Design And Experimental Study On Profiling Obstacle Avoidance Mower For Mountain Orchard

With the increasing demand for fruit,the scale of fruit planting is gradually expanding,and the mechanization of orchard production and management is the future trend.Orchard weeding is a more advanced method in orchard vegetation management,but it needs weeding on time,with mechanical weeding instead of herbicide,can reduce fertilizer and pesticide use,protect the environment and improve sustainable development.The terrain and landform of mountain orchards are relatively complex,the road surface is uneven,and the passage of operation machinery is difficult,which puts forward higher requirements for mechanized mowing.The special terrace planting method of orchards in southern Jiangxi makes it difficult to mow among plants.For this reason,this paper developed a Mountain Orchard profiling obstacle avoidance mower,so as to adapt to the complex terrain and improve mowing efficiency and operation safety.The main research work is listed as follows:1)The plant mechanical properties of common grasses in Mountain Orchard were tested.The shear and bending characteristics of weeds with different species,different cutting positions and different growth cycles were studied,and the influence of multiple weed aggregation on cutting effect was studied,so as to provide a theoretical basis for the design of lawn mower and the selection of operation parameters.The results showed that the average shear force of the three kinds of weeds from large to small is Elymus Kamoji,annual fleabane and goose grass,and the average bending resistance from large to small is annual fleabane,Elymus Kamoji,goose grass;In general,the shear force and bending force increase with the increase of diameter;In the range of 40-80 mm from the root,generally,the shear force increases with the increase of the distance,and the bending force decreases with the increase of the distance.50 mm is the more appropriate shear height.With the increase of the number of plants,the shear force increases superlinearly,and the bending force increases approximately linearly.2)The whole structure of the profiling obstacle avoidance mower was designed.In order to meet the requirements of uneven ground,narrow passage and grass cutting between rows and plants in mountain orchards,the overall structure scheme of separating crawler chassis and front and rear headers was adopted.The crawler chassis adopted differential drive structure,and the left and right drive wheels adopted1.5KW servo motor to drive the drive wheels through reducer and chain drive.The crawler is 150 mm wide,the maximum climbing angle is 25 °,and the overall width of the chassis is 720 mm.In order to meet the needs of obstacle avoidance mowing between rows and plants in orchard,the separation scheme of front header and rear header was adopted.The two cutters of the front header were arranged in parallel with a cutting width of 600 mm.The profiling mechanism of the front header was designed with a profiling amount of 62.6mm.The rear side cutting profiling header was designed,and a multi-directional profiling mechanism was proposed.The horizontal and longitudinal profiling amounts were 40 mm,which realizes the profiling function of the rear cutter head close to the ground.The obstacle avoidance adjustment mechanism of the rear header was designed,which can adjust the cutting width of0-200mm;ADAMS simulation was used to verify the profiling effect of side cutting profiling header.The trial production of the whole machine had been completed,and the cutting width of the whole machine is 600-800 mm adjustable.3)The control system of profiling obstacle avoidance mower was designed and implemented.According to the structural characteristics and operation requirements of the profiling obstacle avoidance mower,the whole machine control system adopted the hierarchical control scheme.The upper computer was the obstacle avoidance control system.The industrial computer was adopted and the Ubuntu system was installed.The obstacle detection of the whole machine was mainly realized by the two-dimensional laser scanner.The lower computer includes chassis STM32 controller and header STM32 controller.The obstacle avoidance scheme combining the local obstacle avoidance of the rear cutter head and the overall obstacle avoidance of the whole machine was adopted,and the obstacle avoidance decision was made through the cluster analysis of the detection information of laser scanning: when the obstacle is close to the center of the chassis,the overall obstacle avoidance strategy of left-right detour is adopted;When the obstacles are far away,the local obstacle avoidance strategy of rear cutter head is adopted.In addition,the chassis performance test was carried out.The climbing angle of the chassis is 25 °,which can pass through15 cm high obstacles and over the trenches of 20 cm deep and 25 cm wide.Thus the mower can meet the requirements of orchard walking.4)The obstacle avoidance function test and mowing performance test of the profiling obstacle avoidance mower were carried out.The minimum stopping distance of the mower is 1442 mm,the distance error is stable within 10 cm,and the accuracy of obstacle avoidance decision is 100%.The mowing performance of the prototype was tested by the indexes of stubble height,cutting width and grass crushing rate.The test results show that the mower can adapt to the undulating terrain of 4cm.The average cutting width of the front header is 596.3mm,the average cutting width utilization rate is 99.4%,the average stubble height is 53.3mm,the average stubble height stability coefficient is 88.8%,the average grass crushing rate is 88.5%,and the average missing cutting rate is 1.93%.The overall cutting effect is good and meets the requirements of horticulture.