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

atferrari

Joined Jan 6, 2004
4,065
View attachment 186262
Target supported by wires under tension.
From the readings of four strain gauges on the wires it should be possible to calculate where the ball hits and the force involved. The maths would be interesting :).
Hola @Alec_t

Your reply got me thinking. Just for the challenge of something unusual for me, could you outline how you would do it? Started to to consider a possible solution myself.
 

ag-123

Joined Apr 28, 2017
40
one may also want to think in terms of the piezo solution as like the strain gauges.
but for piezo it is different. the surface has to be rather hard so that it can transmit the vibrations to the sensors as elastic surface waves.
it is probably too fast for the eye to see like microseconds, but that i think the piezos will trigger at different time / delays
this is pretty much like locating the epicenter of earthquakes. in addition, the piezos measures the force, velocity as mentioned earlier
 
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Alec_t

Joined Sep 17, 2013
11,501
Just for the challenge of something unusual for me, could you outline how you would do it?
The 4 strain gauges would initially give readings for static loads. A hit would change all 4 readings and the relative magnitudes of those changes would be an indiction of where the hit occurred. The absolute magnitudes would need to be processed (trigonometry involved no doubt, I haven't gone into the maths) to come up with a value for impact force. Calibration would enable that to be converted to ball speed.
 

Bernard

Joined Aug 7, 2008
5,600
What is the size of the target? You could make a matrix of solderable plates, tin plated steel, brass, copper etc.,
attached to target of 2 cm plywood with double faced tape. Solder a wire to each plate & feed thru holes in target. Cover with pressure sensitive membrane, " Velostat ". Cover membrane with a sheet of aluminum foil
taped to target. A hit will drop resistance to around 6 to 9 ohms. Could cover Al. with cloth for protection.
 
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Bernard

Joined Aug 7, 2008
5,600
Crude test of force attenuator. Using one element of matrix applied + 4.5 V to top of cell in series with 120 ohm sensing resistor, - return to other end of R. No cricket ball or baseball so dropped a 9 oz. rounded rock from 1 ft. O-scope read 2.5 V. covering cell with 2 cm. polyethylene foam, V = 1 V.
 
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Thread Starter

Sudip Mandal 2

Joined Mar 29, 2017
27
Crude test of force attenuator. Using one element of matrix applied + 4.5 V to top of cell in series with 120 ohm sensing resistor, - return to other end of R. No cricket ball or baseball so dropped a 9 oz. rounded rock from 1 ft. O-scope read 2.5 V. covering cell with 2 cm. polyethylene foam, V = 1 V.
Than you for your answer but It is not clear please explain it in details.
 

atferrari

Joined Jan 6, 2004
4,065
The 4 strain gauges would initially give readings for static loads. A hit would change all 4 readings and the relative magnitudes of those changes would be an indiction of where the hit occurred. The absolute magnitudes would need to be processed (trigonometry involved no doubt, I haven't gone into the maths) to come up with a value for impact force. Calibration would enable that to be converted to ball speed.
The way I undesrtand this up to now, the four strain gauges should be located perpendicular to the plane containing the target, isn't it?
 

Bernard

Joined Aug 7, 2008
5,600
Size of target still unknown so I picked 1 meter X 2 meters with 200 pressure cells of 98 X 98 mm each.
A lead is brought out from each cell thru target to a LED latching circuit which could display a LED matrix on a 20 cm X 10 cm panel for hit location. A single output for all cells via large diode OR gate. is processed by a sample & hold circuit by others. Ideal diodes would be nice but expensive so might settle for 1N4048's. Shottky's seem to be a bit leaky. Figures for force of a soft hit or hard hit are not available to me so all of this is impure speculation.
 

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Thread Starter

Sudip Mandal 2

Joined Mar 29, 2017
27
Size of target still unknown so I picked 1 meter X 2 meters with 200 pressure cells of 98 X 98 mm each.
A lead is brought out from each cell thru target to a LED latching circuit which could display a LED matrix on a 20 cm X 10 cm panel for hit location. A single output for all cells via large diode OR gate. is processed by a sample & hold circuit by others. Ideal diodes would be nice but expensive so might settle for 1N4048's. Shottky's seem to be a bit leaky. Figures for force of a soft hit or hard hit are not available to me so all of this is impure speculation.
Thank you
 

Bernard

Joined Aug 7, 2008
5,600
To calibrate sensor matrix I figured that a baseball would free fall 80 meters for hit force of
5.8 k gm. Does not seem right, my math skills are dissipating in inverse porportion to age, same with spelling.
Thought this graph is interesting. Where did the color go ??
 

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swr999

Joined Mar 30, 2011
27
Could you do something like, say, 3 or 4 accelerometers on the back side of the target plate, then calibrate by dropping balls from known heights onto the plate impacting at different locations. Maybe the relative responses of the accelerometers could triangulate to the impact location? Just thinking out loud...
 

cho

Joined Dec 24, 2015
4
Best option is to put the measurement devices (accelerometer etc) into the ball and communicate using BLE or other low power method. You only activate the unit and comms once a G threshold has been reached which would help conserve battery or look at the new SOTB devices.
 
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