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Topic: LDR grid (Read 1 time) previous topic - next topic

N2DFIRE

I was wondering if anyone thinks its possible to build a ldr grid.  Using a number of ldr's in a vertical and horizontal format to make a grid.  So if an object passed through the grid.  The ldr's would be triggered to give a location within the grid.

What I'm thinking of is a grid(screen) that you can pitch a softball or baseball through and give a location for training purposes.  The arduino would need to be fast enough to read all or the sensors(ldr) to capture a ball going through the grid in the split second the ball travels through the grid(strike zone).

I don't even know if the ball would be enough to change the state of the sensor in outdoors in bright light and distance from the ldr.  If you had 3" by 4" grid.  Maybe a different sensor would be needed.  If you place the sensors a couple of inches apart in the grid.  To capture the location of the ball within the strike zone.

Any input would be appreciated.


CrossRoads

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

N2DFIRE

ldr=Light Dependent Resistor or photoresistor

Maybe an IR led would be better for the sensor?

liudr

IR is not good outside under the sun. Why not using a video camera to capture an image to show where the ball goes through? How fast it the ball?

N2DFIRE

What I'm thinking of is a training tool/ pitching game.  Where the pitcher would be given a certain pitch and location.  So if a fastball in the upper right hand corner is called by the arduino.  It would sense if the correct location was made and give instant feed back.  Kind of a game to make it fun to train.  The ball would be about in the low 60 mph.

CrossRoads

Will need to make it sturdy to protect against errant pitches.
60 MPH, that's 88 feet per second, 1056 inches per second.
Baseball is about 3 inch diameter, will be thru your frame in about 2mS.
You will need a 18" x 18" opening to simulate the strike zone.
Sensors at least every 2" I would guess so at least a portion of the ball is always picked up.
So 8 sensors (2", 4", 6", 8", 10", 12", 14", 16") in vertical &  horizontal, 16 total, scanned rapidly enough so that every intersection is read within 2mS. So reading at 125 uS clip?
You can make a loop that can go that fast no problem.
Not sure if having 2 interrupts occur, then you scan the inputs to see which 2 detectors got momentarily blocked, will do it.
May need to have the detectors trigger a flip-flop or similar to capture the transition, scan them after any one is triggered, similar to the keypad tutorial.
Don't know if IR will do it for you, you'll have look at the radiating spread angle of your sending device and see if it will be picked up by the neighboring detectors.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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