Tuesday, December 02, 2003

I finally got arount to watching the eXtreme Martial Arts showcase that was aired on the Discovery Channel on Sunday. Overall I had to say it was a fairly entertaining two hours even for the non-martial artist/non-engineer type. For those of us who are both however, it was something else entirely.

First, a bit of background. Last year, a fellow student and I designed a martial arts force-plate training device known as BRUCE (Basic Real-time Universal Combat Environment) for our fourth year engineering project. Lord knows it took forever for my partner and I to get the thing to even begin to function, and it was never the most reliable system (The computer we used was woefully inadequate, and admittedly, I over engineered the structure of the prototype to the point of massive insensitivity), it none the less ends up having many of the same qualities as the sensor systems the scientists in the show ended up using.

The first similarity (and by far the most striking) was the use of a 1000Hz sampling rate. This surprised me because I felt that a higher sampling rate (two to three times) would have made for better analysis of reaction time and pressure monitoring. However, they probably made the same compromise we had to; they sacrificed sampling speed in order to reduce the raw processing the computer would have to achieve.

They used a pressure-based sensing system to determine pounds per square inch and then determing the force. This was part of our initial brainstorming on the project as well, but we never could figure out how we could find a sensor that could measure the forces we predicted would occur without breaking, or the proper vessel we would need to contain the sensor. While it seems they solved the problem with the vessel (and I for one would love to know how they did it), it looks like they didn't completely solve the durability problem, as they showed at least on of the sensors breaking.

We opted for a direct force measurement (as opposed to integrating the force from the pressure) and to use multiple sensors to triangulate the position of the point force. They used this same feature, but applied it to measure changes in the martial artist's BALANCE as he stood on force plates. An application that seems so blindingly obvious in hindsight that I'm kicking myself over not having thought of it myself.

They used motion capture technology to triangulate the various body mechanics and to determine speed and reaction time. An option that was way too expensive for a pair of engineering students, but one that would work very well. We had to do a much more indirect measurement of reaction time, but supplemented what we already knew of human ergonomics to try and make up for that shortcoming.

Kind of nice to know we could have achieved what they did if we had a team of specialists and several hundred thousand dollars more.

In terms of the show itself, it was a nice insight into the SCIENCES (Plural) that the martial arts take advantage of. Whether it is the old fashioned "drawing strength from the earth" or the pschological effect of horse-hair on a spear, there was a truly canny analysis of the tools of the martial artists.

Damn good watching,


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