Sensor to count punches

Thread Starter

bisb

Joined Jan 26, 2020
8
I am no tech head and do not have a clue where to start, but I have something I want to create for myself. basically, I have a ball ( size of a tennis ball) that is attached to a string. the string is attached to a headband. if you can picture it, you wear the headband with string attached and at the end of the string is the ball. you strike the ball with your fists. I want to put some sort of device/sensor inside the ball so that when I strike it, it counts each punch that lands. what can I do to create this?? (I have attached image of what this headband ball looks like)

I know it sounds so simple, but I literally have no clue on where to start and what to use to make this. Any help will be much appreciated!!
 

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jpanhalt

Joined Jan 18, 2008
9,034
Three sensors come to mind:
1) Absolute pressure sensor that would detect the change in internal pressure with a blow;
2) Accelerometer that will detects an abrupt change in direction or acceleration with a blow; and/or
3) A sound generator inside the ball for each punch, then count beeps externally.

Unless you want to open the ball to read results, for the first two ideas, you will also need a remote link like low power RF.
Either solution will require some expertise in electronics and microcontroller programming.

EDIT: You might be able to find a squeeze toy that beeps when squeezed. Also made for dogs. Put the mechanism inside your ball. Then all you need to do is count beeps. Like this: https://www.amazon.com/Animolds-Squeeze-Dollars-Limited-Orange/dp/B07GRFH4G1
 
Last edited:

Reloadron

Joined Jan 15, 2015
5,333
I would start with a shock and vibration sensor in the ball. Thre is a number of ways to go about this between inexpensive and more expensive wireless solutions. I would start with a wired solution and the light wires on the ball's tether. I would say it all begins with the sensor. Maybe as simple as a common Ceramic Piezo Vibration Piece Sensor would work. You can even purchase just the sensor. I would not overly worry about signal conditioning as when I flick these sensors I get about a 2 volt voltage spike, I am not 100% since it's been awhile.

With sensor done I would take the sensor output and run that voltage spike into a small "One Shot" along the lines of a 74123 which will give you pulses to count. Then run those pulses into an incremental Up Counter. Counter modules with various displays can be had pretty inexpensive. The idea here is keep the approach as modular as possible so you need only connect a few building blocks. Truth is there is likely a dozen ways to do what you are looking to do.

Ron
 

Thread Starter

bisb

Joined Jan 26, 2020
8
Three sensors come to mind:
1) Absolute pressure sensor that would detect the change in internal pressure with a blow;
2) Accelerometer that will detects an abrupt change in direction or acceleration with a blow; and/or
3) A sound generator inside the ball for each punch, then count beeps externally.

Unless you want to open the ball to read results, for the first two ideas, you will also need a remote link like low power RF.
Either solution will require some expertise in electronics and microcontroller programming.

EDIT: You might be able to find a squeeze toy that beeps when squeezed. Also made for dogs. Put the mechanism inside your ball. Then all you need to do is count beeps. Like this: https://www.amazon.com/Animolds-Squeeze-Dollars-Limited-Orange/dp/B07GRFH4G1
Thanks for the quick response and info!

What I Ideally would want is a device externally that counts the number of strikes I have produced in increments of 1. so the squeeze toy idea is not a route I would want to go down.
 

Thread Starter

bisb

Joined Jan 26, 2020
8
I would start with a shock and vibration sensor in the ball. Thre is a number of ways to go about this between inexpensive and more expensive wireless solutions. I would start with a wired solution and the light wires on the ball's tether. I would say it all begins with the sensor. Maybe as simple as a common Ceramic Piezo Vibration Piece Sensor would work. You can even purchase just the sensor. I would not overly worry about signal conditioning as when I flick these sensors I get about a 2 volt voltage spike, I am not 100% since it's been awhile.

With sensor done I would take the sensor output and run that voltage spike into a small "One Shot" along the lines of a 74123 which will give you pulses to count. Then run those pulses into an incremental Up Counter. Counter modules with various displays can be had pretty inexpensive. The idea here is keep the approach as modular as possible so you need only connect a few building blocks. Truth is there is likely a dozen ways to do what you are looking to do.

Ron
Thanks for the quick reply! very informative too!

so you would simply need to put the sensor inside the ball? and the voltages by striking the ball will output onto external counter display?
 

djsfantasi

Joined Apr 11, 2010
6,334
Thanks for the quick response and info!

What I Ideally would want is a device externally that counts the number of strikes I have produced in increments of 1. so the squeeze toy idea is not a route I would want to go down.
Why do you think the squeeze toy won’t work?

