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Post by imperfectgolfer on Jan 25, 2024 10:23:40 GMT -5
I still find it 'mind boggling' looking at JS's swing, how he doesn't early cast. Here is his swing from a back view Here are some screen images where I have guessed the 'direction' (I haven't a clue about the magnitude) of some net force in images 1-5 applied via the hands (see the little red arrows at the grip of the club). The direction of those arrows will 'more or less' cause the COM of the club (red dot) to move from image 1 to 5. How on earth can those red arrow net force directions across the grip be created when his hands are moving down and out? It just doesn't seem possible for him to anatomically recreate such a force. Further, because the shaft is in backward bend, this means he is applying a positive torque (clockwise from this back view) about the mid-hand-point. And if he is applying a positive torque , why isn't the club releasing it's lag angle? In fact, when you look at JS's wrist graph, he increases his lead wrist radial deviation slightly in the early downswing increasing lag. Could he be actively holding/increasing the lag angle using his wrists while the club and arms are being rotated in space as a single unit by his upper body pivot? Inverse dynamics cannot confirm if that particular scenario is happening because all they are doing is working out the forces that need to move the club in space. Theoretically , all they do is look at snapshot high frequency images of the club (without the golfer) on a computer and work out all the forces and couples required (at and about the mid-hand-point) to cause its movement in the golf swing. I doubt he is holding lag as above, therefore he must be creating that net force (to be transmitted via his arms and hands onto the grip) using some other kinematic movement, while also applying a positive torque about the mid-hand-point. The net effect , will stop the club releasing its lag angle from image 1-5 , and in JS's case, it increases lag by a small amount. Whatever it is, I cannot figure it out. DG PS. What about protraction of his right scapular? Can that independently push on the whole bent right 'arm/hand/club grip' in the direction of those red arrows from image 3-5? Image 1 net force force could simply be a part of a stopping torque by the left and right hands (ie. end of range of movement of the wrists at P4). The club wishes to continue to rotate in the backswing against the momentary static left/right wrists. We then have a small rebound effect of the shaft bend that could provide some impetus between image 1 and 2. Then from image 3-5 the increasing protraction of his right scapular might get involved. Still all guesswork ! DG, You posted this series of images of JS holding clubhead lag between P4 => P5.5. You are trying to understand how it is possible considering the forces/torques (MoF due to the lead hand pulling the club handle along the hand arc path, and the existing hand couple torques) that are happening at the level of the club handle. I think differently and mainly in terms of human golf biomechanics and not in terms of physics, and I think that the main factor that allows JS to maintain clubhead lag and avoid casting is the way he moves his right upper limb between P4 => P5.5. He is actively adducting his trail upper arm using a pitch elbow motion of his trail elbow - but most importantly he maintains a roughly right angle bend in his trail elbow and he keeps his trail wrist very extended and upcocked (radially deviated) during that entire P4 => P5.5 time period. If he allowed his trail elbow to straighten, or if he straightened his trail wrist and simultaneously downcocked (ulnar-deviated) his trail wrist, then it would be physically impossible for him to prevent casting.
Another biomechanical factor in play is the motion of his trail shoulder socket. Note that at P5, his lead hand is at its furthest "away-from-the-target" position. However, look at the position of his trail shoulder socket at P5 - note that the distance between his trail shoulder socket and his right hand's position on the club is small enough to allow him to maintain a very flexed trail elbow. If he didn't rotate his upper torso enough and simultaneously protract his trail scapula enough between P4 => P5, then his trail elbow would straighten and predispose him to casting.
Jeff.
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Post by dubiousgolfer on Jan 25, 2024 11:08:41 GMT -5
Dr Mann
You said
"but most importantly he maintains a roughly right angle bend in his trail elbow and he keeps his trail wrist very extended and upcocked (radially deviated) during that entire P4 => P5.5 time period".
That makes sense to me but doesn't this imply that JS is holding the lag angle? When I say holding lag angle , I mean his right hand/wrist is physically preventing early release?
DG
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Post by imperfectgolfer on Jan 25, 2024 12:10:21 GMT -5
Dr Mann You said "but most importantly he maintains a roughly right angle bend in his trail elbow and he keeps his trail wrist very extended and upcocked (radially deviated) during that entire P4 => P5.5 time period". That makes sense to me but doesn't this imply that JS is holding the lag angle? When I say holding lag angle , I mean his right hand/wrist is physically preventing early release? DG Yes - I agree that JS is using his trail arm/wrist to "hold his clubhead angle". I think that it would be much more difficult to "hold the clubhead lag angle" between P4 => P5.5 like JS if one did not have a trail arm. Jeff.
