Development of an infrared seed-sensing system to estimate flow rates based on physical properties of seeds

Seed drills are usually used for sowing various seeds with different physical properties. It is important to develop a sensing system for planters capable of measuring the sowing rate of various kinds of seeds with the same settlement. For this purpose, an infrared sensing system was developed comprised of IR LEDs and photo-diodes on the opposite sides. When a seed stream passes, the output voltage of the light-receiving sensor changes proportionally in response to changing in the intensity of light at the receiving element. The voltage changes were added using a microcontroller and converted to an analog value by DAC chip. The test apparatus was designed to calibrate and evaluate the sensor with three types of seeds of chickpea, wheat, and alfalfa. These seeds respectively represent the large, medium and the fine seeds. The results revealed a good correlation between the voltage received from the seed sensor and the mass flow of seeds in the delivery tube. A model was developed for seed flow rate based on sensor output voltages, thousand seed weight and equivalent diameter of seeds. The coefficient of determination for the model was 0.94. So, it was concluded that the seed flow rate could be estimated based on some physical properties and output sensor voltage. The developed infrared sensing system could be used for the assessment of planter rows performance in the laboratory. It could provide an easy calibrating method for seed drills before planting in the field.