You build an external counter, that listens for the sound from the squeeze toy, and increments a counter.

Sounds simple to me.
 

Reloadron

Joined Jan 15, 2015
5,333
Thanks for the quick reply! very informative too!

so you would simply need to put the sensor inside the ball? and the voltages by striking the ball will output onto external counter display?
Along those lines. There are different ways to go where you want to go. I would start simple and try to keep it simple. Part of my reasoning here is:
I am no tech head and do not have a clue where to start,
With that in mind I would think about keeping things simple and using a modular approach. Something low power making batteries practical and something small enough to be comfortably worn on the waist and easily wired to the sensor. Also as
jpanhalt points out there are wireless sensors available which come with a higher cost.

Ron
 

Thread Starter

bisb

Joined Jan 26, 2020
8
Why do you think the squeeze toy won’t work?

You build an external counter, that listens for the sound from the squeeze toy, and increments a counter.

Sounds simple to me.
I think this will not be suitable for me simply due to environmental factors. for example - i would use this equipment outdoors (also indoors), therefore the surrounding area may be noisy and not able to pick up the sound of the squeeze toy as easy, therefore it might distort the accuracy of the strikes counted.
 

Thread Starter

bisb

Joined Jan 26, 2020
8
Striking the ball would almost surely be picked up by a load cell on the string. Your headband could double up as a battery, counter thingy.
Yes, so with the help of all those have commented i thought of a rough idea of how this product would work. i was thinking to have the counter on the headband (and battery) so that the wires can be concealed. possibly some how have the wire from the sensor/cell run through with the balls string to the headband. Regarding a load cell, what type would i need to use? and will it be small enough to fit into a tennis sized ball? any idea of costs too?
 

Thread Starter

bisb

Joined Jan 26, 2020
8
Striking the ball would almost surely be picked up by a load cell on the string. Your headband could double up as a battery, counter thingy.
Yes, so with the help of all those have commented i thought of a rough idea of how this product would work. i was thinking to have the counter on the headband (and battery) so that the wires can be concealed. possibly some how have the wire from the sensor/cell run through with the balls string to the headband. Regarding a load cell, what type would i need to use? and will it be small enough to fit into a tennis sized ball? any idea of costs too?
 

Thread Starter

bisb

Joined Jan 26, 2020
8
If you can't use off the shelf solutions and plan to roll your own with accelerometers, strain gauges and so forth, you have a very steep learning curve ahead of you.
Yeah i won't lie, i did not think it would be this complicated (well for me lol) but im up for the challenge. always good to learn new things!
 

Thread Starter

bisb

Joined Jan 26, 2020
8
Along those lines. There are different ways to go where you want to go. I would start simple and try to keep it simple. Part of my reasoning here is:

With that in mind I would think about keeping things simple and using a modular approach. Something low power making batteries practical and something small enough to be comfortably worn on the waist and easily wired to the sensor. Also as
jpanhalt points out there are wireless sensors available which come with a higher cost.

Ron
Thanks Ron, you've been very helpful. let the advise keep rolling through! hopefully i will have a end product to show you guys
 

Reloadron

Joined Jan 15, 2015
5,333
Just my thinking on this but as I mentioned, this and countless other projects start with a sensor. Once a sensor for any project is selected then we move along to signal conditioning meaning what do we need to do to the sensor output to get a signal we can use. I would try a piezo sensor as I mentioned because it is designed detect a shock or vibration and what you describe is pretty much a shock. There is no concern with measuring the exact force of the shock in any engineering units, merely detecting a shock or a bang. I can buy 15 pieces of these plain piezo sensors for about $7.00 USD.

The next problem is how to mount the sensor of choice. Looking at the link it becomes a matter of getting creative. I would be looking at the ball and trying to figure out how to open it or somehow get a sensor inside it and secured to when punched some of that punch energy is transferred to the sensor, this can be a trial and error process. Automobile engines use "ping" or "anti-knock" sensors to detect engine ping or knock and adjust the engine timing accordingly. Those sensors send their signals to an engine control unit to make decisions.

Here is an example and I provide it only as an example of using a common piezo sensor and a micro-controller to detect a shock. The code could be modified to count knocks or shocks. Again, this is just a little of my thinking on this and how I might approach things.

Ron
 

GetDeviceInfo

Joined Jun 7, 2009
1,702
I wouldn’t put it in the ball, but rather make it the anchor point for the string on the headband. To make it simply, you could spring load a rod that moves on string tension. That rod movement could then be sensed in a number of ways.
 
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