面向林果振动采收的电子果实设计与研究

发布时间：2018-05-05 10:50

本文选题：机械收获 + 机械冲击　；参考：《浙江理工大学》2017年硕士论文

【摘要】：中国是世界林果种植大国,种类繁多、产量巨大。但是新鲜林果在鲜果市场中的供应方式主要以人工采摘为主。虽然在果品采收过程中可以利用机械装置代替手工劳动,但是不稳定的采收效率和高比例的果实损伤始终阻碍着采收设备的发展。为改善现有收获设备的采收性能以及验证经典动力学采收模型,本学位论文开发了一种扁球型传感器记录林果在振动采收过程的动态信息,综合评判林果所受冲击情况,并对比理论分析结果找到差异。本文主要的工作和研究成果如下:1.分析了“电子果实”动态信息获取技术的基本原理,在已有果树动力学模型的研究基础上建立了无柄果实的“果实-树体”振动动力学方程,建立拉格朗日振动微分方程并求解得到果实的单摆模型运动方程。研究果实与树体的分离条件可知:当在较小果实的情况下可忽略自身重力和切向惯性力作用,法向惯性力为影响果实脱落的主要参数,即法向惯性力大于果实-树体结合力。得到果实脱落的实际条件,这不仅从理论角度分析了果实脱落的影响因素也为电子果实对模型的验证实验提供了依据。2.设计了电子果实各部分系统实现。硬件部分主要采用Atmega-328p MCU、1GSD存储模块、7.4V电源模块、ADXL345加速度检测单元和3.3V稳压电路组成;控制系统的主要功能包括:I/O口阻态控制、传感器初始化设置、振动信号检测、采集数据存储;基于Matlab的上位机分析软件能够加载数据信息,采用Fourier算法处理采集信号,并输出振动波形。3.完成了电子果实的检测精度校核实验。由试验结果可知:电子果实的X轴检测误差范围在5.6%-6.4%之间,Y轴检测误差范围在4.4%-4.9%之间,Z轴检测误差范围在3.3%-3.6%之间可以满足农业使用要求。对已建立的果实-树体动力学模型进行了验证试验,通过4组验证试验发现电子果实在惯性力的作用下摆幅为25.5mm,分离力为11.32N,理论模型计算值为17.25N,比果实-果柄结合力大,证明果实脱落过程中法向惯性力起主要作用。根据电子果实采集的运动加速度计算得到分离力为11.4N,所以根据理论模型计算的分离惯性力值可以满足实际果实脱落条件。进行了电子果实野外试验,通过四组试验数据可知:电子果实在采收过程中可分为采摘阶段和下落阶段两大部分。采摘阶段的平均冲击最大值和平均冲击均值分别为215g和123g,下落阶段所产生的最大冲击平均值和平均冲击均值分别155g和76g。研究四组冲击数据的机械冲击分布模式不难发现超过190g的冲击个数约占总比例的6%,150g-190g范围内的平均冲击个数约占总比例的18%,100g到150g范围内的平均冲击个数约占总冲击个数的37%,50g-100g的机械冲击平均个数约占总冲击个数的6%。
[Abstract]:China is a big country of forest and fruit planting in the world, with a great variety and huge output. But the supply mode of fresh forest fruit in fresh fruit market is mainly artificial picking. Although manual labor can be replaced by mechanical devices in the process of fruit harvesting, unstable harvesting efficiency and high percentage of fruit damage always hinder the development of harvesting equipment. In order to improve the harvesting performance of the existing harvesting equipment and to verify the classical dynamic harvesting model, a flat spherical sensor was developed to record the dynamic information of the harvesting process in vibration. And compare the theoretical analysis results to find the difference. The main work and research results of this paper are as follows: 1. In this paper, the basic principle of "electronic fruit" dynamic information acquisition technology is analyzed. Based on the existing dynamic model of fruit tree, the vibration dynamic equation of "fruit tree" without handle fruit is established. The Lagrange vibration differential equation is established and the equation of motion of the fruit is obtained. The study on the separation condition of fruit and tree shows that the normal inertia force is the main parameter to affect the fruit shedding, that is, the normal inertial force is greater than the fruit-tree binding force when the fruit is smaller than the tangential inertial force and the normal inertial force is the main parameter affecting the fruit shedding. The actual conditions of fruit shedding were obtained, which not only analyzed the influencing factors of fruit shedding theoretically, but also provided the basis for the verification experiment of electronic fruit to the model. The system realization of electronic fruit is designed. The hardware is mainly composed of Atmega-328p MCUU 1GSD memory module (7.4V), ADXL345 acceleration detection unit and 3.3V voltage stabilizing circuit, the main functions of the control system include: I / O port resistance control, sensor initialization setting, vibration signal detection, data acquisition and storage. The upper computer analysis software based on Matlab can load the data information, use the Fourier algorithm to process the collected signal, and output the vibration waveform. 3. The testing accuracy of electronic fruit was verified. The results showed that the error range of X axis detection of electronic fruit was between 5.6% and 6.4%, and the error range of Y axis detection was between 4.4% and 4.9%. The error range of Z axis detection was between 3.3% and 3.6%, which could meet the requirements of agricultural application. The established fruit-tree dynamics model was verified by four groups of experiments. It was found that the electronic fruit swung 25.5 mm under the action of inertial force, the separation force was 11.32 N, and the calculated value of theoretical model was 17.25 N, which was greater than that of fruit and fruit stalk. It is proved that the normal inertial force plays a major role in the process of fruit shedding. The separation force is 11.4N according to the acceleration calculation of the electronic fruit collection, so the separation inertia force calculated by the theoretical model can satisfy the actual condition of fruit shedding. The field experiment of electronic fruit was carried out. Through four groups of experimental data, it can be concluded that the electronic fruit can be divided into two parts: picking stage and falling stage. The mean and average impact values of the harvest stage were 215g and 123g, respectively, and the mean values of the maximum impact and the average impact in the falling stage were 155g and 76g, respectively. It is not difficult to find that the number of shocks over 190g is about 6% of the total, and the average number of shocks in the range of 150g ~ 190g is about 18 / 100g to 150g / 150g, respectively, by studying the mechanical shock distribution model of the four groups of shock data. The average number of shocks in the range of 100g to 150g is about the total impact. The average number of mechanical shocks of 50 g to 100 g is about 6% of the total number of shocks.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S225.93

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