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  1. latej is offline
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    #21
    Quote Originally Posted by Lula
    Have never heard the expression wrapping the ball. Care to elaborate? Maybe need to read that thread.
    Yes please. It's a good read. Notice that according to the proponent of that idea, it is done by pronation/supination, a rotation of the forearm around its own axis. Put the arm to right angle, now make palm up (pronation), palm down (supination), or the other way round, doesn't matter that much. What's your take on this?

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    #22
    Quote Originally Posted by brokenball
    This is why I have made the big bucks.

    Even small angles of paddle error make a big difference it where the ball will be 3-4 meters out. It is amazing people do as well as they do but it is also easy to see why we miss so many balls.
    Hi BB,
    Is there an optimal bat angle and swing plane for producing both most speed and spin?
    so if you're bat angle is 45 degrees would the best swing plane be 45 degrees as well?

    Cheers,

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    #23
    Quote Originally Posted by latej
    Yes please. It's a good read. Notice that according to the proponent of that idea, it is done by pronation/supination, a rotation of the forearm around its own axis. Put the arm to right angle, now make palm up (pronation), palm down (supination), or the other way round, doesn't matter that much. What's your take on this?

    I think I understand what you mean. I have a friend that those something like this. I believe he loses momentum/speed in the arm by doing it. Think he could just close the angle and go over the ball.

    I can imagine some coaches say to really turn over the ball to exaggerate for beginners so they really go over the ball, get power forward or to keep the elbow from moving forward. Like if you tell someone to show the forehand side up when ending a bh loop to make them exaggerate so they really go over the ball. Or like tell someone to aim for the net to make them hit forward.

    So I think if someone tell you this it is more like a pedagogical way to make the player change the motion before they hit the ball.

    If I understood it correctly. I probably need to read that thread haha

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    #24
    Quote Originally Posted by IB66
    But there could be more to it than just the hand, arm muscles etc, think of a boxer, in order to best transfer all the power produced into the opponent there has be be an amount of tenseness. How often does a commentator use the term that was a really ‘stiff’ jab!! Or ‘solid’ jab!!
    Thought about this recently too. I think there is a difference, but I am not clear on this. In boxing you make short strong breathe-out, the body automatically tenses at the end of such breathe-out (see the abdominal muscles), so it is timed as to end as you hit the opponent or bag or whatever. You need this because the opponent or the bag gives resistance :-) But the TT ball gives virtually no resistance, we feel the impact but it is not that the ball impact would change the direction or angle of the bat much, much less stop the movement completely. Also the breathe-out I think ends at the end of follow through, not so abruptly. So I am not sure about how much "tensing" is really needed precisely at the TT ball impact. As I said, I'm not clear on this. In this stage I like the most what TT Nuri said, just a bit vague mental idea of concentration of energy.

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    #25
    Quote Originally Posted by IB66
    Hi BB,
    Is there an optimal bat angle and swing plane for producing both most speed and spin?
    so if you're bat angle is 45 degrees would the best swing plane be 45 degrees as well?

    Cheers,

    No! This is something they got right on the other forum.
    It depends on what you want to do and the circumstances.
    The most obvious thing is compensating for the incoming spin. The paddle can't be closed too much when returning chopped balls. The paddle can be closed more when looping balls off the bounce.

    The player generates power and transfers the energy ( power x time ) to the paddle in the form of kinetic energy.
    The impact with with the ball transfer a little of the paddle's energy to the ball but energy the ball gets is in two forms.
    1 Rotational kinetic energy, spin.
    2 Translational kinetic energy, speed.
    The ratio of the two energies is dependent on whether you hit through the ball or are brushing the ball and that depends on the racket angle and where the paddle hits the ball. Sometimes you want a slow spinny loop that you can hit at an angle that lands near the edge and as close behind the net as you can. In this case brushing the ball skinny loop is required and you want more spin than spin.
    When back from the table you will probably need more speed that spin.
    The Magnus effect is basically proportional the spin x speed.
    It is up to you to choose the right ratio of spin to speed for the given situation. The pros are very good at imparting a lot of energy to the ball very precisely and getting just the right spin to speed ratio for that particular shot. It is amazing what humans can do.

    About throw and throw angle.
    Some blades and rubbers will generate different ratios of spin to speed given the same impact speed and angle. All normal rubbers can generate the same spin to speed ratios but the impact speed and angle may need to be a little different.
    I don't see where this is that difficult but it challenged the f__ls on mytt over 12 years ago.

    Engineers think about where the energy comes from and goes.

