Form is simply a means of consistency (a physics based approach)

[pongguy69]

I'm posting here mostly to jot my thinking down and see if others have had similar ideas.

I've found that reducing ping pong to a simpler physics model has helped me understand the game way better. Note that I'm ~intermediate and this is intended for beginner / intermediate level.

Given an incoming ball with:

• velocity (3D vector + linear speed), and
• spin (3D rotational vector about the centre + rotational speed),

we can reduce the "shot" to a couple variables in our control:

1. contact point on the ball
2. relative speed of racket along the tangent (where, tangent is described as the vector along the surface of the ball)
3. relative speed of the racket along the normal (where, normal is described as the vector between the contact point and the centre of the ball)
4. when along the ball's arc to execute the shot

NB:

• racket motion is "componentized" (def). This is typically understood as how much you are "brushing" vs "hitting" the ball. It's simply: how fast is racket moving "along the surface", and how fast "into the ball".
  
• Incoming speed + spin is definitely a factor, so I use "relative speed" as it relates to the incoming values. I.e. heavy underspin balls will need a different set of variables (contact point, speed_tangent and speed_normal) vs light underspin.
• I use speed here vs. force, since the mass of the ball is negligible in this model
• There are tons of assumptions i'm not stating for simplicity purposes (ball/topsheet/sponge/blade deformation + reaction + vibration, etc).

Back to the model, so with these 4 variables, in theory you're able to craft any shot you want. In practice it's harder of course. It begs the question: (1) How can I identify what motion to apply and where, and (2) how can I execute it consistently?

The former question (1): I believe this is a pattern recognition problem. So just seeing more balls and trying and playing around – this is how you develop your "repertoire of shots".

For the latter question (2): you can think of your "form" is a consistent means to get you these 3 things. The question becomes:

• How can I position my body to reach my contact point with the motion that I want?
• How can I leverage my tools to achieve the racket motion?
  • Tools: legs, hips, core, shoulder, arm, forearm, wrist, fingers
• How can I consistently time it?

Cues like wrist snap, blade angle, "power from the legs", "pushing down on the ball", "follow through", all of that are mental models for you to achieve these 4 things. This physics approach helps me cut through the noise of advice. I've learned to tune out others' advice, as our bodies, minds, and journeys are all unique.

A practical example:
Short heavy underspin to backhand side. I could do the "FZD BH flick", coiling my body and arm system, and skimming the very top of the ball at its apex:

• Contact point: almost top of the ball (y-axis), slight bias towards me (z-axis) and maybe on the left side (right hander) (x-axis)
  • as a result racket angle is almost flat.
• relative tangential speed: very high
• relative normal speed: very low
• Contact time: apex (at highest point, not early not late)

But this is a low percentage shot for me (noob). Thusly, i can tweak these knobs and still get the ball over, with more consistency.

• Contact point: 30% down from the top (y-axis). at 11 o'clock (slight bias for left side) (x-axis). and about 25% in from the point closest to me (z-axis).
  • as a result, racket angle ends up maybe 30deg above the horizon.
• relative tangential speed: high
• relative normal speed: low-medium
• Contact time: slightly early

To do this, I don't have to coil as much as FZD. I generate force from my legs to push my hips out while engagint my shoulder to whip my (loosely held) wrist quickly to generate that tangential force. I don't need to think about normal force as it happens on its own with the BH motion.

What do you think? Over-reductive? Too complex? Obvious?

What got me thinking about this model is the fantastic drupe pong series on physics.

 

[golden_son]

I think you're hitting at the crux of the game mechanics but the calculations (even if mental, and not actually mathematical) are way too complex for most folks. There's also the effect rubber has on these calculations, which can't be ignored. That said for people who think in math/physics terms regularly, it could perhaps help with visualizing certain shots. But I can't imagine it being any more than a tool for figuring out how to play your shots in general, not in real-time.

 

[pongguy69]

yeah absolutely, this is mostly when I'm in the lab/coaching/working on my form, definitely not real time. the mental cues help with turning the lab setting into real time reminders.

 

[NetProphet]

I'm posting here mostly to jot my thinking down and see if others have had similar ideas.

I've found that reducing ping pong to a simpler physics model has helped me understand the game way better. Note that I'm ~intermediate and this is intended for beginner / intermediate level.

