Velocity/Position Integration Formula (I): Application to In-flight Coarse Alignment

TL;DR

This paper introduces an optimization-based in-flight coarse alignment method using GPS data and a new velocity/position integration formula, achieving high accuracy without prior attitude info.

Contribution

It presents a novel coarse alignment approach leveraging GPS data and velocity/position integration, improving initial heading accuracy in airborne INS/GPS systems.

Findings

Achieves up to one degree heading accuracy in ten seconds

Effective without prior attitude information

Applicable to other real-time INS alignment scenarios

Abstract

The in-flight alignment is a critical stage for airborne INS/GPS applications. The alignment task is usually carried out by the Kalman filtering technique that necessitates a good initial attitude to obtain satisfying performance. Due to the airborne dynamics, the in-flight alignment is much difficult than alignment on the ground. This paper proposes an optimization-based coarse alignment approach using GPS position/velocity as input, founded on the newly-derived velocity/position integration formulae. Simulation and flight test results show that, with the GPS lever arm well handled, it is potentially able to yield the initial heading up to one degree accuracy in ten seconds. It can serve as a nice coarse in-flight alignment without any prior attitude information for the subsequent fine Kalman alignment. The approach can also be applied to other applications that require aligning the INS on the run.