A motion sensor (or motion detector) is the linchpin of your security system, because it’s the main device that detects when someone is in your home when they shouldn’t be. A motion sensor uses one or multiple technologies to detect movement in an area.
There are two popular types of passive motion sensors. These are mostly found in residential homes. Passive infrared motion detectors (PIR) detect emitted infrared energy – given off by humans and animals in the form of heat. When there is a sudden increase in infrared energy, an alarm is sounded.
Motion detectors are small electronic eyes that detect infrared waves—heat waves that radiate from moving objects. When the detector senses an object moving across its field of view—especially warmer objects such as people, animals and cars—it electronically turns on the lights.
When the sensor is idle, both slots detect the same amount of IR, the ambient amount radiated from the room or walls or outdoors. When a warm body like a human or animal passes by, it first intercepts one half of the PIR sensor, which causes a positive differential change between the two halves.
The Motion Detector is used to measure position, velocity, and acceleration of moving objects.
A motion detector is a device that detects moving objects, particularly people. Such a device is often integrated as a component of a system that automatically performs a task or alerts a user of motion in an area. They form a vital component of security, automated lighting control, home control, energy efficiency, and other useful systems.
An electronic motion detector contains an optical, microwave, or acoustic sensor, and in many cases a transmitter for illumination. However, a passive sensor senses a signature only from the moving object via emission or reflection, i.e., it can be emitted by the object, or by some ambient emitter such as the sun or a radio station of sufficient strength. Changes in the optical, microwave, or acoustic field in the device’s proximity are interpreted by the electronics based on one of the technologies listed below. Most low-cost motion detectors can detect up to distances of at least 15 feet (4.6 m). Specialized systems cost more, but have much longer ranges. Tomographic motion detection systems can cover much larger areas because the radio waves are at frequencies which penetrate most walls and obstructions, and are detected in multiple locations, not only at the location of the transmitter.
Motion detectors have found wide use in domestic and commercial applications. One common application is activating automatic door openers in businesses and public buildings. Motion sensors are also widely used in lieu of a true occupancy sensor in activating street lights or indoor lights in walkways, such as lobbies and staircases. In such smart lighting systems, energy is conserved by only powering the lights for the duration of a timer, after which the person has presumably left the area. A motion detector may be among the sensors of a burglar alarm that is used to alert the home owner or security service when it detects the motion of a possible intruder. Such a detector may also trigger a security camera to record the possible intrusion.
Passive infrared (PIR)
Passive infrared (PIR) sensors are sensitive to a person’s skin temperature through emitted black body radiation at mid-infrared wavelengths, in contrast to background objects at room temperature. No energy is emitted from the sensor, thus the name passive infrared. This distinguishes it from the electric eye for instance (not usually considered a motion detector), in which the crossing of a person or vehicle interrupts a visible or infrared beam.
These detect motion through the principle of Doppler radar, and are similar to a radar speed gun. A continuous wave of microwave radiation is emitted, and phase shifts in the reflected microwaves due to motion of an object toward (or away from) the receiver result in a heterodyne signal at a low audio frequency.
An ultrasonic wave (sound at a frequency higher than a human ear can hear) is emitted and reflections from nearby objects are received. Exactly as in Doppler radar, heterodyne detection of the received field indicates motion. The detected doppler shift is also at low audio frequencies (for walking speeds) since the ultrasonic wavelength of around a centimeter is similar to the wavelengths used in microwave motion detectors. One potential drawback of ultrasonic sensors is that the sensor can be sensitive to motion in areas where coverage is undesired, for instance, due to reflections of sound waves around corners. Such extended coverage may be desirable for lighting control, where the goal is detection of any occupancy in an area. But for opening an automatic door, for example, a sensor selective to traffic in the path toward the door is superior.
Tomographic motion detector
These systems sense disturbances to radio waves as they pass from node to node of a mesh network. They have the ability to detect over large areas completely because they can sense through walls and other obstructions.
Video camera software
With the proliferation of low-cost digital cameras able to shoot video, it is possible to use the output of such a camera to detect motion in its field of view using software. This solution is particularly attractive when the intent is to record video triggered by motion detection, as no hardware beyond the camera and computer is needed. Since the observed field may be normally illuminated, this may be considered another passive technology. However it can also be used together with near-infrared illumination to detect motion in the dark, that is, with the illumination at a wavelength undetectable by a human eye.
Photodetectors and infrared lighting elements can support digital screens to detect hand motions and gestures with the aid of machine learning algorithms
Dual-technology motion detectors
Many modern motion detectors use combinations of different technologies. While combining multiple sensing technologies into one detector can help reduce false triggering, it does so at the expense of reduced detection probabilities and increased vulnerability. For example, many dual-tech sensors combine both a PIR sensor and a microwave sensor into one unit. For motion to be detected, both sensors must trip together. This lowers the probability of a false alarm since heat and light changes may trip the PIR but not the microwave, or moving tree branches may trigger the microwave but not the PIR. If an intruder is able to fool either the PIR or microwave, however, the sensor will not detect it.
