A look at various pivot torques

[JeffM]

Daniel

It is not at all clear to me that the hand action is V-shaped. Here is a photo showing the splined movement of the hands in the downswing - I think that the hands move along a circular-shaped arc down to impact, through the impact zone, and into the followthrough. The lowest part of the hand arc is very shallow as seen from the front.

Jeff.

 

[mandrin]

mandrin

I was aware that the PingMan machine has a dead stop that prevents the club from going back to >90 degrees at the end-backswing position. However, it still has a free hinge throughout the ENTIRE downswing. The dead stop does not prevent premature release or otherwise interfere with the release phenomenon once the downswing commences. The dead stop does not allow the machine to "hold" the release until a set point in the downswing - as you pre-specified in your paper.

I look forward to see how you deal with three problem issues that I brought to your attention.

Jeff.

JeffMann,

You don’t have any technical specifications and yet decide how the machine operates. Is this to be qualified as wishful thinking rather than objective information?

Mathematics clearly show that it is really very, very dificult indeed to have two linked segments describe a motion such as a golf swing and not have the inner segments slow down.

You most likely respect Brian for his knowledge re to matters regarding golf. If he assures you that hands do slow down, are you going to believe him?

If you still want to believe that the hands have ideally a constant linear velocity throughout the swing, well that is fine with me. You are definitely free to believe whatever suits you.

You remarks about the COG don’t make sense whatsover. There are so many preconceived ideas that it is like having to start absolutely from zero to help you understand.

A simple flexible mathematical model is not to exactly duplicate a real golfer neither is a very primitive golf robot. The special interest in a math model is to be able to analyze various trends, such as did.

I have posted about a varity of subjects such as for instance the self regulating effect inherent in a golf swing, so please be a bit careful with presumptuous conclusions supported by anectdotal tidbits.

 

[daniell]

Jeffman,

That's why it's an illusion.

You are placing the hand position of a 3D swing in 2D. Go and test it out yourself whether you can swing in a circular arc shape in 2D? Try it. By that I mean in only the vertical plane which is what you see in 2D images and without and pivot rotation. It will not look like a golf swing, I assure you.

cheers,

daniel

 

[JeffM]

Daniel

When presented with two 2D images of the hand swing arc at right angles to each other, I believe that it is very easy to imagine the 3D image of the hand swingarc. Although the hand swingarc is U-shaped as seen from the front, it is along an inclined arc when viewed from the side. I have zero difficulty moving my hands in space along that imagined 3D hand swing arc.

Mandrin

I don't need to know how the PingMan machine operates internally - I only have to look at the movement of the central arm in space, and freeze its action frame-by-frame to note that it does not slow down through the impact zone.

You state that mathematics shows that it is difficult to have a golf swing motion where the inner segment (left arm) doesn't slow down. That's the problem with mathematics! Mathematics doesn't create reality - its main function is to explain reality. I don't think that Tiger Woods, and most good golfers have that problem - of needing to slow the left arm down 0.1 seconds prior to impact. Regarding Brian's opinion regarding hand slowing - I haven't seen him state when the hands slow down (0.1 seconds prior to impact as your mathematical model predicts, or 0.03 seconds prior to impact as Jay's analysis of Tiger Woods swing shows).

Although the PingMan machine has a constant velocity hand downswing action, I don't know if that is the best approach for a golfer. It may well be that a downswing action that causes the hands to have a low rate of steadily increasing acceleration throughout the downswing (maintaining constant lag pressure on the right second finger's lag pressure point) may be better in terms of sustaining lag through the impact zone.

I agree that mathematics can be useful in analysing trends, like the effect of varying degrees/patterns of shoulder torque on club release. However, the mathematical analysis must not have artifical "a priori" assumptions - eg. that the club must retain a 90 degree lag angle at a point 60 degrees to the negative Y axis, and that the COG of the club is at the grip end of the club. I think that if you ignore the fact that the COG of the club is near the peripheral end of the club, and that it results in the club gaining angular momentum when a linear force pulls the grip end of the club towards the ball in the downswing, then your mathemtical analyis of the release phenomenon is going to be inaccurate (not concordant with reality).

