Bannner IR sensor Measures Ball Exit Velocity

[Dale(294engr]]

The banner IR sensor has a range ~1' using blue/green poof balls

(IR doesn't reflect from balls with a black half, Visible LED type may - TBD)

I conducted a test yesterday (prelim) using a 1+ meter AL pole over the ball exit path with 2 sensors attached directed downward,
1m apart
black output lead pull up = ~2.2mA, (produces neg. going ball pulse)
5.6k to 12v or 2.2k to 5v)

Oscilloscope used for time between their falling (leading) edges.
83.3ms = 12m/s (1/.0833)

NOTE: In lieu of Oscilloscope (or external electronic timer)
RC may be used with software to measure time:

between two sensors using 2 input ports (above)

or one port to measure pulsewidth for Simple method (below)

Example: measured 60ms on 12.5" skyway
direct driven by lg CIM at 12.6V (~2500 rpm)
so 1/.06 = 16.7m/s

The 2 sensor method eliminates
ball dia. and edge dropoff errors at cost of 2nd sensor
by measuring leading -edge start to leading -edge stop times

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Simple 1 sensor method: (assumes sensor sees full 7" ball dia):
assumes 7" ball diameter =measured path leading to falling edge = pulsewidth

Also requires blue/green balls (IR reflection is not reliable with BLACK balls)

the Velocity in m/s is 1/(5.624*pulsewidth_sec)

1 / ( (39.37"/m /7"ball)*pulsewidth_sec)

Example: pulsewidth of 15 ms = 11.85m/s

12m/s = 83.3 ms/m /5.634 = 14.8ms for 7" ball path

realistically sensor likely senses a bit short of 7" due to the sphere edge slope. Measure the test ball(s) dia + Perform Edge detection test for an accurate dia. to use for better accuracy -- 6.9 or ?


note
select the white sensor output w/pullup R to +V for positive going pulses

Dale.Hall@earthlink.net
Team 294 Redondo Beach, CA

note:
m/s meters/sec
ms = millisec (1/1000 sec)