Gyro Wander Correction by Periodic Reversals of Gyro Spin

An inertial platform is described in which three gyroscopes of the two-degree-of-freedom type are disposed in a coplanar configuration with their spin axes at 120° one to another. Cycles of operation are described in which two or all three of the gyroscopes undergo periodic reversals of the direction of rotor spin. The periodic spin reversals are intended to provide a correction for the greater part of the gyro wander, by reversing the precessions caused by extraneous torques. An intrinsic cancellation of the wander results directly from the spin reversals. An alternative method is described in which the signals fed to the gyro torquing motors are compared during successive modes of the operating cycle. This permits the computation of estimates of the gyro wander rates, so that correcting signals may be applied.