MCU Examples.com
PIC Microcontroller Project Examples, free source codes and resources collection.
IR Range Finders
The IR Range Finder is probably the most powerful sensor available to the everyday robot hobbyist. It is extremely effective, easy to use, very affordable, very small, good range, and has low power consumption.
How IR Range Finders Work
The IR Range Finder works by the process of triangulation. A pulse of light is emitted and then reflected back. When the light returns it comes back at an angle that is dependent on the distance of the reflecting object. Triangulation works by detecting this reflected beam angle - by knowing the angle, distance can then be determined. The IR range finder receiver has a special precision lens that transmits the reflected light onto an enclosed linear CCD array based on the triangulation angle. The CCD array then determines the angle and causes the rangefinder to then give a corresponding analog value to be read by microcontroller.
Beam Width
A major problem with the IR rangefinder is beam width. Unlike sonar, it’s fairly thin - meaning to detect an object our sensor must basically point directly at that object.
Non-Linear Output
The IR has a non-linear output. This means that as the distance increases linearly, the analog output increases or decreases non-linearly. This is because the range finder is not capable of detecting very short distances. Range finder can determine the range that it is capable.
To effectively use IR Range Finder, we can use voltage output versus distance chart.
Disadvantages
One major issue with the IR Range Finder and that is going below the minimum sensor range. This is when an object is so close the sensor cannot get an accurate reading.
Another issue is the narrowness of the IR beam. In reading sharp details and getting high accuracy, a thin beam is ideal. But the problem with a thin beam is that if it is not pointed exactly at the object, the object is therefore invisible.
A Disadvantage that these range finders have in common with sonar is cross interference. This means that the signal emitted by one sensor can potentially be read by another sensor and therefore give you bad readings.
