Design of sound control counter in automatic measurement system of pile-driving ship

1 Introduction
With the rapid development of automation technology and the widespread application of microprocessors, sensor technology has been increasingly valued. Various sensor products have appeared one after another and have been applied to various control fields and measurement systems to replace traditional manual operations. With the continuous development of China's marine resources and the rapid development of water transportation, major coastal cities in China have been vigorously developing port construction in recent years. Various sensor equipment has broken the traditional manual measurement method and played a huge role in the measurement system of offshore construction ships. For example, a ship pile driving automatic measurement system integrates high-precision GPS receivers, inclinometers, laser rangefinders, voice-controlled counting systems, etc. to collect various data during the pile driving process, and to perform real-time correction of the ship's posture, etc., to control the pile driving accuracy, greatly improving the construction quality and work efficiency. The
voice-controlled counter in this paper is a component of the system, which is mainly used to record the number of times the pneumatic hammer piles when driving a pile, solving the shortcomings of the previous manual recording, which is time-consuming and labor-intensive, and has low accuracy, and can be automatically transmitted to the computer database software for recording.

2 Working principle and system structure
2.1 Working principle
The sound control counting system uses an electret condenser microphone to pick up the sound made by the pneumatic hammer of the pile-driving ship when hitting the pile column, and after amplification and filtering to eliminate the noise such as the engine rotation sound on the ship and the knocking sound of the workers at work, it is converted into a digital signal by the analog-to-digital conversion circuit and sent to the single-chip microcomputer for digital processing. According to the knocking rules and waveform analysis, various interferences are eliminated again, and after accurate recording, it is sent to the host computer database software through the serial port for recording.
2.2 System structure
The sound control counting system mainly includes five parts: pickup head, preamplifier, filter intermediate amplifier, analog-to-digital conversion, and microprocessor. Its system block diagram is shown in Figure 1.

3 Analog design
3.1 Preamplification
The principle of preamplification is shown in Figure 2. Analog circuits have the advantages of high reliability and good stability. Once the circuit parameters are determined, their performance is also determined. Due to the large number of equipment on board, the noise coverage of various equipment during operation is large, including the roar of the engine, the high-frequency sound of metal hitting each other, and the low-frequency sound of waves hitting the hull. Therefore, in such a complex environment, the sound of pile driving must be processed many times. Due to the low sensitivity of the pickup head, in order to improve the receiving sensitivity, the microphone is connected to one arm of the Whitdens bridge, and is sent to the reverse end of the inverting amplifier after being isolated by a DC-isolating capacitor, while the other node of the bridge is connected to the in-phase end of the amplifier. In actual application, the environmental noise will change accordingly, and the sound quality and frequency of steel piles and cement piles are different. The preamplifier can manually adjust the gain to achieve the best effect. Its principle is shown in Figure 2.

3.2 Analog-to-
digital interface The processing principle of analog-to-digital interface is shown in Figure 3. After pre-amplification, the sound signal is sent to the filtering and second-stage amplification, detection and other processing links to become a relatively clean analog signal with recognizable amplitude. In order to send it to the microcontroller for further error correction and corresponding control processing, the output analog signal needs to be digitally converted. Here it is divided into two paths for processing, one of which is sent to the microcontroller A/D sampling interface for waveform sampling after buffering drive; the other is sent to the monostable trigger for de-jittering processing to prevent the pulse output caused by noise from being miscounted.

4 Control part design
In order to count the pile driving sound and upload the data to the upper computer database management software for recording, this counter selects the STl2C2052AD microcontroller as the system controller. This is an 8051 microcontroller with A/D conversion interface, external interrupt request input, and enhanced asynchronous serial port. It has the advantages of small size and low price, and its resources are very suitable for the application of this system.
The counting control process is shown in Figure 4. The analog signal is processed by the analog-to-digital interface. The first channel is driven by the linear buffer and sent to the microcontroller A/D sampling interface to sample the sound waveform to record the characteristics of the waveform. Since the intensity of the pile driving sound is greater than other noises after being processed by the analog circuit, and its duration is relatively long, the waveform can be adaptively identified based on this characteristic. However, there will be temporary metal impact sounds during ship operations that break this characteristic, so the waveform recognition alone cannot guarantee the high reliability of counting. Therefore, two inputs are designed here, and the other one is converted into a digital counting pulse after being filtered by a monostable de-jitter and input into the microcontroller interrupt input request end for counting interrupt request. Since the sound of pile driving has a certain periodicity in time and the hitting interval is regular, a timer is started inside the processor to record the pile driving cycle and identify the authenticity of the sound from the cycle. There are limitations when processing these two inputs separately, but if the two are combined, one of them identifies the waveform characteristics and the other identifies the cycle, they complement each other and greatly improve the counting accuracy.

5 Conclusion
The development of sound control, sound sensing and other technologies has been widely used today, but with the rapid development of electronic technology, the degree of automation in various fields has been improved, and the requirements are also increasing. In practical applications, controllability, high precision and high reliability have become the focus today. In order to improve the system integration, a universal interface is often required to connect to the microcomputer. According to the characteristics of the actual environment, this design combines analog circuit processing with digital circuit processing and microcomputer control, combines the advantages of the three, complements the shortcomings of the three, and manually adjusts the fixed parameters according to the actual environment and piles, which greatly ensures the stability and accuracy of the system. After practical application, the counting system has an accuracy of more than 98%, and is very convenient for the integration of the piling system. It is an important part of the automatic control and measurement system of the ship piling system.