Design and field experiment of precise control and monitoring system for a solid fumigant sterilizer based on IoT

Abstract

With the development of soil disinfection technology, solid fumigant sterilization has become one of the most practical methods for the elimination of soil-borne diseases in China. To improve the accuracy of solid fumigant control and monitor the whole operation process for solid fumigant sterilizers, especially over large-scale farms, a precise control and monitoring system for solid fumigant sterilizers was designed and experimented. A linear equation was established between rotational speed and fumigant distributed per revolution of the shaft for the solid fumigant sterilizer to calculate the rotational speed of the shaft for the control system. The control system was modified by a linear correlation. The monitoring system based on the Internet of Things (IoT) platform was integrated into the solid fumigant sterilizer, which could record a variety of information such as coordinates, operation trajectory and distribution quantity in real-time. Experiments to investigate the performance of the control and monitoring systems were carried out in the laboratory and the field. The results showed that the coefficient of variation (C.V.) of all six outlets did not exceed 3%. Furthermore, the average C.V. at high rotational speed of the shaft (22 r/min to 34 r/min) was 16.18% larger than that at a low rotational speed (10 r/min to 22 r/min). For the stability and accuracy of the control system, the C.V.s of the application rates of 450 kg/ha, 525 kg/ha and 600 kg/ha were 2.52%, 4.80% and 4.48% respectively with an average of 3.93%, and the corresponding control accuracies were 95.3%, 95.6% and 92.5%. The experimental accuracy of the application rate at 600 kg/ha was relatively low because it was affected by the natural wind and incomplete collection of fumigants from the film. The error of the control and monitoring systems did not exceed 3% for the five application rates from 300 kg/ha to 600 kg/ha at an interval of 75 kg/ha in the field experiment. This research can provide technical support for precise control of solid fumigants, remote monitoring of field operations and performance evaluation of solid fumigant sterilizers.