Given an incoming ball with:

• velocity (3D vector + linear speed), and
• spin (3D rotational vector about the centre + rotational speed),

we can reduce the "shot" to a couple variables in our control:

1. contact point on the ball
2. relative speed of racket along the tangent (where, tangent is described as the vector along the surface of the ball)
3. relative speed of the racket along the normal (where, normal is described as the vector between the contact point and the centre of the ball)
4. when along the ball's arc to execute the shot

NB:

• racket motion is "componentized" (def). This is typically understood as how much you are "brushing" vs "hitting" the ball. It's simply: how fast is racket moving "along the surface", and how fast "into the ball".
  
• Incoming speed + spin is definitely a factor, so I use "relative speed" as it relates to the incoming values. I.e. heavy underspin balls will need a different set of variables (contact point, speed_tangent and speed_normal) vs light underspin.
• I use speed here vs. force, since the mass of the ball is negligible in this model
• There are tons of assumptions i'm not stating for simplicity purposes (ball/topsheet/sponge/blade deformation + reaction + vibration, etc).

Back to the model, so with these 4 variables, in theory you're able to craft any shot you want. In practice it's harder of course. It begs the question: (1) How can I identify what motion to apply and where, and (2) how can I execute it consistently?

The former question (1): I believe this is a pattern recognition problem. So just seeing more balls and trying and playing around – this is how you develop your "repertoire of shots".

For the latter question (2): you can think of your "form" is a consistent means to get you these 3 things. The question becomes:

• How can I position my body to reach my contact point with the motion that I want?
• How can I leverage my tools to achieve the racket motion?
  • Tools: legs, hips, core, shoulder, arm, forearm, wrist, fingers
• How can I consistently time it?

Cues like wrist snap, blade angle, "power from the legs", "pushing down on the ball", "follow through", all of that are mental models for you to achieve these 4 things. This physics approach helps me cut through the noise of advice. I've learned to tune out others' advice, as our bodies, minds, and journeys are all unique.

A practical example:
Short heavy underspin to backhand side. I could do the "FZD BH flick", coiling my body and arm system, and skimming the very top of the ball at its apex:

• Contact point: almost top of the ball (y-axis), slight bias towards me (z-axis) and maybe on the left side (right hander) (x-axis)
  • as a result racket angle is almost flat.
• relative tangential speed: very high
• relative normal speed: very low
• Contact time: apex (at highest point, not early not late)

But this is a low percentage shot for me (noob). Thusly, i can tweak these knobs and still get the ball over, with more consistency.

• Contact point: 30% down from the top (y-axis). at 11 o'clock (slight bias for left side) (x-axis). and about 25% in from the point closest to me (z-axis).
  • as a result, racket angle ends up maybe 30deg above the horizon.
• relative tangential speed: high
• relative normal speed: low-medium
• Contact time: slightly early

To do this, I don't have to coil as much as FZD. I generate force from my legs to push my hips out while engagint my shoulder to whip my (loosely held) wrist quickly to generate that tangential force. I don't need to think about normal force as it happens on its own with the BH motion.

What do you think? Over-reductive? Too complex? Obvious?

What got me thinking about this model is the fantastic drupe pong series on physics.

Interesting angle.

I'm not gonna pretend I understand or can critique the calculations.
I would say it is an intelligent deconstruction of the game in a way to isolate the core mechanical componentry. Maybe it's correct, maybe not. If there are things/factors that unconsidered, ommitted or wrongly calculated I am not the guy to point them out.

I would think tho, that for most people it probably won't help their game to think of it in this way. It's just too complicated and excludes the human, emotional, situational, and environmental aspects of the game and all need to be included.

Like, does knowing mechanically and scientifically, every single aspect of how your cars engine and gearbox works make you a better driver?
Or does driving it, experiencing it and learning it through feel make you a better driver?
I think someone can learn to drive equally well if they have no clue about how a car works 🤷
Maybe my analogy doesn't match perfectly but you get my drift 😉

 

[golden_son]

...but you get my drift 😉

 

[pongguy69]

Like, does knowing mechanically and scientifically, every single aspect of how your cars engine and gearbox works make you a better driver?
Or does driving it, experiencing it and learning it through feel make you a better driver?
I think someone can learn to drive equally well if they have no clue about how a car works 🤷
Maybe my analogy doesn't match perfectly but you get my drift 😉

great point! i get your drift

I would say the end state of "better driver" is a bit too general. Let's instead pose a specific case:

• E.g. driving a car in snowy conditions, i attempt to take a turn and I slide, resulting in a wide turn. Knowing that objects in motion tend to stay in motion (car wants to continue straight), and the traction between the tires and the floor is lessened due to the snow, i might diagnose that that turn was too fast for the current conditions.
• I know this example is a bit simplified but this is an example of how understanding the underlying mechanics can help diagnose what went wrong. This can easily be scaled to F1 drivers, who might have varying levels of traction in varying conditions where every inch matters.

overall, i think my post should have clarified this: this is theory. my hope is that once one gains an understanding of this, then shot-making (figuring out why something works vs. why not) becomes much easier. Definitely not calculating these things in real-time; otherwise I'd be Sony's Ace robot.

