A look at various pivot torques

[mandrin]

Perfect robot

Mandrin...

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.

nmgolfer,

I was hesitating between color of servo motor and initial conditions but decided to take color of servo motor since I expected you to pick the initial conditions and wanted to know if you were that predictable. And no surprise, I was perfectly on the money. You picked indeed initial conditions. You are so predictable my dear friend it is almost like a programmable golf robot.

Oh well, by having one’s nose continuously in the dirt there is not much more than left than picking up some dust particle here and there. But don’t despair keep reading me and slowly and steadily you will see the light. You might even forget your Latin in the process.

Are you feeling any better now having told mandrin what you feel about him. It truly hope so. It definitely has a therapeutic value to get it all of your chest. For any support I can possibly give you, in any way possible, to help you to regain some confidence, just let me know.

 

[JeffM]

Bronco Billy

My presumption that the PingMan machine has a constant velocity could be wrong. When I refer to "constant velocity" there obviously has to be a short period at the very start of the downswing when the central arm has to gain speed as it starts at zero velocity. Therefore, the central arm has to accelerate initially. However, it "appears" to move at a constant velocity in the mid-late downwsing and followthrough. I can easily imagine designing a torque motor with a gearing system that can produce a constant velocity arm swing after a short initial period of acceleration. I use the word "appears" with respect to "constant velocity" because it is simply based on my observation of the PingMan machine's swing action using a swing analyser program. It could well be true that the central arm actually accelerates through impact, as you claim the Iron Byron machine does. Either way, it certainly doesn't seem to decelerate through impact. Most importantly, the PingMan machine can execute a natural release pheneomenon and get forward shaft lean at impact. Mandrin seems to believe that this is impossible if the arm is moving at constant velocity. What is the basis for Mandrin's claims? It is based on a simplistic mathematical model for a two lever system. His model produces a diagram that shows that the clubhead outraces the hands (peripheral hinge joint) well before impact. However, we know nothing about the inbuilt assumptions used in his mathematical modelling. Most importantly, his model obviously doesn't consider a critical factual element that applies to a "real" golf swing - that the COG of the club is close to the peripheral end of the club and that it will result in angular acceleration of the clubshaft if the force pulling the grip end of the club is linear. NOT including that critical factor in his calculations makes his mathematical modelling inherently inaccurate.

Mandrin states that we cannot learn anything useful from the PingMan machine. I think that we can learn something very useful - that it is possible for a machine to have a constant velocity (or near-constant velocity) arm swing through the impact zone, with no slowing near impact, and still produce a perfect release action and a perfectly sustained lag at impact - despite theoretical mathematical models claiming that this feat is simply not possible.

Jeff.

 

[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

Bronco Billy,

As you mentioned my intention was simply to clear up Jeffmann’s ideas, translating it into mathematics.

I am glad someone is seeing the peculiar tactics of nmgofler. He could be a perfect spin doctor for any president.

 

[JeffM]

danieel - you write-: "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."

There is one major problem with your conception of the golf swing. You conceive that hand speed is a function of pivot torque, and you believe that the pivot slows down PRIOR to impact. However, although the hip pivot action slows down prior to impact, there is no necessary biomechanical reason why the shoulder pivot action has to slow down prior to impact. The two forces driving the conjoined hand unit during the downswing can be thought of as a pull-force and a push-force. The pull-force comes from the downswing pivot action which throws the entire torso around to the left towards the ball, and the leftwards rotation of the torso pulls the left arm leftwards + a pulling force from the left shoulder girdle muscles that pull the left arm across the chest during the downswing. Both of these pull-forces probably dissipate prior to impact for obvious biomechanical reasons. However, there is a push-force also operant during the dowswing. That push-force comes from the right mid-upper torso muscles which cause the right shoulder to move actively down the RSP line. The force from the right shoulder (really right mid-upper torso) pushes the club forward via the right arm/forearm and that force is applied to the grip end of the club via the right hand. The following diagram shows how the force from the right-side is applied to the top of the left hand and consequently to the grip end of the club (see yellow-colored area).

