排种器振动种盘内种群质量实时监测方法

摘要

To monitor the seeds mass in reciprocating vibrating tray for vacuum-panel precision seeder in real-time, a cantilever force sensor was used to measure the impact force of seeds action on the monitoring board.Then, based on the analysis of variation characteristics of output signals of force sensor under different parameters, a signal processing circuit mainly composed of analog adder, precision half-wave rectifier, second-order Butterworth low-pass filter, and differential amplifier in series was designed to detect seeds mass.With vibration amplitude A of 3, 4 and 5 mm, corresponding frequency f of 11-13, 10-12 and 9-11Hz, calibration tests were carried out on vibration test-rig in laboratory.Fitting results showed that non-linear measurement errors between output voltage of signal processing circuit Vout and seeds-mass-per-unit-area κ were less than 5.5% with κ in the range of 0-1.8g/cm2.When κ was greater than 2.0g/cm2, the instability of seeds periodic vibration motion enhanced the fluctuation range of Vout, which led to an increase of non-linear measurement errors.Zero-point output voltages of Vout were increased with the increasing of vibration strength of tray, and measurement sensitivities were reduced when increasing the vibration frequency at same amplitude.The proposed monitoring method has a good adaptability because the effect of seeds shape and mechanical properties on Vout could be neglected.%采用悬臂梁称重传感器测量排种器振动种盘内种群的冲击力,在分析不同参数下输出信号变化特征的基础上,设计了由加法器、精密半波整流、二阶巴特沃斯低通滤波和差动放大串联组成的信号处理电路,实现了振动状态下种群质量的实时监测.在振动种盘试验台上进行了性能试验,设定振幅为3、4、5mm,相应振动频率分别在11~13Hz、10~12Hz、9~11Hz范围,结果表明:当单位面积籽粒质量κ<1.8g/cm2时,信号处理电路输出电压Vout与κ的非线性误差小于5.5%;当κ>2.0g/cm2时,由于种群振动运动的不稳定导致输出电压Vout的波动性增强,测量的非线性误差增大.信号处理电路零点输出电压随种盘振动强度的提高而增大,测量灵敏度随种盘振动频率的提高而降低,籽粒形状和力学特性差异对测量结果的影响可以被忽略,监测方法具有很好的适应性.