| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 101 === Nowadays Global Positioning System (GPS) has been widely used in different navigation applications. One of these important applications is GPS attitude determination. Given the antenna configurations the baselines can be defined and then the attitude is determined by the change of baseline on the coordinate. Practically it takes single difference carrier phase as measurements and decides a geometric matrix according to satellite distribution on the sky to conduct attitude estimation. However since there are multipath and noise after conducting line bias and integer ambiguity resolutions, the attitude estimation will deviate from the true vehicle attitude. Under normal condition with prior inspection for algorithm the linear relation between measurement residual and attitude estimation error can be derived. Further given the probability of integrity risk and the probability of continuity requirement, the protection level is determined. This protection level can be further compared with the alert limit which is decided according to different application requirements. Previously the protection level for attitude determination is calculated by least squared method, this kind of integrity system is lack of a mechanism to detect and exclude faulty measurement. As a result the Multiple Hypothesis Solution Separation (MHSS) method is therefore suggested in this thesis to add this feature. First the nominal bias and standard deviation of the measurements are decided and what kinds of fault hypothesis should not be taken into monitoring is determined. Following distribute the total probability of Hazardously Misleading Information (PHMI) to each fault hypothesis by integrity risk allocation. Due to the fact that the total probability of Hazardously Misleading Information (HMI) is the sum of the product between a prior probability of the hypothesis and the integrity risk allocated under the corresponding hypothesis case, the protection level value that satisfy the allocation condition is selected as the final overall protection level. Experiment is conducted in this work to validate the MHSS method and show the fault detection and exclusion capabilities. The results of experiment reveals that the protection level calculated by MHSS can bound the attitude estimation error through the experiment period as well as the MHSS can successfully detect and exclude the faulty measurement.
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