Active observer: A discrete event dynamic system model for controlling an observer under uncertainty

In this work we establish a framework for the general problem of observation, which may be applied to different kinds of visual tasks. We construct intelligent high-level control mechanisms for active visual recognition of different processes within a hybrid dynamic system. We address the problem of observing a manipulation process in order to illustrate the ideas and motive behind our framework. Active and autonomous tracking mechanisms are developed for the observer agent which is completely decoupled from the manipulation agent. We use a discrete event dynamic system as a high-level structuring technique to model the manipulation system. The formulation utilizes the knowledge about the system and the different actions in order to solve the observer problem in an efficient, stable and practical manner. The model uses different tracking mechanisms so that the observer can see the workspace of the manipulating robot. An automaton is developed for the hand/object interaction over time and a stabilizing observer is constructed. Low-level modules are developed for recognizing the visual events that causes state transitions within the dynamic manipulation system in real time. A coarse quantization of the manipulation actions is used in order to attain an active, adaptive and goal-directed sensing mechanism. The formulation provides high-level symbolic interpretations of the scene under observation. The discrete event framework is augmented with mechanisms for recovering the continuous parametric evolution of the scene under observation and for asserting the state of the manipulation agent. This work examines closely the possibilities for errors, mistakes and uncertainties in the manipulation system, observer construction process and event identification mechanisms. We identify and suggest techniques for modeling these uncertainties. Ambiguities are allowed to develop and are resolved after finite time. Error recovery mechanisms are also devised. The computed uncertainties are utilized for navigating the observer automaton state space, asserting state transitions and developing a suitable tracking strategy for the observer agent. The approach used can be considered as a framework for a variety of visual tasks, as it lends itself to be a practical and feasible solution that uses existing information in a robust and modular fashion. Theoretical aspects and experimental results of the work support adopting this framework as a new basis for performing several task-oriented recognition, inspection and observation of visual phenomena