Rapid Rough North-Finding Method of Gyrotheodolite in Any Initial Orientation

Advanced high-efficiency rough north-finding method is the crux of rapid accurate measurement of gyrotheodolite. Based on gyroscope working principle, a formula to determine azimuth in any initial orientation was derived through analyzing a mathematic model of gyro motions. In combination with trend forecast method, the cursor data of gyro motion captured by CCD sensor for short moment was used to predict the whole period of data, which could calculate the measurement result rapidly. According to the regularity of prediction results in different orientation of 360°, a multiple-stepping north-finding method based on distribution characteristics of prediction results was proposed, which made the gyroscope approach the true north gradually in short time. The experiments demonstrate that this rough north-finding method can reach within ±30´ precision only in 1min of gyro´s working time. It provides a new idea for gyroscope to achieve rapid high-accuracy north-finding, which is a major breakthrough in improving speed of rough north-finding.