碰撞位姿对开心果碰撞声离散性的影响

Research on the influence of impact pose on the discreteness of pistachio's impact sound

为了研究碰撞位姿对开心果碰撞声离散性的影响,在除碰撞位姿不作控制、其余条件均相同的情况下,分别对单个开闭口开心果进行100次重复碰撞试验,对两组碰撞声信号的频谱离散性和统计参数的离散性进行分析研究。频谱的离散性以样本信号频谱向量与其平均向量间的夹角均值和夹角变异系数作为度量;统计参数的离散性采用信号的能量、熵、过零率等参量,以其变异系数作为度量。试验结果显示:1单颗开口开心果重复碰撞声信号的频谱向量与其平均向量间夹角均值为30.94°,夹角变异系数为16.56%;能量、熵、过零率参数的变异系数分别为38.33%,2.30%,20.00%,均值分别为11.20,4.39,63.43;2单颗闭口开心果重复碰撞声信号的频谱向量与其平均向量间夹角均值为20.52°,夹角变异系数为25.11%;能量、熵、过零率参数的变异系数分别为18.36%,2.27%,13.08%,均值分别为6.08,4.28,62.94。结果表明:1不作控制的碰撞位姿对单颗开闭口开心果重复碰撞产生的声信号均有影响,会发生离散;2在由碰撞位姿导致的碰撞声的离散程度上,开口离散程度比闭口的高;3除碰撞位姿不作控制、其余试验条件均相同的情况下,虽然单颗开闭口开心果碰撞声的频谱和统计参数都会发生离散,但各参数均在其均值附近有限的范围内变动,所以,通过提取均值差异大且变异系数小的特征参数可以实现开口果和闭口果的有效分类。

In order to know the influence of impacting pose on the sound discreteness of a single pistachio , the sounds of the closed and open pistachio during impacting were recorded, and the 100 times data for each lype on the same condition were analyzed including the discreteness of spectrum and statistical parameter. The discreteness of spectrum was evaluated by the angular separation between each sample signal with its average and variation coefficient, ant that of statistical parameter was then assessed by its variation coefficient, represented by energy, entropy and zero-cross rate, respectively. Moreover, the variation coefficient of the parameter was defined as the standard deviation over the average. The results were demonstrated as follows. Firstly, we found that for the open pistachio, angular separation was 30.94°, and the variation coefficient was 16.56%. What is more, the statistical parameter＇s variation coefficient were 38.33%, 2.30%, 20.00%, and its average were 11.20, 4.39, 63.43 for energy, entropy and zero-cross coefficient, respectively. Sencond- ly, it was found that, for closed pistachio, the angular separation was 20.52%, the variation coefficient was 25.11%, the statistical pa- rameter＇s variation coefficient were 18.36%, 2.27%, 13.08%, and its average were 6.08,4.28,62.94 for energy entropy and zero cross coefficient, respectively. Thus we could get the conclusions that the random impact pose could have an influence on impact sound signal discretely.Furthermore, the discreteness of open pistachio was higher than the closed ones. Lastly, The random impact pose was also found making spectrum and statistics parameter discretely in a limit range, so it was possible to sort open and closed pistachios using the paran3 eters of larger differences on average whereas smaller value on varia tion coefficient.