How ultra sensors work

Author: sumeeti mittal

Robots are very much useful and find a wide application in day to day in various fields. Humans have developed many machines in order to make their work easier. Machines can be simply defined as any device or thing which reduces human effort. But the quest for improvement of these machines and most importantly to make a more versatile powered mechanisms lead to the inventions of different types of robots. Robots generally can be defines as any machine which can sense the parameters of the external environment is known as robot. In a technical way robots can be defined as an electro-mechanical machine that is controlled by the use of an electronic circuitries or computer programs. As mentioned above, a comparison between the robots and machines can be easily drawn. A robot can sense the external environment but machines can’t. Hence it can be said “all robots are machines but all machines are not robot”.


Robots sense the environmental parameters through the use of sensors. Sensors are the devices which can respond to the physical stimuli. There are different types of sensors for sensing different environmental parameters like light sensor, color sensor, touch sensor, sound sensor, ultrasonic sensor, etc. Sensors are basically a class of transducers which converts a physical quantity into an electric signal. They have a wide range of applications such as in cars, machine, manufacturing, robotics and medicine. A good sensor must have the below mentioned properties:

1. Sensor must be specific and sensitive to the particular measured quantity only.

2. It must not be sensitive to any other physical quantity.

3. It should not alter or influence the measured quantity.


Ultrasonic sensors are the transducers which work on the basis of sound waves. The working principle is exactly similar to the radar or sonar. It is a transceiver, means it has both the transmitting and receiving part assembled together. The ultrasonic sensor analyses the distance of the target or object by interpreting the echoes of the sound received from it. The emitter emits the sound waves towards the target or object and the sound waves get reflected back and detected by the detector. By measuring the time between sending of the signal and receiving of the echo, the calculation of the distance of the target object is done through it.


As discussed above that the sensors are transducers, the ultrasonic transducer converts one form of energy into the sound waves which lies in the ultrasonic range which is not audible to the humans. They generally use the piezoelectric crystals. Piezoelectric crystals have the property of changing their size and atomic structure whenever any voltage is applied to it. This leads to their oscillation at very high frequency and as a result sound waves of very high frequency are produced.


The ultrasonic sensor can work basically in two different ways:

1. Thru-beam mode

2. Diffusive reflective mode


Let us have an overview of these two different working modes of the ultrasonic sensor:

1. Thru-beam mode: In this particular mode, the emitter emits the sound waves which in turn are detected by the detector. The emitter and detector are packed into two different and separate units. Whenever any object passes through between them the target is detected.

2. Diffusive reflective mode: In this particular operating mode the transmitter (emitter) and receiver (detector) are packed into the same unit. The emitter emits the high frequency sound waves and whenever any target comes into the way of the wave it gets reflected back and then detected by the detector. The distance of the target object is measured by calculating the time between the emission of the wave and detection of the echo.


The ultrasonic sensor finds its application in many areas as mentioned above. Let us discuss few of them.

1. Use in industry: The ultrasonic sensor is used to detect the objects into the production line and automated plants. It also had gained popularity in assisting the movement of the unmanned autonomous vehicle.

2. Use in medical fields: It is used for making pictures of the various parts of the human body. It can be done by passing the sensor over the body surface or inserting into the body opening.


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