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"Are we getting close? Proximity Sensors + Arduino"

fustini

Howdy -

 

Inspired by Jeri Ellsworth's creative "PIR Sensor - Motion Activated Art" video, a friend of mine who's an artist was inspired to embed LEDs in his paintings with insenisty corresponding to the closeness of the viewer.  I decided it would be fun to make a proof-of-concept for him by using the sensors output to control LED brightness via PWM.

 

I picked up a PIR sensor from Parallax at Radio Shack on the spur of the moment.  Unfortunately, this PIR sensor is too "smart" for my use.  It simply outputs a digital signal incidating that motion was detected unlike the varying analog voltage output by the "dumb" PIR in Jeri's video.

 

I decided I need to do my homework and started researching different methods of sensing proximity.  Here's a nice writeup I found that I'd like to share:

 

Are we getting close? Proximity Sensors + Arduino

http://bildr.org/blog/wp-content/uploads/2011/03/proximity.jpg

Cheers,

Drew

http://twitter.com/pdp7

  • That's useful, thanks.

     

    You are right, PIR is only any use for detecting movement, not how close things are.

     

    So which approach did you end up using? In my experience, ultrasonic works better than the sharp IR sensors for the longer range.

     

    Simon.

  • in reply to simon.monk

    I did try the parallax ultrasonic sensor and it was very accurate providing cm resolution.  I found it difficult though to map its large distance range to a corresponding PWM duty cycle for the LED.  I ended up defining a range between 15 cm to 40 cm where by the LED duty cycle would increase from 0% to 100%.  This gave the effect of LED brightening as you moved closer within the range.  However, I found with the basic diffused green LED the brightness at any duty cycle above around 65% was hard to distingush from 100%.
    Originally, I had in mind of a sensor that would produce an analog voltage that I could just do ADC on and map to a duty cycle for the LED (or transistor for the plan LED array).  I believe the IR proximity sensor offers this and just received my order with two different Sharp models.  I'll try those next.
    Ultimately, I need to nail down desired distance range with the artists and how rapidly he wants to have the brightness change versus distance.  I suspect the final solution will use IR proximity, ultrasonic or a comination of both.
    Cheers,
    Drew

    I did try the parallax ultrasonic sensor and it was very accurate providing cm resolution.  I found it difficult though to map its large distance range to a corresponding PWM duty cycle for the LED.  I ended up defining a range between 15 cm to 40 cm where by the LED duty cycle would increase from 0% to 100%.  This gave the effect of LED brightening as you moved closer within the range.  However, I found with the basic diffused green LED the brightness at any duty cycle above around 65% was hard to distingush from 100%.

     

    Originally, I had in mind of a sensor that would produce an analog voltage that I could just do ADC on and map to a duty cycle for the LED (or transistor for the plan LED array).  I believe the IR proximity sensor offers this and just received my order with two different Sharp models.  I'll try those next.

     

    Ultimately, I need to nail down desired distance range with the artists and how rapidly he wants to have the brightness change versus distance.  I suspect the final solution will use IR proximity, ultrasonic or a comination of both.

     

    Cheers,

    Drew

    http://twitter.com/pdp7

  • in reply to fustini

    Hi Drew,

     

    Many people are interested in using Arduino for Human Interaction art etc.

     

    Can you point to your project information, or your code ?? Thanks!

     

    Some How-To on Ultrasonic Distance Measurement I did is here:  http://arduino-info.wikispaces.com/UltraSonicDistance

     

    Regards, Terry King

    ...In The Woods In Vermont

    terry@yourduino.com