Design Of Automatic Reseeding Systom For Large Grain Crops

Corn precision plant is the important measure for seedling and yield, as well as seed saving, time saving, higher yield and lower cost. The precision planter is the main mechanization technique means for sowing quality. Corn is one of China’s three major grain crops, is typical for precision planting. Precision seeding technology is the inevitable trend of development of agricultural modernization, therefore, reasonable to promote the use of precision seeding technology is a key technology to achieve income yield of maize. Precision seeder is a core component of precision planter work, seeding performance seeder sowing determines the quality of the planter. However, the loss sowing phenomenon of sower for crops with large grain is common which endangers our national food security and economic benefits of farmers. Therefore, how to quickly and accurately solve miss-seeding problem is the key to improve the quality of sowing and economic benefits, and to accelerate the development of precision seeder, and to alleviate the problem of food security in our contury.The loss sowing phenomenon of sower for crops with large grain is common. Reseeding and seed-metering device now available are independent of each other. This method has some problems such as reseeding inaccurately. In order to solve these problems, an automatic reseeding method based on overrunning clutch was proposed in this paper. An automatic reseeding device that was composed of both reseeding device and seed-metering device was designed. The device adopted a hall sensor to get the speed of the seed-metering device. The hall sensor got the time interval between every two seed spoons of the seed-metering device to calculate the real-time speed of the seed-metering device. A laser sensor was used to monitor the loss of seeds. Seeds in the plate of the seed-metering device could block the light propagation path of the laser. If the light propagation path of the laser was not blocked, the seed was lost. An overrunning clutch was used to connect a step motor and the axle of the seed-metering device. The step motor was used to drive the seed-metering device to reseed with high speed. The overrunning clutch is a kind of compound function bearing which transmits torque between the inside hub and outside hub in one direction and allows free overrun in the opposite direction. It was used to switch torque source between the wheels of the seed-metering device and the step motor. The torque source came from the wheels of the seed-metering device when seeding but from the step motor when reseeding. When the laser sensor monitored the loss of seeds, the controller based on the real-time speed of seeding and position of the missing seeds to calculate the rotational speed and angle of the step motor. The step motor drove the seed-metering device to reseed with a higher speed than seeding speed. The subsequent seed was added to the vacant position quickly. The system of the automatic reseeding device would give failure warning to the user if the seed-metering device has a breakdown. Specific contents and conclusions are as follows:(1) According to the design requirement, inner monitoring method was used in this paper. Fast overrunning reseeding project was proposed. Structural concept and monitoring scheme were determined. The working principle was analyzed.(2) Hardware composition of the system was elaborated. It included system controller, speed monitoring module, leakage monitoring module, seeding module, etc. According to the functional requirements, each hardware module of circuit system was designed.(3) The leakage and automatic seeding control algorithm was proposed. Based on embedded technology, system program of each functional module was designed.(4) According to the design requirements, the system is divided into signal detection and processing, human-computer interaction, actuator control of three modules; each module hardware circuit was designed and produced a controller; using C language development environment in Linux various functional modules corresponding program, debug hardware and software will successfully combine the various functional modules and the entire system to be tested. By testing and certification system, LCD screen can realize the function of the work bench speed information displayed in real time; perform motor can be realized from stop to maximum speed stepless adjustment.(5) Experiments show that when the seeding speed is between 2 km/h and 5 km/h and the continuous missing seeds number Q is less than 3, the error of the reseeding time interval ΔT increases as the seeding speed V and the continuous missing seeds number Q increase. However, the max relative error of the reseeding time interval ΔT is less than 1.37%. The automatic reseeding device has a good performance of reseeding timeliness. The failure warning system of the automatic reseeding device can warn users of the failure of the seed-metering device accurately. The accuracy of the failure warning is 100%. The qualified index of seeding space A is 100%. The variation rate of seeding space C is 14.48%. Both of the qualified index of seed space A and the variation rate of seed space C are much better than the performance indicators of precision seeder in Chinese standard. The reseeding accuracy of the automatic reseeding device is high. The average rate of successful reseeding is 92.98%, the comprehensive missing rate M decreases to 0.8%, and the average sowing rate increases to 99.5%. The automatic reseeding device has a good effect. The study can provide a reference to improve the design of the precise seeder for large grain.