Patent for Contact detection system and method

[esskreemr]

Patent # 6,878,870
April 12, 2005

Abstract

A system electronically detects and registers contact, especially in contact sport embodiments. An example contacting instrument includes a switch, a tone generator and a conductive mesh. An example detecting instrument includes a conductive mesh and a tone decoder. In a contact sport embodiment, each combatant possesses, for example, as part of the combatant's respective uniform, one or more contacting instruments and one or more detecting instruments embedded in prescribed contact zones. The basic goal of a combatant is to strike a contact zone of their opponent with one of their contacting instruments. The detecting instrument will recognize the tone, thereby recognizing a hit.

http://patft.uspto.gov/netacgi/nph-P...=/netahtml/sea

How would this be differe and/or better than detecing an electrical signal?

[blue_falcon]

After reading part of the document, it looks like they wanted something that would be able to automatically score not just where the hit occurred but also the force of the impact.

It's actually kind of neat -- let's say we have two combatants, A and B. They both wear detecting equipment (e.g. helmet and vest) and both wield contacting equipment (e.g. boxing gloves). When the contacting equipment of A is in contact with the detecting equipment of B, then A's equipment generates two tones -- one indicating where the hit occurred and another indicating the force. I think they use capacitive plates or something like that to figure out which and what tones are generated. B's equipment (or the scoring equipment) detects the tone or tones and scores according to what the tone or tones indicate. So, a head shot would be scored higher than, say, a body blow. Similarly, if the hit was TOO hard, they can take off points or somehow penalize the overly brutal combatant.

I imagine the whole thing can be implemented wirelessly. My only problem with the whole mess would be the ambient noise possibly drowning out the tones.

Neat idea though. But that doesn't mean it's practical.

[Larrison]

Hmm.. I couldn't get any of the figures to show off the patent site. Anybody get a look at Figure 3? Description is below...

FIG. 3 depicts an alternative contacting instrument 301 similar to a fencing foil that is covered with foam padding 305 and can be used as a child's toy. The instrument 301 includes a hand guard 303, a semi-rigid shaft 304 and a pressure-sensitive switch 306 similar to that used in modern electrically conductive fencing foils. The semi-rigid shaft 304 detects a forceful jab or lunge and turns on the tone generator circuit 302. An impulse switch 307, described below, which in this embodiment is inside the foam padding 305 and located on the rigid shaft 304, detects a forceful side blow and turns on the tone-generating circuit 302. The tone-generating circuit 302 may be disposed inside the handle grip 301 and electrically connected to the conductive, contacting instrument mesh. If the instrument 301 is used for fencing, the tone generator 302 may be electrically connected to the metallic shaft 304 and to the impulse switch 307. The circuit may be triggered by a closure of the pressure switch 306 for a forward thrust or of impulse switch 307 for a side hit. If this closure occurs on a valid contact zone of the opponent's gear 200, similar to that described in FIG. 2, a valid strike will be registered. In the toy embodiment, the tone-detecting vest 203 and headgear 201 and 202 may be more simple. That is, the transmitter may be omitted, and a valid hit could be registered via sounds or lights.

[blue_falcon]

I'll send you a copy of Figure 3 on Monday -- I don't have the software here at home to grab just that figure and the jpg of the page itself is quite large (i.e. the darned website won't let me upload it all!).

[sjkontos]

Originally Posted by Larrison

Hmm.. I couldn't get any of the figures to show off the patent site. Anybody get a look at Figure 3? Description is below...

In order to view patents on the USPTO website, you need to download alternatiff - http://www.alternatiff.com/install/. You can also go to http://www.freepatentsonline.com and put in the patent number. It will let you download a pdf version of the patent. Finally, you can try http://free.patentfetcher.com for a pdf version of the patent (it actually pulls it from the USPTO site), but this site only allows around 5 downloads a day.

[SensibleStu]

Yeah - I had thought about this a few years ago but applied to martial arts where specific areas have a particular points value. This is really the only way i can see this being implemented! For fencing - I had the same problem of not being able to see the pictures - I think it sounds the same as a normal system; altough it would be a nice implemtation of off target for foil and sabre!!

[KD5MDK]

Depending on the nature of the tones, you could have several of them, enabling a melee or otherwise using multiple fencers/combatants at once.

