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Disposition Switching Algorithm for Two-Gripper Picker

IP.com Disclosure Number: IPCOM000120141D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 91K

Publishing Venue

IBM

Related People

Hartung, JC: AUTHOR [+3]

Abstract

An automated optical or tape library can use a robotically controlled picker with either one or two cartridge grippers to load cartridges into drives and to put unloaded cartridges into storage slots. This article gives a means of improving the response time of libraries with a picker having two cartridge grippers.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Disposition Switching Algorithm for Two-Gripper Picker

      An automated optical or tape library can use a
robotically controlled picker with either one or two cartridge
grippers to load cartridges into drives and to put unloaded
cartridges into storage slots.  This article gives a means of
improving the response time of libraries with a picker having two
cartridge grippers.

      The figure shows a management algorithm for a dual-gripper
picker.  The disposition of the picker is switched between two
possible activities, either mount servicing or housekeeping,
depending on the state of the mount queue.

      When there is a continuous queue of mount requests, the picker
will be totally dedicated to mount servicing.  When the picker is
seized for a new mount request, it will first travel to the new
cartridge and remove it from its slot with the free gripper.  Then
the picker indexes to position the previous old cartridge, which it
had been carrying, to a point in front of the newly vacated slot and
places that old cartridge in this slot before traveling to the target
drive. Then the picker empties the cartridge from the drive with its
empty gripper, indexes, and loads the new mount request. The picker
then travels to the next cartridge to be mounted and the cycle begins
again.

      When the mount queue is empty, the picker can be freed to do
housekeeping chores which will enhance the response time of the next
mount request when it does come.  When the mount queue is empty, the
picker can first place the recently removed cartridge that it had
been carrying in one of its grippers in the nearest available slot.
If at this time the mount queue is still empty, the picker could then
unload the least-recently-used cartridge from its drive and put that
old cartridge away in any available slot.  When a new mount request
does c...