Measurement Analysis And Application On Farmland Ground Roughness

Agricultural machinery causes vibrations in rough farmland,which results in the redu ction of agricultural machinery operation efficiency,over abrasion of the components,shor t life time,unsafe work environment for the operator,and a series of unfavorable results,th erefore,research on the ease of agricultural machinery vibration in the operation process is an important subject for scientific workers.In the research about reducing vibration of kind s of agricultural machinery working on the different fields,rough farmland research becom es vital which is one of the fundamental reason of agricultural machinery vibration.In view of the current situation that the systematic and comprehensive study on the surface roughness of different farmland has not yet begun in China and research workers study the vibration of agricultural machinery without the field ground vibration spectrum as a random excitation,and based on the research experience and method of road surface roughness,a set of measuring system has been designed and made for different types of tractor and convenient installation.Through the measurement and analysis for three kinds of ground roughness(cobbled road,solid road and vegetation cover)in Shaanxi Haisheng modern agricultural park,three different ground roughness and power spectral density are obtained.The measured results are in agreement with the real condition,which verifies the reliability of the system.The main working and researches have been completed as follows:(1)To review literature and understand the research status of road surface roughness,focus on understanding the research status of farmland surface roughness to prepare for the determination of the subject;(2)To learn and master measurement principle of road roughness and collection of data,to analyze the reason why the existing instrument can not measure the surface roughness of farmland,and to design and make the measuring instrument for measuring the roughness of farmland according to the principle of inertial reference;(3)To learn signal sampling theory(sampling and mixing theory,anti aliasing filter and the determination of the sampling frequency),to select the representative farm(cobbled road,solid road and vegetation cover)as the test field,and to carried out the measurement experiment of farmland surface roughness after the preparation work is completed;(4)To learning the theory of data preprocessing(zero mean normalization,remove the trend item and digital filtering),programme to make the change of farmland groundroughness with time converted to the change with displacement based on the Matlab.Then,to calculate the power spectrum density of the discrete data through the Welch algorithm.By comparing standard grade power spectral density,it is concluded that the ground level of soft pavement and hard dirt road is between class C and class D,and the ground level of cobblestone street is between class B and class C,indicating that the cobbled road surface flatness is higher than the other two kinds of pavement;(5)The application of land surface roughness is briefly introduced,with the introduction of the large spray rod dynamic simulation platform.The structure and working principle of the large spray rod dynamic simulation platform,and Road spectrum reproduction process are elaborated to lay the foundation for the application of the field surface roughness in the vibration simulation analysis of large spray rod.