Baseball - Release Point Detection

Thread Starter

Johnny1010

Joined Jul 13, 2014
96
Hi Guys,

I am working on sports analytics and mostly on baseball so I want to find the time instant at which the ball leaves the hand of the pitcher. For this I was previously using a Force resistive Sensor.

https://www.sparkfun.com/products/9673

But since it has to be placed on the finger, I am looking at other ways to detect the release point without something being in contact with the fingers.

I am looking at accelerometers and also EMG for this purpose but I haven't worked with them before so any suggestions on whether they would work or if you guys could suggest some other method for this problem.

Thanks in advance.
 

ScottWang

Joined Aug 23, 2012
7,046
I am working on sports analytics and mostly on baseball so I want to find the time instant at which the ball leaves the hand of the pitcher.
What the measure for?

Are you talking about this EMG:

EMG test.

What you trying to use the accelerometer and EMG?
 

ScottWang

Joined Aug 23, 2012
7,046
My brother had one of these about 30 years ago.
http://www.amazon.com/Markwort-Speed-Sensor-9-Inch-Baseball/dp/B002N6P5XQ

It didn't seem to work well because the switch was hard to hold before throwing the ball.

What is your goal? Measuring the speed of the pitch or determining the technique and the arm position when the ball is released? Something else?

A GoPro camera is an amazing tool that can do all of this.
When the hand throw the ball away, does the Speed Sensor will record the speed?
 

GopherT

Joined Nov 23, 2012
8,012
When the hand throw the ball away, does the Speed Sensor will record the speed?
Not directly. You have to have a catcher exactly 90 feet away. The impact of the catch stops a timer and calculates the speed and displays the speed on a micro-sized LCD on the ball.
 

ScottWang

Joined Aug 23, 2012
7,046
Not directly. You have to have a catcher exactly 90 feet away. The impact of the catch stops a timer and calculates the speed and displays the speed on a micro-sized LCD on the ball.
Thank you.
So the ball leave the hand and start to counting, and the ball must be hitting the catcher, and the impact stops the timer of ball, and calculates the speed and displays the speed on a micro-sized LCD on the ball, is that right?
 

djsfantasi

Joined Apr 11, 2010
7,749
Have you considered open source image recognition and tracking software? Are you an accomplished enough programmer to use something like OpenCV software?

I've always wanted to try
 

GopherT

Joined Nov 23, 2012
8,012
Thank you.
So the ball leave the hand and start to counting, and the ball must be hitting the catcher, and the impact stops the timer of ball, and calculates the speed and displays the speed on a micro-sized LCD on the ball, is that right?
That is exactly how it works.

I think the impact switch that stops the timer was a simple vertical wire on the circuit board with a fine spring slid over it. When the impact happens, the spring bent a bit and touched the wire. I only say this because accelerometers were not on consumer toys 30 -35 years ago and the ball was only $5 to $10 range. Also, you had to throw it fairly hard to get a reading. If the ball was thrown gently, the LCD would be blank when you catch it and then say Err a second or two later. I am sure a much better device could be built today - even recording the rpm and axis of rotation.
 

ScottWang

Joined Aug 23, 2012
7,046
As what you said when we throw the ball away then the direction must be very precisely to hit the catcher, that is not easy to do for the general people.

I saw the automatic pitching machine, the speed was decided by the the machine, and the speed can be adjust, and I also saw the radar or Ir system to test the speed, they used two devices, one for start and another for stop, when the ball pass through the procedure of start and stop devices and calculating the results for speed.

Do you have any ideas what the TS will do for accelerometers and EMG?
 

Thread Starter

Johnny1010

Joined Jul 13, 2014
96
Could you wire a baseball?
No, I can't wire it. Actually what I want is to study the effect of arm angle (at the release point) on the pitch and want to make a wearable band that could do this I have got the angle part covered but the release point detection is an issue. I don't only want it for training purposes, I want to use it within matches so can't temper with the ball or hand.
 

Thread Starter

Johnny1010

Joined Jul 13, 2014
96
What the measure for?

Are you talking about this EMG:

EMG test.

What you trying to use the accelerometer and EMG?
- I want is to study the effect of arm angle (at the release point) on the pitch.
- Yes, I am talking about the EMG you mentioned.
- Accelerometers could be used for gesture recognition so I was thinking if the gesture of ball release could be detected with the accelerometer. As for an alternate the EMG could be used to see the particular muscle movements at the point of release and then it could be detected.
 

GopherT

Joined Nov 23, 2012
8,012
- I want is to study the effect of arm angle (at the release point) on the pitch.
- Yes, I am talking about the EMG you mentioned.
- Accelerometers could be used for gesture recognition so I was thinking if the gesture of ball release could be detected with the accelerometer. As for an alternate the EMG could be used to see the particular muscle movements at the point of release and then it could be detected.
If you have an accelerometer, the arm speed would definately go up as soon as a 5 ounce ball is released.
 

Thread Starter

Johnny1010

Joined Jul 13, 2014
96
My brother had one of these about 30 years ago.
http://www.amazon.com/Markwort-Speed-Sensor-9-Inch-Baseball/dp/B002N6P5XQ

It didn't seem to work well because the switch was hard to hold before throwing the ball.

What is your goal? Measuring the speed of the pitch or determining the technique and the arm position when the ball is released? Something else?

A GoPro camera is an amazing tool that can do all of this.
Good suggestion but the thing again is that I don't only want it for training purpose rather wan't to see the analytics within a real match and want a wearable band worn on the hand to do this stuff so, a Gopro or a ball like that won't work.
 

Thread Starter

Johnny1010

Joined Jul 13, 2014
96
If you have an accelerometer, the arm speed would definately go up as soon as a 5 ounce ball is released.
So what could be a good position for the accelerometer the wrist may be? Also any suggestions on any specific kind of accelerometer to use for this particular problem
 

Thread Starter

Johnny1010

Joined Jul 13, 2014
96
Have you considered open source image recognition and tracking software? Are you an accomplished enough programmer to use something like OpenCV software?

I've always wanted to try
Are you talking about the one with reflective markers placed on the body and then using high speed cameras. Like this one:
http://www.quintic.com/software/biomechanics/

If yes then that would work but the constraint is to use the thing in matches so I am looking at a wearable rather than a complete testing equipment.
 

GopherT

Joined Nov 23, 2012
8,012
Sure. I'll be waiting for your productive input on it.
How can I specify an accelerometer when you are not defining the problem? What level of accuracy do you need? What are the other key variables of an accelerometer?
What values do those have to be for such a project?
Which manufacturers and part numbers are available that meet your price target (what is your price target)? That the distributors have in stock, that are big enough to be hand-soldered, that are small enough to fit on a wristband, that...

Do you see how this works?...
 
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