Analysis and experiment research on droplet coverage and deposition measurement with capacitive sensor

Droplet deposition and coverage real-time measuring with capacitive sensor could provide valuable information for pesticide application. This article firstly built a mathematical model and elaborated the theoretical basis of the droplet coverage and droplet deposition measuring in typical deposition situation with capacitive sensor, the droplet coverage and deposition experiments in lab condition were completed to verify the theoretical analysis. The mathematical model revealed the theoretical relationship between droplet coverage and deposition measuring with capacitive sensor, and provided in-depth theory analysis of multiple droplets coverage measuring. The theoretical derivation and experimental verification results indicated that the droplet coverage could be calculated with sensor output voltage increment using good linear regression equations, the determination coefficients of linear regression equations were more than 0.98 in lab condition, the maximum MRE of droplet coverage between the general linear regression curves and experimental results was 11.88%. Meanwhile, this article proved that the droplet deposition can be calculated with sensor output voltage increment using good linear regression equations while the droplet size distribution was stable, the determination coefficients of linear regression equations were more than 0.98 in lab condition. The theoretical coefficient k ' 4 calculated from coverage results are basically equal with experimental results with the MRE of 2.62%, the maximum MRE of droplet deposition between the theoretical linear regression curves and experimental results was 9.09%. Although these theoretical and verification works were carried out under a typical deposition condition without considering droplet overlapping and other realistic conditions, these results provided a theoretical basis for the droplet coverage and deposition measuring with capacitive sensor, and the accuracy of droplet measuring is acceptable once the operation condition is stable enough.