Task queuing methodology for reducing traffic jam and to control transmission priority in an automatic material handling system

A method in an Automatic Material Handling System (AMHS) for assuring constant product movement and for controlling priority of movement of product, said product being contained in a unit referred to as a stocker, said method comprising:

• receiving and interpreting a timer signal;
• accessing and updating databases, said databases including a Task-Q file that stores task related records, each task related record represented by a Task-Q record, wherein a task is a movement of a product from a current position to a destination position, and a Stocker Resource Q file that stores stocker resource related records;
• checking, by a computer, the Stocker Resource Q file for an available stocker, wherein said checking comprises sequentially accessing the Stocker Resource Q file and extracting a first stocker resource related record indicating an available stocker, said available stocker being identified by an available stocker ID (ASID);
• and
• checking, by the computer, the move priority of the task related records in the Task-Q file, wherein said checking comprises:
• accessing said Task-Q file, therefrom accessing all Task-Q records having a task scheduled against said ASID, creating a first file;
• selecting from said first file all records representative of tasks scheduled against said ASID being in a wait state, creating a second file, said second file comprising indicators of task priority and task wait time;
• sorting records of said second file in priority order, a highest priority being listed first after which lower priorities are sequentially listed in descending order and in accordance with a numeric value assigned to this priority, creating a third file;
• sorting said records of said third file in task wait time order, a longest task wait time being listed first after which lesser task wait time are sequentially listed in descending order and in accordance with a numeric value assigned to this task wait time, creating a fourth file, said fourth file comprising a first record of highest priority and longest wait time, said first record comprising a Selected Current Position ID;
• modifying a Wait status indicator in said Task-Q file to a Run status indicator;
• and
• directing, by the computer, said AMHS to issue a Move command for said Selected Current Position ID.

A method for assuring constant product movement and for controlling priority of movement of product in an Automatic Material Handling System (“AMHS”), said product being contained in a unit referred to as a stocker, said method comprising:

• creating, maintaining, updating, and deleting of task related records, each task related record represented by a Task-Q record stored in a Task-Q file, whereby a task is a movement of a product lot from a current position to a destination position, wherein the creating, maintaining, updating, and deleting of the task related records comprises, on a per task basis:
• entering a task as represented by a Task-Q record into the Task-Q file, thereby including entering a current position and a destination position, concurrently entering a time indicator of said entry of said task into said Task-Q file;
• deleting the task as represented by a Task-Q record from the Task-Q file, concurrently entering a time indicator of said deleting of said task from said Task-Q file;
• calculating a first time expired between said entering of the task into said Task-Q file and deleting the task from said Task-Q file;
• recording and updating the task's run and wait status, concurrently entering a time indicator of initiation or termination of said task's run and wait status;
• recording a time indicator of task completion;
• calculating a second time expired between said task completion and said initiation of said run status, said second time expired being a transmission time;
• calculating a third time expired between said initiation of said run status and initiation of said wait status, said third time expired being a waiting time;
• and
• recording and updating path traveled data by recording said current or from position and said to or destination position;
• creating, maintaining, updating and deleting of stocker related records, each stocker related record represented by a Stocker Resource Q record stored in a Stocker Resource Q file, whereby a stocker is a basic unit for transportation of said product;
• evaluating, by a computer, stocker resources, thereby using the Stocker Resource Q file, identifying an Available Stocker ID (ASID);
• evaluating, by the computer, move priority, thereby accessing the Task-Q file using said ASID as a search argument, thereby selecting a Highest Move Priority record having a longest wait time;
• and
• issuing, by the computer, a move command to said AMHS for the Highest Move Priority record having the longest wait time.