| Since the 19th century, biological technology was developed continuously and a lot of pesticides and chemical fertilizers were used in agricultural production. Many problems such as resource waste,environment pollution and destruction of biological diversity appeared while agricultural production acquired unprecedented development. The traditional mode of agricultural production is seriously challenged because it can not realize the fast and well development of agriculture. The rapid development of information technology resulted in profound changes in various field of industrial and agricultural production and a new technology system of agricultural production appeared which called "precision agriculture".Precision agriculture is developed with the technologies of GIS,GPS,RSS,ES,SS,DSS and ICS and has become a hot field of research where high technology is intensively applied for the continuous development of agriculture.The research in precision agriculture includes precision seed engineerings precision planting,precision fertilization,precision irrigation,dynamic regulation of crop and precision harvesting. Based on the latest achievements of high technology such as modern spatial information technology,biological technology,seed engineering,variable rate fertilization technology,new irrigation technology,automatic testing and monitoring technology,mechanical and electrical technology, Precision agriculture is developed into a modern systematic project with strong comprehensiveness. It is the basic way to bring agriculture production low consumptions high efficiency,good quality and pollution-free. Precision agriculture is a new trend of international agricultural development and is also the best choice for our country.The core idea of precision agriculture is to acquire the spatial and temporal difference of block yield and environmental factors by means of information and automation technology, then search the reason of block yield difference for taking feasible and economical measures to change the traditional extensive averagely-inputting production mode, at last, implement positioning in farming and inputting so as to realize the variable rate operation (planting, fertilizing, spraying , irrigation, etc) according to need.Researches on the relevant technology in modern agriculture have important theoretical and practical significance when it is advocated nowadays to guide the construction of socialist new countryside with scientific development concept and actively promote the comprehensive, coordinate and sustainable development of economy and society in rural area.Precision harvesting is either the start point or the destination of precision agriculture system. Only by obtaining accurate yield data can the decision made for the subsequent jobs such as planting, irrigation and fertilization. In other words, it is the basis of precision agriculture to obtain yield data. Currently, study on grain yield monitoring is relatively mature in overseas and grain yield monitoring systems are put into commercially batch production. In China, some units have obtained certain progress and achievement in the research on grain yield monitoring. But there is no report about cob corn yield monitoring. In this paper, experimental study on cob corn yield monitoring was preceded. The following works were finished and the relevant conclusions were reached.1. The hardware construction, software system and operation method of PF advantage were deeply studied and the method of installation, setup, calibration, adjust and manipulating were mastered as well as the yield monitoring theory.2. The similarity of yield monitoring between granular and cob corn and the feasibility of experiment were analyzed theoretically and a conclusion was drawn after calculation and judgment that PF advantage could be applied to cob corn yield monitoring.3. The yield data of 2001-2004 was analyzed. The kernel-ear weight ratio and humidity of dry corn from Tianzhen County, Shanxi Province and Lishu County, Jilin Province was studied from Dec.2007 to Jan.2008. Scatter diagram was made and statistical regularity was found that the kernel-ear weight ratios of corn in the same land block and year were in a certain interval with a short length. It was proved by calculation that the maximal average relative error of kernel-ear weight ratio is 5.3% and 7.8% for humidity.4. The direction and origin height of corn which impact the strain impulse sensor were calculated and analyzed. A decelerating mechanism for motor was designed independently to help excite the ground speed sensor and elevator speed sensor which provide input signals to PF advantage. Then simulated yield experiments were implemented on the test bed and a series of data were obtained after seven corn ears separately impacted the sensor circularly.5. After lateral and longitudinal statistical analysis and linear regression, a mathematical model was built on the relationship between the real yield "X" and the tested yield "Y" from PF advantage system. By correlation coefficient check,error analysis and correction, an empirical formula was obtained and considered acceptable to predict kernel yield after harvesting and yield monitoring with PF advantage. The formula is Z=0.14*E(Y+132.83047)/(11.49072*H). The maximal reckon error of the formula is 12.3%.Technologies such as electronics, information, automation and high-tech equipments for example GPS and etc are involved in precision agriculture, so it is too expensive for Chinese peasants to implement all or some links of precision agriculture. Therefore, researches on precision agriculture in China are forward-looking and we should seek a practical and feasible way to implement precision agriculture with Chinese characteristics. It is the urgent affair to absorb and digest the imported equipment and technology, then research and develop high performance and low consumption precision agriculture equipments for Chinese peasants based on national conditions. We could propose the following ideas:1. Check and correct the formula built in this paper by experiments with more fresh corn ears in the autumn of 2008. The cumulative error will be reduced because weight loss of fresh corn ear should be less than that of dry corn ear in impacting experiments.2. In the areas where grain yield monitoring systems were imported, try to use the equipments for corn ear yield monitoring by analyzing, calculating and refitting so as to improve the utilization ratio and application range of them. Therefore, we should design and develop corn ear delivering mechanism for corn combine to make corn ear move smoothly from the elevator outlet to the impulse sensor.3. Develop corn ear yield monitoring system with independent intellectual property after full understanding of the theory on foreign grain yield monitoring systems and especially solve the problems in the link of impulse sensor. Based on the experimental results in this paper, stain type sensor could be applied as impulse sensor.
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