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PhD Thesis

State Estimation for Distributed and Hybrid Systems

Peter Alriksson

Abstract

This thesis deals with two aspects of recursive state estimation: distributed estimation and estimation for hybrid systems. In the first part, an approximate distributed Kalman filter is developed. Nodes update their state estimates by linearly combining local measurements and estimates from their neighbors. This scheme allows nodes to save energy, thus prolonging their lifetime, compared to centralized information processing. The algorithm is evaluated experimentally as part of an ultrasound based positioning system. The first part also contains an example of a sensor-actuator network, where a mobile robot navigates using both local sensors and information from a sensor network. This system was implemented using a componentbased framework. The second part develops, a recursive joint maximum a posteriori state estimation scheme for Markov jump linear systems. The estimation problem is reformulated as dynamic programming and then approximated using so called relaxed dynamic programming. This allows the otherwise exponential complexity to be kept at manageable levels. Approximate dynamic programming is also used to develop a sensor scheduling algorithm for linear systems. The algorithm produces an offline schedule that when used together with a Kalman filter minimizes the estimation error covariance.

Keywords

Distributed State Estimation, Sensor Networks, Networked Embedded Systems, Sensor Scheduling, Markov Jump Linear Systems, Joint Maximum a Posteriori Estimation


PhD Thesis ISRN LUTFD2/TFRT--1084--SE, Department of Automatic Control, Lund University, Sweden, September 2008.

 
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