| Transplanting seedlings technology has many unique advantages for the dry land crops, such as, giving stable and high yields, raising the utilization of land, etc.. But, so far, the application of this technology mainly relies on manual operation. The overall economic efficiency and the productivity would be further improved if using mechanical device to replace the current manual operation on this transplanting technology. At present, China has developed semi-automatic transplanter. But the efficiency couldn't be improved because of the limits of the speed and strength of manual-feeding-seedlings. Transplanting automatically would be better realized if developing a device to feed seedlings instead of the monotonous and heavy manual working based on this semi-automatic transplanter. This not only can promote the development of transplanting technology, but also is very important for the development of agricultural machinery. According the rule which agricultural machinery should be compatible with the agricultural, this paper puts forward the key technology of automatic plug seedling transplanting, and develops a fully automatic equipment for picking seedling up from tray to replace the manual operation. The main work has been accomplished as followed.1. Using the nursing technology to breed plug seedlings, and make the measurement and statistical analysis on the plug seedlings' morphological characteristics in different seedling ages. The research results showed that the morphological characteristic of seedlings meet the time scale effect, the characteristic includes leaf height, width, leaf number, stem diameter and weight of seedling. That means the measured parameters increase accompany with the growth of seedling age. However, if the seedling age continues to grow, it would make no rooms for seedling recruits, and coupled with insufficient light, then lead to a tall leggy seedlings. And the tall leggy seedlings'root would be injured easily during transplanting, and result in the consequence of premature aging. The experimental results showed that:almost 30-day-old plug seedling is better for transplanting.2. A test system was constructed to record the discipline in the process of picking up plug seedling from the tray. The test results convinced that it performed well as required, meanwhile the quality and force of picking seedlings under various conditions was detected by this system. The conditions include plug seedling's own physical characteristics, plug moisture content, angle of picking seedlings, velocity of picking seedlings and the number of gripper needles. The experimental results showed that:this test system offer a good man-machine interface, it can record testing process and display the results data real-timely; the mechanical properties test results showed that the factors of number of needles has the greatest impact on the clamping force, the followed factor was the seedling age, the velocity of picking, the angle of picking, and the effect of seedling plug moisture content was minimal; the force of picking seedling up from the tray has no great react on the conditions of picking seedlings, it basically keeps in the context of 2-3N. The optimized experimental condition is:30-day-old seedling,4 gripper needles, seedling plug with 20% moisture content, pick plug-seedlings with 36°angles and 25mm/s velocity.3. Build an automatic supplying seedlings mechanism in line with the implementation of picking seedlings automatically. According to the requirements, supplying mechanism should intermit supplying seedlings horizontally and vertically. This papaer designed a feeding mechanism for moving alternately. It supplies seedling vertically by means of wheel chain controlled by a stepping motor, the tray moves a plug cell distance when the chain driven by the sprocket; seedling transmitted horizontally by means of screw nut, the tray moves corresponding distance intermittently controlled by the rotate angles of the lead screw, reciprocates was controlled by its rotate directions.4. The suitable motion discipline of picking and releasing seedling was proposed through analyzing the working way of automatic pick-up device. According to this motion planning, a set of equipment for automatic picking plug seedling was designed, which includes the pick-up device and its driven institutions. The pick-up device was the core component of the whole set. It clamping seedlings by deformed sliding needle. The clamping seedlings process is:4 needles sliding out of tube and tilting into seedling plug to clamping it, and the needle tube pushed the seedling fallen when the needle sliding retractably, cleared away the substrate adhesion on the sliding needles at the same time. The driving mechanism was composed of two pairs of intermittent pinion and rack mechanism respectively. It not only drives the pick-up device to get picking function, but also drives the plug seedling's straight and turning transferring. Based on the theoretical analysis of pick-up seedling device and plug seedling, the dynamic analysis of driving mechanism was executed by using Mechanism model of 3-D software Pro/E Wildfire. Through these analysis, we get the specific displacement, velocity, acceleration, force, torque and other parameters of every moving parts. We also get the best point to release plug seedlings through the dynamitic analysis on the moving seedling. These results can provide a favorable reference for the mechanism optimization and the driving equipments' selection.5. The controlling system was developed based on the virtual instrument and A/D card for administrating the movements of picking equipment. Its control principle was that the supply seedlings equipment begins to work when this system issuing a start order, and then the pick-up device starts the picking process, detector sends the signal to the control system after one picking up working finished, then the system sends the control instructions from A/D card to dominate the vertical or horizontal feed driving motor to rotate corresponding angles and directions to fulfill the joint operation requirements of supplying and picking equipments.6. Complete the performance test of driving mechanism for pick-up device, supplying equipment and their linkage separately. The test results showed that the controlling system based on the virtual instrument meet the control requirements of picking up seedlings automatically; the driving equipment also meet the designed requirements, just needs one driving force to drive every components to finish the commissions of transferring, turnning, picking up and releasing seedlings. Furthermore, whole equipments wok in place and smoothly without any stop or damage. The structure of the feeding device and its driving also meet the requirements of picking seedlings up automatically. Its testing results showed that the supplying success rate is more than 99% in the position prepared to be taken. The seedling trays come in and empty trays come out of the feeding device fluently without any pause. The linkage results showed that the supplying and picking seedling equipments work well with each other. It hasn't appeared mechanical or control failures. The testing results showed that the picking success ratio decreased with the number of pick-up device increasing.
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