In daily production and life, ultrasonic distance measurement transducers are mainly used in car reversing radar, robot automatic obstacle avoidance walking, construction sites and some industrial sites such as liquid level, depth measurement , pipeline length, etc. occasion. There are currently two commonly used ultrasonic ranging solutions. One is an ultrasonic ranging transducer based on a single-chip microcomputer or embedded device, and the other is an ultrasonic ranging transducer based on CPLD (Complex Programmable Logic Device). To understand the related application design of ultrasonic ranging sensors, we must first understand the working principle of ultrasonic sensor ranging transducer.
Working principle of ultrasonic ranging sensor
Ultrasonic sensors are sensors that convert ultrasonic signals into other energy signals (usually electrical signals). Ultrasound refers to mechanical shock waves generated in elastic media with frequency greater than 20 kHz. It has the characteristics of strong directivity, slow energy consumption, and relatively long propagation distance. Therefore, it is often used for non-contact distance measurement. Due to the great penetration of ultrasonic waves on liquids and solids, especially in solids that are opaque to sunlight. Ultrasonic waves are encountering impurities or interfaces will produce significant reflections and form reflections into echoes, and touching moving objects can produce the doppler effect. Therefore, ultrasonic ranging has a better adaptability to the environment. In addition, ultrasonic measurement can also achieve a good compromise in real time, accuracy, and price.
At present, there are many methods of ultrasonic transducer circuit: such as round-trip time detection method, phase detection method, acoustic wave amplitude detection method. The principle is that the ultrasonic sensor emits ultrasonic waves of a certain frequency, propagates through the air medium, and then reflects back after reaching the measurement target or obstacle. After the reflection, the ultrasonic receiver receives the pulse. The time it passes is the round-trip time. The distance is related. Test the transmission time to find the distance.
Assuming that s is the distance between the measuring object and the rangefinder, the measuring time is t/s, and the ultrasonic propagation speed is v/m·s-1. In the case of high accuracy requirements, The influence of ultrasonic propagation speed is corrected according to formula (2) to reduce the error. T is the actual temperature unit is ℃, v is the propagation speed unit of ultrasonic wave in the medium is m/s.
Working principle of ultrasonic ranging sensor
The principle of ultrasonic distance measurement is to transmit ultrasonic waves in a certain direction through the ultrasonic transmitter, and start timing at the same time as the transmission time.When the ultrasonic waves propagate in the air, they will return immediately when they encounter obstacles, and the ultrasonic receiver will stop timing immediately after receiving the reflected waves. . The ultrasonic ranging transducer adopts the principle of ultrasonic echo ranging and uses accurate time difference measurement technology to detect the distance between the sensor and the target. It uses a small angle and small blind area ultrasonic sensor, which has accurate measurement, no contact, waterproof and anti-proof.it is corrosion, low cost and other advantages. The common method of ultrasonic ranging transducer is that one radiating head corresponds to one receiving head, and also multiple transmitting heads are correspond to one receiving head. Based on the characteristics of simple, easy to operate and no damage based on ultrasonic ranging, it is necessary to measure the time of ultrasonic round trip , You can find the distance. This is how the ultrasonic ranging transducer works. For the ultrasonic rangefinder network editor, we recommend a ultrasonic range sensor module-HG-C40U.
The ultrasound piezoelectric transducer module has two optional transmission modes, which are free-running modes: when there is power, the sensor itself sends trigger and burst signals (for basic applications); external trigger mode: external system (controller or processor) circuit) control trigger signal is used for advanced applications, these two modes are suitable for various uses, in addition the sensor also involves two input power sources, one is low voltage (5V) suitable for processor circuit and the other is high voltage (12V) suitable The controller can measure the distance to obstacles at 3.5m (at 5V) and 5m (at 12V), and send data using UART communication with a resolution within 5mm. On the other hand, in various occasions, users can choose different setting modes according to their environment, such as free running / UART trigger / external trigger settings, etc. At the same time, they can also decide whether to use the ring buffer according to the setting of the UART communication baud rate test, output .The signal has a high-performance ASIC chip to ensure stable transmission and sensitive reception. Therefore, the sensor-to-PC communication uses the'interface board' (RS232, power conditioner) data display. The monitoring program on the PC (available super terminal) can be used to The real-time amplification of the received ultrasonic wave uses UART (ASCII, mm) output distance to convert the detection signal into a TTL level rectangular signal (square wave) in real time.
Hubei Hannas Tech Co.,Ltd is a professional piezoelectric ceramics and ultrasonic transducer manufacturer, dedicated to ultrasonic technology and industrial applications.
