Robust set-valued estimation and its application to in-flight alignment of sins

Seymen, Niyazi Burak
In this thesis, robust set-valued estimation is studied and its application to in-flight alignment of strapdown inertial navigation systems (SINS) with large heading uncertainty is performed. It is known that the performance of the Kalman filter is vulnerable to modeling errors. One of the estimation methods, which are robust against modeling errors, is robust set-valued estimation. In this approach, the filter calculates the set of all possible states, which are consistent with uncertainty inputs satisfying an integral quadratic constraint (IQC) for given measured system outputs. In this thesis, robust set-valued filter with deterministic input is derived. In-flight alignment of SINS with Kalman filtering using external measurements is a widely used technique to eliminate the initial errors. However, if the initial errors are large then the performance of standard Kalman filtering technique is degraded due to modeling error caused by linearization process. To solve this problem, a novel linear norm-bounded uncertain error model is proposed where the remaining second orders terms due to linearization process are considered as norm-bounded uncertainty regarding only the heading error is large. Using the uncertain error model, the robust set-valued filter is applied to in-flight alignment problem. The comparison of the Kalman filter and the robust filter is done on a simulated trajectory and a real-time data. The simulation results show that the modeling errors can be compensated to some extent in Kalman filter by increasing the process noise covariance matrix. However, for very large initial heading errors, the proposed method outperforms the Kalman filter.


Parameter extraction and image enhancement for catadioptric omnidirectional cameras
Baştanlar, Yalın; Çetin, Yasemin; Department of Information Systems (2005)
In this thesis, catadioptric omnidirectional imaging systems are analyzed in detail. Omnidirectional image (ODI) formation characteristics of different camera-mirror configurations are examined and geometrical relations for panoramic and perspective image generation with common mirror types are summarized. A method is developed to determine the unknown parameters of a hyperboloidal-mirrored system using the world coordinates of a set of points and their corresponding image points on the ODI. A linear relati...
Joint frequency offset and channel estimation
Avan, Muhammet; Candan, Çağatay; Department of Electrical and Electronics Engineering (2008)
In this thesis study, joint frequency offset and channel estimation methods for single-input single-output (SISO) systems are examined. The performance of maximum likelihood estimate of the parameters are studied for different training sequences. Conventionally training sequences are designed solely for the channel estimation purpose. We present a numerical comparison of different training sequences for the joint estimation problem. The performance comparisons are made in terms of mean square estimation err...
Novel impedance tuner, phase shifter, and vector modulators using rf mems technology
Ünlü, Mehmet; Demir, Şimşek; Department of Electrical and Electronics Engineering (2009)
This thesis presents the theory, design, fabrication, and measurement results of novel reconfigurable impedance tuner, phase shifter, and vector modulators using the RF MEMS technology. The presented circuits are based on triple stub topology, and it is shown both theoretically and experimentally in this thesis that it is possible to control the insertion phase and amplitude of the input signal simultaneously using this topology. The presented circuits are implemented using an in-house, surface micromachini...
Design and anaylsis of transfer aligment algorithms
Yüksel, Yiğiter; Demirekler, Mübeccel; Department of Electrical and Electronics Engineering (2005)
Transfer Alignment is the process of simultaneously initializing and calibrating a weapon inertial navigation system (INS) using data from host aircraft̕s navigation system. In general, this process is accomplished by calculating the difference of navigation solutions between aircraft and weapon INSs to form observations which are then used in a Kalman filter to generate desired estimates. Numerous techniques about the problem of transfer alignment exist in the literature. In this thesis, those techniques t...
Modelling and noise analysis of closed-loop capacitive sigma-delta mems accelerometer
Boğa, Biter; Külah, Haluk; Department of Electrical and Electronics Engineering (2009)
This thesis presents a detailed SIMULINK model for a conventional capacitive Σ-Δ accelerometer system consisting of a MEMS accelerometer, closed-loop readout electronics, and signal processing units (e.g. decimation filters). By using this model, it is possible to estimate the performance of the full accelerometer system including individual noise components, operation range, open loop sensitivity, scale factor, etc. The developed model has been verified through test results using a capacitive MEMS accelero...
Citation Formats
N. B. Seymen, “Robust set-valued estimation and its application to in-flight alignment of sins,” M.S. - Master of Science, Middle East Technical University, 2005.