# Need help to select a pressure sensor to sense the pressure impact of cricket ball.

Thread Starter

#### Sudip Mandal 2

Joined Mar 29, 2017
32
I am going to start a project where I need to measure the pressure of a cricket ball throwing by the bowler. My main objective is to sense the pressure of ball throwing by the bowler to the batsman such that the bowler can realize his bowling performance.

For this, I need a large area precise pressure sensor with low power consumption and also it can tolerate the pressure of a ball. I have seen some capacitive type pressure sensor like this https://pressureprofile.com/sensors/tactarray

Please give me some suggestion pressure sensor for my application. Thank you.

#### MaxHeadRoom

Joined Jul 18, 2013
23,932
What about a measure of the speed rate of the ball, this should be directly relative.
Maybe easier and already out there.
Max.

#### jpanhalt

Joined Jan 18, 2008
11,088
Or, keep up with the play-by-play in the newspaper.

Thread Starter

#### Sudip Mandal 2

Joined Mar 29, 2017
32
What about a measure of the speed rate of the ball, this should be directly relative.
Maybe easier and already out there.
Max.
actually my purpose is two, the first one is measuring the speed of the ball. second, is the ball hitting on a particular area?.

#### oz93666

Joined Sep 7, 2010
737
What about a measure of the speed rate of the ball, this should be directly relative.
Maybe easier and already out there.
Max.
My thought exactly .... the problem with a pressure sensor is it will have to be attached to a metal plate which the ball has to hit ... this will be difficult enough for the bowler to target , but if the ball hits the plate away from the center it will give a different reading than if it were to hit center ... there's just no way of getting around this, it's to do with the mass of plate and other factors .

#### oz93666

Joined Sep 7, 2010
737
actually my purpose is two, the first one is measuring the speed of the ball. second, is the ball hitting on a particular area?.
Hitting a particular area is easy , just a whole matrix of push buttons .....When a button is hit it lights up for 3 secs .

Do you really need to measure speed ??? if so another system is needed ,,, one set up will measure speed , another accuracy . I don't think you can have one system that does both....

Unless there is already on the market a mat that has pressure sensors integrated into it ....a thousand or so individual sensors

#### ag-123

Joined Apr 28, 2017
61
the simplest way is to use piezo disc(s)
https://www.ebay.com/sch/i.html?_from=R40&_nkw=piezo+disc&_sacat=0
but if the ball hit the surface or for that matter the interfacing surface at high speeds, it may generate thousands of volts of piezoelectricity
it would easily short out or burn out an mcu, you may need to put a 1 meg ohm resistor in series with the sensor and mcu to prevent that electric shock lol

the rest are physics, math and experiments
in terms of the position, multiple sensors (discs) may just do it, but the physics and math may be complicated to work out, the notion is that if the ball hit a surface and say behind that are deliberately spaced piezo sensors, the sensors would trigger one after another based on the waves radiating out of a hit spot, so there may perhaps be nanoseconds, microseconds between the wavefronts being detected by the piezos

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Thread Starter

#### Sudip Mandal 2

Joined Mar 29, 2017
32
Hitting a particular area is easy , just a whole matrix of push buttons .....When a button is hit it lights up for 3 secs .

Do you really need to measure speed ??? if so another system is needed ,,, one set up will measure speed , another accuracy . I don't think you can have one system that does both....

Unless there is already on the market a mat that has pressure sensors integrated into it ....a thousand or so individual sensors

Thread Starter

#### Sudip Mandal 2

Joined Mar 29, 2017
32
Hitting a particular area is easy , just a whole matrix of push buttons .....When a button is hit it lights up for 3 secs .

Do you really need to measure speed ??? if so another system is needed ,,, one set up will measure speed , another accuracy . I don't think you can have one system that does both....

Unless there is already on the market a mat that has pressure sensors integrated into it ....a thousand or so individual sensors
Okay, let me explain more to clear the confusion. measurement of speed secondary, the primary objective is to ensure the bowler that he is throwing the particular area. There are varties of bowling delivery style in cricket like short pitch, overpitch & yorker etc, for each style bowler has to hit the ball on a certain area to achieve his goal. for the yorker, the bowler has to hit on the stamp position.
When a bowler will practicing he should know his accuracy or how correct he is doing.. that is my objective. Previously I have done by 2-D conductive array-like keyboard matrix technology this can tell you the position but not the speed thats why I was looking for a sensor it can be any sensor that can fulfill my dema

Thread Starter

#### Sudip Mandal 2

Joined Mar 29, 2017
32
the simplest way is to use piezo disc(s)
https://www.ebay.com/sch/i.html?_from=R40&_nkw=piezo+disc&_sacat=0
but if the ball hit the surface or for that matter the interfacing surface at high speeds, it may generate thousands of volts of piezoelectricity
it would easily short out or burn out an mcu, you may need to put a 1 meg ohm resistor in series with the sensor and mcu to prevent that electric shock lol

the rest are physics, math and experiments
in terms of the position, multiple sensors (discs) may just do it, but the physics and math may be complicated to work out, the notion is that if the ball hit a surface and say behind that are deliberately spaced piezo sensors, the sensors would trigger one after another based on the waves radiating out of a hit spot, so there may perhaps be nanoseconds, microseconds between the wavefronts being detected by the piezos
Thank you, I like the idea. I got your point... how to measure the speed

#### jpanhalt

Joined Jan 18, 2008
11,088
If you just want to know where the ball hits the bat, why not put wet paint on the bat? Resurface it after each hit.

