| The measuring instruments used in agricultural machinery was lack behind comparing with those applied in other industries such as electrics, electronics, aviation, automobile and medicine. According to literature review, the head reason is the lack of eligible sensors that can work well at field condition. Based on this viewpoint and to meet the need of the study of no-tillage planter test in the meantime, a thorough study focusing on the seeding quality monitoring sensors was conducted in this dissertation. And distinct advancements was achieved as follow:1. For the first time Red Laser Diode (RLD) was used as light source to develop a laser beam grid sensor for monitoring seeding distribution. Hence, monitoring covering problem is solved and monitoring precision percentage was improved. Using the sensor as calculating transporting of corn and soybean , the pecision rate can be 100% . Up to now , the sensor has been used on a meter study equipment more than one year. On this part, a paper is published and a new patent is attained.2. The anti-dust problem of opto-electronic sensor used in agriculture was studied deeply in the paper. Referring the sensitization monitoring method, the quantitative measurement by the wedge and the anti-dust performance expressed by optics density quantity had been developed. The concept of the indicator of anti-dust was put forward. At the same time, the anti-dust function was used as a index of optoelectronic sensor' s performance evaluation. One article had been published.3. It is urgent to replace agricultural machinery driver with seeding absence alarm device. Whether the seeding absence alarm device works well or not is mainly decided by anti-dust condition of seeding absence monitoring sensor. It had been analyzed the factors affecting the anti-dust performance of optoelectronic sensor. Double-way laser reverse direction sensor has been made (Anti-dust index access to 0.95 , while the index of the LED only reach 0.5 around). It has been proved that the seeding absence alarm device can meet with the requirement of the field operation, which is a great progress for seeding absence alarm device into practicality.4. Tape coiling velocity measuring sensor device. The slide rate of driving wheel of the tractor and the shift of land wheel of the seeder are closely related to the quality of seeding. However, the accuracy and instantaneity of the most used mark post measurement method are not good and the errors of five-wheel measure device with contacting measurement principle are serious when it is used in soft and undulated surface field. According to the idea, five-wheel device converting the straight line movement into the rotation movement which is convenient to measure, a non-contacting velocity measurement sensor device using optical switch and steel tapeline to measure the straight line movement has been designed and produced, which is an exploration in this field. If further development of its structure and supporting velocity measurement devices can be taken, it could become general equipment for measuring the velocity of the agricultural machines.5. The metering performance detection device for planter and the practical seeder detection alarm device had been developed. One paper had been published respectively.
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