Jeff.

 

[nmgolfer]

SECUNDUM QUID

JeffMann,

You don’t have any technical specifications and yet decide how the machine operates. Is this to be qualified as wishful thinking rather than objective information?

Pot calls kettle black... Isn't this is exactly what you've done by assuming a math model in any way shape or form resembles the actual pingman machine or further still... golf swing?

Mathematics clearly show that it is really very, very dificult indeed to have two linked segments describe a motion such as a golf swing and not have the inner segments slow down.

Nonsense. The math model shows that torque would need to vary in order to keep the inner segment rotating at constant speed. This is easily achieved using either electric or fluid power drive mechanisms... that is if (constant speed) is indeed is the design goal.

You most likely respect Brian for his knowledge re to matters regarding golf. If he assures you that hands do slow down, are you going to believe him?

This is a fine example of multiple logical fallacies...

ARGUMENTUM AD POPULUM Description: An argument that appeals to the beliefs of the multitude (i.e., the "populace"). Another way of putting it: Speaker deals with passions of audience rather than with salient issues. This fallacy is also known as "Appeal to Tradition" Ad populum arguments often occur in (1) propaganda, (2) demagoguery, and (3) advertising.

SHIFTING THE BURDEN OF PROOF Description: The burden of proof is always on the person making the assertion or proposition. Shifting the burden of proof, a special case of "argumentum ad ignorantium," is a fallacy of putting the burden of proof on the person who denies or questions the assertion being made. The source of the fallacy is the assumption that something is true unless proven otherwise.

Appeal To False Authority: Your logical fallacies aren't logical fallacies at all because Einstein said so.

If you still want to believe that the hands have ideally a constant linear velocity throughout the swing, well that is fine with me. You are definitely free to believe whatever suits you.

Nowhere did I read JeffMann claim that constant velocity is ideal. This is an example of:

STRAW MAN: a fallacy to misrepresent someone else's position for the purposes of more easily attacking it, then to knock down that misrepresented position, and then to conclude that the original position has been demolished. It is a fallacy because it fails to deal with the actual arguments that one has made.

A simple flexible mathematical model is not to exactly duplicate a real golfer neither is a very primitive golf robot. The special interest in a math model is to be able to analyze various trends, such as did.

Exactly... Which is why assuming a golfer's hand slow down (because the central pivot in a simple math model does) is ridiculous.

I have posted about a varity of subjects such as for instance the self regulating effect inherent in a golf swing, so please be a bit careful with presumptuous conclusions supported by anectdotal tidbits.

FALSE ANALOGY Description: An analogy is a partial similarity between the like features of two things or events on which a comparison can be made. A false analogy involves comparing two things that are NOT similar. Note that the two things may be similar in superficial ways, but not with respect to what is being argued.

You've shown a matlab (or other canned math package) double pendulum model that is limited by various assumptions (see club head acceleration thread) any one of which disqualifies it as being representative of a real golf swing.... that's all. Valid conclusions about the golf swing cannot be made from it.

For those who may not know... there are four steps involved when ever a scientific or engineering problem is solved:

1) CLEARLY state the problem, including simplifying assumptions

2) Develop a mathematical statement of the problem in a form that can be solved for a numeric answer.

3) Solve the equations from 2.

4) INTERPRET the numerical results to arrive at conclusion(s). This step required experience and understanding of the situation in which the problem is embedded. INTERPRETATION of results is always the hardest part of solving any problem and interpretation cannot be taught. Interpretation is where most scientists, engineers (and mathematicians) go astray.

Because of difficulties involved in step 4. the target audience must think critically.... they must look for the logical fallacies in the scientist's (engineer or mathematician) argument. Failure to think critically leads one to being duped... sold a bill of goods... misinformed.... made a fool of. Hence the need for peer review and presentation of papers at conferences etc. so-forth.

 

[mandrin]

nmgolfer, thanks for another fun post. I am surprised hcw has not yet shown his appreciation but I am sure he will come around. Anyhow, thanks for great entertainment.