If you want something more high tech, there are pressure sensitive paints that change color when pressed, much like liquid crystal displays. Here is one type: https://innssi.com/wp-content/uploa...cumentation/UniCoat-PSP-UNC-12-Data-Sheet.pdf ,and here is a research article about the subject: https://pdfs.semanticscholar.org/50cb/1ba9e58e1d55e910660a93e61458c84c7c10.pdf

Even temperature sensitive liquid crystal coatings may show a reversible color change with the higher forces of hitting a ball. Your LCD screen demonstrates that.

Thread Starter

#### Sudip Mandal 2

Joined Mar 29, 2017
32
If you just want to know where the ball hits the bat, why not put wet paint on the bat? Resurface it after each hit.

If you want something more high tech, there are pressure sensitive paints that change color when pressed, much like liquid crystal displays. Here is one type: https://innssi.com/wp-content/uploa...cumentation/UniCoat-PSP-UNC-12-Data-Sheet.pdf ,and here is a research article about the subject: https://pdfs.semanticscholar.org/50cb/1ba9e58e1d55e910660a93e61458c84c7c10.pdf

Even temperature sensitive liquid crystal coatings may show a reversible color change with the higher forces of hitting a ball. Your LCD screen demonstrates that.
No, I don't want to know where the ball hit on the bat. I want to know where the ball hit on the field after throwing the ball by the bowler. I think you got my point.

#### Alec_t

Joined Sep 17, 2013
12,317
You could support a rectangular vertical sheet target by its four corners and have a strain gauge at each corner.

#### ag-123

Joined Apr 28, 2017
61
Thank you, I like the idea. I got your point... how to measure the speed
i'm not too sure about this too, but I once pounced upon somewhere that these piezoelectric charges can goto the thousands of volts if the force is large enough. that's how the butane cigarette lighter generates the spark that ignites the butane flame

based on the piezoelectric theories
https://en.wikipedia.org/wiki/Piezoelectricity
the *charge* generated is proportional to the *force*
but *charge* is static electricity

based on the concepts of capacitance
https://en.wikipedia.org/wiki/Capacitor
C = Q / V
C is the capacitance
Q is the charge
V is voltage
(side note that PZT has very high permittivity. hence C would be pretty large)
https://en.wikipedia.org/wiki/Relative_permittivity

then we need to study the electrostatics
https://en.wikipedia.org/wiki/Electric_potential_energy
electric potential energy U = 1/2 QV = 1/2 CV^2 = Q^2 / 2C
the most interesting one is the middle term which provides that energy in terms of the square of the voltage.
and from the capacitor equation:
V = Q / C - i.e. voltage is proportional to the charge
the charge Q is generated by piezoelectric effect
so you have a V (voltage) that would be proportional to the charge.

next we can make a guess. the kinetic energy of the ball = 1/2 x mass x velocity ^2
if we deem conservation of energy
kinetic energy = electric potential energy (generated by piezoelectric effect) + heat
1/2 x mass x velocity ^ 2 ~ 1/2 x capacitance x volts ^ 2 + heat
if we make a simplification assumption that heat is a constant
then we have
velocity - proportional to - voltage
but for that matter you can assume that this voltage is in the thousands of volts, so perhaps you can use a resistor divider across the to reduce this voltage to managable levels that the adc can measure. but really this charge is very small so it would be necessary to use high resistances like 1 mega ohms and say 100 k ohms or probably lower for the mcu adc middle tap.

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Thread Starter

#### Sudip Mandal 2

Joined Mar 29, 2017
32
You could support a rectangular vertical sheet target by its four corners and have a strain gauge at each corner.
Thank you. Can you please explain it bit more.

Thread Starter

#### Sudip Mandal 2

Joined Mar 29, 2017
32
i'm not too sure about this too, but I once pounced upon somewhere that these piezoelectric charges can goto the thousands of volts if the force is large enough. that's how the butane cigarette lighter generates the spark that ignites the butane flame

based on the piezoelectric theories
https://en.wikipedia.org/wiki/Piezoelectricity
the *charge* generated is proportional to the *force*
but *charge* is static electricity

....... (typing in progress ... )
Thank you

#### ag-123

Joined Apr 28, 2017
61
this video shows just how sensitive it really is
the position will be the hard part, but say if there are a few piezo disc sensors
my guess is that by virtue of physics, the physical elastic wave would take a very short time to travel from the position hit to each sensor just say nanoseconds to microseconds.
if we can measure that and if for that simplification we assume a planar surface. you can work out the position using pythagoras theorem or triangle geometries. pretty much gps on a plane

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#### jpanhalt

Joined Jan 18, 2008
11,088
I think I understand what you are are trying to detect. In American baseball, cameras (or umpires) are used to determine whether the ball is in the "strike" zone. There is some disagreement as to which is better. I like the camera views.

You could detect the ball's approach with reflected IR and then trigger the camera.

Thread Starter

#### Sudip Mandal 2

Joined Mar 29, 2017
32
this video shows just how sensitive it really is
the position will be the hard part, but say if there are a few piezo disc sensors
my guess is that by virtue of physics, the physical elastic wave would take a very short time to travel from the position hit to each sensor just say nanoseconds to microseconds.
if we can measure that and if for that simplification we assume a planar surface. you can work out the position using pythagoras theorem or triangle geometries. pretty much gps on a plane
yes, you're right

Thread Starter

#### Sudip Mandal 2

Joined Mar 29, 2017
32
I think I understand what you are are trying to detect. In American baseball, cameras (or umpires) are used to determine whether the ball is in the "strike" zone. There is some disagreement as to which is better. I like the camera views.

You could detect the ball's approach with reflected IR and then trigger the camera.
thank you

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