UBC Theses and Dissertations

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UBC Theses and Dissertations

Observability based techniques to analyze and design user-interfaces : situation-awareness and displayed information Eskandari Naddaf, Neda


For continuous-time LTI systems under human control and under shared control, this thesis studies techniques to determine whether or not a given user-interface provides the information required to accomplish a certain task. It is well known that attaining Situation Awareness (SA) is essential to the safe operation of the systems involving human-automation interaction. Hence, through two different approaches, the work in this thesis evaluates and designs user-interfaces based on the satisfaction of SA requirements by the user. In the first approach, observability-based conditions under which a user-interface provides the user with adequate information to accomplish a given task are identified. The user is considered to be a special type of observer, with capabilities corresponding to different levels of knowledge regarding the input and output derivatives. Through this approach, the ``user-observable/user-predictable'' subspaces for systems under shared control are defined and formulated. In addition, state estimation is considered to incorporate a processing delay. Hence, the ``delay-incorporating user-observable/user-predictable'' subspaces are formulated and are compared with the space spanned by the combination of the states which create the task. If the task subspace does not lie in the relevant space, then the user-interface is incorrect, meaning that the user cannot accomplish the desired task with the given user-interface. In the second approach, to determine the required information to be displayed, a model of attaining SA for the users is proposed. In this model, the user is modeled as an extended delayed functional estimator. Then, the information needed for such an estimator to make correct estimations as well as the desired expansion of the functional of the states to let the user precisely reconstruct and accurately predict the desired task is determined. Additionally, it is considered that in practice, to attain the situation awareness, the estimation of the task states does not necessarily need to be precise but can be bounded within certain margins. Hence, the model of the user attaining SA is also modified as a ``bounded-error delayed functional observation/prediction''. Such an observer/predictor has to exist for a system with a given user-interface, otherwise, the safety of the operation may be compromised.

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