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Use of Force Feedback in an Automated Screw-Driving Machine

IP.com Disclosure Number: IPCOM000120055D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Kohlmeyer, WC: AUTHOR [+4]

Abstract

Automation of the screw-driving process requires that the screw be presented and torqued in a smooth fashion. To do this, the screw driver needs to maintain a constant force on the screw so that jamming is prevented and no slipping occurs between the driver and the screw. To maintain this constant force, a force sensor can be mounted on the linear slide attached to the driver to measure the amount of force the driver applies to the screw. That information can then be used in feedback to control the linear slide speed and fastener driver speed so that the prescribed force is maintained. This will ensure smooth, even contact between the driver and the screw whether the screw is being loosened or tightened.

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This is the abbreviated version, containing approximately 82% of the total text.

Use of Force Feedback in an Automated Screw-Driving Machine

      Automation of the screw-driving process requires that the
screw be presented and torqued in a smooth fashion.  To do this, the
screw driver needs to maintain a constant force on the screw so that
jamming is prevented and no slipping occurs between the driver and
the screw.  To maintain this constant force, a force sensor can be
mounted on the linear slide attached to the driver to measure the
amount of force the driver applies to the screw.  That information
can then be used in feedback to control the linear slide speed and
fastener driver speed so that the prescribed force is maintained.
This will ensure smooth, even contact between the driver and the
screw whether the screw is being loosened or tightened.

      Fig. 1 shows a basic outline of the major components involved.
Fig. 2 shows essentially the same components with a block diagram
showing how the implementation would occur. The basic operational
sequence would be to have the driver pick up a screw and proceed to
the work piece until contact between screw and work piece is sensed
by the force cell. Then the force control takes over to drive the
screw with a constant even pressure until final torquing is
completed.

      For the removal of a screw, the above sequence would
essentially be the same.  The driver would proceed until it contacted
the screw.  Then, force control would take over with the driver
rotating in reverse.  The id...