Ultrasonic Sensor: An ultrasonic sensor is as sensor which measures the distance of respective object by sending the sound wave of specific frequency. This sound wave is reflected after the collision with respective object and this wave is received by the ultra-sonic receiver. Distance is measured by calculating sending and receiving time of this sound wave. you may also like to read distance measurement using ultrasonic sensor and arduino. Basic operational diagram of ultrasonic sensor is shown in figure 1
Figure 1 The Basic Operation Diagram of Ultrasonic Sensor
Distance is measured by the formula
Distance = Sound speed x time taken / 2
Sound travels through the air with almost speed 344m/s (1129ft/s) and this speed is mutiplied with the total time (sending and receicving) of sound wave. In this formula because total time is counted therefore ,it is devided by 2 for calculating the totall distacnce of that respective object. May be some obects are not detected by ultrasonic sensors due to their improper shape, positon and too samall size that object.
Working with Circuit Diagram of Ultrasonic Senor
Figure 2 Circuit Diagram of Ultrasonic Senor
The ultrasonic sensor circuit consists of set of ultrasonic transmitter and receiver which are operated at same frequency. When anything or object comes into the area of covered circuit then its frequency sound reflected to receiver and alarm is triggered. Ultrasonic sensor circuit is very sensitive and it could be reset automatically or still in triggered until it is reset manually. This sensor consists of two NAND gates which are wired as an inverter to form the multi vibrator output for driving the transduce. It also consists of two trimmers P1 and P2. P1 is used for adjusting the amplification factor of inverting and non-inverting circuit or op-amp. P2 is used for adjusting the output frequency of transmitter and for acquiring good efficiency the output frequency should be same as resonance frequency of traducer which is in use. Transducer is used for receiving the output signal which is reflected after the collision and this signal is amplified through the resistor TR3. Ultrasonic sensor is shown is figure 3
Different Types of Ultrasonic Sensor with Working
There are four major different types of ultrasonic sensors are currently in used,
- Ultrasonic Proximity Sensors
- Ultrasonic 2 Point Proximity Switches
- Ultrasonic Retro-reflective Sensors
- Ultrasonic Through Beam Sensors
Ultrasonic Proximity Sensors
In this ultrasonic proximity sensor, a special type of sonic transducer is used for alternate transmission and reception of sound wave. This sonic transducer emits the sonic waves which are reflected by an object and after this emission, this sensor switched into receive mode. The total time which is passed between emitting and receiving of sound wave is inversely proportional to the distance of object from sensor. The digital output is only possible or sensed with in detection area. Sensing range can adjust with sensor’s potentiometer. This sensor is shown in figure 4
Figure 4 Ultrasonic Proximity Sensor
Ultrasonic 2 Point Proximity Switches:
This sensor consists of 2 points for switching, therefore it is called 2-point proximity switches. It is almost similar with standard sensor only differ the 2-touch set up key and this function is called Tech-in function. Its switches Sde1 and Sde2 could be easily programmed within the sensing range with the help of built in Tech-in button. This sensor is shown in figure 5
Figure 4 Ultrasonic 2 Point Proximity Switch
Ultrasonic Retro-reflective Sensors:
The operation of ultrasonic retro-reflective sensor is similar with ultrasonic proximity sensor. Only difference, in this sensor the distance between sensor to reflector is measured by measuring the propagation time. In this sensor, the stationary object could be used as a reflector and sensing distance (SD) could be adjust by adjusting the potentiometer resistance with in ultrasonic sensor. Its working is so much simple, when any object comes with in sensing distance then its propagation time is changed and by changing this propagation time, the sensor has switched into active mod. This sensor also allows the detection of sound absorbent and object deflecting sound. This sensor is shown in figure 5.
Figure 5 Ultrasonic Retro-reflective Sensor
How to Measure Speed with Ultrasonic Senor
For measuring speed with ultrasonic sensor, a microcontroller or any controller such as Arduino is necessary to connect with this sensor. Ultrasonic sensor consists of two transducers one is act as a speaker which converts the electrical pulses into sound pulses and then emit them with high frequency almost 40KHz.Similary the other one acts as a microphone for receiving the sound pulses which are reflected after the Collison of specific object. Because a microcontroller or any controller is attached with ultrasonic sensor therefore the timer of controller starts to count the pulses when it is transmitted and is stop when sound waves are received by microphone. Based on sending and receiving the sound pulses the microcontroller or any controller determined to speed of that specific object.
Applications of Ultrasonic Sensor
- Ultrasonic sensor is used in oil, chemical, milk or water tanks for level measurements or for liquid level control.
- This sensor is used in thru beam detection for high speed counting.
- This sensor is used in robotic industry for robot sensing.
- This sensor is used in car parking system where car entry is controlled through barrier system, the barrier must not be lowered when there is beneath a vehicle. This whole process is controlled through ultrasonic sensor.
- This sensor is used with bottle cutting and drink filling machines, where bottle is detecting at serval points and for this continuous monitoring the ultrasonic sensor is used.
- This sensor is used in transporting printed circuit boards (PCBs) industry where smart phones, computer mother boards and home appliances circuit boards are designed and print.
- This sensor is used in car manufacturing industry for manufacturing or assemble the car automatically.
- This sensor is used in car washing system for detecting and washing the car automatically.
- This sensor is used for detecting the speed of motor or generator.
- This sensor is also used in presence detection system.
Advantages of Ultrasonic sensor
- The ultrasonic sensor has high frequency, high sensitivity and high penetrating power therefore it can easily detect the external or deep objects.
- These sensors easily interface with microcontroller or any type of controller
- These sensors have greater accuracy then other methods for measuring the thickness and depth of parallel surface.
- These sensors could easily sense the nature, shape and orientation of that specific objects which is within the area of these sensors.
- There sensors are easy to use, not dangerous during operation for nearby objects, person, equipment or material
Disadvantages of Ultrasonic Sensor
- During use of ultrasonic tester for testing it is very important to know the operational manual, in other words it required careful attention for experienced technician.
- During the development inspection procedure of equipment using ultrasonic tester extensive knowledge is required is testing technicians.
- When these sensors are used for inspection purpose then these should be water resistive otherwise they could be damaged.
- When these sensors are interfaced with microcontroller or any controller then experienced person or programmer is required.