Optimum Mixing of Inertial Navigator and Position Fix Data
Walter M. Hollister, MICHEL CLAUDE BRAYARD · Journal of Aircraft · 1971
The filtering problem is studied analytically for a system composed of an inertial navigator giving continuous indication of position and velocity and an external position fixing device giving continuous or discrete positional information. Accelerometer and external position errors are represented by white noise. Gyro drift is represented by a random walk process. Reasonable approximations lead to simplified models plus analytic predictions of the filter's performance. The analytic results are verified by comparison with computer simulations using more accurate models. Error growth of the inertial navigator without external information is shown to be extremely small for the first eight minutes following alignment. During that interval accelerometer noise is the predominant source of error. Estimation of the platform misalignment is not necessary unless the inertial system must subsequently navigate without external position information.