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Post by dubiousgolfer on Jan 26, 2024 16:45:34 GMT -5
Dr Mann You said "but most importantly he maintains a roughly right angle bend in his trail elbow and he keeps his trail wrist very extended and upcocked (radially deviated) during that entire P4 => P5.5 time period". That makes sense to me but doesn't this imply that JS is holding the lag angle? When I say holding lag angle , I mean his right hand/wrist is physically preventing early release? DG Yes - I agree that JS is using his trail arm/wrist to "hold his clubhead angle". I think that it would be much more difficult to "hold the clubhead lag angle" between P4 => P5.5 like JS if one did not have a trail arm. Jeff. Intuitively, I agree that it would be difficult to hold the clubhead lag angle if one didn't have a trail arm , yet Dave Tutelman has confused me by implying the opposite in his article below, when he visited Ping Headquarters and was able to see the PingMan robot. www.tutelman.com/golf/justgolf/PingVisit.phpThe bolded sentences below from his article has confused me: - The "wrist joint", where the arm holds the club's grip, is completely unpowered. It just hinges freely, with a stop at the maximum wrist cock angle. This is what the best golf swings do, though almost everybody I play with tries to use the hands and wrists to add power. If you want to see why a free-hinging wrist is the right way, read almost any of the articles on my "Swing" page.
- The maximum wrist cock angle is well beyond 90º. Calvin tells me that is because the robot is designed for clubhead speeds up to 150mph. Trying to attain that speed with a wrist cock of only 90º would place too much strain on a graphite shaft less than XX flex; it would probably shatter. This is consistent with the long drive competitors, the only golfers who can even approach a 150mph clubhead speed. (They are typically in the 130s.) For instance, look at any video of Jamie Sadlowsky's swing; you'll see a huge wrist cock, which he holds almost to impact. This is the sort of swing that PingMan imitates.
Firstly , JS doesn't retain a huge wrist cock almost to impact, because his wrist graph shows about 60 degrees ulnar deviation in the late downswing. Secondly, how can PingMan retain such a late clubhead lag angle without a trail arm? I wish to know whether PingMan would release the club earlier or later if there were more wrist cock, so have asked DT this question. He doesn't have the answers but has noted down the question and will not be able to respond for at least a few weeks. But I did look at another article on DT's website (by Rod White ) who already produced a graph for a driven double-pendulum with different wrist cock angles while no change in any other parameters. It seems that as long as PA#2 is naturally released (ie. just allowed to release away from the wrist cock stopper by the 'In Plane MOF'), peak clubhead speed occurs at approximately the same time near impact even with different wrist cock angles. So I suspect the timing of PA#2 release is not really an important factor for PingMan, although the graphs do show that increased wrist cock at beginning of downswing creates greater clubhead speed, as long as its a natural release. 'Wrist cock angle' is the angle between the arm and the club shaft. 'Downswing angle' is the angle the proximal arm has traversed from an identical P4 position. One can see that peak clubhead speed peaks at about the same downswing angle for all wrist cock angles. Rod White says "The key point is that the peak speeds all occur at a very similar downswing angle, showing that the swing timing is almost unchanged" Anyhow, I will await DT's response in a few weeks time. DG
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Post by imperfectgolfer on Jan 26, 2024 18:25:25 GMT -5
Yes - I agree that JS is using his trail arm/wrist to "hold his clubhead angle". I think that it would be much more difficult to "hold the clubhead lag angle" between P4 => P5.5 like JS if one did not have a trail arm. Jeff. Intuitively, I agree that it would be difficult to hold the clubhead lag angle if one didn't have a trail arm , yet Dave Tutelman has confused me by implying the opposite in his article below, when he visited Ping Headquarters and was able to see the PingMan robot. www.tutelman.com/golf/justgolf/PingVisit.phpThe bolded sentences below from his article has confused me: - The "wrist joint", where the arm holds the club's grip, is completely unpowered. It just hinges freely, with a stop at the maximum wrist cock angle. This is what the best golf swings do, though almost everybody I play with tries to use the hands and wrists to add power. If you want to see why a free-hinging wrist is the right way, read almost any of the articles on my "Swing" page.
- The maximum wrist cock angle is well beyond 90º. Calvin tells me that is because the robot is designed for clubhead speeds up to 150mph. Trying to attain that speed with a wrist cock of only 90º would place too much strain on a graphite shaft less than XX flex; it would probably shatter. This is consistent with the long drive competitors, the only golfers who can even approach a 150mph clubhead speed. (They are typically in the 130s.) For instance, look at any video of Jamie Sadlowsky's swing; you'll see a huge wrist cock, which he holds almost to impact. This is the sort of swing that PingMan imitates.
