A Theoretical Study on Free Gyrocompass

The authors aim to establish the theory necessary for developing the free gyrocompass. The following considerations are taken One is to suggest north-finding principle by the angular velocity of the earth's rotation, and the other is to suggest that the motion rate of the spin axis in the free gyro frame is transformed into the platform frame and this transformed rate is again transformed into the NED navigation frame. After transformation ship's heading is obtained using the fore-aft and athwartship components of the motion rate of the spin axis in the NED frame In addition it was suggested how to solve the transformation matrix necessary for transforming each frame.