Where and why the presence sensors are used

Presence sensors are often confused with motion sensors, but this is not the same thing. The latter are focused on motion detection, due to which the object caught in the field of action of the device is fixed. The human presence sensor responds to the location of people and large animals, regardless of whether they move or are motionless in place.

This is a very useful invention, which has found its application in many spheres of human activity. The presence detector is used to equip security systems and video surveillance systems, in "smart" homes as an energy management device, in toys with interactive mode, in taxis, etc. At the same time, such devices can react to completely different parameters. Presence sensors can determine the person's location by its weight, thermal energy, any sound and many other parameters.

For security systems, such devices are simply indispensable - they can detect the presence of strangers in the protected area and take appropriate measures.

For the "smart house" system, these devices turn on and off the lighting devices, which not only does not allow to search for the switch in the dark, but also considerably saves energy costs. At the same time, one should not think that presence sensors are a privilege of exceptionally wealthy people, in fact, devices with such or similar principle of operation are installed in many entrances of high-rise buildings. They are used to reduce the general housekeeping costs for electricity and react, as a rule, to the sound of the walking person's footsteps. Such devices are also popular in various taxi services - sensors help to monitor in real time and to separate free cars from cars with passengers.

Very pleased that in terms of ease of installation, these devices can be put to anyone who understands even a little technology. But the presence sensors have one significant drawback - it's a false alarm. Of course, for some areas of activity it is quite harmless phenomenon and does not cause significant harm, for example, in interactive toys. However, for security or military purposes, this shortcoming is very significant.

Fortunately, the problem of false triggering can be successfully combated, for this purpose two different methods are used. The first method involves the use of several sensors that operate separately from each other. These devices, in fact, duplicate each other, which is especially important in the presence of external interference. Another no less effective method is the use of sensors that detect the presence of a person in different parameters. For example, you can pair a device that reacts to the electrical capacity of the human body and a sensor that reacts to heat. These devices will be affected by various types of external interference, which means that the probability of a false alarm of the entire system as a whole becomes negligible.