What Is Planning in the Presence of Sensing?

Despite the existence of programs that are able to generate so-called conditional plans, there has yet to emerge a clear and general specification of what it is these programs are looking for: what exactly is a plan in this setting, and when is it correct? In this paper, we develop and motivate a specification within the situation calculus of conditional and iterative plans over domains that include binary sensing actions. The account is built on an existing theory of action which includes a solution to the frame problem, and an extension to it that handles sensing actions and the effect they have on the knowledge of a robot. Plans are taken to be programs in a new simple robot program language, and the planning task is to find a program that would be known by the robot at the outset to lead to a final situation where the goal is satisfied. This specification is used to analyze the correctness of a small example plan, as well as variants that have redundant or missing sensing actions. We also investigate whether the proposed robot program language is powerful enough to serve for any intuitively achievable goal.