[Drifter]

The big plus is no common grounds. Everything becomes wireless and a differing tone used for each combatant rules out cheating. In addition since the "Blade" (in our case) is looking for a specific tone floor shots or any other touch not on your opponet for that matter do nothing regardless for what surface you're fencing on.

I do think however, that this type of technology will never come to fencing because it means the loss of a number of profit centers for the fencing manufacturers. No need for metal strips would be significant blow to the manufacturers.

[DHCJr]

Originally Posted by Drifter

The big plus is no common grounds. Everything becomes wireless and a differing tone used for each combatant rules out cheating. In addition since the "Blade" (in our case) is looking for a specific tone floor shots or any other touch not on your opponet for that matter do nothing regardless for what surface you're fencing on.

I do think however, that this type of technology will never come to fencing because it means the loss of a number of profit centers for the fencing manufacturers. No need for metal strips would be significant blow to the manufacturers.

If you have been reading the many post, you would find something different. There have been several posts on the fact the FIE wants to get rid of pistes. That is one of the reasons they are trying to go wireless, but without RF or IF.

[blue_falcon]

Ok, someone asked for Fig 3 -- here's a jpg of it.

[Drifter]

Originally Posted by DHCJr

If you have been reading the many post, you would find something different. There have been several posts on the fact the FIE wants to get rid of pistes. That is one of the reasons they are trying to go wireless, but without RF or IF.

That would indeed cause me to be quite happy. Make no mistake I'd like to see it happen, it just seems to me that with so many technological advancements that could be made to fencing that there has to be something holding them from coming into the sport, mainly the manufacturers. (I confess it's entirely possible for my naturally suspicious nature to be the root of this feeling.)

Another example of tech that could make things far easier for everyone today that hasn't made it to the sport would be solid state tips for epee and foil that use pzeio-electric force sensors like this one:
http://www.parallax.com/detail.asp?product_id=30056 These are the same type of sensors that are found in PS2 and Xbox game controllers and can differentiate force from 1g to many thousands of Kg. Yet nothing has been done, at least to my knowledge and I confess I'm not really in that loop, to incorporate that type of tech into the tips I think (possibily because of my conspirtorial nature) because it would do away with the need for foilists and epeeists to regularly buy things like screws and springs and wires and tips. All the fiddly little bits could be engineered away with the use of solid state force sensors but then profit streams would go away.

[DHCJr]

I think the manufacturers would love to see those tips, by your reasoning, because they would sell more and at a higher price. First, what is more durable metal or plastic. I would see more breakage. Second, if those broke could you repair them or would you need to buy a new sensor. I have seen many tips come apart both Foil and Epee, I can usually put them back together. Third, for Epee, force is not the only consideration and if the new tip for Foil, it won't be the only consideration either. Distance of travel is also a consideration. Would those sensors be able to distinguish that? Fourth, can they be adjusted, so if they can be taken as close as possible?

[Drifter]

Originally Posted by DHCJr

I think the manufacturers would love to see those tips, by your reasoning, because they would sell more and at a higher price. First, what is more durable metal or plastic. I would see more breakage. Second, if those broke could you repair them or would you need to buy a new sensor. I have seen many tips come apart both Foil and Epee, I can usually put them back together. Third, for Epee, force is not the only consideration and if the new tip for Foil, it won't be the only consideration either. Distance of travel is also a consideration. Would those sensors be able to distinguish that? Fourth, can they be adjusted, so if they can be taken as close as possible?

Threadjack.

1. Durability. The force sensors that I've seen have been made out of a number of types of materials and are currently used in applications that make our little poking, jabbing sport seem like a cake walk. Keep in mind these types of force sensors can measure up to many thousands of pounds and are used in heavy manufacturing environments every day. Yes the one I linked to is a plastic variety but even it, if housed inside a metal tip would last a very long time as it is litterally a 2 or 3 mil piece of plastic with a specialized conductive coating cooked into the center of it. No moving parts means the mean time to failure is much longer. Here is a link to the company that makes the sensor I referenced, http://www.tekscan.com/industrial/tirescan_system.html Notice that it shows a number of industrial uses including tire footprint anaylsis. Driving vehicles over a sensor suggests to me that they'd be more than adequate for our uses.

