Design of a magnetic torquing system for an ESG north finder

Abstract

This paper describes the design and experimental investigation of a magnetic torquing system for a strapdown north finder using an electrostatic gyroscope (ESG). The specially designed magnetic torquing system consists of 3 pairs of coils, which are located symmetrically around the gyro rotor. The supporting electronics consists of a rotor speed regulator, radial null control and torque rebalancing circuit and a current stabilizer of Z-coils. The system generates orthogonally distributed magnetic fields and ensures a linear controllable torque along the X- and Y-coils. When the spin axis of the gyro rotor has been aligned along the local vertical, the azimuth can be obtained by measuring the equilibrium torque on the gyro rotor. Experimental results show that the ESG north finder with the special magnetic torquing system provides a north-seeking accuracy of 10" (1/spl sigma/) with a measurement time less than 30 min.