The right-sided push-force can still operate through the late phase of the downswing and push the conjoined hand unit (and secondarily the left arm) at a fast rate through the impact zone. Can you postulate a biomechanical reason why the right-sided push-force must lessen prior to impact?

Jeff.

 

[JeffM]

mandrin

Can you be fair/neutral, and accept this challenge?

Plug the following parameters into your mathematical model - a short period of central arm acceleration at the start of the downswing which allows the central arm to reach a constant rate of velocity at about the 9 o'clock position, and then a constant central arm velocity from the 9 o'clock position to impact (~ 5 o'clock position) with NO slowing in the pre-impact phase of the downswing. What type of diagram does your revised mathematical model produce?

Jeff.

 

[Bronco Billy]

mandrin

Can you be fair/neutral, and accept this challenge?

Plug the following parameters into your mathematical model - a short period of central arm acceleration at the start of the downswing which allows the central arm to reach a constant rate of velocity at about the 9 o'clock position, and then a constant central arm velocity from the 9 o'clock position to impact (~ 5 o'clock position) with NO slowing in the pre-impact phase of the downswing. What type of diagram does your revised mathematical model produce?

Jeff.

Hi There

I Also Would Like to See a Diagram of a Constant Acceleration of the Arm from 0 Start Thru Impact.... I'm Bettin No Release Occurs .......

Cheers

 

[mandrin]

Most importantly, his model obviously doesn't consider a critical factual element that applies to a "real" golf swing - that the COG of the club is close to the peripheral end of the club ……… NOT including that critical factor in his calculations makes his mathematical modelling inherently inaccurate.

Discussion in short posts is already a dificult matter thing but simply saying things which are not true makes any useful exchange rather arduous and perhaps even impossible and hence a waste of my time.

 

[nmgolfer]

nmgolfer,

I was hesitating between color of servo motor and initial conditions but decided to take color of servo motor since I expected you to pick the initial conditions and wanted to know if you were that predictable. ... blah blah blah more lies and nonsense deleted...

Yah... right everything's ex post facto with you. Your credibility is shot. Now its all just lies.

Oh well, by having one’s nose continuously in the dirt ... blah blah blah more lies and nonsense deleted...

You would know... As hcw wisely pointed out... pigs love playing in the dirt preferably with water added.

Are you feeling any better now having told mandrin what you feel about him.... blah blah blah more lies and nonsense deleted...

Huh? I haven't told "mandrin" what I feel about him... that post would surely be deleted and lead to my immediate expulsion from this forum.

On another note, this exchange has become boring... Its clear you have nothing to contribute to my better understanding of the golf swing and that you have but one goal: (to get Brian to seal off this thread too because in it your technical ineptitude and deviousness has exposed once again). So I shall leave this discussion to those who are still amused by you and your vainglorious and puerile ways.

 

[Jared Willerson]

Yah... right everything's ex post facto with you. Your credibility is shot. Now its all just lies.



You would know... As hcw wisely pointed out... pigs love playing in the dirt preferably with water added.



Huh? I haven't told "mandrin" what I feel about him... that post would surely be deleted and lead to my immediate expulsion from this forum.

On another note, this exchange has become boring... Its clear you have nothing to contribute to my better understanding of the golf swing and that you have but one goal: (to get Brian to seal off this thread too because in it your technical ineptitude and deviousness has exposed once again). So I shall leave this discussion to those who are still amused by you and your vainglorious and puerile ways.

I get the feeling you guys are not mad at all, just funning with each other.

