Optimized Design And Test Of End Effector For White Asparagus Selective Harvest

White asparagus is a perennial herb,which nutritional value is more than 5 times higher than that of ordinary vegetables.And it has anticancer and health-care effects,and is known as the king of vegetables.China is a big country of asparagus cultivation,with the harvest area accounting for 90% of the world.But manual work is the main way of harvesting.The white asparagus should be harvested when the bamboo shoot tip is unearthed.Because the harvesting time is concentrated in the morning or in the early evening,the manual harvesting workload is large and the efficiency is low.The harvest of white asparagus in China is mainly by manual work with bamboo shoot harvesting knife,with large labor intensity and low efficiency.The existing white asparagus harvester in foreign countries is one-time harvest.This kind of harvester cut from the root of the white asparagus at one time,ignoring the growth condition and shoot bud length of asparagus of asparagus.As a result,it has strong destructive power and high damage rate,and seriously reduces the yield of asparagus.The selective,high efficient and low-damage harvesting of white asparagus has become a bottleneck restricting the development of asparagus industry in China.It is urgent to realize the mechanized harvesting of white asparagus.Due to the lack of machinery which can realize intelligent and selective harvesting of white asparagus,the project team proposed self-propelled intelligent white asparagus selective harvesting machine based on machine vision.Based on the subject of project team,this paper studied an end effector applied to the selective harvesting machinery of white asparagus.In this paper,a self-designed end effector for selective harvesting of white asparagus was designed,and the interaction process between the end effector and white asparagus and soil was analyzed.A calculation method of driving force,shearing force and clamping force in soil was deduced.The three driving forces were quantitatively described by universal testing machine and DEM simulation.Through single factor and multi-factor test to determine the optimal parameter combination scheme,and indoor recovery test,the specific content is as follows:1.Firstly,the harvesting scheme of cutting,clamping and pulling the white asparagus harvesting operation part is determined;the whole machine of the selective harvesting machine of the white asparagus is modeled by three-dimensional modeling software;Two generations of design for the key harvesting parts of selective harvesting mechanism of white asparagus were carried out.2.The structural relationship of each part of the end effector is determined through the design of the whole structure of the end effector,the bending angle of the clamping plate and the blade guard.And the driving force required by the end effector to complete the actions of burying,shearing and clamping is analyzed.The statics models of burying driving force,shearing force and clamping force are established respectively,and the calculation formulas of them are deduced.3.The physical properties of white asparagus were tested.The shear strength and compression strength of white asparagus were obtained by shear test and compression test.The minimum shear force required by the end effector in cutting white asparagus and the maximum clamping force to achieve low damage when clamp white asparagus was determined.4.Based on DEM simulation,the white asparagus-end effector-soil model was established,and the harvesting process of the end effector was simulated by discrete element method.The driving forces of the two kinds of white asparagus harvesting end effectors were analyzed,and the optimal end effector scheme was selected.The shear force and clamping force required by the end effector to complete the cutting and clamping action of white asparagus were determined by discrete element simulation analysis of the selected end effector.5.The driving force,shearing force,clamping force and other factors affecting the recovery efficiency of white asparagus were tested by single factor and multi-factor orthogonal experiments.And the shearing and clamping conditions of the end effector were observed during the recovery process.Take the recovery rate and damage rate in the recovery test as evaluation indexes and the optimal recovery parameter combination scheme of white asparagus was obtained by providing driving force,shearing force and clamping force for the end effector.The recovery parameters determined by multi-factor test are used for indoor recovery test.The results show that the end effector designed in this paper can complete the recovery work and achieve low damage recovery,and can be used as a recovery component in the selective recovery machinery of white asparagus.