Patent ID: 7664561

Claim:
A method for assuring constant product movement and for controlling priority of movement of product in an Automatic Material Handling System (“AMHS”), said method comprising: periodically checking task related records, wherein a task is a movement of a product from a current position to a destination position, and further wherein each task related record includes: a lot identification number; a current position identification number, being a stocker identification number; a destination position identification number, being a stocker identification number; move priority, being a numerical indicator; move status, being a run status and a wait status; transmission time, being a time expired between issuing of a move command and arrival at the destination position; and waiting time, being a time expired between entering a wait status and entering a run status; path traveled, being a running record of current position identification number and destination position identification number, each of these running records being provided with a time stamp; creating, maintaining, updating, and deleting of the task related records; creating, maintaining, updating, and deleting of stocker related records, whereby a stocker is a basic unit for containing and transporting said product; evaluating, by a computer, stocker resources, thereby using the stocker related records to identify an available stocker, said available stocker identified with an available stocker ID (ASID); evaluating, by the computer, move priority, thereby accessing the task related records using said ASID as a search argument, thereby selecting the task related record with a Highest Move Priority record having a longest wait time; and directing, by the computer, said AMHS to issue a move command for the task related record with said Highest Move Priority record having the longest wait time.