Distance sensor
An infrared proximity sensor shines a beam of IR light from an LED, and measures the intensity of light that is bounced pack using a phototransistor. If you stare at the sensor, you can see one of the LED’s glowing slightly red as some of the IR falls into the visible-light spectrum. A new approach was developed that not only gives object detection at a longer range than previous method but also offers range information for certain type of sensors. These new rangers all use triangulation and a small linear charge coupled device (CCD) array to compute the distance and/or presence of objects in the field of view. The basic idea is this: a pulse of IR light is emitted by the emitter. This light travels out in the field of view and either hits an object or just keeps on going. In the case of no object, the light is never reflected and the reading shows no object. If the light reflects off an object, it returns to the detector and creates a triangle between the point of reflection, the emitter, and the detector.
An infrared proximity sensor shines a beam of IR light from an LED, and measures the intensity of light that is bounced pack using a phototransistor. If you stare at the sensor, you can see one of the LED’s glowing slightly red as some of the IR falls into the visible-light spectrum. A new approach was developed that not only gives object detection at a longer range than previous method but also offers range information for certain type of sensors. These new rangers all use triangulation and a small linear charge coupled device (CCD) array to compute the distance and/or presence of objects in the field of view. The basic idea is this: a pulse of IR light is emitted by the emitter. This light travels out in the field of view and either hits an object or just keeps on going. In the case of no object, the light is never reflected and the reading shows no object. If the light reflects off an object, it returns to the detector and creates a triangle between the point of reflection, the emitter, and the detector.
The angles in this triangle vary
based on the distance to the object. The receiver portion of these new
detectors is actually a precision lens that transmits the reflected light onto
various portions of the enclosed linear CCD array based on the angle of the
triangle described above. The CCD array can then determine what angle the
reflected light came back at and therefore, it can calculate the distance to
the object.
When the distance
is far or increases the output voltage is decreasing gradually. But when the IR
sensor is near to the obstacle the output voltage will increase. The value of
output voltage is useful as a reference for the microcontroller (ATmega328).
For a gas leakage detector system, if the output voltage is higher than a set
point level, the DC motors will be turn off. But if the output voltage is lower
than the set point the DC motors will be operated. The set
point can be created in the program. This means that to one value of the output corresponds two
values of distance. This problem can be avoided by noticing that the object is
not too close to the sensor.
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