The disclosed technology relates to a method and system for localizing and confining an autonomous mobile work system or systems for performing work in a user defined space. The system can include two or more variable reflective base stations at first and second locations that can modify their optical or electromagnetic reflectivity based upon either an external command via wired or wireless communications interface, or automatically on a regular or asynchronous time schedule under programmed or user settable control. The system also can include one or more autonomous mobile work systems capable of sensing the state of the variable reflectance base stations via sensors such as electromagnetic or optical sensors capable of measuring distance to the reflective base stations.