基于光量阻挡原理的颗粒化肥流量检测方法

Flow Detection Mechanism of Granular Fertilizer Based on Light Blocking Principle

针对化肥排施过程流量较大,化肥颗粒相互遮挡导致难以准确检测的问题,提出了基于光量阻挡原理的颗粒化肥流量检测方法,该方法以颗粒流量与传感器响应电压间的相关性为基础建立检测模型;通过理论分析初步确定了该检测方法的可行性;借助离散元仿真分析了化肥排施过程在输肥管中的分布规律,为颗粒流量传感器结构设计和安装位置确定提供了依据;基于上述分析设计了颗粒流量传感器,并搭设了颗粒化肥流量检测试验台;以尿素和复合肥为试验材料,以排肥轮转速为试验因素对上述理论进行了验证,结果表明化肥流量与化肥颗粒流量传感器累计响应电压存在较强的线性相关,各排肥轮转速下,两者相关性决定系数均高于0.992。为确定最优检测模型,建立了各排肥轮转速的检测模型,以平均绝对百分比误差为指标对不同检测模型进行了对比,基于加速组建立的检测模型对尿素和复合肥的平均绝对百分比误差分别为5.18%和4.07%,检测误差低于其他组,确定了最优检测模型。为解决颗粒流量传感器与不同直径输肥管匹配的问题,以敏感元件数量和颗粒流量传感器内径为因素进行试验,结果表明当检测元件密度为0.075~0.75时,对于尿素和复合肥各流量传感器的平均绝对百分比误差分别为4.75%~9.33%和4.07%~9.11%,且平均绝对百分比误差随检测元件密度增大而降低。

In agricultural production,it is challenging to detect the flow rate of fertilization due to the large amount and the mutual shielding of fertilizer particles.A granular fertilizer flow detection method based on the principle of luminous flux blocking was proposed to solve this problem.The feasibility of the detection method was preliminarily determined by theoretical analysis;discrete element simulation was used to analyze the distribution of granular fertilizer discharge in the conveying tube,which provided a basis for the structural design and installation position of the particle flow detection sensor(PFDS).Based on the above analysis,the PFDS and test-bench were designed.Experiments were carried out by selecting urea and compound fertilizer as materials and the fertilizer discharging wheel(FDW)speed as factors to verify the method.The results showed a strong linear correlation between fertilizer flow and the cumulative response voltage of PFDS.Under different fertilization frequencies,the correlation determination coefficient(R~2)of both was higher than 0.992.The detection models of each fertilizer frequency were established.Absolute percentage error(AE)and mean absolute percentage error(MAPE)were selected as the index.The MAPE of the detection model based on the“accelerate”for urea and compound fertilizer were 5.18%and 4.07%,respectively.And the detection error was lower than that of others,so the establishment method of the optimal detection model was determined.To solve the matching problem between the PFDS and fertilizer tube with different diameters,the experiments were carried out by taking the number of sensitive elements and the inner diameter of the PFDS as factors.The results showed that when the density of detection elements was 0.075~0.75,the MAPE range for urea and compound fertilizer were 4.75%~9.33%and 4.07%~9.11%,respectively,and the MAPE was decreased with the increase of detection element density.The detection method would provide technical support and solutions for granular fertilizer flow detection.