| In recent years,the precision rice hill-drop drilling technology has been developed rapidly in China.It is difficult to observe the missing and over sowing for the precision rice hill-drop drilling machine by human labor.Therefore,the sowing quantity monitoring system,which can monitor the sowing quantity in real time,and dealing with the problems of missing and over sowing in time is great significance to improve the quality of rice sowing of precision rice hill-drop drilling.At present,the research on sowing quantity monitoring system are mainly focuses on corn,soybean i.e,very limited research has been reported on sowing quantity monitoring system for rice hill-drop drilling machine.Therefore,the sowing quantity monitoring system for precision rice hill-drop drilling has been designed and tested in the present study.The main research contents and achievements are as follows:(1)The structure and working principle of precision rice hill-drop drilling machine was studied,and the sowing quantity monitoring system based on STM32H743IIT6 microprocessor was developed.(2)Monitoring algorithm based on time series for sowing quantity and number of hills monitoring was developed.The rice sowing quantity was monitored based on infrared photoelectricity sensor.When the rice seeds enter the monitoring area,there would be alternating of high and low electrical levels,the data of sowing time interval and pulse duration for rice in the monitoring area was obtain based on time series of high and low electrical levels alternating.The time segmentation node was obtained by synchronously monitoring of the time series of sowing and the rotation speed of seed metering device,and then,the number of hills were counted by the time segmentation node.The sowing quantity was obtained by the characteristic information of the movement time of rice seeds.The experiment results showed that the monitoring system has a good monitoring accuracy.(3)The monitoring system for seed quantity of precision rice hill-drop drilling machine was designed.The schemes for the monitoring number of seeds per hill,the height of the seed box and the moving speed of the machine was determined.The hardware circuit and software program of the monitoring system were designed.In order to carry out multi-node data transmission and facilitate system expansion,a fieldbus network based on RS485MODBUS/RTU protocol was constructed with STM32H743IIT6 microprocessor as the core component.The communication between pricinple computer and slave computer based on RS232 was realized.(4)Experiments was carried out for testing the seed quantity monitoring system of precision rice hill-drop drilling.The test rice varieties were Nan Jing 46 and Xiang YAxiangzhan.The laboratory experimental results showed that,for rice varieties of Nan Jing 46 and Xiang YAxiangzhan:a)the relative error of the number of rice seeds per hills were less than 7.99% and 24.07% respectively,b)the relative errors of the number of hills were 6.07% and 5.66%.The results of field experiments showed that,for the rice varieties of Nan Jing 46 and Xiang YAxiangzhan,a)the absolute error of the number of seeds per hill were 2.61 and 2.20,b)and the relative error of the number of hills were 12.6% and12.7%.At 30r/min,the monitoring stability was good,and the average coefficient of variation was less than 23.08% and 32.10% of Nan Jing 46 and Xiang YAxiangzhan.The relative error of the per unit of area of Nanjing46 is 4.67%,and the relative error of the per unit of area of Xiang Yaxiangzhan is 10.77%.At the rice variety,the average coefficient of variation increased with increasing speed.The rice variety and the speed of rice metering device had influences on the precision of the monitoring system,it is observed that the metering device had a greater influence on the monitoring accuracy than that of rice variety.The test results in laboratory and field good monitoring accuracy for the monitoring of the number of seeds per hill and the number of hills.The test results verified the working performance of the monitoring system and the application feasibility of this system in field working. |
