PathSim: A Tool for Finding Minimal Energy Device Operation Sequence for Reaching a Target Context in a Smart-Home

In this paper, aiming to achieve minimal energy consumption in context-aware device control in a smart-home, we propose a tool called PathSim which derives a minimal cost sequence of device operations for moving between two arbitrary contexts. PathSim properly divides the domain of each constituent smart-space context variable into a finite number of ranges, so that a finite discrete context space (finite number of contexts) is obtained. PathSim simulates the context move (range movement of a context variable) by every available event (device operation) at current context, and derives a minimal cost path (event sequence) using the proposed cost functions for events and derived contexts, from the current context into the intended one. To find a minimal cost path, PathSim adopts A* algorithm. PathSim prototype that we implemented can simulate the context moves for the events such as device attributes, temperature, humidity and user location, taking into account the size and structure of the smart-space, performance and power consumption of each device, and so on. Through a case study supposing a typical requirements specification in a smart-home, we confirmed that PathSim´s device operations consume about 72% less energy than the conventional method based on intuitive device operations.