2. Breakage. Yes I imagine if the tip broke one would have to buy a new one, but seeing as how these types of sensors are currently used in game controllers and buying a game controller can cost you less than $20 bucks these days in which you get as many 8 of these sensors, I would have to imagine the price point wouldn't be higher than the recurring costs of screw, spring, wire and tip replacement now. I think also, that it's important to remember that I'm proposing a solid state tip, as such the tip wouldn't come apart. A break would mean a break in the barrel of the tip, an extremely uncommon event even now. (A side note, in addition the use of a force sensor could potentially do away with the need for blade wires as well if kind of coax cable style blade were manufactured, though I confess that would take a LOT more thinking. Somthing that a two circuit spring style tip could never do.)

3. Distance of Travel. In truth I don't know why distance of travel is a required measurement now. I could only spectulate that it is to insure that the tip stays on the target for a predetermined amount of time, for example the new debounce time in foil. My response to a distance of travel query needs to be predicated with why we have this requirement now. Perhaps you could help me with this. To take a stab in the dark however, these sensors measure the amount of force applied to them during a particular period of time, i.e. a cycle of every .01ms, as such force and time can be measured by any computer that is using these sensors to sense its' surroundings. In other words if I put the sensor between my fingers and squeeze, the computer that the sensor is hooked up to can tell how hard I squeezed and for how long. It seems to me that force and time depressed should be able to adequately measure a substanative hit in epee.

4. Adjustment. I see this as being one of the best aspects of moving to force sensors. Adjustment is moved from the tip to the computer (fencing box). Naturally each sensor is going to have very minute voltage differences from sensor to sensor. But as with any sensor and I might add the current spring based tips, a thereshold can be quickly and easily be defined. Plug the sensor into the computer (fencing box) and the computer immediately reads the no force voltage coming from the sensor. Apply 750 grams or 500 grams depending on weapon, the computer reads the voltage under force and bam you're done. No different than how things are done today except that so long as the tip works, a person would never have a tip fail because of not passing weight.

As a last note, all of these speculations are exactly that, just ideas from a non-engineer. It seems to me that if someone with an interest in the sport and no background in engineering can put these ideas together into something reasonably possible than an actual engineer could do much better. Every aspect of technology for the last 40 years has doubled in ability and halved in cost rought every 18 months EXCEPT the technology in fencing. Why is that? Why do we still use the same equipment that has been used since the 70's? My cynical nature points to profit as the reason, but I confess I am not 'in the know'. (Not that profit is inherently a bad thing. I'm all for profit, just not when it stands in the way of progress.)

End threadjack. Sorry guys.

[DHCJr]

First a very good answer. I will respond to 3 as that is the only one you asked a question. The reason for the travel in Epee is the same reason they are looking at travel in Foil. It is not just the amount of force, but the direction and sustained force. The trouble with what Foil became is fencers were fencing Sabre with Foils. The Foil is a point weapon. The theory is that you are driving THROUGH your opponent, not just slapping them with the side of the blade. For Foil all you needed was a imfinitely small break in a circuit to get a light to go off. The amount of force actually meant little. They did a test of how much force fencers hit with. With straight attacks it was around 2 to 3 kg. The amount of force with a flick was 5 to 10 times. In other words, so what would there be a problem with the amount of force.

As fencers have found out making the changes in the box to eliminate flicks does not work. There has to be something in the tip to eliminate them or get Foil referee to penalize those fencing Sabre with a Foil in their hand.

[KD5MDK]

Would it be possible to mount/shield the pressure-sensitive part such that the only way to deliver enought force to it is parallel to the blade?

[Drifter]

Originally Posted by DHCJr

First a very good answer. I will respond to 3 as that is the only one you asked a question. The reason for the travel in Epee is the same reason they are looking at travel in Foil. It is not just the amount of force, but the direction and sustained force. The trouble with what Foil became is fencers were fencing Sabre with Foils. The Foil is a point weapon. The theory is that you are driving THROUGH your opponent, not just slapping them with the side of the blade. For Foil all you needed was a imfinitely small break in a circuit to get a light to go off. The amount of force actually meant little. They did a test of how much force fencers hit with. With straight attacks it was around 2 to 3 kg. The amount of force with a flick was 5 to 10 times. In other words, so what would there be a problem with the amount of force.

As fencers have found out making the changes in the box to eliminate flicks does not work. There has to be something in the tip to eliminate them or get Foil referee to penalize those fencing Sabre with a Foil in their hand.

