STRUCTURE DESIGN AND LEVELLING CONTROL SYSTEM DEVELOPMENT FOR SELF-PROPELLED SPRAYER BOOM

To address the issues of poor boom stability and inconsistent spray quality due to harsh field conditions and varying boom height relative to the target, a five-section planar truss boom capable of height adjustment, overall tilt adjustment, and unilateral tilt adjustment was designed. A contour levelling control system for the boom was developed based on the STM32F103 platform. The levelling system uses ultrasonic distance sensors to detect the distance between the boom's ends and the target in real-time. The limit average filtering method is employed to eliminate sudden signal interference and process feedback data. The control system then drives electric actuators to adjust the boom's posture in real-time. Field and spray tests were conducted using a small electric self-propelled sprayer as the test platform. The results indicate that the best levelling performance was achieved with overall height adjustment, overall tilt adjustment, and unilateral tilt adjustment thresholds set to 30mm, 30mm, and 40mm, respectively. The field spray tests showed minimal relative errors in droplet deposition coverage and density on both sides. The coefficient of variation CV of deposition along the boom direction was less than 15%, ensuring good spray distribution uniformity. These findings provide valuable references for the design and optimization of sprayer booms.