• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.413-424
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• 2003

Up to now it has been widely conceived that mariner's compass was introduced to Europe from China via the Arabic people. But the proofs to support the above orthodox dissertation have not been found yet. In general it has been approved that the Chinese used the compass for navigation in the 11th century and European did in the 12th century. During the above period the communication between the Europe and the China was made only by the mediation of the Arabic people. But it is known that the beginning of Arabic people's compass usage was one century later than that of the European. It may raise a historical question about ‘was mariner's compass introduced to Europe from China via the Arabic people\ulcorner’ In this paper the authors tried to prove the simultaneity of the mariner's compass usage by the European with the Chinese by reviewing historical materials and modern researches. The results are as following; The first, there is a strong similarity in the evolving steps of compass appliance of both civilizations, such as from using magnetized and pivoted needle to fixing card thereto. Second, the Chinese and the European started to use the mariner's compass almost at the same time, and they developed it independently.

• Current Research on Agriculture and Life Sciences
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• v.32 no.3
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• pp.159-163
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• 2014

Agricultural unmanned helicopters have become a new paradigm for aerial application. Yet, such agricultural helicopters require easy and affordable attitude control systems. Therefore, this study presents an affordable attitude measurement system using a DCM (direction cosine matrix) algorithm that would be applied to agricultural unmanned helicopters. An IMU using a low-cost MEMS and an algorithm to estimate the attitude of the helicopter were applied in a gimbals structure to evaluate the accuracy of the attitude measurements. The estimation errors in the attitude were determined in comparison with the true angles determined by absolute position encoders. The DCM algorithm and sensors showed an accuracy of about 1.1% for the roll and pitch angle estimation. However, the accuracy of the yaw angle estimation at 3.7% was relatively larger. Such errors may be due to the magnetic field of the stepping motor and encoder system. Notwithstanding, since the intrinsic behavior of the agricultural helicopter remains steady, the determination of attitude would be reliable and practical.