小型方捆机草捆动态称量系统信号分析与处理

Signal Analysis and Processing of Dynamic Weighing System for Small Square Baler

为实现小型方捆机草捆动态称量系统的准确测量,降低地面颠簸和机械传动引起的振动对草捆质量测量精度的影响,分析了打捆机作业速度、拖拉机PTO启停对草捆动态称量系统压力和角度噪声信号的作用机理。当系统采样频率为40 Hz时,压力噪声信号频率主要在0.1~16 Hz;角度噪声信号频率主要在3~4 Hz和16~17 Hz;打捆机作业速度与噪声信号强度呈正相关。在信号分析基础上,研究了信号处理方法。为提高滤波精度,首先采用基于3σ准则的双阈值动态滤波方法对信号进行预处理,消除奇异值影响,再利用分段线性插值补充空缺点,最后设计一种巴特沃斯带阻滤波器对噪声信号进行消除。田间试验结果表明,采用该方法对信号进行处理后,草捆质量预测相对误差为-4.15%~4.17%,优于均值滤波得到的结果,且该滤波方法适应性更好,更符合实际生产需要。

Aiming to accurately measure the dynamic weighing system of straw bale in small square baler and reduce the influence of vibration caused by ground jolting and mechanical transmission on the measuring accuracy of straw bale.The influence mechanism of different working speeds of baler and the start or stop of the tractor PTO on the pressure noise signal and angle noise signal of dynamic weighing system of straw bale was analyzed by an experiment.When the sampling frequency of the system was 40 Hz,the signal frequency of pressure noise was mainly within the range of 0.1~16 Hz.The frequency of the angle noise signal was mainly in the range of 3~4 Hz and 16~17 Hz.The working speed of baler was positively correlated with the noise signal strength.On the basis of signal analysis,the signal processing method was researched.First of all,aiming to eliminate the influence of singular value about the original signal,the double threshold based on the rule of 3σmethod for signal preprocessing was carried out.Then piecewise linear interpolation was used to supplement the vacancy point.Finally,a Butterworth band stop filter was designed to eliminate the noise signal and further improve the filtering precision.The field test results showed that the relative error of straw bale quality prediction was between-4.15%and 4.17%after the signal was processed by the method.The relative error of straw bale quality prediction was between-5.15%and 5.08%after the signal was processed by the method of average filtering.The signal processing method was better than the average filtering.Moreover,this filtering method was more adaptable and met the actual production needs.