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

Abstract

This paper explores the concept of using a high rate (i.e. 100 Hz), high accuracy integrated velocity (i.e. mm accuracy) estimate from stand-alone GPS measurement for sensor stabilization. The velocity algorithm uses GPS L1 code measurements at a rate of 2 Hz and L1 carrier measurements at 100 Hz. This velocity can be used for heading determination and then for inertial alignment or stabilization of other sensors. The integrated velocity vector accuracy is at the mm level and can be used to provide heading measurements better than 1 deg. This paper addresses several issues such as the velocity propagated position, relation between the velocity error and position error due to sensor lever-arms, timing accuracy of measurement association between various sensors, and a statistical technique to estimate the velocity error on a dynamic platform using two or more GPS antennas. High update rate position estimates, formed using the propagated velocity is shown to improve upon the noise performance of a triple difference technique. A velocity vector alignment technique is compared to a navigation-grade inertial heading alignment over a long lever-arm. A tradeoff discussion illustrates some measurement alignment and integration considerations for a remote sensor. Analysis of these concepts is provided using flight test data collected on April 12, 2006. 1,2

Smoothing GPS carrier phase double differences using inertial measurements for high performance applications

“…Further discussion of the static survey and sensitivity to error can be found in (Dickman and Bartone 2007).…”

“…Several techniques can be utilized to determine an absolute attitude and heading calibration as outlined below. For example, GPS can provide accurate heading information via sequential differenced CP (Dickman and Bartone 2007) when sideslip motion is not present. Also, GPS can provide an absolute attitude and heading estimate using the relative positions from multiple antennas (Cohen et al 1994;Van Graas and Braasch 1991).…”

Dynamic Lever Arm Error Compensation of POS Used for Airborne Earth Observation

“…Over the past few years, many researches have been carried out to reduce the lever arm errors. The mechanization and compensation methods of the lever arm between IMU and GPS are analyzed in [9,10]. In [11], multilevel lever arm errors have been analyzed and compensated, including the inner lever arm caused by the displacement of the sensing center of an accelerometer from the center of inertial sensing assembly, the first-level lever arm between IMU and GPS, and the second-level lever arm between POS and remote sensing load.…”