Authors

Abstract

For tractor operation on deformable terrains, accurate terrain profiles are critically needed to determine the dynamic tractor response, which is affected by the terrain roughness. Effective profiles for tractors operating on agricultural terrains were identified in this study. A novel technique, called independent component analysis (ICA), was used to estimate the effective profiles. ICA can use a known system dynamic response (observed signals) to identify road-induced excitation. In this context, tractor wheel vibration signals were used as observed signals, and the ICA method was used to estimate the source signals, which are the effective profiles of the terrain. The proposed approach was validated by comparing the estimated profiles with those measured by a profiling apparatus in the time and frequency domains. The calculated root mean square error RMSE and the relative error Ef between the measured and estimated profiles showed that the proposed approach can be used to accurately estimate road profiles. A group of grass-field roughness data was taken as an example to compare the characteristics of the original and effective profiles, and the parameters of the effective profiles, such as the RMS, roughness index C and waviness W were found to noticeably change during the interaction between the tractor wheel and the terrain soil.

Abstract in Chinese

拖拉机在可变形地面上运行时，准确了解地面不平度特征是研究受地面不平激励的拖拉机动态响应的关键因素。本文研究拖拉机在农田地面上作业过程中地面有效不平度的识别问题，采用独立分量分析（ICA）这种新方法来估计农田地面的有效不平度，通过系统的动态响应（观测信号），ICA可识别路面的不平激励源。为此，以拖拉机车轮振动信号为观测信号，采用ICA方法对地面有效不平度的源信号进行估计，为了验证该方法的有效性，在时域和频域将估计的不平度与通过不平度测试装置实测的不平度进行了比较，计算实测不平度与估计不平度之间的均方根误差RMSE和相对误差Ef，结果可知该方法能很好地估计地面不平度。以一组田间草地不平度数据为例，通过比较草地原始不平度与有效不平度特征可知，在拖拉机车轮与地面土壤相互作用过程中，有效不平度特征参数RMS、不平度系统C和频率指数W均发生了明显的变化。