Design and experiments of seed pickup status monitoring system for cotton precision dibblers

A seed planting dibbler has been commonly used to make holes for transplants and bedding plants. However, the dibbler rolls with the ground can be easy to vibrate for the undesired empty hole in the seed row during sowing operation, particularly when turning or moving forward, due to the harsh working environment. Furthermore, the empty hole cannot be found in time, where the dibbler can be completely closed inside, leading to a large area of empty holes for the yield reduction when sowing cotton. A cotton precision dibbler has been a high demand to deal with the empty holes caused by the seed extraction and discharge during hole sowing operation. In this study, a new monitoring system was developed for the seed pickup in a precision dibbler during cotton sowing. The position of the monitoring point was first determined in the working process of the toothed disk dibbler. The indoor and field tests were then conducted, where the laser alignment and Hall sensors were used as the monitoring elements, an STM32 microcontroller was used to calculate the number of qualified holes and the empty hole rate, and an nRF24L01 wireless communication module was for the human-machine interaction terminal data interaction. The bench test showed that the monitoring accuracy was not less than 97% and 93.48% for the numbers of qualified and empty holes, respectively, as the working speed of the dibbler increased in the range of 30-45 r/min. Specifically, the overall monitoring accuracy was not less than 96.17% and 93.11% for the number of qualified and empty holes, with the increase of the sower travel speed in the range of 2.5-4 km/h. It infers that the monitoring system of seed extraction fully met the requirements of cotton sowing. Moreover, the lighting did not affect the monitoring system. More importantly, the accuracy of the monitoring system decreased by no more than 1%, compared with the bench test. A chi-square test was also performed on the system monitoring and manual measurement data samples using F-test. It was found that F<F0.05 (6.39), P0.05>0.05 for the number of qualified and empty holes of system monitoring and manual measurement, indicating excellent accuracy and stability under field operation. Anyways, the monitoring system can be effective and feasible for the seed extraction performance of the tine disc, fully meeting the requirements of seed extraction monitoring in the cotton precision dibbler. The finding can also provide a strong reference to promote the automation and intelligence of cotton precision hole sowing. © 2022, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.