Attitude determination in dead reckoning navigation with reduced inertial support

This paper further develops the new approach for compensation of the motion induced disturbances in dead reckoning navigation that was recently suggested by one of the authors [1], [2] and then presented internationally [3],[4]. The approach is alternative to the conventional one when an INS-type AHRS is used to provide attitude and heading data in order to transform the velocity components to the geographical frame. The new approach which was named Indirectly Correctable Pendulum (ICP) uses two techniques: one - is the construction of one-channel inertial vertical based on two vector observation. In doing so one vector is the specific force vector and the vertical is constructed in the plane that contains true vertical and the second vector regardless of its nature. The natural frequency of the inertial loop is defined by the nature of the second vector and can differ from the Schuler one. The second technique includes the compensation of the motion induced disturbances in the tilt angles generated from the accelerometer outputs but provided in the position components using the log data and the motion acceleration component generated in the inertial vertical channel. As a result the higher navigation accuracy and/or the reduced amount of gyros as compared to the conventional solution can be achieved.