Human Sensor
What are Human sensors ?
Human sensors are the electronic sensors that are able to detect the motion of humans in a particular area. The sensors that serve this purpose utilize different technologies depending upon the applications like automatic doors, automatic lights, anti theft alarms/intrusion detection systems, etc.
Types of Human sensors
Human sensors are of different types and that differentiation is based on the technology they are incorporating while present in the devices serving their respective applications.
1. Active Infrared Based Human Sensors
The active infrared based sensors are those that detect humans by transmitting infrared waves in a straight line.
Working Principle
An active infrared sensor is a combination of a transmitter and a receiver arranged in a straight line with each other. These sensors are called Active because they transmit Infrared waves by their own. The transmitted waves keep travelling in the straight line to the receiver in front. As long as there is no interference in the path of the travelling waves, the system is considered to be working normal. When a human comes in between the path of the waves, the waves travelling to the receiver get blocked and the system signals the control panel the presence of a human in its detection area.
Advantages
- Point to point interaction between the transmitter and the receiver makes these sensors a secure mode of communication.
- The sensors are capable of detecting the objects without being in contact.
- The sensors are light independent and hence can detect in dark as well without any compromise in the efficiency.
- The AIR based sensors are not harmful to anyone if exposed to the infrared.
Applications
- Burglar Alarms/Anti Theft Alarms/Intrusion Detection System
- Automatic Light
- Automatic Doors
- Proximity Sensors
2. Passive Infrared Based Human Sensors
The passive infrared (PIR) based sensors are those that measure the infrared waves released in the form of heat from an object.
Working Principle
A Passive Infrared (PIR) sensor does not have any source of infrared waves and it just measures the changes in temperature of its surroundings on the basis of infrared waves released by the nearby objects. The PIR sensor keeps on scanning the area it is placed in and records the heat maps of all the objects in its vicinity. Whenever there is any motion or entrance of a human in that area, the heat map of the complete area changes and is detected by the PIR sensor immediately. This change in the surroundings’ temperature is what indicates the presence of a human in the detection range of the human sensor.
Advantages
- These sensors are very much accurate in detecting humans.
- The sensors are independent of light and have the same detection efficiency at night also.
Applications
- Burglar Alarms/Anti Theft Alarms/Intrusion Detection Systems
- Night Vision Cameras
- Automatic Doors
- Automatic Home Appliances
- Smoke and Fire Detectors
3. Microwaves Based Human Sensors
These sensors detect the presence of humans by releasing and then detecting the microwaves in their surroundings.
Working Principle
The microwaves based human sensors are composed of two components i.e. a transmitter and a receiver fixed side by side in the device they are put in depending upon the application. The sender of the microwaves continuously releases the waves in its surroundings that get reflected back by any object opposite to it. In a normal case, this too and fro of the waves keeps taking place without any change in the pattern. When someone comes in the path of the waves, the waves get distorted and the number of received back waves is not the same that was there when the waves were released from the transmitter. This change in the number of transmitted waves and the received waves indicates the presence of a human in the detection range of the device.
Advantages
- Microwaves based sensors do not get affected by any other device’s interference.
- The detection ability of these sensors is not impacted by dust and smoke.
- These sensors are very much weather resistant.
Applications
- Burglar Alarms/Anti Theft Alarms/Intrusion Detection Systems
- Automatic Lights
- Automatic Industrial Doors
- Speed Guns
- Remote Sensing
4. Dual Technology Based Sensors
There exist a lot of sensors in the security market that utilize two technologies to detect the motion of humans. The most common and the most efficient combination is the combination of a PIR sensor with a Microwave sensor. Such types of sensors have better detection efficiency and are not prone to false alarms.
5. LASER (LiDAR) based sensors
LASER based sensors detect the motion with the help of a narrow beam of light emitted in the surroundings.
Working Principle
A LASER (LiDAR) based security sensor continuously releases a narrow beam of light produced by the process of optical amplification into its surroundings. The light travels in the air as a medium and hits the object or wall present in opposite to it. After hitting the object/wall, the light gets reflected and hits the detector present in the device itself. The detector keeps a record of the intensity of the light falling on it after getting reflected. Whenever any person comes in the path of the light, it gets altered and the light intensity falling on the detector also gets changed. This change in the intensity of light is noticed by the detector and as per its programming, sends a warning signal to the control panel for some suspicious activities.
Advantages
- LASER system creates a highly secure zone.
- LASER system is used to create the virtual security curtain or Carpet for precise identification of an object in a defined zone.
Applications
- Burglar Alarms/Anti Theft Alarms/Intrusion Detection Systems.