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| Abstract | Gyrocompasses detect the Earth's rate with gyros in stationary conditions and indicate azimuths with respect to true north. They do not need any external aid, and are not influenced by surrounding ferrous materials. However, in order to detect the Earth's rate, traditional gyrocompasses use expensive high-performance gyros, which are mechanically fragile, and are too bulky to be used for borehole applications. In the last decade, the evolution of MEMS gyros has been remarkable in terms of not only cost and size, but also accuracy and reliability. They have micro-machined vibrating structures of silicon, and detect the Coriolis force induced by angular velocity. Their performance is now approaching the level to be able to sense the Earth's rate. However, MEMS gyro output errors are still larger than those of traditional gyros. This paper presents a novel single-axis northfinder to compensate for the errors of MEMS gyros. A prototype with cylindrical body of 60mm diameter was fabricated and evaluated. The test results demonstrated a north-finding performance of about 1.5 degrees root mean squared in all attitudes. |
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