ABSTRACT:  Estimating the position and attitude of a rigid body has applications to many systems, including inertial navigation of aerial vehicles (both piloted and uninhabited), underwater vehicles, and robotic systems, to name a few. The most common algorithm for inertial navigation is based on the famous quasi-linear (extended) Kalman filter algorithm. This algorithm has been the workhorse for most systems that require position and attitude knowledge. Due to the inherent nonlinearities associated with inertial navigation, numerous nonlinear estimation techniques have been developed. Some have shown global, or near-global, convergence while others focus on robust methods to handle model errors or non-Gaussian characteristics. Much less attention has been given to the problem of estimating vector state coordinates with respect to the proper coordinate frame. This work presents a new error definition in which vector error quantities are defined using elements expressed in a common frame. It is claimed here that the new error definition is more grounded theoretically than the usual error definition used by all other known techniques. Examples in inertial navigation of an aerial vehicle are given to show the advantages of the new error definition over the standard error definition.

BIOSKETCH:  Dr. John L. Crassidis is the Samuel P. Capen Chair Professor in the Department of Mechanical and Aerospace Engineering at the University at Buffalo (UB), State University of New York. Before joining UB in 2001, he held previous academic appointments at the Catholic University of America and Texas A&M University. He also held a position as a NASA Postdoctoral Research Fellow at Goddard Space Flight Center, where he worked on a number of spacecraft. Currently, he is Director of UB’s Center for Multisource Information Fusion, which is the only dedicated university data fusion center in the country. It is involved in basic research and developmental programs through various government laboratories, companies and university partners. He is also Director of UB’s Nanosatellite Laboratory. Dr. Crassidis is a Fellow of the American Astronautical Society, and a Fellow of the American Institute of Aeronautics and Astronautics.