| 摘要 |
A two-axis platform comprises an azimuth gimbal rotatable about an azimuth axis. In the azimuth gimbal an inner gimbal is mounted about an axis. A two-axis gyro having input axes and a spin axis is located in the inner gimbal. The spin axis is always maintained horizontal by a torquer which is controlled by a level sensor. By the horizontal component of the rotary speed of the earth, which acts on the input axis of the gyro, the spin axis is rotated into North through the torquer. The azimuth angle of the spin axis is measured in a first position for elimination of the influence of gyro drifts including axial mass unbalance. Then, azimuth gimbal and inner gimbal are simultaneously rotated by 180 DEG about their axes. Subsequently, the azimuth angle is measured again, to which the spin axis is adjusted. The middle between these positions provides a North indication compensated for gyro drifts. Furthermore, means for determination of errors due to deviations of the azimuth axis from the vertical are described.
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