Passive Infrared Sensors /PIR Sensors Applications

Passive infrared sensors are everywhere around us! They have a wide range of applications that it is nearly unthinkable to imagine everyday modern life without them. These sensors are common in PIR-based motion detectors. Examples are security alarms, door opening, automatic lighting switches, vending machines, lift lobbies, etc. They are stand out with the advantage of being cost-effective, simple to use, and reliable in most cases. This article explains what PIR sensors are and its working principle. It further enumerates several sensor applications, most of which have become commonplace in our everyday lives.

 What is the PIR Sensor?

Passive Infrared sensors or PIR sensor is an electronic device that detects infrared light radiating from an object. This object could be human or animal. It does not emit waves like an active sensor since it is a passive sensor. Instead, it measures any significant increase in the energy level within its field of view.

A PIR sensor comes with infrared-sensitive materials that measure the ambiance of an environment. Positive and negative differential changes take place when a warm body passes through the field of the sensor. Considerable changes to the surroundings’ heat map will trigger a sensor’s reaction, depending on its application.

Applications of PIR Sensors

Here are some of the popular applications of PIR sensors.

1. Lighting Control

PIR sensors in lighting controls can detect a human body’s presence and automatically turn on the room’s lights. With a PIR lighting control, you do not need to operate the light switch manually. These lighting controls usually have a blank screen above the light switch.

PIR sensors create an excellent energy-saving solution. It does this by eliminating wastes that can occur when people forget to switch off the lights. This happens when they leave their homes or offices. These days, it is not uncommon to find PIR sensors for all outdoor lights, garden lights, smart luminaires, smart LED bulbs, etc.

2. Smart Home and IoT Applications

Installing a PIR-based device such as a ceiling mount PIR motion sensor in a lift lobby, common staircases, basement, corridor, restroom, ATMs, parking area, or any other part of a building is enough create a smart home or smart workplace.

With the advent of the internet of things (IoT), many mechanical, digital, and computing devices with unique identifiers (UIDs) can interrelate seamlessly. This makes the home and workplace more comfortable and efficient. Add to that PIR sensors, and it opens up a vast world of possibilities.

A few of these possibilities include the following.

• Occupancy Measurement: these sensors use computer algorithms from high granular images to gather anonymous data. The data could be from the occupants in a building (usually an office or a work setting). The data provides useful information to administrators or building owners about space utilization, open areas, providing better fire escape routes, and many others.
• Remote Thermometers: These devices use PIR sensors to read the intensity of infrared radiation from a body. It then compares the intensity against a baseline to generate a numeric value representing the body’s temperature.
• Thermostats: PIR sensors in thermostats tell the system or device what a room’s temperature set point is. It also controls when the system turns on or off. These devices or systems include HVAC (heater, ventilator or air conditioner), water heaters, refrigerators, scientific incubators, ovens, etc.

3. Motion Detection Using PIR Sensor

Passive infrared motion detectors come with some form of screen that is translucent to visible light. In other words, the screen allows light to pass through but captures vivid shapes. This technology prevents false alarms that can result from small obstructions such as dust.

Sensing units in motion detectors record the general infrared ration. It also measures the temperature of the environment. A change in the temperature means a warm body is in the device’s vicinity. This will trigger the alarm panel in the motion detector.

Some motion detectors have gait analysis and pattern recognition. This helps to filter human movement from animal movements. Others only measure changes in the temperature and raise the alarm regardless of the warm body in question.

4. Automatic Door Opening System

Automatic door opening systems are common in garage doors, shopping malls, hospitals, banks, cinemas. They also find application in many public and commercial buildings. These doors slide open when people come a few feet from them and close a few seconds after, as long as no person is standing nearby. This function is typical of a PIR sensor. This is because it detects motion or senses the presence of a warm body. It then activates a preset action, in this case, opening or closing a door.

PIR sensors in automatic door opening systems eliminate the need for a doorman or doorkeeper. Another advantage of installing these sensors on doors is that they significantly reduce air conditioning loss in a room. This is due to the door’s capacity to open only when it detects a human being (or warm body). It also remains shut when there is no one nearby activates the opening mechanism.

5. Security Alarm System Based on PIR Sensor

Security alarm systems with PIR sensors provide digital signals that translate into an alarm or siren. This is a more efficient way to provide security at home, offices, and other buildings.

The PIR sensor detects unusual activities in an environment and sends a signal to the alarm panel for processing. Alarm type PIR sensors consist of four common types, including magnetic contact switches, glass break protection devices, microwave beam, photoelectric devices, and the more popular motion detection devices.

Regardless of the type, PIR-based security alarm systems are a more effective way to burglar-proof your home and any building.

6. Human Detection Robot Using PIR Sensor

It is not enough to detect human motion only when we want to prevent burglary or unwanted entry. In some cases, detecting human presence can be a matter between life and death. For example, when a building collapses, it might be necessary to find anyone under the rubbles. Earthquakes and other natural disasters can bury thousands of people under debris.

