Abstract: A visual navigation system provides absolute position information to multiple automatically guided vehicles (AGVs) such as mobile robots. The beacon-equipped AGVs emit light visible to overhead television cameras. The beacons are arranged and controlled so that the vision systems can acquire, measure, and report the locations of multiple AGVs. The system controller incorporates a programmable "factory map", or knowledge base, of allowable paths of travel for the AGVs, which navigate by dead reckoning with periodic position updates from the visual navigation system. The visual navigation system notifies the autonomous AGVs and the system controller when an AGV strays from its command path. The combination of computer controls in the elements of the system provides the means to stop and to recover straying AGVs. The navigation system visually monitors normal AGV travel, off-course corrections, "lost" AGV searches, and recovery. Thus, it provides closed-loop, servo-like operation.

Abstract: The invention is a method of dynamic collision avoidance for multiple automatically guided vehicles (AGVs) on bidirectional paths. It calculates windows, or areas of computer memory, against which it matches the reported positions of AGVs. The invention acts on information from a central data base in which the factory or operating space of the AGVs is mapped and from AGV position updates supplied by an independently operating visual navigation system. The invention dynamically calculates the locations and dimensions of the windows for each position update. Since these position updates occur in real time, many times each second, the invention provides the means for the AGV system's controller to prevent collisions between the AGVs and other objects without minimizing the degrees of freedom of AGV movement.