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Post by dubiousgolfer on May 10, 2019 7:45:18 GMT -5
Dr Mann I couldn't figure out how to paste a drawing image into this post so I have had to attach an .odg file ( I use 'Libre office' open source software - unsure whether you can open it). Doesn't applying a PP1 pressure force during the downswing (using PA1) cause a negative 'Moment of Force' (Torque) on the clubs COG? Therefore act in a way as to slow the clubhead speed into impact? If a golfer used excessive PA1 and PP1 pressure , wouldn't this interfere with the CF evoked release (which is really the forces across the club that create a positive MOF without any active wrist torque)? And if too excessive , is it possible that a golfer would react by countering this negative negative MOF by pulling up more via his lead arm and maybe chicken wing (if he wasn't able to pull up enough via his lead shoulder joint)? DB
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Post by imperfectgolfer on May 10, 2019 8:32:42 GMT -5
Dr Mann I couldn't figure out how to paste a drawing image into this post so I have had to attach an .odg file ( I use 'Libre office' open source software - unsure whether you can open it). Doesn't applying a PP1 pressure force during the downswing (using PA1) cause a negative 'Moment of Force' (Torque) on the clubs COG? Therefore act in a way as to slow the clubhead speed into impact? If a golfer used excessive PA1 and PP1 pressure , wouldn't this interfere with the CF evoked release (which is really the forces across the club that create a positive MOF without any active wrist torque)? And if too excessive , is it possible that a golfer would react by countering this negative negative MOF by pulling up more via his lead arm and maybe chicken wing (if he wasn't able to pull up enough via his lead shoulder joint)? DB I don't know why you believe that the active use of PA#1 will produce a negative torque - please explicate further. If PA#1 is actively used and it increases the speed of right arm straightening it can cause increased push-pressure by the right palm against PP#1 and/or PP#3. It's ultimate effect will depend on whether the right palm's push-pressure is applied above-or-below the coupling point. Either way, it can certainly interfere with a CF-induced (passive) release of PA#2 that occurs passively secondary to the shape of the hand arc path. Jeff.
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Post by dubiousgolfer on May 10, 2019 10:32:41 GMT -5
Dr Mann I am assuming that PA1 will cause a PP#1 and/or PP#3 across the grip. From what I've read " A force not directed through the COM of an object will tend to cause rotation'. The direction of rotation of the COM will always move towards the tail end of that force. The physics is described in Sasho's video below from 02:49 - 06:00 vimeo.com/158419250I still do not understand the relevance of a coupling point with regards the effect on the clubs motion by PP#1 or PP#3. Any forces applied across the grip (and not through the COM) will cause a 'Torque' (or 'moment of force') that will tend to align the COM with the force vector direction. Note: The closer the tail end of these individual palm/finger forces are to the COM, the more linear the motion compared to rotation. Sasho has really simplified the maths in his inverse dynamics modelling by splitting all these individual complex finger/palm forces on the grip into a 'couple' (with no lateral movement) + 'leftover net lateral force' (that can also cause a 'MOF'). The 'coupling point' (which I assume is the central position between the hands) was used during this simplification but may have no relevance to the 'real life' instantaneous dynamic forces that a golfer is applying to the grip. DB
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Post by imperfectgolfer on May 11, 2019 9:33:58 GMT -5
Dr Mann I am assuming that PA1 will cause a PP#1 and/or PP#3 across the grip. From what I've read " A force not directed through the COM of an object will tend to cause rotation'. The direction of rotation of the COM will always move towards the tail end of that force. The physics is described in Sasho's video below from 02:49 - 06:00 vimeo.com/158419250I still do not understand the relevance of a coupling point with regards the effect on the clubs motion by PP#1 or PP#3. Any forces applied across the grip (and not through the COM) will cause a 'Torque' (or 'moment of force') that will tend to align the COM with the force vector direction. Note: The closer the tail end of these individual palm/finger forces are to the COM, the more linear the motion compared to rotation. Sasho has really simplified the maths in his inverse dynamics modelling by splitting all these individual complex finger/palm forces on the grip into a 'couple' (with no lateral movement) + 'leftover net lateral force' (that can also cause a 'MOF'). The 'coupling point' (which I assume is the central position between the hands) was used during this simplification but may have no relevance to the 'real life' instantaneous dynamic forces that a golfer is applying to the grip. DB You wrote-: " I still do not understand the relevance of a coupling point with regards the effect on the clubs motion by PP#1 or PP#3. Any forces applied across the grip (and not through the COM) will cause a 'Torque' (or 'moment of force') that will tend to align the COM with the force vector direction." If a force is applied above the coupling point at PP#1 it will induce a PA#2 release according to the laws of physics (according to the D'Alembert principle). If an additional force is applied manually below the coupling point at PP#3 (eg. by a right wrist straightening action) it can potentially cause PA#2 to release faster than predicted by the D'Alembert principle.
