عنوان مقاله [English]
Introduction Seed drills are the planters that plant the seeds in rows in close proximity. The sowing rates of seed drills are regulated by fluted roller seed metering mechanism which may have different seed numbers each time in their grooves. Given the nature of these types of seed, it is not possible to completely prevent the change in seed flow rate. In addition, during sowing with seed drills over a field, seedless areas may remain largely due to unavoidable problems, such as a malfunction of the seed metering mechanism, clogging of seed tubes, emptying of the seed hopper, etc. Due to the closed-loop of the sowing process seed drills, seeds can be placed with an undesirable population per unit area. In this regard, the seed drill performance monitoring system by providing online feedback on the operating status of various parts could optimally improve sowing efficiency.
Materials and Methods At first step, to develop a seed drill monitoring system, an infrared seed sensor was designed to be installed in sowing tubes of seed drills. To establish an equation for mass flow rate estimation, the sensor was evaluated by a roller seed metering system and three types of seeds including chickpea, wheat and alfalfa (respectively, representative of large, medium and fine seeds). It was found that a completely acceptable equation can be made between the voltage and the flow rate of each type of seed. Afterwards, designing and constructing a seed drill performance monitoring system based on developed seed flow sensors was considered. In the proposed monitoring system, the seed flow sensors were installed separately in each seed tube, so that the amount of seed flow rate, the presence or absence of seed flow in the graphical interface can be displayed. The forward speed is measured with the Hall sensor and, taking into account the mass flow rate of the seed, the sowing rate is calculated according to the seed mass sown per unit area. During operation, the system registers sowing data with the location information provided by the GPS module. The overall information from the sowing performance is then recorded simultaneously on the embedded memory card and displayed in the graphical interface. In addition to sowing operations, the proposed system continuously indicate the seed and fertilizer levels of the hoppers measured by ultrasonic sensors.
Results and DiscussionThe developed monitoring system was constructed and installed on a seed drill, equipped with 13 sowing units. With applications of three levels of ground speed and sowing speed during field experiment, the sensing system is assessed under outdoor operating conditions, including planter vibrations, tractor speed variation, and the dust. The field test resulted in a correlation coefficient of 85 percent between the mean of the weighted data obtained from the scale and the mass flow estimates. The outdoor experiments results appeared to be weaker than laboratory evaluation. Regarding the outdoor operating conditions, the obstruction of the optical elements by the dust seems to have the most adverse effect on the performance of the proposed sensing system. In addition, increased forward ground speed and sowing rate resulted a negative impact on the performance of the developed seed flow sensor. So that with increasing speed and mass flow rate, the passing seed flow becomes denser and more seed remains hidden from the measuring elements. In the case of the hopper level control sensor, ultrasonic sensors had proven to be a suitable and inexpensive practical solution for checking the fertilizer and grain level.
Conclusion There are some suggestions for the development of the sowing monitoring system in future research. When designing an optically based seed sensor, optical elements with a smaller propagation angle are preferred. In this case, the error caused by optical overlap would be minimized. The sowing performance monitoring can be triggered as appropriate feedback received from the forward speed sensor. The flow sensor can therefore only be activated when the tractor is moving and exceeds a predefined threshold. In this case, the environmental effects that affect the performance of the seed sensor can be automatically zeroed when the tractor is stopped. Reduce the wiring between system components by establishing wireless communication protocols, CAN, etc., the use of new operating methods for the modification and cleaning of infrared elements against dust, the development of a graphical interface in Android and iOS systems and the use of tablets and mobiles Phones to display sowing information are some of the issues that could be considered in future system updates and developments.