Design And Experiment Of An Air-assisted Cotton Boom Sprayer Which Separating Row And Spraying Inside And Upper Canopy

Xinjiang is one of the most important cotton producing areas in China. Due to Xinjiang cotton are mainly adopted stunted and close planting pattern, the cotton canopy is dense. In the process of preventing and controlling diseases and pests of cotton, spray droplets cannot penetrate the canopy.This results uneven distribution of liquid droplets in the middle and lower canopy of cotton and poor application effect.For this reason, an air-assisted cotton boom sprayer which separating row and spraying inside and upper canopy by combining separating row and spraying inside canopy technology and air-assisted spraying technology was designed. This sprayer braced the droplet diffusion space of inside cotton canopy by row separator and improved droplet diffusion range and distribution uniformity by airflow disturbance and transport of inside and upper cotton canopy.The structure of air-assisted boom sprayer was described. The row separator was designed and optimized by using rear multilayer guide frame and front V type guide mechanism which combined by plow body curved surfaces. The air-assisted system was designed by combining substitution principle and end speed principle.The air-assisted cotton boom sprayer was tested by wind field test and spray deposit distribution test. Wind field test showed wind velocity of the air flow field was big enough and well-distributed and also met the requirements of end speed principle. Spray deposit distribution test showed the average droplet coverage of front side of leaves at inside cotton canopy was 65.30% and the average droplet coverage of back side of leaves at inside cotton canopy was 39.83%. The biggest difference of the average droplet coverage of front side of leaves among upper canopy, middle canopy and lower canopy was 10.25% and the biggest difference of the average droplet coverage of back side of leaves among upper canopy, middle canopy and lower canopy was 11.75%.The spray deposit distribution uniformity of the whole cotton canopy and the application effect were good.In order to avoid spray boom scratching crops and ensure the application effect,in the work process, spray boom and canopy need to be maintained approximately parallel and proper distance. This paper also designs an online control system of spray boom height and balance. This online control system uses ultrasonic sensors for detecting the height from ground to spray boom. The controller calculates thedirection and speed of hydraulic cylinders by comparing the setting spray boom height and the actual spray boom height which was detected by ultrasonic sensors.Then the controller sends out control signals of hydraulic cylinders to adjust spray boom height and balance.The structure of boom sprayer and the composition and working principle of spray boom height and balance hydraulic system were described. The software and hardware design of spray boom height and balance online control system were elaborated, and a spray boom height signal filtering algorithm of branches and leaves interference was designed.The online control system of spray boom height and balance was tested by ground test and field test. Ground test showed that the system could effectively improve the spray boom height change caused by step excitation pavement. The spray boom height change could be controlled within ±3cm. Field test showed that the spray boom height signal filtering procedure could effectively filter interference of occasional a small amount of cotton branches and leaves and realize online control of spray boom height and balance.