State estimation in unmanned aerial vehicles: theoretical approaches for increasing accuracy.

[摘要] ENGLISH ABSTRACT: The utility of unmanned aerial vehicles (UAVs) are enhanced by their abilityto navigate accurately. Unfortunately, it is not possible to capture the states which describe a UAV's position and orientation in a measurement system without some degree of uncertainty. The work presented here resolves this issue by developing strategies for generating accurate navigational outputs from the measurements taken on board an UAV.The three strategies that are ultimately developed address fundamental misnomers that are related to the processing of navigational measurementdata. The first strategy relates to the choice of state variable when exogenous signals are available in the UAV's measurement matrix. It is suggested that these signals be used to update error estimates related to other sensors instead of acting as observations of internal system states. The second strategyaddresses a common theoretical conflict which arises in UAV applications where accelerometers are used for orientation observations. It is suggested that redundant accelerometers be added to the measurement system and a strategy for distilling orientation rate information from this redundant information is also provided. The final strategy which is provided addresses the numerical errors which slowly disintegrate the orientation estimates of a UAV. It is suggested that a singular value decomposition be leveraged to restore the welfare of the orientation estimates. All the proposals which are made improve the navigational performance of the UAV and are validated through simulation.

[发布机构] Stellenbosch University