青贮饲料紧实度与含水率复合传感器设计与试验

Design and Test of Combined Probe for Compactness and Water Content of Silage

为了同步获取青贮饲料的紧实度和含水率,综合评价青贮饲料品质,本文基于电阻应变效应和频域法设计了一种复合传感器。复合传感器采用一体化结构设计,将电阻应变片和含水率测量电极嵌入圆锥探头内,实现了青贮饲料紧实度和含水率的实时同步测量。对复合传感器进行了标定和验证试验:标定结果表明,青贮饲料紧实度和含水率与复合传感器输出电压均呈线性关系,决定系数分别为0. 99和0. 909。验证试验表明,本文设计的复合传感器不仅可以实时、同步测量青贮饲料紧实度和含水率,还能消除圆锥杆与被测饲料间摩擦力对紧实度测量造成的测量误差。

In the process of silage production,the compactness and moisture content will affect the quality of silage and even lead to failure of silage.But most instruments are designed to obtain a specified parameter which is unable to accurately evaluate the silage quality.A combined probe was designed to simultaneously measure the compactness and water content of silage based on the American Society of Agricultural and Biological Engineers(ASABE)standard.Cone angle was 30°,probe diameter was 12.83 mm and probe length was 50 mm.According to the principle of resistance strain and frequency domain method,the moisture electrode and resistance strain gauge were designed in the cone probe.In order to evaluate the applicability of the combined probe,calibration and validation were carried out with a motor-operated penetrometer.The calibration included two processes:power stroke and return stroke.The force calibration test showed that,in each process,there was a linear equation with a determination coefficient(R 2)of 0.99 relating the output of the combined probe to force values within the range of 0~1 kN.The water content calibration was tested by ten kinds of silage samples,and it was showed that the water content was linearly related to the outputs of the combined probe in the range from 29.9%to 67.8%,and the determination coefficient reached 0.909.The validation was tested by three kinds of silage samples,and it was demonstrated that the combined probe could response the variation of the compactness and water content of silage simultaneously and eliminate the effect of penetration friction component.