A basic ultrasonic distance sensor measures distance using sound waves in a simple yet effective way. Here's how it works:
Principle of Operation: The sensor emits ultrasonic sound waves and then measures the time it takes for the sound waves to bounce back after hitting an object. By knowing the speed of sound in the medium (usually air), it can calculate the distance to the object.
Transmitter and Receiver: The sensor consists of two main components - a transmitter and a receiver. The transmitter emits short bursts of ultrasonic waves, and the receiver detects the echoes of those waves after they bounce off an object.
Emission of Ultrasonic Waves: The sensor's transmitter generates an electrical signal that is converted into ultrasonic sound waves through a piezoelectric transducer. Piezoelectric materials can convert electrical energy into mechanical vibrations and vice versa. When an electric signal is applied to the transducer, it vibrates, creating ultrasonic waves in the frequency range of around 20 kHz to several hundred kHz.
Propagation of Sound Waves: The ultrasonic waves propagate through the air in the direction pointed by the sensor. As the waves encounter an object in their path, some of the sound waves are reflected back towards the sensor.
Detection of Echo: The receiver, which also contains a piezoelectric transducer, picks up the reflected sound waves (echo) that return from the object. When the echo strikes the receiver's transducer, it generates an electrical signal proportional to the received sound.
Time Measurement: The sensor's electronic circuitry measures the time between sending the ultrasonic wave and receiving the corresponding echo. This time interval is known as "time of flight."
Distance Calculation: Since we know the speed of sound in air (approximately 343 meters per second at room temperature), we can calculate the distance to the object using the formula:
Distance = (Speed of Sound × Time of Flight) / 2
The division by 2 is necessary because the sound wave travels the distance to the object and back.
Output: The calculated distance is then typically converted into a digital value and made available through an output interface, such as an analog or digital signal, which can be read by a microcontroller, computer, or other processing devices.
Ultrasonic distance sensors are widely used in various applications, such as obstacle detection, distance measurement, robotics, and industrial automation, due to their accuracy, simplicity, and reliability.