Dr Mann
Have Gears improved the accuracy of their "left wrist extending" and "left forearm supination" since your last conversation with Michael Neff?
If they haven't then can one really use their Gears Avatars for analysing the above biomechanical events (unless we also knew who the golfer was and could also compare to the video footage like you did with Jamie Sadlowski below)?
DG
PS. Looking again at that Michael Neff video , he has placed a marker on the elbow . Can't the relationship of the orientation of the 'left wrist marker' vs 'elbow marker' provide a measurement of left forearm supination?
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I had a 1-hour Skype conversation with Michael Neff, owner of the GEARS 3-D system, yesterday. I was hoping to discover how his GEARS system could measure the amount of "left wrist extending" and "left forearm supination" happening between P7 and P7.2. What I discovered is that the standard GEARS 3-D motion analysis system cannot even measure those biomechanical events because they do not have any markers on the left hand or left lower forearm's radial bone.
Here is a video showing how one places the markers in place.
Note that there is only a single marker placed on the back of the lower left forearm, but that there are no markers on the back of the left hand or on the left lower radial bone and the middle of the left antecubital fossa. Therefore, the GEARS system cannot be used to measure the amount of "left wrist extending" and "left forearm supination" happening between P7 and P7.2.
To get an idea of how the GEARS-avatar system "invents" biomechanical events that do not correlate with reality - consider this video showing the GEARS analysis of Jamie Sadlowski's golf swing.
Here are comparison capture images of a 2-D capture image of Jamie Sadlowski at impact versus the GEARS avatar.
At impact, Jamie Sadlowski's ulnar border of his left hand faces the target because he uses a very strong (4-knuckle) left hand grip, while the back of his left hand is roughly parallel to the inclined plane while it faces the ball-target line. Note that the clubface is square to the target at impact, which means that the clubface is angled about 60 degrees closed relative to the back of his left hand (as it was at address). However, note that the back of the GEARS-avatar's left hand faces the target and it is parallel to the clubface.
Here is another comparison image at P6.
Note that the clubface is slightly tilted beyond vertical, but it is about 45 degrees closed relative to the back of his left hand (blue line).
In other words, the GEARS avatar's left wrist/hand motions have no correlation with reality. The GEARS system accurately measures the clubface angle because there are 3 markers on the clubhead, but it artificially "invents" the position of the left wrist/hand.
I spoke to Michael Neff about placing more markers on the back of the left hand, over the left lower radial bone at the level of a watchband and over the middle of the left antecubital fossa, so that the GEARS system can accurately measure the amount of "left wrist extending" and "left forearm supination" happening between P7 and P7.2. "Time" will tell whether he is responsive to my suggestions and whether a future GEARS motion analysis system has this capability.
An interesting tidbit of information. I asked Michael Neff how he checks to see whether his GEARS system can accurately measure the position of the clubshaft, clubhead, clubface and body parts at every moment of the golf swing - by using another measuring device - and he stated that he uses a Phantom camera operating at 20,000 FPS as a "gold standard" check. I wonder what the "flat-earthers" at Golf WRX will think when they read about that interesting tidbit of information!
Jeff.
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