Because of difficulties involved in step 4. the target audience must think critically.... they must look for the logical fallacies in the scientist's (engineer or mathematician) argument. Failure to think critically leads one to being duped... sold a bill of goods... misinformed.... made a fool of. Hence the need for peer review and presentation of papers at conferences etc. so-forth.

I suggest that you show again your post #201, you so quickly deleted, as a very nice example of a serious logical fallcy in a scientist's (engineer or mathematician) argument.

 

[nmgolfer]

Blah Blah Blah deleted....
I suggest that you show again your post #201, you so quickly deleted, as a very nice example of a serious logical fallcy in a scientist's (engineer or mathematician) argument.

Quickly deleted? My 201 post stood for more than a day during which you had ample time to respond. Yet you didn't respond. You waited until AFTER I exposed my error, after I openly admitted I was WONG and after I told everyone WHY! The record doesn't lie... but you do don't you mandrin.

I encourage everyone to read that thread and the one that preceded it (on the CF myth) where Ringer (who I believe admits to having received no technical education) effectively check-mated mandrin. He's been attempting to rescue his sullied reputation every since ringer embarassed him but as we all know, egomaniacs seldom admit their mistakes, learn and move on.

I dare say the only thing mandrin has demonstrated on this forum is how a person devoid of defensible positions quickly reaches the bottom of the barrel and resorts to:

ARGUMENTUM AD HOMINEM Description: An argument that attempts to disprove the truth of what is asserted by attacking the speaker rather than the speaker's argument. Another way of putting it: Fallacy where you attack someone's character instead of dealing with salient issues. There are two basic types of ad hominem arguments: (1) abusive, and (2) circumstantial.

then he cries foul and acts surprised when the dialog devolves into ordinary mud-slinging.

 

[mandrin]

Having fun

nmgolfer, I definitely like your posts for their entertainment value. But honestly I did not expect so much of it. So, thanks, and keep trucking.

 

[daniell]

JeffMan,

The arc is caused by pivot action (including shoulder turn) and axis tilt. If you keep you shoulders totally square and do not rotate at all, how does the hand movement look like? Not a 'V'? Can you move the club in an arc?

cheers,

daniel

 

[JeffM]

Daniel

Of course! The swingarc will be more V-shaped if one simply moves the arms without simultaneously moving the torso.

However, the "real" golf swing is a synchronous combination of a torso pivoting-shift-rotation movement + arms swinging across the front of the pivoting-rotating torso. The end-result is a smooth hand swing arc as demonstrated by Aaron Baddeley in those two 2D photos. It's the simultaneously-occurring synchronised movement of the torso that turns a V-shaped hand swingarc into a shallower U-shaped hand swingarc.

Jeff.

 

[mandrin]

reading skills

If you still want to believe that the hands have ideally a constant linear velocity throughout the swing, well that is fine with me. You are definitely free to believe whatever suits you.

Nowhere did I read JeffMann claim that constant velocity is ideal. This is an example of:
STRAW MAN: a fallacy to misrepresent someone else's position for the purposes of more easily attacking it, then to knock down that misrepresented position, and then to conclude that the original position has been demolished. It is a fallacy because it fails to deal with the actual arguments that one has made.

nmgofer, to help you improve a bit your reading skills just a reminder of what JeffMann posted before on this matter. I know that you are going to perform your usual spin/twist re. to the word 'ideal' to save your face but you won't fool nobody.

I presume that the downswing action is due to a central force acting at the central hinge point that causes the central arm to move at a "fixed" and CONSTANT rate of speed during the downswing, and that this speed is user-controllable.

I presume that the reason is due to the fact that the clubhead is gaining momentum during the start of the downswing, but that it cannot move faster than the central arm and hands (peripheral hinge joint) which are pulling the club around in a circle at a CONSTANT rate of speed.

It will happen naturally/automatically if one moves the hands at a reasonably fast and CONSTANT rate of speed during the downswing AND if one has very relaxed wrists that do not impede/resist the automatic uncocking of the wrists that will occur after the club reaches the delivery.
In other words, one must maintain a CONSTANTLY fast forward movement of the hands through impact and into the followthrough.

I think that Tiger Woods swings like that (like the PingMan machine), and that there is NO slowing of his hands at impact .

