Ultrasonic Sensor
What is an Ultrasonic Sensor?
The ultrasonic sensor is an electronic device that measures the distance of the target object by emitting ultrasonic sound waves and converts the reflected sound to an electrical signal. Ultrasonic waves travel faster than the audible sound speed (i.e. the sound that humans can hear). Ultrasonic sensors have two main components: the transmitter (which emits the sound using piezoelectric crystals) and the receiver (which encounters the sound after it has traveled to and from the target).
To calculate the distance between the sensor and the object, the sensor measures the time it takes for the transmitter to come into contact with the receiver between the emission of the sound.
The formula for this calculation is D = ½ T x C (where D is the distance, T is the time, and C is the speed of sound ~ 343 meters/second).
Working Principle of Ultrasonic Sensor
The ultrasonic sensor (or transducer) operates on the same principles as the radar system. The ultrasonic sensor can transform electrical energy into acoustic waves and vice versa. The acoustic wave signal is an ultrasonic wave that passes at a frequency above 18 kHz. The famous HC SR04 ultrasonic sensor generates ultrasonic waves at a frequency of 40 kHz.
Usually a microcontroller is used to work with an ultrasonic system. The microcontroller sends a trigger signal to the ultrasonic sensor to continue calculating the gap. The duty cycle for this trigger signal is 10μS for the HC-SR04 ultrasonic sensor. When triggered, the ultrasonic sensor generates eight acoustic (ultrasonic) waves and initiates a time counter. The timer stops as soon as the reflected (echo) signal is received. The performance of the ultrasonic sensor is a fast pulse of the same length as the time gap between the emitted ultrasonic burst and the obtained echo signal.
Advantages of Ultrasonic Sensors
These are a few ultrasonic sensor advantages that help clarify what applications our sensors are suited for:
Ultrasonic sensors reflect sound from objects so that color or transparency does not affect the reading of the sensor. Unlike proximity sensors that use light or cameras, dark conditions have little impact on the sensing capabilities of the ultrasonic system. Sensors are starting at $29.95. They come completely tested and ready for use. They provide a low cost, high-quality product suited to specific needs. Although the sensors work well in these environments, they can still deliver incorrect readings with a heavy build-up of dirt or water, especially under extreme conditions.
Uses and Applications of an ultrasonic sensor
Multiple areas of engineering use ultrasonic sensors. “No-contact” distance measuring is very useful in automation, robotics and instrumentation.
Below we investigate the applications of ultrasonic sensors:
Weather stations usually use anemometers as they measure wind speed and direction effectively. 2D anemometers can only calculate the horizontal portion of wind speed and direction, whereas 3D anemometers can also calculate the vertical component of force.
Apart from measuring wind speed and direction, ultrasonic anemometers can also measure temperature because the speed of ultrasonic sound waves is affected by variations in temperature while maintaining independence from changes in pressure. Temperature is calculated by measuring speed variations in ultrasonic sound.
The tide gauge is used to monitor the sea level. It also senses floods, storm waves, tsunamis, swellings and other coastal cycles. An ultrasonic system may be used to measure water temperatures in real-time. The gage is often linked to an online database where the record is maintained and in the event of a risky situation, the system can trigger an alarm.
Measuring the fluid level in the tank is like that of the tide gauge. In this case, however, the fluid can be clear water, a corrosive chemical or a flammable fluid. Unlike optical sensors and float switches, ultrasonic sensors are less likely to corrode because they are not in contact with the fluid.
The sunlight on Earth's surface is made up of about 52-55 percent of infrared light. If an infrared sensor detects an object using infrared light, the process is disturbed by infrared light interference. Ultrasound sensors, however, are not affected by the infrared spectrum present in sunlight.
Unmanned aerial vehicles (UAVs)—or drones — commonly use ultrasonic sensors to monitor any object in the UAV path and distance from the ground.
The autonomous feature of detecting safe distances enables the aircraft to avoid crashes. And as the path flight changes instantaneously, ultrasonic distance detection can prevent a drone from crashing.
