Design And Control Of Orchard Self-leveling Lifting Platform

The national orchard area and production of China respectively increased 6.1% and 5.2% on last year according to the 2015 CHINA Agriculture Yearbook.Due to harvesting and conveying are the labor-extensive and most expensive practices in orchard production,the development of mechanization is necessary.The current orchard management operations on the top area of the canopy mainly rely on simple harvest-aid tools,such as ladder.The orchard platform is not suitable for working in mountain orchards,for the lack of leveling function.Therefore a self-leveling mechanism was designed in this research base on orchard construction and terrain.The self-leveling platform can be adjusted on the wide range of angle.It's meaningful to carry out this study to improve the safety of workers and comfort of labor.The research work in this dissertation is as follows.1.A hydraulic leveling mechanism based on bidirectional active adjustment of planar was designed,which can adjust the angle of range from 0 to 20°.A mathematical model and self-leveling principle was established in theoretical.Compare the maximum working slope of the vehicle before and after leveling2.Self-leveling mechanism's movement characteristics was analyzed,obtain curve between platform angle and operating units displacement in four different environmental conditions.The results showed that: the model can accurately reflect the movement state of the components of the leveling mechanism in practice.3.The model analysis of self-leveling mechanism are made in AYSYS.By the result of model analysis of mechanism,the mechanism's stress and strain are got in the paper,under full load conditions.And the natural frequency and vibration mode of the balance adjustment mechanism are obtained.The results showed that: under full load and in terrain environment,maximum displacement of mechanism were found in cylinder bracket between platform and #3 hydraulic cylinder.The maximum of displacement of mechanism was 0.30mm;Maximum stress were found in the bracket of left rod.The maximum was 61.7MPa.The lowest modal frequency was 45.329 Hz.The maximum stress was less than material yield strength of Q235 and the lowest modal frequency was higher than platform working frequency,therefore verify the rationality of mechanism structure.4.The model of single-channel hydraulic system for leveling mechanism was established.By using of test system,joined the PID control method to the experiment system of hydraulic cylinder.The result showed that: the control of the single-channel hydraulic system can correctly reflect the cylinder's displacement,flow and pressure parameters in hydraulic system.The same control method was putted in the co-simulation model of leveling mechanism.The experiments errors of angle leveling were less than 0.5 °.It can be meet the mountain orchard operating requirements.