Firstly , JS doesn't retain a huge wrist cock almost to impact, because his wrist graph shows about 60 degrees ulnar deviation in the late downswing. Secondly, how can PingMan retain such a late clubhead lag angle without a trail arm? I wish to know whether PingMan would release the club earlier or later if there were more wrist cock, so have asked DT this question. He doesn't have the answers but has noted down the question and will not be able to respond for at least a few weeks. But I did look at another article on DT's website (by Rod White ) who already produced a graph for a driven double-pendulum with different wrist cock angles while no change in any other parameters. It seems that as long as PA#2 is naturally released (ie. just allowed to release away from the wrist cock stopper by the 'In Plane MOF'), peak clubhead speed occurs at approximately the same time near impact even with different wrist cock angles. So I suspect the timing of PA#2 release is not really an important factor for PingMan, although the graphs do show that increased wrist cock at beginning of downswing creates greater clubhead speed, as long as its a natural release. 'Wrist cock angle' is the angle between the arm and the club shaft. 'Downswing angle' is the angle the proximal arm has traversed from an identical P4 position. One can see that peak clubhead speed peaks at about the same downswing angle for all wrist cock angles. Rod White says "The key point is that the peak speeds all occur at a very similar downswing angle, showing that the swing timing is almost unchanged" Anyhow, I will await DT's response in a few weeks time. DG I suspect that Rod White could not show any differences in clubhead speed at impact with different wrist cock angles because the hand arc path was equally circular in each case. Human golfers have the advantage in the sense that they can shape their hand arc paths in order to optimise the release of PA#2 for different club lengths and different clubhead lag angles existing at the start of the PA#2 release phenomenon. I suspect that the Pingman golf robot has a stopper that prevents an early release of the club, and which can be manually pre-programmed during the set-up process. Jeff.
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Post by dubiousgolfer on Jan 27, 2024 8:39:46 GMT -5
Dr Mann
I don't think PingMan or Iron Byron have a stopper to prevent early release but I do think the shape of a real golfers hand path may help retain clubhead lag. I still don't know what forces/torques they are generating with each hand on the grip, but whatever they are doing to create that hand path seems to work, and is creating the required forces/torques.
For example, I was looking at Paul Wilson's youtube video comparing Iron Byron swings with Rory (and other pro golfer swings) in slow motion, and one can definitely see that Iron Byron is releasing PA#2 earlier while also having more wrist cock at P4 (although difficult to confirm because of parallax issues). Further , when I look at the full speed Iron Byron video , it seems to be swinging significantly faster than Rory, therefore Paul Wilson must have used different slow motion rates when doing the comparison.
So with regards Iron Byron, it's faster swing, with more wrist cock , hand path moving on a circular path coupled with a natural release, causes an earlier PA#2 release.
DG
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Post by imperfectgolfer on Jan 27, 2024 10:26:25 GMT -5
Dr Mann I don't think PingMan or Iron Byron have a stopper to prevent early release but I do think the shape of a real golfers hand path may help retain clubhead lag. I still don't know what forces/torques they are generating with each hand on the grip, but whatever they are doing to create that hand path seems to work, and is creating the required forces/torques. For example, I was looking at Paul Wilson's youtube video comparing Iron Byron swings with Rory (and other pro golfer swings) in slow motion, and one can definitely see that Iron Byron is releasing PA#2 earlier while also having more wrist cock at P4 (although difficult to confirm because of parallax issues). Further , when I look at the full speed Iron Byron video , it seems to be swinging significantly faster than Rory, therefore Paul Wilson must have used different slow motion rates when doing the comparison. So with regards Iron Byron, it's faster swing, with more wrist cock , hand path moving on a circular path coupled with a natural release, causes an earlier PA#2 release. DG That's interesting! I also noted that the Iron Byron's central arm is vertical at P6 while a human golfer's lead arm is only vertical at impact - suggesting very different PA#2 release mechanics. Aothern interesting phenomenon regarding the Iron Byron machine is how its central arm slows down at impact making it impossible for it to perform a DH-hand release action. That fact would increase my suspicion that its PA#2 release mechanics work very different to human golfers who use a DH-hand release action - like Patrick Rodgers below. Jeff.
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Post by dubiousgolfer on Jan 27, 2024 13:35:10 GMT -5
Dr Mann
Iron Byron's swing seems quicker than Rory so I'd expect the lead arm to be closer to vertical by P6.
But I think overall , the golf robots do not offer a high similarity to a real golfers swing, plus there is no PA3 angle , just one plane.
DG
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