MAX: human-centric search of the physical world

MAX is a system that facilitates human-centric search of the physical world. It allows humans to search for and locate objects as and when they need it instead of organizing them a priori. It provides location information in a form natural to humans, i.e., with reference to identifiable landmarks (e.g., on the dining table) rather than precise coordinates. MAX was designed with the following objectives: (i) human-centric operation, (ii) privacy, and (iii) efficient search of any tagged object. In the system, all physical objects, from documents to clothing, can be tagged and people locate objects using an intuitive search interface. To make search efficient, MAX adopts a hierarchical architecture consisting of tags (bound to objects), sub-stations (bound to landmarks) and base-stations (bound to localities). Tags can be marked as either public or private, with private tags searchable only by the owner. MAX also provides for privacy of physical spaces.MAX requires minimal initial configuration, and is robust to reconfiguration of the physical space. To optimize system performance, we present a methodology to design energy and delay optimal query protocols for a variety of device choices. We have implemented MAX using Crossbow motes and conducted user trials in a 5m by 5m cluttered office. The user feedback was positive, demonstrating the feasibility of MAX for human-centric search. We contend that a MAX-like search system will enable sharing (e.g., books on a college campus) and trading (e.g., buying and selling used books) of physical resources, and will be the engine for a host of new applications.