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Real-time interrupt driven PC control system for a storage and retrieval machine

  • US 5,838,572 A
  • Filed: 11/22/1995
  • Issued: 11/17/1998
  • Est. Priority Date: 04/02/1993
  • Status: Expired due to Fees
First Claim
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1. A method of controlling a storage and retrieval machine in event driven fashion, the method comprising:

  • (A) providing said storage and retrieval machine with a horizontally movable base, a vertically movable carriage, and a microprocessor-based control system that controls movement of said base and said carriage of storage and retrieval machine, said microprocessor-based control system including a motion controller, a machine control task, an input/output interface, an input/output task, and at least one microprocessor that executes said machine control task and said input/output task;

    (B) issuing a plurality of interrupts to said machine control task in response to events which occur in an operating environment of said storage and retrieval machine, at least some of plurality of interrupts being issued by said motion controller, and at least some of plurality of interrupts being issued by said input/output task in response to input signals from sensors received at said input/output interface; and

    (C) responding to said interrupts, said responding step including the steps of(1) receiving said plurality of interrupts at said machine control task, and(2) executing at least one subroutine in response to the reception of each interrupt, said execution of said subroutines controlling movement of said base and said carriage of said storage and retrieval machine, and said executing step including the step of providing information to said motion controller which enables said motion controller to cooperate with base and hoist servo motors of said storage and retrieval machine to deliver said carriage to a next rack location;

    wherein movement of said base and said carriage of said storage and retrieval machine (1) is substantially entirely controlled by issuing and responding to said interrupts in steps (B) and (C) as different events occur in said operating environment that cause said interrupts to be issued and (2) is controlled in a manner which is substantially free of polling by said machine control task of said input/output interface and said motion controller for status information.

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