What is the Difference between the Motion Sensor, Position Sensor and Proximity Sensor

In today’s world sensors became a part of life. In each application sensors are playing crucial role in every device. Life is done so with the sensors. Every sensor is different from others and has unique applications. Without any effort humans can operate the devices with the gestures and other devices. Sensors are very important organs of any measurement system. Here in this article out of many sensors we are using three sensors, i.e. the motion sensor can also be called as IR, position sensor is also called as ultrasonic and proximity sensor. Each of these sensors is discussed in detailed and their differences too.

Difference between the Motion Sensor, Position Sensor and Proximity Sensor

The difference between the motion sensor, position sensor and proximity sensor mainly include working principle, circuit diagram, advantages, disadvantages and applications

Difference between the Motion Sensor, Position Sensor and Proximity Sensor
Difference between the Motion Sensor, Position Sensor and Proximity Sensor

Motion sensor

Here motion sensor is also called as an infrared sensor. It is an electronic device, which emits in order to sense some aspects which are happening in the surroundings. An IR sensor will not only measure the heat of an object, but also detects the motion. These sensors measure infrared radiation, rather than emitting it, so it is called as a passive IR sensor. Generally the infrared spectrum will radiate some form of thermal radiations which are invisible to our eyes and that can be detected by an infrared sensor.

IR Sensor
IR Sensor

IR Sensor

The emitter is simply an IR Light Emitting Diode (LED) and the detector is an IR photodiode which will be sensitive to IR light that of the same wavelength as is emitted by the IR LED.

IR Sensor Working Principle
IR Sensor Working Principle

The moment IR light falls on the photodiode these output voltages and the resistances, change in proportion to the magnitude of the IR light received.

Position Sensor

The position sensors play an important role in different systems. Whether it is, drive-by-wire cars, bullet trains taking round curves, fly-by-wire aircraft systems, packaging machines, medical equipments, injection molding machines and so on. The sensor which is used for measurement of pressure is called pressure sensor.

Position Sensor
Position Sensor

PIR Sensor Working Principle

These position sensors basically measure the distance travelled by the body by talking the starting point as a reference position. It is like how far the body moves from its initial or reference position is sensed by the position sensors and every time it is quite often that the output is given as a fed back to the control system which will take the appropriate action. The motion of the body can be curvilinear or rectilinear; accordingly, position sensors are called angular position sensors or linear position sensors.

PIR Sensor Working Principle
PIR Sensor Working Principle

Different Types

  • Resistance-based or Potentiometric Position sensors
  • Capacitive position sensors
  • Linear Voltage Differential Transformers
  • Magnetostrictive Linear Position Sensor
  • Eddy Current based position Sensor
  • Hall Effect based Magnetic Position Sensors
  • Fiber-Optic Position Sensor
  • Optical Position Sensors

Proximity Sensor

Proximity sensors basically detect the presence of objects without physical contact. A proximity sensor detects objects when the objects approach within the detection range and boundary of the sensor. Proximity sensors includes all sensors that perform non contact detection in compassion to sensors such as limit switch that detects the object by physically contacting them. Proximity sensors are used in various sides of manufacturing for detecting the approach of non-mental and metal objects. What is inductive proximity sensor?

What is an Inductive Proximity Sensor?

It is an electronic proximity sensor, which has a property of detecting the metallic objects without touching them. The principle involved in the inductive proximity sensor is that it is based on a coil and high frequency oscillator which creating a field in the closed surrounding of the sensing surface.

Inductive Proximity Sensor

The distance of operation of this sensor depends on the coil’s size and the target’s shape, material and size.

Inductive Proximity Sensor
Inductive Proximity Sensor

Construction and working

The main components are

  • Oscillator
  • Detector
  • Coil
  • Output Circuit

The coil generates the very high frequency magnetic field in front of the face, when the metallic target comes in this magnetic field and it absorbs some of the energy. From this oscillator field is affected. The fall or raises of such oscillation are defined by a threshold circuit. It changes the output of the sensor.

Inductive Proximity Sensor Working Principle
Inductive Proximity Sensor Working Principle
  • Inductive proximity sensors are very accurate when compared with other technologies.
  • It will work in the very harsh environment.
  • Having very high switching rate.
  • The sensing range is more than 6 cm.
  • It has a limit of operating range.
  • It will only detect the metallic target.
  • It detects the metal
  • Detects host of automated industrial processes
NoNoSS Motion sensor Position sensor Proximity sensor
1 The motion sensor is also called as the IR sensor Position sensor is also called Passive IR sensor The proximity sensor is called by many different names
2 Figure
3 Different types of sensors 1.      Active infrared sensor

·         Reflectance Sensors

·         Break Beam Sensors

2.      Passive Infrared sensor

·         Thermocouple-Thermopile

·         Extrinsic type

·         Intrinsic type

1.      Photovoltaic

2.      Photoconductive

·         Pyroelectric detector

·         Bolometer

·         Vibration

·         Area Reflective Type

·         Microwave

·         Ultrasonic

·         Dual Technology Motion Sensors

·         Capacitive displacement sensor

·         Laser ranger finder

·         Photocell

·         Radar

·         Sonar

·         Reflecting of ionizing radiation


·         Capacitive.

·         Magnetic.

·         Doppler effect

·         Eddy-current

·         Capacitive displacement sensor.

·         Laser .rangefinder.

·         Passive optical

·         Inductive.



4 Applications
  • Lighting appliances

·         Thermography

·         Night vision

·         Communications

·         Hyperspectral imaging

·         Tracking

·         Heating

·         Other imaging

·         Climatology

·         Meteorology

·         Spectroscopy

·         Health hazard

·         Astronomy

·         Infrared cleaning

·         Thin film metrology

·         Photobiomodulation

·         Art conservation and analysis

·         Biological systems

  • Household or other appliances


·         Television sets

·         VCRs

·         DVD

·         Doorways in grocery stores, grocery stores

·         Military purposes such as laser range-finding, heat-seeking missiles and night vision

·         Position Measurement

·         Air Gauging

·         Detecting Dynamic Motion

·         Touch pads

·         Speeding

·         Assembly Testing

·         Speeding

·         Ground Proximity Warning System

·         Speeding

·         Differential Systems


The difference between the motion sensor, position sensor and proximity sensor are explained in the article and hoping that the basic function of these three sensors is understood well i.e. basic circuit diagram, working principle, advantages, disadvantages, applications. If there is any such thing which is not clear yet or to implement sensor based projects, feel free to ask about any of these sensors. Here is a question for you, What is the function of a sensor?

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