| The air assisted spraying technology, which greatly reduces the droplet drift, and has good adhesion, significantly reduces the risk of environmental pollution. One of the most important factors affecting spray effect is the fan speed. But until now, fan speed of the air-blast sprayer at home and abroad is mostly controlled by the operator through the gears, which had not only the unattainable required accuracy, but also the poor scheduling. Therefore, this article firstly proposed and designed the hydraulic stepless speed regulation control system of the air-blast sprayer, which provided a way for better spray.Based on the platform of the orchard self-propelled air-blast sprayer with type 3WZ600, the air-blast sprayer fan hydraulic stepless speed regulation control system was designed, which focused on SCM control technology, and adopted DC stepper motor speed control technology. The hydraulic continuously variable transmission system model was established and analyzed, which used the fuzzy control strategy and verified by the experiments. Main contents were as follows:1. According to the system accuracy and stability requirements, the controlled object characteristics and the operating environment, the selections of microcontroller hardware system, stepper motor and devices, screw and sensor were finished. Simultaneously, the connected device between actuator and controlled object was adjusted reasonably.2. The ideal model of the hydraulic continuously variable transmission was established and analyzed with the actual operation. The ideal model of the hydraulic continuously variable transmission, added different disturbances to reflect the actual operating conditions, was simulated with fuzzy control strategy using Simulink. The results showed that the fuzzy controller had better dynamic response and good immunity with different interferences, which met the needs of control system.3. The software and hardware designs of air-blast sprayer fan speed regulation control system were finished, which were composed of speed detection,the hydraulic continuously variable transmission system and speed control system, including programs of LCD display,key detection speed detection and fuzzy control. The return-to-zero program for system reliability and stability adopted Absolute-Zero method, which eliminated the problem of the fan reversal and instability, caused by the delay of the hydraulic continuously variable transmission in practical application.Experiments showed that the system met the expected requirements, stable and reliable. |
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