【作者】 孙进；

【导师】 李耀明；

【作者基本信息】 江苏大学 ， 农业机械化工程， 2007， 硕士

【摘要】 风筛式清选装置的应用已有悠久的历史，有关机械振动的基本理论也已建立，但这种装置仍然存在着很多问题：如潮湿物料的清选损失率大；清选效率不能适应联合收割机高速、高效、高性能、高可靠性的发展要求等。究其原因：到目前为止，该装置的设计仍主要靠经验进行，农业物料振动筛分时颗粒运动规律的理论研究还很不成熟。为此，开展农业物料颗粒运动规律的系统理论的研究尤为重要。本文首先在前人的基础上进行了深入探讨，得出了物料颗粒在振动筛面的复杂运动规律。其完整表述为：物料在整个运动过程中同时体现了定常运动规律和非线性运动规律。物料在从抖动板落下至物料在清选筛上停止跳动这段时间遵循非线性运动规律；当物料在清选筛上进行滑动时，其运动遵循定常运动规律；物料由于清选筛的运动，又重新抛起，其运动又遵循非线性运动规律直到跳动结束为止。其次本文运用高速摄像系统对物料颗粒在振动筛分过程中的运动规律进行了试验研究。测定了与清选性能相关的物料特性，针对物料颗粒运动规律的研究进行了试验规划，在此基础上论述了物料运动图像处理系统的设计，主要包括：物料二维运动轨迹的图像法分析；物料三维运动轨迹的图像法分析；VB和MATLAB混合编程，即由VB开发可视化友好的界面，由MATLAB进行图像处理，运用ActiveX技术将VB和MATLAB集成起来，开发了一套物料运动图像处理系统。在试验时，分别使用单目摄像系统和双目摄像系统对物料不同工况进行拍摄试验，通过分析物料的二维运动轨迹和速度以及三维运动轨迹，发现物料能较好遵循定常运动规律和非线性运动规律，但理论分析中所描述的周期运动和倍周期运动并未严格出现，仅出现了近似倍周期运动的情况。综上所述，本文在物料颗粒运动规律的建立、物料运动图像处理系统的设计、试验研究等方面进行了一些有益的探索，为以后的进一步研究提供了良好的基础，为风筛式清选装置的优化提供了一定的理论和试验依据。更多还原

【Abstract】 Air-and-Screen Cleaning Mechanism has been used in cleaning agriculture materials for a long time and its basic theory of mechanical vibration has already established, however, there remains many troubles: For example, high lossing rate for humid materials; low cleaning efficiency unappeaseable for the needs of modern combine harvester. All these means: The theory of material motion is still unripe, so making an in-depth study is necessary.In this thesis, with proper assumption, a new theory of material motion on the vibration sieve was established based on collision and force theory, the full narration is as follows: During the total process of their motion, materials follow stationary motion law and nonlinear motion law. From the time they fall from the dithering plate to that they stop jumping on the vibration sieve, the materials will follow the nonlinear motion law. While sliding on the vibration sieve, they will follow the stationary motion law and when jumping from the vibration sieve again, they will follow the nonlinear motion law.Thenceforth an experiment was conducted to verify the theory. firstly, the characteristics of the materials related to cleaning performance were measured; the experiment plan was made, then motion processing system was designed : 1) The acquirement of 2-D materials moving track based on digital image processing technique; 2) The acquirement of 3-D materials moving track based on digital image processing technique ; 3) The processing software was developed with the combination of VB and Matlab, by utilizing excellent computing capacity of Matlab and the friendly user interface of VB.In the part of experimental verification, by using monocular stereo vision system and binocular stereo vision system, a conclusion was drawn: material’s moving track follows stationary motion law and nonlinear motion law approximately.In this study, some instructive gropes were acquired: theory of material motion, design of motion processing system and experimental verification.To sum up, a favorable basis for more researches was made and a better reference for optimizing of the Air-and-Screen cleaning mechanism was provided .更多还原