Research On Structure Design And Control Of Weeding Robot In Hilly Orchard

China ranks first in the world in terms of orchard area and fruit production,and more than 60% of orchards are located in hilly and mountainous areas.Mowing is an important part of soil management in hilly orchards,and mowing machinery has gradually become an important development direction for future orchard management operations,so the development of intelligent weeding robots for hilly orchards is an urgent problem to be solved.In this paper,we propose a variable width weeding robot with flexible obstacle avoidance function to avoid the problem of tool damage caused by the black mulch and to improve the operating efficiency of the weeding robot in orchards with different monopoly spacing.The design of real-time autonomous navigation control system of weeding robot is completed based on vision perception technology to realize real-time autonomous navigation of weeding robot in hilly orchard environment.The main research contents are as follows:(1)Analyze the unstructured terrain environment of hilly orchards,determine the working area of the weeding robot according to the soil weed management requirements and weed growth characteristics of orchards,and complete the overall structure design based on the functional requirements of the weeding robot.The overall size of the weeding robot designed in this paper is 1200×900×600mm,the stubble retention height is 50mm～95mm,and the width variation range is1000mm～2000mm.(2)According to the mechanical characteristics of weed stalks,the design of throwing knives is completed,the arrangement of throwing knives is determined as interleaved balanced arrangement,the rotational speed of throwing knife shaft during operation is solved through the mechanical analysis of throwing knives,the rotational speed of throwing knife shaft during operation is solved according to the mechanical characteristics of waste branches in orchards with different water content,and the moving speed of weeding robot is determined by combining with the analysis of movement trajectory of throwing knives.The maximum rotational speed required for the effective operation of the weeding robot designed in this paper is 3453r/min,and the operating movement rate is 0.5m/s.(3)Analyze the operation area of the weeding robot in the hilly orchard environment and plan the autonomous navigation route of the weeding robot.According to the planting characteristics of the fruit tree rows,the type and location of the markers are determined,the original image data is collected by OV5640 camera,and the design of image pre-processing system,display and storage system is completed based on FPGA.(4)Complete the processing and assembly of the weeding robot prototype,and through the weeding test and branch breaking test of the weeding robot in the hilly orchard environment,the results show that the stubble retention stability coefficient of the weeding robot is above 88%,the cutting width utilization rate is above 92%,and the branch breaking cut is smooth and effective,meeting the requirements of flexible obstacle avoidance and width change function.According to the experiment of autonomous navigation of the weeding robot in hilly citrus orchard,the deviation angle threshold of the navigation line was determined as 5°,and the 90° steering was performed at 0.3m from the blue marker,and the results showed that it took 4.7s to turn 90° to the left and 4.9s to turn 90° to the right.The centerline spacing of adjacent monopoly heads was analyzed to determine the straight travel time of the weeding robot at the monopoly head passage,and the parameters were set in the autonomous navigation system to complete the autonomous navigation of the weeding robot in the hilly orchard environment.