Study Of Precise Seed-meter Test System Based On The Virtual Instrumentation

It is very important, the precision and efficient test instrument, to the study, design and production of seed-meter -the key component of precise seeder, whereas, in our country, it is still behindhand on the test devices and methods of precise seed-meter performance, so it blocks the design and development of new product in some degree; On the other hand, along with fast development of computer technology, especially the development of programming facing to object, computer fuses the test field with its low cost and high performance. Therefore more and more hardware functions can be realized by software, and under this circumstance, the concept of "Virtual Instrumentation" appears.Virtual Instrumentation has many advantages comparing to traditional instrument, and has successfully applied to military affairs, space flight, medical treatment and so on, whereas it is still exploring and experimental stage in agricultural machinery, especially to the test of precise seeder. The purpose of this study is to develop a precise seeder test system that can test double (or multiply) rebroadcast and improve test precise, exerting computer advantage in high-speed data acquisition. The main works of the study are as follows:The first is to study and develop the test system of dropping performance based on Virtual Instrumentation. According to the design thought of Virtual Instrumentation, and using the way that the software is key and combining with hardware, and the developing platform is Lab Windows/CVI 6.0, I developed the test system software. The test system adopts the high-speed precise timer to collect the seed-interval stylebook and introduces computer RAM through DMA style, moreover, in computer, the data can be shown with curve and digit and data can be saved in database or text. Many experiments show that the system can test almost all estimating indexes: qualified, rebroadcast, loss, average, standard deviation and variance modulus etc, according to tested stylebook, and can test double (or multiply) overlap (or sequence) dropping condition if the size and shape of the seeds are uniformity.The second is to select a suitable photo-electronic sensor to test drop. The precise sensor is the key to realize precise test. The study analyzes the previous photo-electronic shortcomings, furthermore selects the suitable sensor. The experiments show the output signal of the sensor reflects the dropping condition correctly.The third is to improve on the test-bed of dropping performance of precise seed-meter labeled SD-175. The experiments show that the performance is steady, and the operation control panel improved on is more easy and simple, so it reaches the expected purpose.