Monitoring system of cleaning test bench based on single chip microcomputer control

In recent years, with the continuous development of my country's economy and the continuous improvement of people's living standards, people have higher and higher requirements for the quality of life. Therefore, the requirements for the working performance of grain cleaning machinery in grain cleaning operations have also increased accordingly.

However, general cleaning machines have single functions, poor adaptability or unstable technical performance. For this reason, we use 8051 single-chip microcomputers and corresponding detection and conversion devices to design a monitoring system with simple structure, reliable operation, precise control and low price. This system uses the powerful functions and scalability of the series of single-chip microcomputers as a backing to realize various real-time, effective and multi-functional control operations of the cleaning test bench monitoring system. This system monitors and controls the main working parameters of the cleaning test bench through the 8051 single-chip microcomputer, which can improve the production efficiency and cleaning accuracy of the cleaning device, reduce grain losses, and improve its automation level. This paper discusses the design and implementation methods of the system.

1. Design of cleaning test bench

This study is based on the cleaning test bench as the research object, and the development of the monitoring system is based on the cleaning test bench as the test equipment. Therefore, the design of the cleaning test bench is crucial. The cleaning test bench consists of a frame, a conveyor belt, a shaking plate, a screen box, a fan, a motor, a seed receiving box and other components. The main dimensions and motion parameters of the cleaning test bench are shown in Table 1.

Table 1 Main dimensions and motion parameters of the cleaning test bench

2. System working principle

The monitoring system of the cleaning test bench is based on the 8051 single-chip microcomputer. It detects working parameters such as feed volume and fan speed through sensors, converts them into digital quantities through A/D converters, and then sends them to the 8051 single-chip microcomputer for processing. According to the actual situation of the detected feed volume, it controls and adjusts the size of each working parameter to adapt to the current work needs. If the feed volume exceeds the limit (too high or too low), the indicator light will light up, the siren will sound, and it will be displayed on the screen.

The system functional block diagram is shown in Figure 1.

Figure 1 System functional block diagram

3. System hardware design

The system hardware adopts a control structure with 8051 single-chip microcomputer as the core, which is composed of sensors, signal processors, A/D (D/A) converters, control circuits, displays, and external data storage.

The A/D converter uses the 12-bit successive approximation fast A/D converter AD547A, which can quickly convert parameters such as speed, pressure, and frequency. The measured parameters are converted into 0-2VDC signals after detection, sent to the A/D converter to convert into digital quantities, and then sent to 8051 for processing. AD574A has the advantages of fast conversion speed, high precision, moderate price, and very convenient application. Since the AD574A chip has a clock, there is no need for an external clock signal. Because 74A outputs 12-bit digital, when the microcontroller reads the conversion result, it needs to be done twice: first the high 8 bits and then the low 4 bits.

The speed sensor uses JN338 digital torque speed sensor, which uses two sets of special annular rotary transformers to realize energy input and torque signal output, and can also realize the measurement of rotating shaft speed at the same time. Therefore, the sensor can realize multi-parameter output of torque, speed and shaft power. The sensor has the advantages of high measurement accuracy, strong anti-interference ability, no need for zero adjustment, high strength of measuring elastic body, and can withstand 150% overload, high reliability, high signal-to-noise ratio, long working life, small size, light weight, easy installation, etc.

The alarm interface circuit uses the console to set the alarm light and sound effect device to realize its function. The alarm light is divided into 3 levels: the first is that when the feeding amount is normal, the light is off; the second is that when the feeding amount reaches the critical value, the system will warn and the light will turn green; the third is that when the feeding amount exceeds the limit (too high or too low), the system will alarm, the light will turn red, and the siren will sound. Among them, the grounding light always remains on during operation, indicating that the power supply is normal.

In addition, we have also taken a series of anti-interference measures, such as digital filtering, to ensure that the system has high reliability and anti-interference ability.

4. System software design

The single-chip control system mainly receives the control parameters of the host computer and completes the measurement and control tasks of the working parameters of the cleaning test bench. The software design of this system adopts structured and modular design methods to facilitate functional expansion, and the program is programmed in assembly language. The program modules mainly include: main program, A/D conversion, digital filtering subroutine, etc. The main flow chart of the program is shown in Figure 2, and its software functions are:

(1) The power-on self-test process mainly completes the system's own hardware test;

(2) The system sets the software process to complete the setting of the rated value;

(3) Data collection;

(4) Data processing, comparison of data with rated values, and storage of early warning and alarm signal data;

Figure 2 Main flow of system program

5. Conclusion

The innovation of this paper is to integrate the detection, display and alarm functions of the working parameters of the cleaning test bench, and solve the problem of difficult system monitoring of the test bench fan and sieve. In terms of data acquisition and processing, the reliability design is strengthened. The cleaning test bench monitoring system based on 8051 single-chip microcomputer control has the characteristics of simple circuit and convenient control.

References

[1] Deng Chunxiang et al. Research status and development trend of grain cleaning machine. Agricultural Mechanization Research, 2005.3(2)
[2] Results of the national supervision and random inspection of product quality by the General Administration of Quality Supervision, Inspection and Quarantine in the fourth quarter of 2002. Safety problems of cleaning machines and seeding machines are more prominent, http://www.cqvip.com, 2003(2)
[3] Peng Sanhe et al. Experimental study on the structure of vibration screen of grain cleaning machine. Journal of Hubei Agricultural University, 2004.11, Vol. 24, No. 1.
[4] Ye Binyuan, Zhou Xiaoyan. Development of single-chip microcomputer control system for electric fusion machine. Microcomputer Information, 2006, No. 14
[5] Yang Yi. Research on wind screen type grain cleaning test bench. China Agricultural Machinery Research Institute
[6] Zou Bichang et al. Experimental study on optimization design of main parameters of grain cleaning mechanism. Journal of Hubei Agricultural University, 2003.4, Vol. 23, No. 2

[7] Yao Feng et al. Application of single chip microcomputer technology in intelligent gas monitoring system. Journal of Henan University of Science and Technology (Natural Science Edition), 2005.8

[8] Song Jian et al., DC motor PWM speed control system based on single chip microcomputer. Agricultural Mechanization Research, No. 1, 2006.

[9] Diao Yong et al. Design and implementation of network center monitoring system based on 89C51. Computer Technology and Applications, No. 1, 2005, 43

[10] Li Guangdi et al. Fundamentals of Single-Chip Microcomputers [revised edition]. Beijing: Beijing University of Aeronautics and Astronautics Press. Second edition, July 2001