Baseball Speed Detection

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xtech007

Senior Member
Hi all !
Yes, I know speed detectors are available for sports, But they are highly pricey.
My boy staring to learn to pitch along with other kids in the Team, I'm volunteering as assistant coach, currently working on a target Mat with 9 smaller target in the center, strike zone dead center, inside low/high and outsie low high pitch, and ball zones.
So when pitcher hit this zone it will actuate a switch and lit that zone but also display that zone on an LED display so it can keep count on balls and strikes! Like a virtual Umpire.

Planning to use a 28x1 for this project.
Currently just in the planning phase!
But the more I think of it ,more I want to add! Like it will be great to add speed of the pitch option to be displayed on the LED display!

So the real question that's hunting me is if anyone's have done something similar and give me a heads up on what module I can use that's decent of detecting speed, like a range finder or
Any other you can think of!

Thanks!
 
techElder

techElder

Well-known member
I would lean toward a trap. Add a "start" trigger (optical?) out in front of the target. Use the target switches as the "stop" trigger.

The distance away from the target for the "start" trigger would be a fixed distance that you program into your gadget and measure accurately each time you set it up.

I would lean more to a 28X2.
 
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xtech007

Senior Member
Trap system!

Thanks for the reply texasclodopper!
Yes, I would use a 28x2 !
A trap system you mentioned with a trigger and stop switch is duable.
Is this to trigger the reading of the speed gun?

What I was trying to find was a module or sensor I can use to detect speed of the ball. Distance normally would be 40-45 feet from where the pitcher is to the target.

Another option would be hack a radar gun for its internals. Use a trigger /stop system to get the speed reading but Hummm , brings up the next issue: how to display its reading on my Led screen?
The screen on the speed guns are tiny!
 
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eggdweather

Senior Member
You could use one of these: http://www.ebay.co.uk/itm/5V-HB100-Microwave-Probe-Sensor-Module-10-525GHz-Doppler-Radar-Motion-Detector-/381477652949?hash=item58d1d709d5:g:gNEAAOSwbdpWWC1q

Data sheet: http://www.limpkin.fr/public/HB100/HB100_Microwave_Sensor_Application_Note.pdf

The output is a audio frequency that is proportional to speed. The output would need some amplification, maybe x10 and you could either measure the frequency and display the result or convert to DC with a low-pass filter/integrator then measure the DC and display that as speed. The resultant frequency has a direct relationship to the speed of the object.

Typical range that I've seen is 30Metres (120'). There are some YouTube videos that demonstrate their use.

The classic Bushnell type uses a similar module, but with a larger horn type antenna, but then it's range is 100M+.
 
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techElder

techElder

Well-known member
Just once, I wish that someone would choose the simple solution.

I'm not going to design it for you, but you said you wanted an all inclusive approach. Just placing an optical gate out in front of your "target Mat with 9 smaller target in the center" fits in with that with just a little extra programming to time the ball moving between the gate and your "mat" switches.

Actually, you could look at slot/Pinewood Derby car timers for inspiration.

PS. The specs on that microwave detector don't specify target size. There is some mention of RSS so there is some threshold for which it will no longer detect an object.
 
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oracacle

Senior Member
essentially you are looking for a projectile chronograph.
Have a look at gun chronographs to see how they go about detecting the projectile.
From what I know they use IR screens, one to start and one to stop the timer.
 
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eggdweather

Senior Member
The bushnell speed gun for $75 is designed to measure the speed of tennis, golf and base balls, so you know it works, plus checkout YouTube there are videos that explain how to interface with it to get timing data. Another cheap source of Doppler radar modules is from house alarm systems.
 
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xtech007

Senior Member
Texasclodhopper said:
Just placing an optical gate out in front of your "target Mat with 9 smaller target in the center" fits in with that with just a little extra programming to time the ball moving between the gate and your "mat" switches.
Click to expand...
I like your approach with the optical gate, I assume only 1 will be needed to act as start trigger, the switches mentioned on the mat are currently used to lit up the zone the ball hits.
But can be used also as stop trigger with easy code modifications.

Looked at The slot/derby timmer idea in different sites, gathered they all act as a start and stop switch for a timmer.
By means of physical switch or phototransistor.

Back to the mat & switches!
If the optical idea was to be used the math for the resolution for speed would be distance/time = speed.
Exp: start trigger is 36" away from target, kid pitches, ball actuates counter, ball hits mat actuating the switch stoping the timer at .284 sec
So, 36"/.284 sec=786 inch/second
Then convert inch/second to MPH
786 X .0568= 44.64 MPH!!!!
 
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xtech007

Senior Member
timer!!

Almos forgot,
where do we get the timer or counter?
Can the 28x2 do this without the need of external module?

Many thanks for your interest and replies!!
 
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xtech007

Senior Member
Hotwheels radar gun

Erco thank for the link!
Unfortunately that's a very unreliable radar gun, all is done there is changed the casting. No improvement the readings.
 
techElder

techElder

Well-known member
First, remember that this is a kid's baseball pitch speed timer. Precision and resolution isn't really a high priority. Yes, of course you want to do your best.

Second, Hippy showed me how to use a PWM output as a frequency source. I used a gated external counter, but the 28X2 has internal counter.

Third, while the pitch is being thrown your machine doesn't need to do anything else but count until the pitch contacts the "mat."
 
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xtech007

Senior Member
I apologize!

Hippy, Erco!
I apologized for that math, I think it was the theraflu and NyQuil kicking in at that time in the morning!

In deed forgot the convesion to Hrs.
Will try to sort parts to build a test sample.

Any ideas on a reliable optical sensor that can cover a large area?
 
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