M.Ing. (Electrical And Electronic Engineering) / State estimation comprises the estimation of the position and velocity (state) of a target based on the processing of noise-corrupted measurements of its motion. This study views a class of measurement processes where the states are unobservable and cannot be estimated without placing additional constraints on the system. The bearings only target motion problem is taken as being representative of this type of problem. The results of this study indicate that practical state· estimation for systems with unobservable measurement processes is possible with the application of estimation theories and available estimation techniques. Due to the inherent nonlinear geometrical characteristics the problem is classified as a unobservable nonlinear estimation problem. A review of state estimation and estimation techniques is presented. The fundamental bearings only target motion concepts are discussed. A representative selection of bearings only estimators made from the published literature, is evaluated. The evaluation consists of a theoretical analysis and a Monte Carlo simulation of the estimators. Two realistic scenario's are considered. A classification framework is presented which may be useful to practical engineers in selecting suitable estimators. Batch estimators are shown to be more stable and likely to be used in bearings only applications than recursive estimators. The importance of isolating the unobservable states from the observable states by using a modified polar co-ordinate system, is stressed. It is also shown that effective data processing can be achieved by using all available measurements and a maximum likelihood estimator.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:12251 |
| Date | 11 September 2014 |
| Creators | Wiid, Andries Johannes |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
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