Accelerometer based alignment transfer (ABAT)

Hagan, C.E.; Lofts, C.S.

doi:10.1109/plans.1992.185831

Cited by 4 publications

(1 citation statement)

References 5 publications

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“…The acceleration matching method does not require deliberate maneuvering or integration of measurement data. Therefore, it is suitable for rapid TA in shipboard systems [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

A New Bias Error Prediction Model for High-Precision Transfer Alignment

Zhang

Yang

Qin

et al. 2018

Sensors

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The purpose of this work was to study bias error in acceleration-based transfer alignment, which is probably caused by cross-correlation between the dynamic lever-arm and the linear motion of a ship. A new prediction model for the cross-correlation-caused error is proposed in this paper. We adopt the Bernoulli-Euler Beam as a simplified ship hull-girder model to verify the existence of the cross-correlation. Then, the mathematical mechanism and the prediction model of the bias error are deduced via the ordinary least squares theory. Three factors influence the bias error in the prediction model: the amplitude of the dynamic lever arm acceleration, the amplitude of the ship motion acceleration, and the cross-correlation between them. Simulation experiments are then conducted to test the influence of the factors. The results show that the mechanism analysis is reasonable, and the bias error prediction model is in agreement with the experimental results. Thus, the proposed prediction model has the potential to deduce the bias error in high-accuracy transfer alignment.

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“…The acceleration matching method does not require deliberate maneuvering or integration of measurement data. Therefore, it is suitable for rapid TA in shipboard systems [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

A New Bias Error Prediction Model for High-Precision Transfer Alignment

Zhang

Yang

Qin

et al. 2018

Sensors

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Gravity Observation Based Alignment Transfer

Hagan¹,

Lofts²

Proceedings. The First IEEE Regional Conference on Aerospace Control Systems,

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This paper presents a new alignment transfer method which uses only accelerometer measurements in the gravitational field. The TRIAD (Three-Axis Attitude Determination) algorithm is rcformulated to use two pairs of gravitational measurements instead of star observations to achieve three-axis attitude determination. A major benefit of the method is the freedom to choose missile Inertial Measurement Unit (IMU) gyros based solely on in-flight considerations. An additional benefit is the ability ta update the alignment transfer by simply making new measurements of gravity and reprocessing the measurements taken before erection. This new alignment transfer method eliminates 'Time to Complete Alignment Transfer' from the major contributors of the alignment error. Algorithm development, error analysis and laboratory results are provided. INTRODUCTIONAttitude initialization of mobile mllssile systems continues to be a significant cost and time consideration. Self-alignment techniques often call for accurate accelerometers to determine local 1evc:l. A 2-dimensional attitude relationship between an IMU and a local level coordinate system can be solved using accelerometer measurements in the gravitational field However, the accelerometers -do not provide information about the aximuth orientation of the IMU. Therefore, highly accurate gyros are needed to determine azimuth. However, even highly accurate gyros need significant time, urlually measured in minutes, to achieve the desired azimuth accuracy. These drawbacks of self-aligned systems resulted in a division of the azimuth determination problem into two parts. A highly accurate (i.e. expensive) inertial measurement unit (Master IMU) is CO-located on the launch erection structure. This master IMU is initialized before the erection of the missile. The erection motion is then used to determine the relative attitude between the master IMU and the less accurate missile IMU (i.e. less expensive).This attitude correction is then uploatled to the missile IMU. The alignment accuracy is uansfemd from the master [MU to the missile IMU with only modest degradation resulting from inaccuracies in the determination of the attitude correction. The evolution from self-alignment to alignment transfer has relied on gyro based measurements to determine attitude for mobile ground launched missile systems.Typical azimuth alignment transfer schemes match the attitude measurements of the missile and master IMUs resulting from the launcher erection to determine the azimuth attitude correction to be uploaded to the missile. The use of attitude matching calls for accurate gyros in the missile IMU since a major error contribution comes from: (1) Equation 1 and other alignment transfer related error sources have caused the accuracy needed by the missile IMU gyros to be driven more by initialization requirements than by in-flight considerations. Therefore, it is highly desirable to use only accelerometer measurements 110 accomplish alignment transfer. This paper provides such an alignment transfer op...

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Integration and testing of a low-cost land navigator for the army combined arms weapon system (TACAWS)

Pittman¹,

Lanier²,

LeFevre³

Proceedings of Position, Location and Navigation Symposium - PLANS '96

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The Army Combined Arms Weapon System (TACAWS) is currently being developed as a technology demonstration program at the U. S. Army Missile Command (MICOM) located at Redstone Arsenal, AL. The thrust behind the development of TACAWS is to provide the 21st century Army a multiprpose, multitarget, and multi-platform weapon system that can be easily deployed to any location in the world.The TACAWS Land Navigation System (LNS) incorporates data from 3 Ring Laser Gyros (RLGs), 3 quartz accelerometers, a Precision Lightweight GPS Receiver (PLGR) and an odometer into the position and attitude solutions. The LNS is being installed on a modified M2 Bradley vehicle, for the purpose of navigation, targeting, data link attitude control, and missile initialization. Missile initialization includes the transfer of the LNS's north alignmeni accuracy to the missile's Inertial Measurement Unit (1MU). LNS test results reported in this paper include alignment accuracy (static and moving) and drift, inertial sensor error estimation, alignment transfer accuracy, imd navigation accuracy with and without GPS data.

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Accelerometer based alignment transfer (ABAT)

Cited by 4 publications

References 5 publications

A New Bias Error Prediction Model for High-Precision Transfer Alignment

A New Bias Error Prediction Model for High-Precision Transfer Alignment

Gravity Observation Based Alignment Transfer

Integration and testing of a low-cost land navigator for the army combined arms weapon system (TACAWS)

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