Design of PLC controll system of precise seeding assembly line for rice seedling nursing

Agronomic techniques require 1or 2 seedlings in one cavity during the super-rice transplanting. It requested low quantity sowing and high uniformity machine transplantation. A high precision seeding assembly with vibration and air-suction for rice seedling nursing was developed to meet the requiements of precision and small quangtity in super-rice transplanting. An automatic control system based on PLC (programmable logic controller) was designed. Automatic programming techniques, sensor technology, and acceleration and deceleration control of step-motor were integrated into the system. System controlling software was programmed in the form of ladder diagram by GX-Developer-C V8, realizing accurate positioning of act device and coordinated of the action, and it can connect to PC to realize a real-time monitoring to the process of the sowing. The experiment and test of the seedling assembly indicated that seedling accuracy reached about 1-2 seeds per grid, passing rate of uniformity was 93.8%, space rate was 5.6%, unevenness of feeding rate between plates was 2.5%, operation efficiency reached 490 plates per hour. The automatic control system completely meets the requirements of seedling nursing precise sowing and transplanting for super-rice and conventional rice.