Vertical and horizontal path sensing within a data storage and retrieval system

摘要

An accessor moveably disposed within a data storage and retrieval system which includes at least one electromagnetic radiation emitter and at least one electromagnetic radiation detector, where each emitter/detector combination have a facing relationship. A data storage and retrieval system which includes one or more of Applicants' accessors moveably disposed therein. A method using Applicants' accessor to assist the inventory of Applicants' data storage and retrieval system. A method to prevent collisions between Applicants' accessor and one or more portable data storage cartridges improperly stored within Applicants' data storage and retrieval system. A method using Applicants' accessor to monitor the insertion and/or retrieval of a portable data storage cartridge from a storage slot, a data storage device, an import/export station, and the like. A data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein for implementing Applicants' methods.