 

[Bronco Billy]

Bronco Billy

My presumption that the PingMan machine has a constant velocity could be wrong. When I refer to "constant velocity" there obviously has to be a short period at the very start of the downswing when the central arm has to gain speed as it starts at zero velocity. Therefore, the central arm has to accelerate initially. However, it "appears" to move at a constant velocity in the mid-late downwsing and followthrough. I can easily imagine designing a torque motor with a gearing system that can produce a constant velocity arm swing after a short initial period of acceleration. I use the word "appears" with respect to "constant velocity" because it is simply based on my observation of the PingMan machine's swing action using a swing analyser program. It could well be true that the central arm actually accelerates through impact, as you claim the Iron Byron machine does. Either way, it certainly doesn't seem to decelerate through impact. Most importantly, the PingMan machine can execute a natural release pheneomenon and get forward shaft lean at impact. Mandrin seems to believe that this is impossible if the arm is moving at constant velocity. What is the basis for Mandrin's claims? It is based on a simplistic mathematical model for a two lever system. His model produces a diagram that shows that the clubhead outraces the hands (peripheral hinge joint) well before impact. However, we know nothing about the inbuilt assumptions used in his mathematical modelling. Most importantly, his model obviously doesn't consider a critical factual element that applies to a "real" golf swing - that the COG of the club is close to the peripheral end of the club and that it will result in angular acceleration of the clubshaft if the force pulling the grip end of the club is linear. NOT including that critical factor in his calculations makes his mathematical modelling inherently inaccurate.

Mandrin states that we cannot learn anything useful from the PingMan machine. I think that we can learn something very useful - that it is possible for a machine to have a constant velocity (or near-constant velocity) arm swing through the impact zone, with no slowing near impact, and still produce a perfect release action and a perfectly sustained lag at impact - despite theoretical mathematical models claiming that this feat is simply not possible.

Jeff.

Hi There

Just by Visuals and No measurements of my DVD I Do NOT see any slowing down of the arm thru it's entire Path while the release Always Looks the Same in Numerous Takes.... Something Triggers the Release and I'll be Dammed if I Know what it is..... Also for the Life of Me I Cannot Figure out why you never plotted points thruout the Whole Path of the Arm???? To me this is also a form of "Cooking the Books".... Do You Consider the first Quadrant of the Arm Movement Inconsequential????

Cheers

 

[mandrin]

Hi There

I Also Would Like to See a Diagram of a Constant Acceleration of the Arm from 0 Start Thru Impact.... I'm Bettin No Release Occurs .......

Cheers

Bill,

Here you have it. Constant acceleration throughout. Not quite as you expected.

 

[mandrin]

Go in peace my friend

nmgolfer,

Pity, that you have to go again into another early retirement; I started to enjoy the slow process of working at your education.

You mentioned on several occasions your somewhat strange but interesting hobby – pig wrestling.

I will confess my hobby as a farewell gift – needling big fat inflated balloons. I love the sound and the trajectory.

 

[Bigwill]

Bill,

Here you have it. Constant acceleration throughout. Not quite as you expected.

Could you explain this verbally? It seems counterintuitive that the club would catch up to the arm so early if the arm is in a constant state of acceleration. Also, explain verbally how to keep the club from catching up prematurely, as it relates to acceleration?

 

[mandrin]

mandrin

Can you be fair/neutral, and accept this challenge?

Plug the following parameters into your mathematical model - a short period of central arm acceleration at the start of the downswing which allows the central arm to reach a constant rate of velocity at about the 9 o'clock position, and then a constant central arm velocity from the 9 o'clock position to impact (~ 5 o'clock position) with NO slowing in the pre-impact phase of the downswing. What type of diagram does your revised mathematical model produce?

Jeff.

Jeffmann,

Before I am going to do anything for you let’s put a few dots on the i’s.

You keep referring to my ’simplistic’ mathematics. Is this on purpose or you just don’t know any better?

How should one refer to your doodling with the PingMan machine? As serious science?

Are you aware that by imposing your romantic ideas on the swing that you are reducing it to just one degree of freedom?

You and nmgolfer, as he admitted, are unaware of kinetic chains. With your simplistic approaches one eliminates this essential aspect completely.

