The Design And Experimental Research Of Jujube Harvest Device Based On Self-excited Vibration And Force Compensation

Jujube is widely planted in China,its planting area and production accounted for 99% of the world.In recent years,the planting area of jujube in Xinjiang has been increasing,the problem of low efficiency and high cost of artificial harvest has restricted the sustainable development of Xinjiang jujube industry,thus urgent to research and develop jujube mechanical harvesting equipment.In view of the poor recovery factor and high damage rate at the process of traditional vibration recovery,this paper presented a vibration harvesting method that combined self-excited vibration and force compensation based on the analysis of the present situation of fruit harvest at home and abroad,and designed a jujube harvest test device based on self-excited vibration and force compensation to improve the effect of vibration harvesting and reduce the damage of jujube and tree.The main contents of this paper include the following aspects:(1)The planting pattern and material characteristic of jujube were measured.The planting pattern and material characteristic of jujube is the basis for determining the structural parameters and working parameters of the harvesting device.This paper made a statistical analysis of the planting patterns of dwarf and close planting jujube in Xinjiang to get the average plant spacing and average row spacing through the field investigation,and measured the crown diameter,height and minimum branch height of jujube,and obtained the triaxial dimensions and single seed weight of jujube through the material characteristic test.(2)Experimental study on the dynamic properties transmitted was carried out.This paper established the dynamic transfer model of jujube to analyse the relationship between frequency and amplitude by theoretical analysis.The dynamic properties transmitted was tested by adjusting the different vibration displacement and vibration frequency different to shake the different lateral branches of jujube with the vibration test bed on the basis of dynamic transfer theory analysis.In the range of vibration frequency,the peak acceleration of test point appeared at 14 Hz,16Hz and 18 Hz,this means that first-order natural frequency is 14 Hz,the second-order natural frequency is 16 Hz,the third-order natural frequency is 18 Hz,the dynamic transfer effect is more obvious at this frequency.(3)The jujube harvesting device was designed.This paper determined the overall structure and working principle of jujube harvesting device based on the planting pattern of jujube and the early experimental study,and designed the key components.The kinematics equation of deflector rod roller was obtained and the torsion angle threshold 19.4 ° was calculated through the analysis of the movement process of excitation device,and the electronic control system was designed according to the requirements of the force compensation control system.(4)The simulation analysis of test equipment was carried out.The equivalent stress and total deformation of the key components in the test process were obtained through finite element simulationanalysis,and the rationality of the design was verified by checking calculation,and the optimization and improvement suggestions were put forward according to the analysis of the stress concentration.(5)The bench test of jujube harvesting device was carried out.The Trolley forward speed,excitation frequency and angle threshold were selected as influencing factors,and the method of three factors and five levels quadratic orthogonal regression rotation combination test was used to study on the bench test of jujube harvesting device.The regression equation of the response index was established,and obtained the optimum working parameters of the test device: trolley forward speed was 0.4m/s,excitation frequency was 14 Hz and angle threshold was 25°,the error between the predicted value and the measured value was small,which satisfied the harvest requirement.