Presence sensors are often confused with motion sensors, but they are not the same thing. The latter are focused on motion detection, due to which an object that has fallen into the field of action of the device is fixed. The human presence sensor detects the location of people and large animals, whether they are moving or stationary.
This is a very useful invention that has found its application in many areas of human activity. The presence sensor is used to equip security systems and video surveillance systems, in smart homes as an energy management device, in interactive toys, in taxis, etc. At the same time, such devices can respond to completely different parameters. Presence sensors can determine the presence of a person by his weight, thermal energy, any sound and many other parameters.
For security systems, such devices are simply indispensable - they allow you to detect the presence of unauthorized people in the protected area and take appropriate measures.
For a smart home system, these devices turn lights on and off, which not only allows you not to look for the switch at night,but also significantly save energy costs. At the same time, one should not think that presence sensors are the privilege of exclusively we althy people, in fact, devices with this or a similar principle of operation are installed in many entrances of high-rise buildings. They are used to reduce general house electricity costs and, as a rule, react to the sound of steps of a walking person. Such devices are also popular in various taxi services - sensors help to monitor in real time and separate free cars from cars with passengers.
I am very pleased that from the point of view of ease of installation, such devices can be installed by any person who is at least a little versed in technology. But presence sensors have one significant drawback - this is a false alarm. Of course, for some areas of activity, it is a completely harmless phenomenon and does not bring significant harm, for example, in interactive toys. However, for security or military purposes, this disadvantage is very significant.
Fortunately, the problem of false positives can be successfully de alt with in two different ways. The first method is to use several sensors working separately from each other. These devices, in fact, duplicate each other, which is especially important in the presence of external interference. Another equally effective way is the use of sensors that register the presence of a person according to various parameters. For example, you can paira device that responds to the electrical capacity of the human body, and a sensor that responds 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.
