Performance Analysis of GNSS-Aided Inertial Navigation Systems on Spinning Flight Vehicles

Abstract

Inertial navigation on spin-stabilized sounding rockets and missiles is challenging due to the high spin rate about the longitudinal axis. Especially the scale factor error of the roll axis gyroscope causes an accumulating roll angle error, which may subsequently transform to the lateral axes if, for example, the rocket is actively reoriented. This orientation error leads to growing position and velocity estimation errors whenever propulsion or aerodynamic forces act on the rocket. Specialized inertial platforms were developed in the 1970s with gimbaled inertial measurement units isolating the sensors from the high spin rate. Because these platforms are rarely available on the market today, ongoing research focuses on integrated navigation systems with strap-down inertial measurement units and additional aiding sensors such as satellite navigation receivers, Sun sensors, or star tracker. Because satellite navigation receivers are well-established on sounding rockets for range safety anyway, this paper investigates to what extent position, velocity, and particularly orientation errors can be estimated with satellite navigation aiding only. Using the example of SHEFEX-2, the paper discusses the observability of translational and rotational navigation errors by translational aiding measurements along a typical trajectory of a two-staged and actively reoriented sounding rocket both qualitatively and quantitatively.