 

[daniell]

JeffMan,

Now that we are on the same frequency, we probably also agree that at the bottom of the V, the velocity of the hand should be zero or thereabouts. Thus the movement of the hands just before and after impact is a result of the pivot. Please relate this to Mandrin's initial post.

Quote from Mandarin: "... The three different cases analyzed show that it is always there but a function of the pivot torque. If there is torque during impact there will be less slowing down as is to be expected".

They both agree, don't they?

cheers,

daniel

 

[JeffM]

Mandrin

I think that you being unfair to nmgolfer, and misinterpreting my previous comments.

I first stated that the PingMan machine seemed to have a constant velocity arm/hand swing. I then secondarily implied that a golfer could mimic the action of the PingMan machine by trying to move the hands at a constantly fast speed during the downswing. I thirdly stated that I sensed that Tiger Woods also swung like that with no slowing of the hands at impact.

However, I did not state that a constant velocity hand swing was the optimum/ideal method of moving the hands in the downswing. I don't know what's the ideal pattern, and a low rate of steadily increasing hand velocity may even be better, but I remain undecided/neutral regarding this issue pending further information.

Note that I stated in that post that I "think" that Tiger Woods did not slow his hands down at impact. However, I subsequently changed my mind when I personally analysed his BIzHub swing video using my swing analyser program. I then thought that he was definitely slowing his hands down just prior to impact. Now, based on Jay's subsequent input, I am less sure when the slowing actually occurs - it seems to occur immediately before impact (<0.03 seconds prior to impact). What still interest me greatly - what's the biomechanical reason for ANY hand slowing prior to impact.

Jeff.

Daniel

I don't agree that there should be any hand slowing at the bottom of the V, because there is no V in the full golf swing. The hands are actually moving along a shallow U-shaped arc in the immediate pre-impact area - as can clearly be seen in those capture images of Aaron Baddeley's swing, which show the splined hand path.

Jeff.

 

[daniell]

Jeff,

Mandrin puts it that the hand speed is a function of pivot toque. I agree and I have tried to explain the illusion. At and around impact, if the pivot slowed then the hands will slow down, if the pivot stoped then the hand would be quite stationary as it is at the bottom of the V. You have to see the movement of the clubhead relative to the hands.

But I guess the above will not change your mind and you are most welcome to have your own opinion on this one. ;-)

cheers,

daniel

 

[mandrin]

Houston, there is a problem.

Having studied seriously the PingMan's release action using his V1 Home swing analyser tool, JeffMann has come to the conclusion that it operates with constant ‘hand speed’. From there he has gone into the significant implications for understanding the natural release action in the full golf swing, particularly holding the angle in the first part of the down swing.

There is however a small problem.

Analyzing his presumption about the PingMan machine mathematically on derives the conclusion that such a machine does not have to worry about holding any angle since it is simply not able to hit any ball.

For any velocity there is always the identical release pattern. It varies a bit using different golf clubs but it is essentially as depicted in the figure above. It does not really look that one can learn anything useful from JeffMann’s version of the PingMan machine.

Instead of ‘PingMan’ showing us how to hold the angle, the machine, as imagined by JeffMann, is vigorously throwing the club from the top. JeffMann, perhaps time to go back to the drawing table, or perhaps to get inspired by nmgolfer’s unique view on this matter.

Now I am expecting a 100 page long post form nmgolfer, half Latin, half English, to yet again denounce this scoundrel mandrin. Perhaps for not having specified this time the color of the servo motor in my analysis.

 

[hcw]

things that make you go, Hmmmmm

Mandrin

I think that you being unfair to nmgolfer, and misinterpreting my previous comments.

shocking, just shocking...what has gotten into him?

What still interest me greatly - what's the biomechanical reason for ANY hand slowing prior to impact.

besides the whole lead/trail hand pivot point deal try this:

it appears to slows down heading down the target line in 2D front/face on pictures b/c in 3D it has started to go back left/inside the target line

...think about it and check out the "frontview" and "sideview" of tiger's nike commercial...

-hcw

 

[mandrin]

Newton

Mandrin

I think that you being unfair to nmgolfer.

I am so sorry, I really sympatize with the poor lad.

