Study and calibration of azimuth effect in multi-position strap-down north seeking system

In order to reduce the influence of azimuth effect in multi-position strap-down north seeking system, its cause of formation is studied based on the precession principle of the dynamically tuned gyro. A detecting system, composed by true north prism, two Leica theodolites and benchmark prism fixed in the strap-down north seeking system, was designed to calibrate the azimuth effect. By two steps, many measurements are gone on in every position to eliminate the random error. According to the homologous between the error and the position, a sinusoid is made a fit as compensate curve after the error of twelve positions is measured. Then the azimuth effect of the arbitrary position can be corrected by the curve. The experiment result shows that the seeking north standard deviation is only 11.77" after compensation, which is considerably less than the 87.75" without correction.