How come that you are now eager to have me use that ‘simplistic’ mathematical approach?

How do you know that the artificial ‘a priori’ assumptions of your request are meaningful?

 

[Bronco Billy]

Hilarious

Bill,

Here you have it. Constant acceleration throughout. Not quite as you expected.

Hi There

That's Friggen Hilarious .............

Cheers

 

[JeffM]

mandrin

When you first produced the results of your mathematical analysis using varying shoulder torques, I presumed that your mathematical program had to start with an independent variable (central torque power) and then calculate the results for two dependent variables (central arm speed and peripheral arm speed). Your initial calculations concluded that the central arm should slow down prior to impact, although you have NOT explained why the central arm has to slow down (based on your mathematical analysis).

Now, I note that your mathematical program can also regard central arm speed as an independent variable, and then calculate a value for the peripheral arm speed as a dependent variable. Your mathemtical program can even estimate exactly where the peripheral lever (club) will be at each moment of the dowswing. Your mathematical program has seemingly allowed you to determine that if the independent variable (central arm movement) has a constant acceleration, then the club will release prematurely.

So, here is my question. There is presumably only a single force operating at the peripheral hinge point, and that force causes the peripheral arm to release. What is the nature of that force? What is the fundamental basis of the mathematical formula that allows you to categorically state where the peripheral arm (club) will be at each moment of the downswing? I suspect that nm golfer would state that the force operating at the peripheral hinge point is simply a linear force pulling the grip end of the club along a circular path, and that one can use simple physics to predict the movement of the peripheral arm - based on his explanation. Is your mathematical explanation identical/similar/different to nmgolfer's explanation? When your mathematical formula calculates the speed/position of the peripheral arm (club) for ANY point in time during the downswing, does your mathematical formula produce a different result under the following different conditions - i) the peripheral lever is made of a homogenous material where the COG of the peripheral arm is at the center of the arm, ii) the peripheral arm is made of a heterogenous material and where the COG is near the far end of the peripheral arm, iii) the peripheral arm is made of heterogenous material and where the COG is near the near end of the peripheral arm?

Jeff.

 

[JeffM]

Bill,

Here you have it. Constant acceleration throughout. Not quite as you expected.

Mandrin - In this diagram, your mathematical analysis demonstrates that the club releases very early. However, in your initial presentation, when you presented the results of three different shoulder torque patterns, you pre-specified that the peripheral arm should still have a 90 degree angle to the central arm when the central arm reached a position that is 60 degrees from the negative Y axis. Why was it necessary to have that pre-specification in your initial mathematical model, while it seemingly is not necessary in this model?

Second question - do you think that the point of release, and the exact amount of club throwaway, in a "real" golf swing will exactly mimic this diagram's pattern - if the "real" golfer has a constantly accelerating arm/hand downswing action?

Jeff

 

[Bronco Billy]

mandrin

When you first produced the results of your mathematical analysis using varying shoulder torques, I presumed that your mathematical program had to start with an independent variable (central torque power) and then calculate the results for two dependent variables (central arm speed and peripheral arm speed). Your initial calculations concluded that the central arm should slow down prior to impact, although you have NOT explained why the central arm has to slow down (based on your mathematical analysis).

Now, I note that your mathematical program can also regard central arm speed as an independent variable, and then calculate a value for the peripheral arm speed as a dependent variable. Your mathemtical program can even estimate exactly where the peripheral lever (club) will be at each moment of the dowswing. Your mathematical program has seemingly allowed you to determine that if the independent variable (central arm movement) has a constant acceleration, then the club will release prematurely.