Mandrin

What still interest me greatly - what's the biomechanical reason for ANY hand slowing prior to impact.

Perhaps time to seriously start thinking about Newton’s third law.

 

[Bronco Billy]

Having studied seriously the PingMan's release action using his V1 Home swing analyser tool, JeffMann has come to the conclusion that it operates with constant ‘hand speed’. From there he has gone into the significant implications for understanding the natural release action in the full golf swing, particularly holding the angle in the first part of the down swing.

There is however a small problem.

Analyzing his presumption about the PingMan machine mathematically on derives the conclusion that such a machine does not have to worry about holding any angle since it is simply not able to hit any ball.

For any velocity there is always the identical release pattern. It varies a bit using different golf clubs but it is essentially as depicted in the figure above. It does not really look that one can learn anything useful from JeffMann’s version of the PingMan machine.

Instead of ‘PingMan’ showing us how to hold the angle, the machine, as imagined by JeffMann, is vigorously throwing the club from the top. JeffMann, perhaps time to go back to the drawing table, or perhaps to get inspired by nmgolfer’s unique view on this matter.

Now I am expecting a 100 page long post form nmgolfer, half Latin, half English, to yet again denounce this scoundrel mandrin. Perhaps for not having specified this time the color of the servo motor in my analysis.

Hi There

Looks Like You Whiffed this One Jeff..... I Have a DVD with Extensive Views of Iron Byron... In Every View the Arm Starts Out a 0 Velocity and the Arm Appears to Accelerate thru Impact..... Now How in the Hell can the Arm have Constant Velocity when it is Accelerating???? Mandrin's Model Clearly Shows the ClubHead Not Contacting the GolfBall Using Your Scenario .......

Cheers

 

[nmgolfer]

Yawn......

Mandrin... You are so predictable. I knew when you built that constant velocity STRAW MAN you were preparing to shoot down an argument that had not been made (by anyone except perhaps BB). Your chess is not so good. One move ahead won't cut it. Funny how easy it was for ringer to checkmate you mate.

Its cute and I'm flattered how you have taken to copying my verbiage. Maybe you'll copy my example and get instep with reality too.

Why must I have to tell you that what your math package has drawn for you cannot happen in the real word? In the real world things do not have step-function velocity increases. Zero to sixty in zero seconds ain't possible mandrin.

For that reason you should understand why Homer's endless belt analogy is useless. Wait... you did know that yesterday yet it did not stop you from posting a direct corollary that is not physically possible today. One must conclude you do not care to be correct. One must conclude you're never going to be any good at interpreting you own results. You might make a good tech-aid (the people we give mundane routine tasks to) like Homer was at the kite factory though.

Having studied seriously the PingMan's release action using his V1 Home swing analyser tool, JeffMann has come to the conclusion that it operates with constant ‘hand speed’. From there he has gone into the significant implications for understanding the natural release action in the full golf swing, particularly holding the angle in the first part of the down swing.

There is however a small problem.

Analyzing his presumption about the PingMan machine mathematically on derives the conclusion that such a machine does not have to worry about holding any angle since it is simply not able to hit any ball.

For any velocity there is always the identical release pattern. It varies a bit using different golf clubs but it is essentially as depicted in the figure above. It does not really look that one can learn anything useful from JeffMann’s version of the PingMan machine.

Instead of ‘PingMan’ showing us how to hold the angle, the machine, as imagined by JeffMann, is vigorously throwing the club from the top. JeffMann, perhaps time to go back to the drawing table, or perhaps to get inspired by nmgolfer’s unique view on this matter.

Now I am expecting a 100 page long post form nmgolfer, half Latin, half English, to yet again denounce this scoundrel mandrin. Perhaps for not having specified this time the color of the servo motor in my analysis.

 

[Bronco Billy]

Why must I have to tell you that what your math package has drawn for you cannot happen in the real word? In the real world things do not have step-function velocity increases. Zero to sixty in zero seconds ain't possible mandrin.

Hi nm

Why Don't you Tell JeffMan this Startling Revelation???? He's the One that Doesn't Seem to Get This.... Mandrin's just Modeling what the JeffMan Observed......

Cheers