Browse Prior Art Database

Three Dimensional Tooling Position Sensing

IP.com Disclosure Number: IPCOM000106647D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 89K

Publishing Venue

IBM

Related People

Farquhar, DRB: AUTHOR

Abstract

Disclosed is a simple method of identifying any of a set of 3D locations by means of a one-dimensional length measurement of a flexible wire. Also enabled is verification of a correct process sequence of operations where tooling must be used many times sequentially. Avoided is locating each point in three dimensions using numerous and complex position sensors. Benefits are low cost; robust simplicity; low maintenance with easy setup and calibration.

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

Three Dimensional Tooling Position Sensing

      Disclosed is a simple method of identifying any of a set of 3D
locations by means of a one-dimensional length measurement of a
flexible wire.  Also enabled is verification of a correct process
sequence of operations where tooling must be used many times
sequentially.  Avoided is locating each point in three dimensions
using numerous and complex position sensors.  Benefits are low cost;
robust simplicity; low maintenance with easy setup and calibration.

      The invention provides high-accuracy, three-dimensional
position sensing of tooling and can be used to verify the positional
sequence of use of the tool installed.  The device in its simplest
form consists of a pull-wire position transducer and a small
microcontroller circuit.  The position transducer is able to provide
an accurate and repeatable voltage output which is directly
proportional to the linear displacement of the transducer body.  The
microcontroller circuit only needs to be basic - the intel 8097
microcontroller with a small amount of I/O logic and a display
suffices.  The 8097 device is particularly suitable because it has an
on-chip analog to digital converter which allows the transducer
output to be easily processed.

      An example application for a screw torque sequence verification
system follows with reference to the Figure.  The problem is to
ensure that four screws 5 fixing two product parts 3 & 4 together are
tightened to a specific torque in a specific sequence.

      An electric torque driver 11 and commercial 'pull-wire'
position transducer 1 are both linked to a microcontroller circuit 6.
The two product parts 3 & 4 would be placed in position on a suitable
locating fixture 10 on a work bench 8.  The electric torque driver 11
is hung from its sprung return support cable 9 and positioned above
the parts to be screwed together.  The pull-wire 2 needs to be
positioned close to the support cable 9, but off-centre with respect
to the four screw positions 5.  The end of cable 9 is then attached
to the electric torque driver 11.  The transducer 1 is required to be
off-centre so that when the screw driver 12 is offered up to the
screws the extension of the pull-wire 2 is sufficiently different for
each screw position. ...