How this helps me is that I can diagnose the real issues, rather than chasing red herrings from one-liners i've heard from "ping pong form doctors" on the internet.

• E.g. when a ball goes into the net, instead of jumping straight to "I didn't follow through" or "i didn't use my legs enough" (i.e. typical advice you'd hear), I can start with: I didn't brush the ball fast enough, and diagnose from there. what is my biggest lever to get my racket faster brushing?

And i definitely acknowledge – everyone learns differently. I think knowing theory can serve everyone to some degree, but I definitely am a Theory Enjoyer.

 

[Gozo Zyreruna]

I'm posting here mostly to jot my thinking down and see if others have had similar ideas.

I've found that reducing ping pong to a simpler physics model has helped me understand the game way better. Note that I'm ~intermediate and this is intended for beginner / intermediate level.

Given an incoming ball with:

• velocity (3D vector + linear speed), and
• spin (3D rotational vector about the centre + rotational speed),

we can reduce the "shot" to a couple variables in our control:

1. contact point on the ball
2. relative speed of racket along the tangent (where, tangent is described as the vector along the surface of the ball)
3. relative speed of the racket along the normal (where, normal is described as the vector between the contact point and the centre of the ball)
4. when along the ball's arc to execute the shot

NB:

• racket motion is "componentized" (def). This is typically understood as how much you are "brushing" vs "hitting" the ball. It's simply: how fast is racket moving "along the surface", and how fast "into the ball".
  
• Incoming speed + spin is definitely a factor, so I use "relative speed" as it relates to the incoming values. I.e. heavy underspin balls will need a different set of variables (contact point, speed_tangent and speed_normal) vs light underspin.
• I use speed here vs. force, since the mass of the ball is negligible in this model
• There are tons of assumptions i'm not stating for simplicity purposes (ball/topsheet/sponge/blade deformation + reaction + vibration, etc).

Back to the model, so with these 4 variables, in theory you're able to craft any shot you want. In practice it's harder of course. It begs the question: (1) How can I identify what motion to apply and where, and (2) how can I execute it consistently?

The former question (1): I believe this is a pattern recognition problem. So just seeing more balls and trying and playing around – this is how you develop your "repertoire of shots".

For the latter question (2): you can think of your "form" is a consistent means to get you these 3 things. The question becomes:

• How can I position my body to reach my contact point with the motion that I want?
• How can I leverage my tools to achieve the racket motion?
  • Tools: legs, hips, core, shoulder, arm, forearm, wrist, fingers
• How can I consistently time it?

Cues like wrist snap, blade angle, "power from the legs", "pushing down on the ball", "follow through", all of that are mental models for you to achieve these 4 things. This physics approach helps me cut through the noise of advice. I've learned to tune out others' advice, as our bodies, minds, and journeys are all unique.

A practical example:
Short heavy underspin to backhand side. I could do the "FZD BH flick", coiling my body and arm system, and skimming the very top of the ball at its apex:

• Contact point: almost top of the ball (y-axis), slight bias towards me (z-axis) and maybe on the left side (right hander) (x-axis)
  • as a result racket angle is almost flat.
• relative tangential speed: very high
• relative normal speed: very low
• Contact time: apex (at highest point, not early not late)

But this is a low percentage shot for me (noob). Thusly, i can tweak these knobs and still get the ball over, with more consistency.

• Contact point: 30% down from the top (y-axis). at 11 o'clock (slight bias for left side) (x-axis). and about 25% in from the point closest to me (z-axis).
  • as a result, racket angle ends up maybe 30deg above the horizon.
• relative tangential speed: high
• relative normal speed: low-medium
• Contact time: slightly early

To do this, I don't have to coil as much as FZD. I generate force from my legs to push my hips out while engagint my shoulder to whip my (loosely held) wrist quickly to generate that tangential force. I don't need to think about normal force as it happens on its own with the BH motion.

What do you think? Over-reductive? Too complex? Obvious?

What got me thinking about this model is the fantastic drupe pong series on physics.

Your post reminded me of this...