Study On Vibration Harvesting Mechanism Of Wolfberry

Wolfberry is a traditional Chinese precious herbal medicine;Wolfberry is rich in carotenoids,polysaccharides,phosphorus,zinc and other nutrients,it has many pharmacological effects such as enhancing immunity and resisting oxidation.At present,only China is carrying out large-scale planting of wolfberry,the method of artificially harvesting wolfberry can no longer adapt to the development of the wolfberry planting industry and urgently requires the mechanized harvesting of wolfberry.Vibratory harvesting is considered to be the most effective method for large-scale harvesting;therefore,it is of great significance to study the mechanism of vibration recovery of wolfberry.This paper obtains the optimal parameter combination that affects fruit-pedicle separation through the fruit-pedicle vibration separation test,Research on acceleration responseoffruit-pediclevibrationseparationunderoptimumparameters;the three-dimensional solid model of the plant was reconstructed and the dynamics simulation was carried out to obtain the resonance frequency range of the plant.The field plant vibration test was conducted to obtain the plant resonance frequency.Combined with the simulation analysis results,the optimum excitation frequency range was determined.The acceleration response relationship between plant shoots was studied experimentally,combined with the results of acceleration response of the fruit-pedicle vibration separation,and the acceleration demand conditions for the vibration harvesting of the wolfberry were determined.(1)The vibration separation test platform was set up to carry out the fruit-pedicle vibration separation test.The optimum vibration combination parameters were obtained,namely the vibration frequency 18.22 Hz,amplitude 7.87 mm and the fruit branch speed20.93 mm/s.Under this parameter,the fruit separation rate reached 95.18%.Using the high-speed camera technology to capture the fruit-pedicle vibration separation process under the optimal combination of parameters,and obtain the acceleration response range of the fruit-pedicle separation:When the fruit of the branch is directly excited,the acceleration at the excited vibration needs to be between 518.38 and 551.06 m/s~2.The acceleration at the end of the branch needs to be in the range of 347.64 to 390.56 m/s~2.(2)The three-dimensional digital scanner was used to scan the loquat plant to obtain the point cloud data of the plant.Through the data pretreatment,the basic characteristics of the plant point cloud data were extracted to obtain the basic parameters of the main branch and the spatial skeleton structure,and the three-dimensional solid model was reconstructed.The plant finite element model was established based on the solid model of the plant.Dynamic simulation was performed.The natural frequency of the plant was obtained by modal analysis.The vibration frequency range was 12.7-22.4 Hz;through the harmonic response analysis,the resonance frequency range of the plant was obtained as 4~5 Hz,8~11 Hz,13~15 Hz,18~25Hz,and 26~27 Hz.In the frequency range of 13-24 Hz,the most obvious maximum was obtained.The fruit-pedicle vibration separation test results in an excitation frequency of 18.22Hz in the optimal combination of parameters.In summary,the frequency should be chosen in the range of 18 Hz to 22 Hz when excited.(3)Field vibratory tests were conducted on loquat plants to obtain plant resonance frequencies that were consistent with the resonance frequency range obtained by simulation.The optimum frequency range was determined to be 18 Hz to 22 Hz;the acceleration response relationship between wolfberry branches was studied through experiments,combined the result of fruit-pedicle vibration acceleration response range:347.64~390.56m/s~2,We obtain the acceleration of wolfberry harvesting requirement conditions:When all the fruiting branches are directly excited,the acceleration at the excited vibration needs to reach518.38~551.06 m/s~2;When all the third-stage branches are directly excited,and the fruiting branches cannot be directly excited,the acceleration of the third-stage branches to be excited needs to reach 1738.20 to 1952.80 m/s~2.