Turntable Calibration of an Optimal Gyro-Free-IMU and its Application in a full State Integrated INS-GNSS System

U. Bestmann, P. Hecker

Abstract:	Spatial distributed MEMS accelerometers seem to be an economically attractive and alternate way to gyros by indirectly measuring the turn rates of vehicles. Considering the lever arms between the Inertial Measurement Unit (IMU) reference point and the accelerometers, the rotary acceleration in relation to the IMU reference rotary axis can be determined and integrated to turn rates. Recent publications on a so called Gyro-Free IMU (GF-IMU) describe different geometries for the distribution of the sensors in the GF-IMU and it is shown that an optimal configuration can be found [1]. This configuration offers the possibility of measuring angular acceleration independently of the actual turn rate in order to keep the transfer behavior stable. This concept has been used to construct and build a GFIMU based on MEMS accelerometers (Figure 1) within the research project UniTaS IV which is going on at the Institute of Flight Guidance (IFF) of the Technische Universitaet Braunschweig and funded by the German Federal Ministry of Economic and Technology. This paper deals with the specific constraints of calibrating the GF-IMU using turntables, the development of the integrated system and the evaluation of the overall system by means of flight trials. Therefore, the basic equations are introduced in combination with the underlying sensor correction model. In order to determine the parameters of the correction model a calibration procedure is developed and its results are discussed. Afterwards, the necessary navigation differential equations for a generalized GF-IMU are shortly introduced together with the principles of deriving a coupling filter model. This model is finally applied in a filter and verified using a simulation based on real flight tests as well as real GF-IMU data from dynamic tests with the institute’s own test vehicle.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	987 - 994
Cite this article:	Bestmann, U., Hecker, P., "Turntable Calibration of an Optimal Gyro-Free-IMU and its Application in a full State Integrated INS-GNSS System," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 987-994.
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