirmation of the Higgs-Boson particle.
That should make things pretty easy.
That is, if it doesn't accidentally eat the world up with Rogue Strangelets...
Haha, seriously though; here is the only (novel) idea i've had on this topic:
Somehow make the Lame as if it were a touch sensitive device.
Each fencer wears a transmitter that can register both point depression and lame touch.
Transmitters would send signals to a central box. Signals would be read as:
- One weapon register = off target.
- Weapon A + Lame B = on target.
- Lame register only = Rogue Strangelets eat the world.
Of course this doesn't ground the strip - that'd be left up to the ref.
Best of luck.
Last edited by Palisadeur; 02-24-2010 at 02:06 PM.
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I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.
~ Abraham Maslow
Let's start with the requirements: (in order of priority)
1. Low cost (<$TBD),
2. Must be reliable, spoof proof & resilient to jamming,
3. Must be able to coexist with other systems in close proximity,
4. Supports FIE timing requirements for all 3 weapon types,
5. Must use existing weapon/vest/mask configurations/designs without any modifications,
6. Must support anti-fraud,
7. Must be able support metal pistes,
8. Size must be small so not to obstruct.
Let's start with the requirements: (in order of priority)
1. Low cost (<$TBD),
2. Must be reliable, spoof proof & resilient to jamming,
3. Must be able to coexist with other systems in close proximity,
4. Supports FIE timing requirements for all 3 weapon types,
5. Must use existing weapon/vest/mask configurations/designs without any modifications,
6. Must support anti-fraud,
7. Must be able support metal pistes,
8. Size must be small so not to obstruct.
Any more?
Durability is a big issue, and I think there's lot of overlap between 2 and 6 on your list.
I also think anti-tampering is the least important thing. This isn't going to be used at important competitions. Once you get a working and popular model, you can start worrying about tampering with it.
Durability is a big issue, and I think there's lot of overlap between 2 and 6 on your list.
I also think anti-tampering is the least important thing. This isn't going to be used at important competitions. Once you get a working and popular model, you can start worrying about tampering with it.
OK. Here is an updated list based on your recommendations:
1. Low cost (<$300?),
2. Must be reliable & durable,
3. Must be able to coexist with other systems in close proximity,
4. Supports FIE timing requirements for all 3 weapon types,
5. Must use existing weapon/vest/mask configurations/designs without any modifications,
6. Must be able support metal pistes,
7. Size must be small so not to obstruct,
8. Must be anti-fraud, spoof proof & resilient to deliberate jamming,
It's not so simple to design a wireless system for epee.
The problem is bell hits and grounded strip hits. Maybe for a club, you can ignore the latter, but you can't ignore bell hits.
The problem of bell hits is the same as grounded strips, and really is the same as detecting lame hits: you are trying to determine if an electrical connection exists between two conductors when you don't have another connection (a ground reference).
The development of Hitmate is all about detecting bell hits. It does detect bell hits. It does not detect grounded strip hits (at least the last time I looked).
It's not easy.
The way the StM system does it is usually called a "virtual ground", and they couple to the body (using a T-shirt with a conductive panel that contacts the skin of the fencer). It doesn't really work, but it's close.
Let's start with the requirements: (in order of priority)
1. Low cost (<$TBD),
2. Must be reliable, spoof proof & resilient to jamming,
3. Must be able to coexist with other systems in close proximity,
4. Supports FIE timing requirements for all 3 weapon types,
5. Must use existing weapon/vest/mask configurations/designs without any modifications,
6. Must support anti-fraud,
7. Must be able support metal pistes,
8. Size must be small so not to obstruct.
Any more?
Marc
If all you're looking at is club use (as opposed to actual tournaments) then you may not need to worry too much about support for grounded strips. Clubs which are constantly having to set-up and tear down their strips (which appears to be the sort of customer you're targeting) aren't likely to have grounded strips to begin with.
If you do want to have support for grounded strips then I suspect a third unit (perhaps a central unit, similar to what Hitmate uses) might be connected to the grounded strip, adding one more signal to those which Palisadeur has already listed (weapon registers to ground - no touch).
