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Ultrasonic Sensor

Ultrasonic sensor is a sensor that converts ultrasonic signals into other energy signals (usually electrical signals). Ultrasonic wave is a mechanical wave with a vibration frequency higher than 20kHz. It has the characteristics of high frequency, short wavelength, small diffraction phenomenon, especially good directivity, and can become rays and propagate directionally. Ultrasonic wave has great penetrability to liquids and solids, especially in solids with opaque sunlight. When ultrasonic waves touch impurities or interfaces, they will produce significant reflections to form reflected echoes. When they touch moving objects, they can produce Doppler effect. Ultrasonic sensors are widely used in industry, national defense, biomedicine and so on.

Ultrasonic sensors are widely used in non-contact measurement. They can be used to detect liquid water level (especially corrosive liquids, such as sulfuric acid and nitric acid), automobile reverse anti-collision system, metal (or non-metal) flaw detection, robot sensing system design, etc. the "distance sensing system" of intelligent toy robot is composed of a potential difference ultrasonic sensor and 51 single chip microcomputer. The circuit interface is simple and the cost is low, Good stability, but its measurement accuracy is limited by the maximum measurement distance of the potential difference ultrasonic sensor and the reflection angle with the measured object.

1) The distance from the object is more than 3 m. when the measured object is 3 m away from the intelligent toy robot, as shown in Figure 6 (a), the transmitted power of the potential difference ultrasonic sensor is insufficient, and the reflected signal is too weak, so the distance value displayed on the LCD cannot reflect the actual distance value.
2) The measured object is not directly in front. When the measured object is not directly in front of the intelligent toy robot, as shown in Figure 6 (b), it has a certain deflection angle. Because the reflection angle formed with the surface of the object is too small, the sensor receiver cannot receive the reflected signal, resulting in the distance value displayed on the LCD cannot reflect the actual distance value.
3) The cross section of the front measured object is too small. The volume or cross section of the front measured object is too small, as shown in Figure 6 (c). Because there is no signal of sufficient strength returned to the sensor, the distance value displayed on the LCD cannot reflect the actual distance value.