The Development Of Automatic Target-activated Spraying Device Based On PLC

The fruit and ornamental nursery industries are major enterprises in China agriculture. However, existing spray technologies are not efficient. The untended consequence of using conventional sprayers resulted in excessive chemical applications to targeted and nontargeted areas and in environmental pollutions. The overall goal of this study is to develop an infrared target-activated spray system with automatic control. Several tasks are required to achieve this goal:(1) The limitations of existing A/D module are working instability and frequent maintenance requirement. A programmable logic controller (PLC) is used as controller CMOS chip of detection system. The tests demonstrate that the CMOS chip can work as core component of the automatic infrared target-activated spray system, which work in stable operation and implement either automatic or manual working mode.(2) to design an infrared detection circuit by analysis of the reflection spectrum curve of typical trees and reflection characteristic of leaves; to select a high-power infrared LED transmitting tube and optics lens to further improve the transmission power; to design hardware device circuit and develop a set of algorithms to program the microcontroller and PLC controlling module.(3) A infrared LED with850nm wavelength was used as light source to detect ranges and spaces between trees. Both850nm and940nm wavelength were used to verify the operation effect. The results show that:1) detection ranges was affected by foliage density and infrared wavelength. Detection ranges increased as the foliage density increased under the same wavelength; detection ranges for850nm wavelength increased around26%compared with940nm wavelength.2) Detection spaces between trees were independent of infrared wavelength. The average distance between trees used in this test was less than0.25m.3) The overall performance of this spraying system is stable, the coordination between the detection system and solenoid valve、 electric-pump and nozzles was fast response. Once the spray system can detect the target, the nozzle can spray in0.3s. Finally, this spray system can meet the requirement of orchard spraying. (4) In comparison with conventional sprayer, infrared target-activated sprayer increased spray coverage and penetration while it reduced spray volume by38.81%with much less off-target less on ground and in the air.