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    #26
    Quote Originally Posted by latej
    Thought about this recently too. I think there is a difference, but I am not clear on this. In boxing you make short strong breathe-out, the body automatically tenses at the end of such breathe-out (see the abdominal muscles), so it is timed as to end as you hit the opponent or bag or whatever. You need this because the opponent or the bag gives resistance :-)
    Again, it is about generating energy and where it goes. When boxing you want the opponent's head to be absorbing the energy not your arm. That is why the arm must be relatively stiff at contact.

    But the TT ball gives virtually no resistance
    Does anybody care to estimate how much force a TT ball exerts on a paddle ( or paddle on the ball )?
    What if the impact speed is 10 m/s? That speed can be scaled up if you want.
    This is a good topic for another thread.

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    #27
    Quote Originally Posted by latej
    Thought about this recently too. I think there is a difference, but I am not clear on this. In boxing you make short strong breathe-out, the body automatically tenses at the end of such breathe-out (see the abdominal muscles), so it is timed as to end as you hit the opponent or bag or whatever. You need this because the opponent or the bag gives resistance :-) But the TT ball gives virtually no resistance, we feel the impact but it is not that the ball impact would change the direction or angle of the bat much, much less stop the movement completely. Also the breathe-out I think ends at the end of follow through, not so abruptly. So I am not sure about how much "tensing" is really needed precisely at the TT ball impact. As I said, I'm not clear on this. In this stage I like the most what TT Nuri said, just a bit vague mental idea of concentration of energy.
    Hi Latej,

    I use to do Pilates, our instructor said Pilates was 'designed' originally as exercise for Boxing (not sure if this is correct, but that's what we were told). The main aspect we learnt when I first started out was that the stomach muscles are tensed continually, whether breathing IN or OUT, this is really quite difficult to master initially as the slightest lapse in concentration results in relaxed stomach muscles!!! especially as you are also trying to follow new exercises!!!!
    One of the reasons she gave for keeping the stomach muscles engaged is help protect your back.
    For the life of me I can't remember whether we breathed out with the movement or in with the movement, I think it was out !! but Carl would enlighten me on this, I think Yoga is opposite to Pilates, so with one you breathe out with the movement the other in with the movement. Whether with Yoga the stomach muscles are continually tensed I'm not sure as i have never done Yoga.
    Breathing out more for a relaxed state, as you breath out the shoulders slump down become more relaxed, some players breathe out before serving so they are nice and loose.

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    #28

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    #29

    impressive looking study. Interested to hear informed comments!

    ppp

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    #30
    Quote Originally Posted by pingpongpaddy

    impressive looking study. Interested to hear informed comments!

    Yes, the study is good and it has added a lot of factors to the previous ones. With time the future studies would imply more and more factors too.
    Recently many factors are neglected as not so essential.
    For example in this study it is stated that it has been held indoor.
    But it doesn't care about the ceiling height and the hall dimensions.
    And as I have wrote about it in other threads - it matters too, though not significantly.
    Good engineers, even not PhD, would get it why.


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    #31
    I know I'm new here, and probably don't know the full story, but man, I have got to say you are a super arrogant guy BrokenBall. Serious. Should maybe work on your delivery a bit if you want to make the biggest impact. Jeez.

    Sent from my BBB100-1 using Tapatalk

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    #32
    Quote Originally Posted by langel

    That document isn't about paddle angles. It is more about tracking TT balls and estimating their trajectories using 3 cameras and Kalman filters to predict the position and the spin. This helps a lot because the camera update rate wasn't that fast and the ball could move quite a bit between frames.

    That is a lot of work for a research paper. It gives a clue as to what is happening inside the Omron robot.
    The accuracy of prediction was pretty good. If they recorded the 4 balls multiple times they would get a more accurate model.

    For example in this study it is stated that it has been held indoor.
    But it doesn't care about the ceiling height and the hall dimensions.
    I don't think these factors matter as much as the air density. That changes and is one reason the model will not be perfect but I think the study is close enough.
    The matrix math is similar to what we/our customers use for flight or car simulators.
    Kalman filters are cool but in this case they used matrix math. Matrix math is good for expressing formulas concisely but it doesn't take into account the air resistances goes up proportional to the velocity squared. I would use a system of non-linear differential equations.
    Kalman filters are optimal assuming the weights between the system noise and measurement noise are correct. The noise may not really be noise. In the this case the camera was not updating that fast so the reading were pretty coarse.
    We use a simpler form of Kalman filter called an Alpha-Beta-Gamma filter. The Alpha-Beta-Gamma filter achieve 95% of what a Kalman filter does with only 5% of the effort or processing power.




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    #33
    Lol! Nice PM you sent me BrokenBall. No. I'm not from MyTT forum. This is the only forum I use, and I'm brand new, at that. I would suggest using some caution in your communication with people man. Real talk.

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