Computation and evaluation allan variance results

This article deals with Allan variance as useful method for noise performance evaluation of inertial sensors which are used in inertial measurement unit (IMU) and different guidance systems. The noise component of inertial sensors is important part from group of inertial sensors errors, which determines accuracy of inertial navigation systems in real time. Because inertial measurement unit consists from accelerometers and gyroscopes, all sensor errors influence the position determination accuracy. Trajectory length is estimated from double integral of measured acceleration, therefore the error of length trajectory determination is increased rapidly. Gyroscope errors influence measured direction of movement. Knowledge of inertial sensor errors and their changes in time is necessary to increase the inertial navigation accuracy. Inertial sensor stochastic errors could be estimated in time or frequency domain. Allan method is based on the computation of root mean square random drift error as a function of average time [1], [2]. Allan variance (AVAR) could be computed in different way as, nonoverlapped AVAR, not fully overlapping AVAR, fully overlapping AVAR, total variance and modified total variance [1]. Main part of this article deals with design of simplified AVAR computation and simplified AVAR computation performances are evaluated.