So, here is my question. There is presumably only a single force operating at the peripheral hinge point, and that force causes the peripheral arm to release. What is the nature of that force? What is the fundamental basis of the mathematical formula that allows you to categorically state where the peripheral arm (club) will be at each moment of the downswing? I suspect that nm golfer would state that the force operating at the peripheral hinge point is simply a linear force pulling the grip end of the club along a circular path, and that one can use simple physics to predict the movement of the peripheral arm - based on his explanation. Is your mathematical explanation identical/similar/different to nmgolfer's explanation? When your mathematical formula calculates the speed/position of the peripheral arm (club) for ANY point in time during the downswing, does your mathematical formula produce a different result under the following different conditions - i) the peripheral lever is made of a homogenous material where the COG of the peripheral arm is at the center of the arm, ii) the peripheral arm is made of a heterogenous material and where the COG is near the far end of the peripheral arm, iii) the peripheral arm is made of heterogenous material and where the COG is near the near end of the peripheral arm?

Jeff.

Hi Jeff

It's NOT Friggen Algebra...... It's Friggen Differential Equations.... The Gifted can Model anything in the Universe.... In Fact They Have..... This model will Show ALL Cases of a Double Pendulum which is used to Model the Golf Swing...... CHAOS.......

Cheers

 

[mandrin]

mandrin

Can you be fair/neutral, and accept this challenge?

Plug the following parameters into your mathematical model - a short period of central arm acceleration at the start of the downswing which allows the central arm to reach a constant rate of velocity at about the 9 o'clock position, and then a constant central arm velocity from the 9 o'clock position to impact (~ 5 o'clock position) with NO slowing in the pre-impact phase of the downswing. What type of diagram does your revised mathematical model produce?

Jeff.

JeffMann,

You can shuffle your cards as much as you want, it is of no avail. I am trying to be gentle about it since you spent quite a bit of time on it and defending it tooth and nail, with an interesting but rather verbose discourse, but the simple truth is - your are wrong.

I have taken your specifications and you can judge for yourself. Not much of golf swing. I hope this is a good lesson for you and hopefully for others. The numerical solution of coupled nonlinear differential equations is not solved simply by intuition.

 

[JeffM]

Mandrin - I agree with you. Your mathematical model doesn't produce a good club release pattern.

You seemingly believe, with a great deal of certainty, that your mathematical model accurately predicts reality. I, however, disagree - because I think that many PGA tour players (like Tiger Woods) have a downswing arm/hand action that starts with a steady acceleration and then has a constant, or near-constant, velocity through most of the remainder of the swing (even if the hands slows down 0.03 seconds prior to impact). Your model predicts that those PGA tour players should have a club release that is already complete by the 10 o'clock position (arm and clubshaft are in a straight line). Why?

I personally believe that your model's predictive ability regarding the release phenomenon is very poor - with respect to "real" golf swings. Am I right or wrong? Surely, the answer depends on the biomechanical principles underlying your mathematical model's calculations. So, again, I request the following information.

1) There is one independent variable (speed of the central arm) and one dependent variable (speed of the peripheral arm/club). The cause-and-effect relationship between the independent variable and the dependent variable must be defined by a set of mechanical/physical principles. What is the fundamental principle of the force acting at the peripheral hinge point?

Is that force acting on the grip end of the club as a linear force pulling at a passive free-hinge point? Is your mathematical calculations similar to nmgolfer's explanation, and if not, why not?

2) Will the predicted release phenomenon be different for the following three scenarios - i) the peripheral lever is made of a homogenous material where the COG of the peripheral arm is at the center of the arm, ii) the peripheral arm is made of a heterogenous material and where the COG is near the far end of the peripheral arm, iii) the peripheral arm is made of heterogenous material and where the COG is near the near end of the peripheral arm?

You state that I am "shuffling my cards" implying that I am not being clearly forthright about my own position. I may certainly be wrong - but I have stated my position as clearly as I can, and I have divulged my thinking/assumptions as clearly/lucidly as I can accomplish that goal. Now it is your turn to divulge all the assumptions/principles underlying your mathematical model, so that forum members can independently judge the likely legitimacy of your mathematical modelling without being predjudiced by my personal opinions.

Jeff.