Qiu Zhaomei

Design and experiment of automatic transplanting device for potted tomato seedlings

In this study, an automatic machine for transplanting potted tomato seedlings was designed, based on the analysis of physical characteristics of the main varieties of tomato seedlings. The machine is composed of a horizontal and vertical seedling supply mechanism, a picking mechanism composed with a gear-rod component, a planting part featured with an eccentric-disk parallelogram duckbilled mechanism, and a control system. The control system included position sensors, stepper motor, variable-frequency motor and program controller. The force condition for successful picking potted tomato seedlings was studied by analyzing the force and motion during the taking procedure with the use of analytical graphic method. Combined with the parameters of physical characteristics of tomato seedlings, the key parameters of the machine was determined, which included L1 = 105 mm as the distance between the point of the gripper needles and the center of rotation, L0 = 18 mm as the initial opening distance between the two gripper needles, and s = 40 mm as the distance between the two gripper needles when they were at the upper hinge point of the clamping hands. The key structure and the parameters of the seedlings-taking part were determined by theoretical calculation according to the position of the seedling during taking and dropping procedure, and the requirement of the motion. The machine was tested by using the potted tomato seedlings. The result showed that the seedling picking rate was 92.35%–86.61%, and the leakage rate was 12.57%–18.03%, when the transplanting speed was between 60 and 90 seedlings per minute. The result demonstrated that the machine was feasible to transplant the potted tomato seedlings efficiently.

Design and implementation of Intelligent transplanting system based on photoelectric sensor and PLC

Industrial seedling rearing is an important part of seedling transplanting technique. At present, there exists the phenomenon that soil base on the tray may have empty seedling on it, which will lead to a large number of leakage and reduce the yield in the course of automatic transplanting in the field. To solve this problem, automatic seedling identification method is studied to skip picking empty soil bases. An intelligent transplanting system are designed with the use of the picking mechanism five-bar and fixed-axis gear train, the seedling tray conveying mechanism (with transverse and longitudinal seedlings feeding function), the eccentric disc parallel four-bar duck mouthpiece planting mechanism, the electric sensor for seedling detection and identification of the seedling tray, the position sensor, stepper motor and PLC control system. By use of computer logic programming and control, it can be used to identify effectively whether the soil base is empty or not, and to control the automatic transmission of seedling tray. The tray is moved to quickly skip the action path of the manipulator to avoid the picking of empty soil base. The system was tested by using pepper seedlings on indoor condition. The results showed that when the transplanting frequency was 90 / min, the rate of success seedling picking was 88.23% and the leakage rate was 16.46%, which could meet the requirement of pepper transplanting. Compared with the transplanting model without seedling identification, the average rate of leakage was reduced about 12%. The research provides a useful reference for the development of intelligent agricultural transplanting technology and equipment.