Why inertial systems need to be aligned and how to do this effectively

Inertial Navigation Systems (INS) have been gaining popularity in the past years, especially due to the miniaturization and the lower cost of new sensors developed for the automotive world. However, choosing and operating effectively an INS is not straightforward. One of the reasons is that before being operated, an INS needs to go through an initial process called alignment.

The aim of this paper is to explain what the alignment is, why it is necessary and how to perform the alignment effectively. It focuses on the physical principles underlying the performance, and not on the practical implementation, to help understand how the sensor performance impacts the system performance.

Since the number of inertial applications and parameters is almost infinite, this paper aims at providing some simple rules and formula that the reader will be able to adapt to their specific needs. In addition to choosing the best alignment method for a given INS, this will also help the reader to operate an INS more efficiently.