GPS/INS-Streamlined

Abstract

Extensive alteration of common integrated system designs offers major benefits in performance and economy. Estimation of dynamics from carrier-phase sequential differences can relieve the burden of ambiguity resolution, and therefore eliminate system instability from local minima sometimes producing incorrect integers. By placing emphasis appropriately on short-term behavior, computational complexity is also reduced with numerous algorithmic enhancements not commonly used. Various application-dependent alternative formulations are offered, with implications for interface standards for both inertial and GPS data. This work produced a program successfully validated with a low-cost inertial measurement unit, updated by GPS code and carrier at 1 Hz. Correlations are addressed, along with the influence on processing algorithms.

FULL INTEGRITY TESTING for GPS/INS

“…[5] (which was successfully validated in [11]). In that approach, the full motion history is contained in two separate Kalman filters.…”

“…[5], Kalman filters for position and dynamics are separate. The former uses a 3-state model (driven by accurate velocity history from the latter), while velocity states occupy the upper 3 ϫ 1 partition of the dynamics estimator.…”

Considerations for Sensor Stabilization Using Stand-Alone GPS Velocity and Inertial Measurements

“…An IRU alignment is subject to a long lever-arm correction [-3.226, 14.503, 0.14] m. An orientation correction must be applied to this leverarm and all subsequent measurements. If the orientation survey uncertainty is 8 deg in roll, pitch, and yaw, and a corresponding wing deformation of [1,2,0] deg, then the total alignment accuracy would be [9, 10, 8] deg plus a few mrad of IRU alignment error in roll, pitch, and yaw. This is much worse than the GPS velocity vector alignment.…”

“…Measurement integration requires sensor alignment such as can be provided by a GPS velocity vector orientation measurement. Techniques to calculate a high accuracy velocity measurement using low rate GPS carrier phase measurements are discussed in [2] [3]. In this paper, GPS L1 code measurements at 2Hz and L1 carrier phase measurement at 100Hz rate are used to determine a high rate integrated velocity vector at the mm level.…”

Tightly coupled GPS/INS integration for missile applications

“…Another solution is to process the differences of the raw measurements to different space vehicles. This causes the building up crosscorrelations, which have to be considered in the data fusion algorithm, see [3].…”