So long as several units could be used within close proximity to one another without interference I also don't think it would need to be overly spoof proof. If someone feels the need to intentionally mess with the scoring equipment at club then they have bigger issues.
I've been putting together a few ideas with respect to creating a low cost wireless fencing solution. As most of us are aware, the constant setting-up & tearing-down of wired systems is a real deterent for clubs that don't have dedicated gyms. I noticed a few threads in this forum on this subject by not much detail on what is currently available, how the systems may work, or how to design one.
The one system I had an opportunity to disect is the HitMate http://www.hitmate.co.uk/index.shtml Currently, the design only supports Epee; claiming the Foil version is still under development. Personally, I think the HitMate solution is way too expensive for only 1 weapon support ($400), and is not all that reliable based on some trials undertaken by our club. The closest thing I can compare it to is a wireless doorbell system which can be purchased at your local hardware store for less than $50. The marketing folks did right however by picking nice looking boxes.
For those familiar with the technical challenges, coming up with a wireless solution is a relatively simple task for Epee. It is much more complicated for foil & sabre due to the fact that there is no close circuit or signal return path common to both sides. Previous designs relied on single-ended signal detection techniques; i.e. tone detection, etc, which was often too slow or unreliable.
If anyone has any ideas on what would be the proper approach to take on this I'm all ears. I'll be putting together of list of my own which I will post in the next few days.
Why is detecting a bell hit in epee simple but detecting a lame hit in foil or saber much more complicated? Am I missing something here?
It's not so simple to design a wireless system for epee.
The development of Hitmate is all about detecting bell hits. It does detect bell hits. It does not detect grounded strip hits (at least the last time I looked).
It's not easy.
The way the StM system does it is usually called a "virtual ground", and they couple to the body (using a T-shirt with a conductive panel that contacts the skin of the fencer). It doesn't really work, but it's close.
Your right. Thanks for pointing that out.
I've oversimplified the solution for Epee (I'm a foil fencer myself).
I have not heard anything more come out of this, but what was interesting is that they designed it to support all 3 weapons and to be capable of being retrofitted to existing scoring boxes. If you are serious about trying this, you might want to contact them for additional information. Why reinvent the wheel? It remains to be seen if their solution is practical in the real world, but it could not hurt to inquire?
Contrary to some of the comments, the Hitmate is designed to ignore hits to a grounded strip. It does this by virtue of the mass of metal. This also causes it to not register hits on an uninsulated LP epee mask unfortunately.
The more I look at this though, it may not be the Terrassa fencer's solution at all, as the article on theirs does not mention bluetooth, and their proposed cost (400 EUR) is a lot less than this Allstar product.
A deeper look into the specs and video presentation makes it clear they are using RF modulation (which I thought would be the way to go), possibly in combination with capacitance for blocking grounded hits.
I have not heard anything more come out of this, but what was interesting is that they designed it to support all 3 weapons and to be capable of being retrofitted to existing scoring boxes. If you are serious about trying this, you might want to contact them for additional information. Why reinvent the wheel? It remains to be seen if their solution is practical in the real world, but it could not hurt to inquire?
Contrary to some of the comments, the Hitmate is designed to ignore hits to a grounded strip. It does this by virtue of the mass of metal. This also causes it to not register hits on an uninsulated LP epee mask unfortunately.
Dave G.
Dave,
Thanks for the link. It would be interesting to find out how they implemented their design.
There is also this paper which I came across that is an interesting read:
A deeper look into the specs and video presentation makes it clear they are using RF modulation (which I thought would be the way to go), possibly in combination with capacitance for blocking grounded hits.
There may be a problem with this approach if the receiver is too sensitive & detects an RF signal (due to close proximity) prior to a physical hit.
The more I look at this though, it may not be the Terrassa fencer's solution at all, as the article on theirs does not mention bluetooth, and their proposed cost (400 EUR) is a lot less than this Allstar product.
There may be a problem with this approach if the receiver is too sensitive & detects an RF signal (due to close proximity) prior to a physical hit.
Marc
If you ever played with walkie-talkies (portable 2-way radios) as a kid, you know there is an incredible squeal when the antennas touch, so I would think it would be easy to rule out detection by just close proximity.
Originally Posted by yba2cuo3 