Your post does not address my question - "how can an active release of PA#1 produce a negative torque"?
Jeff.
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Post by dubiousgolfer on May 12, 2019 5:37:15 GMT -5
Dr Mann I am assuming that PA1 will cause a PP#1 and/or PP#3 across the grip. From what I've read " A force not directed through the COM of an object will tend to cause rotation'. The direction of rotation of the COM will always move towards the tail end of that force. The physics is described in Sasho's video below from 02:49 - 06:00 vimeo.com/158419250I still do not understand the relevance of a coupling point with regards the effect on the clubs motion by PP#1 or PP#3. Any forces applied across the grip (and not through the COM) will cause a 'Torque' (or 'moment of force') that will tend to align the COM with the force vector direction. Note: The closer the tail end of these individual palm/finger forces are to the COM, the more linear the motion compared to rotation. Sasho has really simplified the maths in his inverse dynamics modelling by splitting all these individual complex finger/palm forces on the grip into a 'couple' (with no lateral movement) + 'leftover net lateral force' (that can also cause a 'MOF'). The 'coupling point' (which I assume is the central position between the hands) was used during this simplification but may have no relevance to the 'real life' instantaneous dynamic forces that a golfer is applying to the grip. DB You wrote-: " I still do not understand the relevance of a coupling point with regards the effect on the clubs motion by PP#1 or PP#3. Any forces applied across the grip (and not through the COM) will cause a 'Torque' (or 'moment of force') that will tend to align the COM with the force vector direction." If a force is applied above the coupling point at PP#1 it will induce a PA#2 release according to the laws of physics (according to the D'Alembert principle). If an additional force is applied manually below the coupling point at PP#3 (eg. by a right wrist straightening action) it can potentially cause PA#2 to release faster than predicted by the D'Alembert principle.
Your post does not address my question - "how can an active release of PA#1 produce a negative torque"?
Jeff.
Dr Mann - Yes , looks like I've made the wrong assumption that only PP1 is the predominant pressure force for the release of PA#1 .
Looking at your website it says: "A TGM hitter will start his right arm/forearm thrust action from his loaded right elbow position (which is moved downplane during the early downswing). A TGM hitter should "feel" that he he is thrusting his right hand in a straight-line thrust action towards the ball (or aiming point located near the ball) when he actively releases PA#1 (actively straightens the right elbow with a very active right triceps muscle contraction). The right arm straightening action must be sufficiently efficient, so that the right hand can apply a constant push-pressure at PP#1 and PP#3 throughout the mid-late downswing in a drive-loading manner. The constant drive-loading of the left hand and clubshaft during the mid-late downswing means that a TGM hitter is actively releasing PA#2 and PA#3 via his active "right arm straightening" action. There should be no centrifugal release of the club in a TGM hitter's action, and a TGM hitter should be actively driving the clubshaft towards impact - like swinging an axe-handle using a radially-directed thrust force against the back side of the axe handle."
So is the coupling point just a 'reference point of rotation' for torque forces?
DB
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Post by imperfectgolfer on May 12, 2019 7:46:00 GMT -5
DG,
You asked-: "So is the coupling point just a 'reference point of rotation' for torque forces?"
That is correct for golfers who use a rotation-about-the-coupling point hand release action where they deliberately apply a right-sided push force against the aft side of the club handle below the coupling point in order to rotate the club handle about the coupling point. That type of golf swing action deliberately induces a flipping subtype of non-DH hand release action. Golfers (using a TGM swinging action) who want to be DHers should avoid applying any manual push-pressure against the aft side of the club handle below the coupling point and there should be no rotation about the coupling point through the immediate impact zone between P7 and P7.2.
Jeff.
