Abstract:Aiming at the problems of low accuracy of variable spray in wide field and insufficient consideration of the influence of agricultural machinery speed changes on the spray effect, a variable spray system with adaptive following speed was designed based on 3WF-1000 sprayer, which could improve the efficiency of accurate application of pesticides and fertilizers. The system consisted of four parts: early warning monitoring, speed monitoring, core control and execution agencies. Based on the multi-sensor real-time monitoring of speed, flow rat, pressure and liquid level height, the system used Bisector fuzzy control algorithm to optimize the system control. It realized the dynamic control of the change angle of the proportional valve and achieved the goal of accurate control of outlet pipe flow. In order to verify the superiority of the system algorithm in accurate variable application, the PID, Bisector fuzzy and Centroid fuzzy control modes were modeled and simulated under the Matlab platform. Through comparison,it could be seen that the Bisector fuzzy control was superior to the other two control modes in terms of adjusting time, overshoot and steady-state error. Field trials were carried out, such as nontravel fixed speed, fixed speed following, dynamic speed following and spray volume per unit area. In three speed states, the variable spray system adjustment times to stable operation were 13.4s, 27.6s and 17s, respectively, the maximum absolute error ratios of unit area spray volumes were 1.20%, 2.27% and 2.87%, respectively, which showed that the control system could meet the accuracy requirements of field accuracy application.