Often, PIR technology is paired with another model to maximize accuracy and reduce energy use. PIR draws less energy than emissive microwave detection, and so many sensors are calibrated so that when the PIR sensor is tripped, it activates a microwave sensor. If the latter also picks up an intruder, then the alarm is sounded.
A motion sensor (or motion detector) is the linchpin of your security system, because it’s the main device that detects when someone is in your home when they shouldn’t be. A motion sensor uses one or multiple technologies to detect movement in an area. If a sensor is tripped, a signal is sent to your security system’s control panel, which connects to your monitoring center, alerting you and the monitoring center to a potential threat in your home.
Microwave and infrared sensors used to detect motion by the changes in the frequencies they produce. To understand the working of motion sensor, you first need to know the working of a camera. The camera uses an image sensor and the lens direct light to – when the light strikes the image sensor each pixel records how much light it’s getting. That outline of light and dark areas in the pixels becomes the entire video image.
Motion sensors are applicable for security systems which are used in offices, banks, shopping malls, and also as intruder alarm at home. The existing motion detectors can stop serious accidents by detecting the persons who are closest to the sensor. We can monitor motion detectors in public places. The main part of the motion detector circuit is the dual IR reflective sensor.
What is a Motion Sensor?
A motion sensor is a device that notices moving objects, mainly people. A motion sensor is frequently incorporated as a component of a system that routinely performs a task or else alert a user of motion in a region. These sensors form a very important component of security, home control, energy efficiency, automated lighting control, and other helpful systems. The main principle of motion sensor is to sense a burglar and send an alert to your control panel, which gives an alert to your monitoring center. Motion sensors react to different situations like movement in your living room, doors, windows being unbolt or closed and also these sensors can
Activate a doorbell when someone comes close to the front door.
These sensors give you an alert whenever kids enter into some restricted areas in the home such as medicine cabinet, the basement or workout room.
Conserve energy by using this sensor lighting in empty spaces.
Types of Motion Sensors
There various kinds of motion sensors are available in the market, which has their ups and downs. They are namely PIR, Ultrasonic, Microwave, Tomographic and combined types.
Types of Motion Sensors
Passive Infrared (PIR) Sensor
All warm blooded animals produce IR radiation. Passive infrared sensors include a thin Pyroelectric film material, that responds to IR radiation by emitting electricity. This sensor will activate burglar alarm whenever this influx of electricity takes place. These sensors are economical, don’t use more energy and last forever. These sensors are commonly used in indoor alarms.
Passive Infrared Sensor
Ultrasonic sensor can be active (or) passive, where passive ones pay attention for particular sounds like metal on metal, glass breaking. These sensors are very sensitive, but they are frequently expensive and prone to fake alarms. Active ones generate ultrasonic wave (sound wave) pulses and then determine the reflection of these waves off a moving object. Animals like cats, dogs, fishes can hear this sound waves, so an active ultrasonic alarm might unsettle them.
These sensors generate microwave pulses and then calculate their reflection off of objects, in order to know whether objects are moving or not. Microwave sensors are very sensitive, but sometimes these can be seen in nonmetallic objects which can be detected moving objects on the outside of the target range. It consumes a lot of power, so these sensors are frequently designed to cycle ON & OFF. This makes it feasible to acquire past them, if you know the cycles. Electronic guard dogs utilize microwave sensors.
These sensors generate radio waves and detect when those waves are troubled. They can notice through walls and objects, and are frequently placed in a way that makes a radio wave net that cover ups large areas. These sensors are expensive, so they are normally used in warehouses, storage units and also in other situations that need a commercial level of security.
Combined types of Motion Sensors
Some types of motion detectors mix some sensors in order to decrease fake alarms. But, dual sensors are only activated when both kinds sense motion. For instance, a dual microwave or PIR sensor will start out on the passive infrared sensor setting, because that consumes less energy. When the passive infrared sensor is tripped, the microwave division will turn ON; then, if the remaining sensor also tripped, the alarm will generate sound. This combined type is great for neglecting fake alarms, but tuns the possibility of missing real ones.
Combined types of Motion Sensors
Thus, this is all about the different types of motion sensors which include Passive Infrared Sensor, Ultrasonic Sensor, Microwave Sensor, Tomographic Sensor and Combined types.
Motion sensors for numerous residential and commercial applications. These come in innumerable types and shapes
Motion sensors and Motion detectors
Motion sensors are the most widely used category of automation sensors and is equally utilized in industrial and commercial applications. The reason for wide usage is that these are the essential part of energy conservation in commercial, residential and industrial applications and the installation is extremely simple enough to be carried out by normal technicians. These are also known as movement sensors and movement detectors. Such sensors are also an integral part of Home automation and office automation systems which can be integrated into an entire system or individual units or a section of the room, corridor etc. as per the customer requirements. These are available in latest Automation protocols such as KNX, Bacnet etc. for integrating into an entire building management system. Ultrasonic sensors and Infrared sensors
are the most commonly used technology for detecting motion.
