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Hi,
I need to design a simple motion sensor that would be mounted on a railway coach. Basically there is a LED billboard mounted on the outside of the coach which needs to be turned-off (to enhance LED life) when the train is in motion. When the train is moving slowly or stationary I need to turn on the billboard.
I have no previous experience. I need suggestion on choosing the sensor.
Right Now I am going through this thread http://www.picbasic.co.uk/forum/showthread.php?p=33853
Put a magnet on the wheel, trigger a timer on a PIC...Quote:
Originally Posted by sougata
Fire an IR LED at a certain angle at the track, put another IR detector downstream a bit, watch for changes in the intensity of the IR pulses...
Put an IR LED and detector pair in the doorway...each pulse resets a 5 minute timer on the PIC...
Put a microphone next to the roadway...at a certain noise level, you'd know you were going above X mph (kph, whatever), and shut the sign off...
Have the person running the coach flip a switch...
Hire somebody else inside the coach to flip a switch...
Buy a GPS module and watch the lat/lon output...when the position's delta is below 'x', turn on the billboard...
Buy a pitot tube and connect it to a pressure sensor...then connect that pressure sensor to the A/D input of a PIC...at a certain point, pressure is too low, coach must be moving slowly and/or stopped...turn on billboard...
Do the same thing as that other thread with a small metal ball on a chain in a metal can...have that 'intermittent' connection trigger a timer for the billboard...
Buy an ADXL330, use the X/Y outputs to calculate speed and turn on the billboard according to that number...
(If this coach is on a railway) Drag a small wire connected to a lever switch, when the wire hits a crosstie in the roadbed, it will trigger the switch, and therefore trigger a timer in the PIC...
And to think...all those ideas (crappy as they may be), came to me at the same time it took me to type this out...
Keeping tabs on the amount of current that the train is drawing would suffice in providing an accurate vref that's directly proportional to movement. Use a hall effect sensor to monitor large amounts of current. They're relatively inexpensive and accurate too.
Best Regards,
Trent Jackson
http://www.picbasic.co.uk/forum/showthread.php?t=5820
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Hi,
Thanks for the replies guys. I am going through the datasheet of accelerometers and seems to be the best option. I hope it is available readily. I am only supplied with a DC supply and nothing else. So cannot probe any other signals from the railways.
Sayzer the thread you pointed is the same that I looked up. But the links are different.