At this point, we have established almost all of the necessary background finally to design a Kalman filter to aid the inertial system with GPS. The one remaining item is the determination of the inertial error model. Recall that the GPS/INS complementary Kalman filter estimates the errors in the INS. It does not estimate the total position, velocity and attitude of the vehicle. In order to design the Kalman filter, we need to define the system equation that models how the state variables change over time. The states are the inertial position error, inertial velocity error, inertial attitude error, and some related parameters that we will describe later. So before we can start the Kalman filter design, we need a model that describes how the inertial errors behave.

Chapter Contents:

• 19.1 Introduction
• 19.2 Reference frames for inertial error analysis
• 19.3 Two primary INS error models
• 19.4 Psi-angle INS error model
• 19.5 INS error state-space model
• 19.6 Example: east gyro bias
• References

Inspec keywords: Global Positioning System; inertial navigation; Kalman filters

Other keywords: inertial errors; inertial error model; inertial error modeling; inertial system; Kalman filter design; inertial velocity error; inertial attitude error; inertial position error

Subjects: Radionavigation and direction finding; Filtering methods in signal processing