The spray seeding machine use the principle of pneumatic conveying to make the seed sprayed through the spray cylinder. The spray cylinder is doing 0-180°circumference swing in a uniform linear motion complying with the machine. So, the trajectory of the seed fall on the ground is trochoid. In this way of seed spraying, some areas are sprayed with seeds repeatedly while other areas are missed completely. This phenomenon affects the seeding uniformity seriously. The repeated seeding area and missed seeding area are affected by the seeding width, the spray seeding machine operating moving speed and the swing frequency of spray cylinder. The swing frequency of spray cylinder is the main factor while the other two factors are restricted. So we take the smallest total area of repeated and missed as the objective function to optimize the spray cylinder swing frequency by MATLAB GUI. Thus, the program can read the parameters from the text box. First, the interpolation method was use to draw the seeding range map in a spray cylinder swing cycle. Then, the repeated and missed area were judged by comparing the seeding boundary. Third, the repeated and missed and total area were calculated using the numerical integration methods and save them in a matrix, each corresponds to the different swing frequencies. Finally, the minimum of total area and the corresponding swing frequency were found from the matrix. The results showed that the optimal swing frequency was 9.5 min-1 when the practical moving speed was 3 m/s, the optimal swing frequency was 5.6 min-1 when the test moving speed was 1.8 m/s , the spray outside radius was 20 m and the inside radius was 9 m. We carried out the test to verify the correctness of the program. The test speed was 1.8 m/s, the test spray cylinder swing frequencies were 4.5, 5.0, 5.6, 6.0 and 6.5 min-1. The working spray seeding machine goes through the gridded test site by constant speed in a straight line. The seeding amounts of each grid were recorded. Then the repeated and missed areas were counted to compare with program results. The result show that the program is consistent, which proved the program is correct and reliable. The study can provide a theoretical basis for spray seeding machine design.% 喷播机的落种范围存在重播区和漏播区,严重影响喷播均匀性.喷播均匀性受落种带宽、喷播机作业速度、喷筒摆动频率的影响,喷筒摆动频率是主要影响因素.为了提高喷播均匀性,该文利用Matlab软件以重漏播总面积最小为目标,对喷筒摆动频率进行了优化,得出在喷播包衣冰草种,单向喷幅外径20 m,单向喷幅内径9 m,前进速度为3 m/s时,喷筒最优摆动频率为9.5 min-1.通过喷播试验验证了优化程序的可靠性,由程序计算出不同作业速度下对应的最优摆动频率.该研究可为喷播机的设计提供参考.
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