Design And Experiment Of Piezoelectric Impact Accurate Real-time Monitoring System For Rice Hill-direct-seeding

As one of the main food crops in China,the rise and fall of rice industry is related to the national policies and people’s livelihood and national food security strategy.In order to realize farmers’ income and modernize agriculture in China,it is of great significance to strengthen the development of rice industry.Rice hill-direct-seeding technology is an advanced technology that rice seeds are sowed on ridge at certain spacing by using rice hill-direct-seeding machine according to the requirements of agronomic planting.It can effectively guaran tee the rational plant structure and avoid uneven growth and density.At present,the seeding process of rice hill-direct-seeding machine is generally in a closed state,and the quality of its operation can not be monitored directly by manpower.Poor ventilation and low seedling rate will happen if the machine arises reseeding or miss seeding,which will affect the cost and benefit of agricultural production.Therefore,it is necessary to monitor and alarm the operation process of rice hill-direct-seeding machine in real time,so that drivers can find and solve problems in time,which can improve the efficiency of seeding operation,so as to ensure the high and stable yield of rice.Consequently,it is very important to realize accurate real-time monitoring under the conditions of rice hill-direct-seeding.On the basis of summarizing and analyzing the development status of sowing monitoring technology at home and abroad,combining with the agronomic requirements of rice hill-direct-seeding and the operation mode of multi-seeds hill-seeding,utilizing the synchronous real-time monitoring technology matched with rice hill-direct-seeding.A seed-conducting tube with functions of assistant monitoring and seed-conducting cavitation was developed.Based on the seed-conducting tube,a monitoring system is designed,which integrated accurate real-time monitoring,synchronous seed-conducting cavitation and efficient wireless communication.It met the real-time fault alarm in the process of rice hill-direct-seeding and the design requirements for improving the quality of rice hill-direct-seeding.Through theoretical analysis,structural design,circuit design,bench test and field experiment,research work has been carried out.The main research contents are as follows:(1)Total design of monitoring system for rice hill-direct-seedingBased on the working principle of rebound dipper rice hill-direct-seeding metering device,the movement trajectory of seeds throwing process was analyzed,and a seed-conducting tube which can assist monitoring and seed-conducting cavitation was designed.According to the performance evaluation index and requirement of the seeder and the actual operation of machine,four kinds of seeding faults which may exist in the process of rice hill-direct-seeding were analyzed and set,and the system monitoring index algorithm for each kind of seeding fault was designed,so that overall monitoring system was designed,which established an important foundation for subsequent hardware and software design of monitoring system.(2)Design of hardware of monitoring systemThe scheme of monitoring system hardware design was proposed,combining the working principle of monitoring system.The design goal is to achieve three functions: accurate real-time monitoring,synchronous seed-conducting cavitation and efficient wireless communication.The SCM main control module,DC voltage regulating power supply module,signal acquisition and processing module,acousto-optic alarm module and wireless serial port transparent transmission module were selected and configured.PVDF piezoelectric film was selected as sensor,and its installation position in seed-conducting tube was determined.According to the planning function goal of each monitoring system module,the overall monitoring system circuit was designed.The working circuit of each module was designed by modular processing method,which provided an important guarantee for design goal of monitoring system.(3)Design of software of monitoring systemCombining with monitoring system hardware design goal,the scheme of system software design was proposed.The total system software program was divided into main program of the monitoring system,subroutine of signal acquisition and processing,fault diagnosis and acousto-optic alarm subprogram and Bluetooth wireless serial port transparent transmission subprogram.Arduino language was used to program and integrate the main program and subprogram of the monitoring system to realize signal acquisition and processing,fault jud gment and acousto-optic alarm.Bluetooth wireless serial port transparent transmission APP was programmed by Android application program software,which realized efficient wireless communication of data.(4)Performance experiment of monitoring systemIn order to explore performance of monitoring system for rice hill-direct-seeding and investigate scientificalness and rationality of monitoring system design.Taking soaked,sprouted and coated Long Qing No.3 as seed for direct-seeding,bench sensitivity test and field performance experiment of monitoring system were carried out respectively.The bench test results shows that monitoring system sensitivity decreases slightly with metering device working speed increased.When metering device working speed is 10~35r/min,monitoring system sensitivity range is 90.83~99.17%,which shows that the monitoring system can effectively collect signals produced from seeds impacting PVDF piezoelectric film sensor,and it has high reliability.The monitoring system sensitivity is validated in the field,and the change rule of monitoring system sensitivity with metering device working speed is basically consistent with the bench test result.On this basis,field performance experiment of monitoring system are carried out.The result shows that metering device working speed has a significant impact on reseeding monitoring accuracy,miss seeding monitoring accuracy and effective monitoring accuracy,and the relationship between metering device working speed and index function is obtained at different levels.At the same time,reseeding monitoring accuracy,miss seeding monitoring accuracy and effective monitoring accuracy decrease with metering device working speed increased,and the minimum average values are 81.79%,80.42% and 97.67%,respectively,and relative error is less than 2.4%,which is within acceptable range.The system can effectively monitor the operation status of rice hill-direct-seeding and meet the monitoring requirement of rice hill-direct-seeding.