Human detection robots with PIR sensors can achieve a more effective rescue operation instead of the traditional way of searching for bodies after disasters. Life human bodies emit thermal radiations even under heaps of debris. A human detection robot with a PIR sensor can pick up these heat signals from up to 20 feet away in all directions. With these robots in place, there is less loss of person-hours during rescue operations. Also, the success rates of the functions are likely to go up with less loss of lives.

7. PIR Sensor Based on Stepper Motor Control

A stepper motor is a brushless electric motor that rotates one step at a time. It converts digital signals into mechanical shaft rotation.

Introducing a PIR sensor in a system that uses a stepper motor will automate the system so that the motor movement will only occur when the sensor detects nearby movement. All these may seem complicated, but several hospitals, kitchen, and bathrooms work by this principle.

Some of the applications include automatic toothpaste dispensers, hands-free liquid soap dispensers, no-contact alcohol dispensers, no-touch toilet flushes, and non-contact water dispensers.

8. Multi-Function Printers

Multi-function printers consolidate the functionality of a printer, scanner, and copier into one efficient machine. Some of these machines have passive infrared motion sensors that combine high reliability, painless integration, and eco-friendly materials.

Some of the sensor functions include automatic document feeder, detecting empty trays, and sensing paper jams. The PIR motion sensors can also help in weight detection to significantly reduce energy consumption over a long time.

9. Video-Conference Systems

With organizations becoming more flexible about remote policies, video conferencing devices are taking center stage in official businesses’ conduct. Video conferencing devices now include PIR motion sensors in smart cameras that enhance virtual meetings.

Standard video-conference systems are single-eye devices that capture images and video from a single point. On the other hand, a PIR conference camera device with a motion sensor features automatic recognition. The system allows the capturing of images and videos intuitively. This happens by adjusting and rotating the camera lens to capture sound and motion.

10. Digital Signage

Digital signage that displays multimedia content is all around us, especially in public spaces, including corporate buildings, gas stations, stadiums, transport systems, hotels, retail stores, restaurants, etc. Whether it is advertising or giving a piece of useful information, these displays consume electricity.

Thankfully, passive infrared sensors included in digital signage systems can control when to turn on the display by sensing a moving body or turn it off if there is no moving object after a preset time. This technology saves power, attracts more attention, and is generally a more effective means of advertising.

11. Vending Machine

Traditional vending machines are not only expensive, but they consume a lot of energy. This is due to its non-stop operation. Annual operating electricity costs can add up significantly.

Thankfully, new designs of modern vending machines now include a PIR sensor that allows the device to function only when it detects a person’s presence in front of it. The lights and other components are out of use when there is nobody present. Also, the compressors in the machine run to generate only sufficient temperature for the entire day. This new technology saves energy and reduces overall operational costs significantly.

An essential design in vending machines with PIR sensors is the inclusion of a comparator that acts as a False Activation Prevention mechanism. The comparator ignores any object that gives off constant infrared. This solves the problem of inadvertently turning on the machine repeatedly without vending anything.

12. Wake-Up Switch for LCD Displays and Panels

A useful application of the PIR sensor is in the wake-up switch for LCDs and panels, especially in areas where critical service such as firefighting is involved.

In such situations, it is important to display information on panels and monitors always. But that can waste power and risk possible screen or computer burn-in. A simple solution is connecting a PIR sensor to a mouse to produce motion-sensitive inputs. When there is motion in the room, the passive infrared sensor picks it up and activates a mouse click through a transistor. In turn, the computer monitor comes awake and displays information. When there is no more movement, the monitor goes back to sleep mode.

13. IP Cameras, Intrusion Alarms

With the proliferation of IoT, it is now possible to automate the process of feeding your pet! Modern pet feeder designs now include PIR sensors that can feed a bowl at preset times or when the dish is empty. Equally interesting is the fact that these pet feeders can connect to mobile devices. This happens through special apps that can record and playback the owners’ voices. The app calls on the pet at mealtimes.

IP cameras with PIR sensors only start recording as soon as there is a motion by an intruder or anyone else. It conserves power and memory space by turning off the webcam and light when there is no motion.

14. Pet Feeder

With the proliferation of IoT, it is now possible to automate the process of feeding your pet! Modern pet feeder designs now include PIR sensors that can feed a bowl at preset times or when the dish is empty. Equally interesting is the fact that these pet feeders can connect to mobile devices. This happens through special apps that can record and playback the owners’ voices. The app calls on the pet at mealtimes.

With automatic pet feeders, pet owners no longer need to worry too much about leaving their pets behind when they have to go home for a long time or even when they have to travel for a few days. It also encourages healthy eating habits among pets.

Conclusion

There seem to be no end in sight for the fascinating applications of PIR sensors. The range of applications continues to expand with the ever-increasing improvements in designs and sensing ability. With the exponential growth of IoT-compatible products, it is not surprising to see a significant increase in manufacturers that include PIR sensors in newer products to deliver better results.

The working principle behind PIR sensors is simple to understand. Taking a cue from the list of applications in this article, any engineer or engineering student can develop worthwhile projects that include these sensors.