Design and Experiment of Seeding Quantity Sensor for Cotton Hill-drop Planters Based on Capacitive Method
To address the installation challenges of conventional photoelectric sensors in hill-drop planters widely used in Xinjiang,which lack seed guiding tubes,a seeding sensor was explored based on weak capacitive signal acquisition and analysis.By analyzing the seed extraction process within the seeder,the optimal detection position and external dimensions of the electrode plates were established.The primary objectives were to enhance signal significance and detection accuracy while ensuring reliability as a critical boundary constraint.To optimize the electrode structure parameters,a response surface methodology was employed,utilizing three factors at three levels.Additionally,the sensitive unit of the sensor was shielded to concentrate the electric field.Following enhancement,the thickness of the sensor's sensitive unit was determined to be 0.64 mm,and a capacitance variation of 0.16 pF,effectively enhancing signal significance and detection accuracy.A capacitive signal acquisition module,centered around the AD7745 capacitive conversion chip,was designed.The upper computer processed the collected signals using adaptive threshold orthogonal wavelet transform filtering and employed the second derivative peak detection to obtain real-time seed sowing rates.Experimental results indicated that with a sampling period of 11 ms and a seeder rotation speed of 20～25 r/min,the sensor achieved high detection accuracy,with relative errors between the actual and measured sowing rates ranged from-2.604% to 1.836%,which were all less than 5% .The designed seeding sensor provided an effective solution to the sowing detection challenges associated with disc-type seeding equipment and played a significant role in advancing precision sowing technology.
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