Monitoring method of rice seeds mass in vibrating tray for vacuum-panel precision seeder

Two cantilever force sensors were back-to-back fixed at the bottom of seed tray. Due to a phasic difference ψ existed between the vibration inertia force and the seeds normal impact force Fn, a differential operation was performed between the output signals of two sensors to eliminate the influence of inertia force and extract Fn effectively. Then, a signal processing circuit mainly composed of differential amplifier, active low-pass filter, bias voltage circuit, envelope detector, and passive low-pass filter in series was designed to detect seeds mass. Calibration tests were carried out in laboratory with vibration frequency f and amplitude A of tray in the ranges of 9-13 Hz and 3-5 mm, the results showed that the comprehensive measurement errors were <3.5% with SMA κ in the range of 0.2-1.8 g/cm2.