Operating principle of Motion Sensors technology
As obvious from the name, these are also known as motion detectors are used to detect motion. The motion thus detected may be that of human beings, machinery parts, mechanical parts etc. depending on the application. The basic principle is that it will be constantly monitoring a certain area or a linear path. If any movement happens in this area, the sensor will detect the same and an output signal will be provided to other connected circuitries and instruments to carry out any related functions. These are also called motion sensor switch since the sensor is only carrying out a switching action. Different models for indoor and outdoor applications are available.
How motion sensors work?
All motion sensors work by detecting an input and providing an output. Motion detectors use different technologies for detecting motion. All such sensors have a transmitter and receiver. The transmitter constantly emits different types of waves based on the technology used and the waves are received back at the sensor after a time delay. Various parameters between transmission and reception are analyzed by the motion detector which determines whether a motion has been detected.
All of them will generally have adjustable sensitivity and delay timing. Sensitivity setting is for adjusting the sensitivity of movement detection. If most sensitive setting is selected, minute movements will be detected. Delay timing is adjusted to set the delay in switching after a movement stops. Eg. if a delay period of 60 seconds is programmed for the motion sensor, the lights will be switched off after 60 seconds from the last detection of a motion. These particular types are also called motion sensor lights.
Few of the major technologies utilized are briefed below.
Presence sensors are mainly used for commercial and residential applications for conservation of energy. Different manufacturers have different models such as wall mounted, ceiling mounted etc. These are often confused with motion sensors, however are slightly different in operating principles. These are also part of home automation systems and can be integrated
Operating principle of Presence Sensors and Occupancy sensors and Presence detector products
Presence sensors operate if any human beings are present in the area being monitored. The term occupancy sensor is also used for the same which means that the sensor operates if the area is occupied by someone. Outdoor and indoor models are available with different ingress protection levels. The device generates a switching action of electric circuits if a presence is detected.
How presence sensor based products work?
Presence detectors are not detecting any movement, but only checking whether a human being or other living beings are present in the area. The presence will be detected even if the person is completely idle without any movement. The principle utilized is that every living being generates a temperature on its own body. This heat is detected by the presence detector and as long as such a presence is detected, the associated switching circuit will remain in on condition. When the presence is not detected, the circuit will be switched off.
Passive Infrared sensor (PIR sensor)
Passive Infrared sensors are the most commonly used presence detectors. These are also known as PIR sensors. These are called passive because the device is not generating infrared rays. Instead it is detecting the heat generated by the human body. Even though the most common application is to detect human beings, it will detect any living being such as dog, cats, bird etc. and it will not be able to distinguish between any of them. PIR sensors are combined by certain manufacturers with other sensing technologies such as ultrasonic sensors for higher precision, thus detecting a combination of motion and presence.
Difference between Presence sensor and motion sensor
In our separate page on motion sensors we have given an example of utilization of motion sensor in a corridor. If any person comes out into the corridor, the motion sensor will be activated and thus it’s associated lights in the corridor. However if the person stops walking and decide to stand in the corridor without any movement, the motion sensor will switch off the electric circuit after the programmed delay period because it did not detect any motion. If the person moves his hand slightly, the lights will be turned on again because a motion is detected. However if a presence detector was used instead of the motion sensor, the electric circuit will not be turned off, since it detects that a human being is standing in its range of vicinity irrespective of his movements.
Presence detecting sensor
Passive Infrared sensor
PIR light switch
PIR light sensor
Ceiling PIR sensor
Occupancy sensor light switch
Light control sensor
Infrared sensor switch
Libraries – the readers will be sitting idle for long times and hence motion sensors may not be preferred.
Classrooms – Especially smaller classrooms will have students idle for some time and hence occupancy sensors are preferred.presence detector dubai uae
Restrooms – obviously the occupants will be idle for a long time
Washrooms – if the occupant is idle for some time, a motion sensor will turn off the lights scaring the occupant. Hence an occupancy sensor is preferred
Most common applications of presence sensor, presence detector and occupancy sensor
Example of simple application
In a library with a small number of people, the readers will be sitting idle and reading books without any movements. In such a case it is better to use a presence detector. For a large library with a huge number of occupants, the probability of all them being idle for a couple of minutes may be possible but remote. As occupancy sensors are costlier than motion sensors, the selection process will involve cost implications.
Difference between Presence sensor and motion sensor
In our separate page on motion sensors we have given an example of utilisation of motion sensor in a corridor. If any person comes out into the corridor, the motion sensor will be activated and thus it’s associated lights in the corridor. However, if the person stops walking and decides to stand in the corridor without any movement, the motion sensor will switch off the electric circuit after the programmed delay period because it did not detect any motion. If the person moves his hand slightly, the lights will be turned on again because a motion is detected. However, if a presence detector was used instead of the motion sensor, the electric circuit will not be turned off, since it detects that a human being is standing in its range of vicinity irrespective of his movements.