Sustained force is easy for force sensors because as I said before time and pressure can be measured with them. As for direction, hmmmm, I suppose a barrel style tip like the ones we use now would be sufficiant to offset side impact style touches. Two tubes one inside the other with the force sensor at the bottom, meaning that only a push on the inside parallel tube would transfer the force. That wouldn't do away with springs though. Perhaps a different type of sensor. I know that directional sensors exist and they do pretty much the same thing as force sensors just in more than one axis, but I don't know about thier sizes or the physics behind them so I don't know how durable they'd be. Perhaps someone in the know could chime in. Also, as you mentioned multiple thresholds could be set up, (If a flick is 10 times the normal pressure of a straight attack then one could set the box to record a hit if the sensor recieved 2Kg of force but to not record a hit if the impact of the force continues past 2kg and reaches 20Kg.) This of course is all speculation and as with any engineering problem I'm sure there are twenty different answers. The beauty I see in force sensors, and for that matter sensors of all kinds is that it drastically opens up the programming capabilities. We are no longer limited by the mechanics of a two circuit spring system and I think we should be looking at all technological possibilities which doesn't seem to be happening.

Thank you for the compliment about the previous post.

[KD5MDK]

Could you build a force sensor that held up 500 (or 750)g once, and didn't thereafter?

[Drifter]

Originally Posted by KD5MDK

Could you build a force sensor that held up 500 (or 750)g once, and didn't thereafter?

If I'm understanding your question, nope. A force sensor's job is merely to identify how much force is being placed on it and pass that information on to a computer in the form of a voltage, i.e. 750g = 2.4V. Therefore once the computer is taught how many volts to expect when 750g is reached on the sensor (2.4V), then the computer is in charge of everything thereafter. Being able to change the voltage the sensor lets through the circuit on the fly would require one to be able to reduce or increase the resistance of the conductive matrix inside the sensor, not something that could be done I think. Though, not being an engineer, I could be entirely wrong.

[Robert Smith]

Originally Posted by Drifter

As for direction, hmmmm, I suppose a barrel style tip like the ones we use now would be sufficiant to offset side impact style touches. Two tubes one inside the other with the force sensor at the bottom, meaning that only a push on the inside parallel tube would transfer the force. That wouldn't do away with springs though.

This basic idea went the rounds a shotr while ago in http://www.fencing101.com/vb/showthread.php?t=16645another thread. Same idea, pretty much, same issues. I still don't entirely see the necessity of "travel" to enforce direction, and had assumed that something like the current arrangement of piston in barrel would provide that enforcement with very little movement. This wouldn't require springs, just enough free movement to be able to apply the necessary force to the sensor. Would be nice if it could be done as a totally sealed unit; no doubt someone could figure that out.

Biggest problem unearthed, in my mind at least, was that brought up by andrewmcleod, who said:

Originally Posted by andrewmcleod

The other problem is quite obvious when you consider the resistance-travel curve of a spring tip. At 0-1mm, resistance is effectively infinite. At some point, resistance drops enormormously as the springs contact to maybe a few ohms (with bad contacts). This curve will be nearly discontinuous - there will be a sudden changing point you can easily measure.
Consider such a plastic as described that drops in resistance as hit. As you reach a certain travel point and begin to compress it there will be a continuous (though not neccessarily linear) drop in resistance. There will not be a sudden sharp boundary to measure, so you will just have to decide that for instance where resistance has dropped to <200ohms to register a hit. But then you have to measure resistance precisely. Also spurious resistances in the spools, wires, weapons, how good the batteries in the box are etc. will start to play a larger role...

Assuming that your proposed sensor works in much the same way, there'd still be the same need for a sudden, drastic change in resistance to indicate a touch with any degree of precision. Too shallow a slope, and you're (even more than usual) at the mercy of flaky body cords, noisy reels, and all those other elements that affect the resistance at the box. Calibration of the tip at the strip could be used to establish a suitable overall resistance, but only as long as you stayed perfectly still, without flexing body cord or reel cable. I think the folks I was talking to have put this on a back burner because of those kinds of issues. And I suspect that burner may be a loooong way back.

[KD5MDK]

When you say it causes a certain voltage, what we're actually looking at is a DC current with variable resistance, right? So resistance is infinite without any pressure, and then as resistance drops, voltage increases for a constant current. Right?

I hope it's that way, because if its any other, cheating would be very easy (just break the connection to get a touch)