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Post by dubiousgolfer on May 12, 2019 18:22:05 GMT -5
Many thanks Dr Mann but I'm still finding the physics of applying a force above or below the coupling point confusing. Here's my diagram but maybe I've got the physics wrong because it suggests any force above or below the coupling point will tend to cause a clockwise rotation. To prevent that clockwise rotation , some turning force is required in the anticlockwise direction. I need to think more deeply about this. DB
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Post by imperfectgolfer on May 12, 2019 21:06:46 GMT -5
Many thanks Dr Mann but I'm still finding the physics of applying a force above or below the coupling point confusing. Here's my diagram but maybe I've got the physics wrong because it suggests any force above or below the coupling point will tend to cause a clockwise rotation. To prevent that clockwise rotation , some turning force is required in the anticlockwise direction. I need to think more deeply about this. DB I personally have no problem with your opinion that any push-force applied below the coupling point, or any pull-force applied above the coupling point, will cause a release of PA#2 (which is an anticlockwise rotation of the club when viewed from face-on). The club never releases in an clockwise direction during a PA#2 release action. The concept of there being any rotation-about-the-coupling point phenomenon only applies to the zone near impact if the golfer pulls back on the club handle with the left hand in a direction away from the target while simultaneously pushing against the aft side of the club handle with the right palm in a targetwards direction - as recommended by Richard Franklin in the following video where he describes a rotation-about-the-coupling point hand release action. Jeff.
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Post by dubiousgolfer on May 13, 2019 5:42:23 GMT -5
Dr Mann - many thanks for this .
What confused me was your sentence in a previous post.
"If a force is applied above the coupling point at PP#1 it will induce a PA#2 release according to the laws of physics (according to the D'Alembert principle)"
My diagram shows that a force applied above (or below) the coupling point (in a general targetwards direction) will not cause a release of PA#2.
If I've got the physics correct in my diagram , any PP#1 force (above or below coupling point) will tend to prevent the club flipping through impact zone (providing the golfer does not pull back on the club handle with the left hand in a direction away from the target while simultaneously pushing against the aft side of the club handle with the right palm in a targetwards direction). I cannot imagine that the PP#1 force would be very large unless one can get that right shoulder moving downplane to prevent the golfer running out of right arm. But it could be enough to exert some degree of limiting DH control on the angular velocity of the club in the impact zone, especially if there is forward shaft bend trying to pull/flip the wrists through the 'impact zone'
DB
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Post by imperfectgolfer on May 13, 2019 7:53:37 GMT -5
Dr Mann - many thanks for this . What confused me was your sentence in a previous post. "If a force is applied above the coupling point at PP#1 it will induce a PA#2 release according to the laws of physics (according to the D'Alembert principle)" My diagram shows that a force applied above (or below) the coupling point (in a general targetwards direction) will not cause a release of PA#2. If I've got the physics correct in my diagram , any PP#1 force (above or below coupling point) will tend to prevent the club flipping through impact zone (providing the golfer does not pull back on the club handle with the left hand in a direction away from the target while simultaneously pushing against the aft side of the club handle with the right palm in a targetwards direction). I cannot imagine that the PP#1 force would be very large unless one can get that right shoulder moving downplane to prevent the golfer running out of right arm. But it could be enough to exert some degree of limiting DH control on the angular velocity of the club in the impact zone, especially if there is forward shaft bend trying to pull/flip the wrists through the 'impact zone' DB You wrote-: " If I've got the physics correct in my diagram , any PP#1 force (above or below coupling point) will tend to prevent the club flipping through impact zone (providing the golfer does not pull back on the club handle with the left hand in a direction away from the target while simultaneously pushing against the aft side of the club handle with the right palm in a targetwards direction)." I don't know much about physics, but I can readily imagine that if a push-force is applied against the back of the shaft below the coupling point at PP#3 by the right hand, that it can potentially induce flipping through impact if it speeds up the targetwards motion of the clubshaft relative to the targetwards motion of the left arm. You also wrote-: " My diagram shows that a force applied above (or below) the coupling point (in a general targetwards direction) will not cause a release of PA#2." I don't understand your claim because in that diagram (which is near-impact) PA#2 has already been released. Jeff.
