Abstract: A novel omni-bearing pre-orientation method based on period-amplitude measuring is put forward through the analysis of motion characteristics of pendulous gyro north seeker in wide azimuth. The proposed method can be used to calculate the azimuth of the gyro shaft by measuring its swing period and amplitude. The effect of gyro-motor rotating rate on pre-orientation time is analyzed, the effect of pertinent parameter errors on pre-orientation accuracy is discussed, and the preliminary experiments are conducted to verify the new method. Both the theoretical and experimental results show that the swing period can be shortened by decreasing the rotating speed of the gyro-rotor, and the rapid pre-orientation can be achieved accordingly within 65 s with the accuracy of higher than 5°, which can meet the accuracy requirement of subsequent north seeking procedures.

Key words: ordnance science and technology, pendulous gyroscope north seeker, wide azimuth, omnibearing north-seeking, period-amplitude measuring