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Post by dubiousgolfer on May 13, 2019 8:55:45 GMT -5
Dr Mann Yes , the physics seems counterintuitive (if I've interpreted it correctly - I might have to check ). Here is another diagram where I've drawn a right hand push Force F1 being applied in 3 different directions around P5.8 I have drawn 3 theoretical directions of the same amount of push force F1 by the right hand . This will cause a MOF across the COM of the clubhead (point A). According to physics that MOF will = F1 X 'closest distance between the force vector line and COM' . It will tend to cause a rotation of the COM in the clockwise direction shown. If my physics interpretation is correct, the more across the shaft the F1 force acts, the greater the MOF in the clockwise direction (assisting lag). The more the F1 forces is aligned with the clubshaft, the less MOF and less inclination to assist lag. However, if you apply a PA#3 force , while also applying a force using the last 3 fingers of the right hand, this will cause a 'couple' and an early release of PA#2. If one just applied a PA#3 force with the index finger (ie. not applying forces with the last 3 fingers of the right hand) , that would cause a similar effect as the F1 forces shown above. Don't know whether this makes sense but I will have to check it out with someone who is quite knowledgeable in dynamic physics. DB
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Post by imperfectgolfer on May 13, 2019 16:53:47 GMT -5
DG,
I presently find it impossible to understand why a push-force being applied by the right hand across the shaft in a direction towards the ground will cause the clubshaft to rotate clockwise and increase lag. I would need to be convinced by seeing you present substantial "evidence" - considering the fact that I presently believe that any push-pressure being exerted by the right hand against the aft side of the club will cause a PA#2 release phenomenon (anticlockwise rotation of the shaft).
Jeff.
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Post by dubiousgolfer on May 19, 2019 19:36:30 GMT -5
Dr Mann Unsure whether the below can be deemed as evidence , but its certainly not substantial and probably inconclusive. I found this double pendulum application on the below site and played around with the masses (one representing the arms and the other the club). www.math24.net/double-pendulum/If one just starts the pendulum with a 180 degree angle (ie. no wrist cock) and let the weight of the heavier mass (ie. analogous to arms) be similar to a force applied across the distal arm (as shown by my arrow in the 1st snapshot image below), a lag effect occurs (see bottom image). It's definitely not enough proof but still a curious effect (ie. just like a compound pendulum). DG
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Post by imperfectgolfer on May 20, 2019 9:16:48 GMT -5
Dr Mann Unsure whether the below can be deemed as evidence , but its certainly not substantial and probably inconclusive. I found this double pendulum application on the below site and played around with the masses (one representing the arms and the other the club). www.math24.net/double-pendulum/If one just starts the pendulum with a 180 degree angle (ie. no wrist cock) and let the weight of the heavier mass (ie. analogous to arms) be similar to a force applied across the distal arm (as shown by my arrow in the 1st snapshot image below), a lag effect occurs (see bottom image). It's definitely not enough proof but still a curious effect (ie. just like a compound pendulum). DG I think that the double pendulum model, which you depict, has no relevance to the release of PA#2 in a golf swing action. The pattern of release of PA#2 in a golf swing has no causal connection with the weight of the clubshaft or clubhead. Jeff.
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Post by dubiousgolfer on Jun 19, 2019 12:04:10 GMT -5
I've revisited the diagrams above and made it slightly more reflective of an actual swing (using a pivot torque rather than weight). It still shows a force F1 that will cause m1 (distal mass point) to rotate and align itself with F1. If I've got the physics correct and it reflects what actually happens in a golf swing ,then to stop that clockwise rotation one would need apply a bracing positive torque/couple via the hands (or let the club rotate clockwise until one reached the limit of left wrist radial deviation - which will then become that bracing torque). I've emailed Dave Tutelman about the above (no reply yet) but I've also asked a physics professor (awaiting reply). I think my confusion is the PP1 pressure force. Isn't it also likely that applying that force on the aft side of the grip may also cause the last 3 fingers of the right hand to also push on the forward side of the grip? This would cause an active right wrist torque (a couple) but this could not be applied if forward shaft bend was happening (as Tutelman has shown using ShaftLab research data for pro swings of 5 iron- Driver). But active right wrist torque might be useful for short irons , and speciality shots out of rough. So I'm wondering whether 'hitting' is actually 'active right wrist torque' happening in the golf swing when using a dominant PA1# release (with PP1 and PP3 linear pressure forces being applied but also pressure forces being applied on the grip by the last 3 fingers of the right hand). DG
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