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Browse Prior Art Database

Unitized In-Line Gimbal

IP.com Disclosure Number: IPCOM000101538D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 125K

Publishing Venue

IBM

Related People

Majewski, FT: AUTHOR [+2]

Abstract

The gimbal in present use in a manipulator is of an offset configuration. The gimbal consists of a yaw rotary actuator mounted to the end of the "Z" axis arm. Attached to the yaw actuator is an "L"-shaped bracket to which the pitch actuator is attached off to the side of the center line of the "Z" axis arm. A bracket is attached to the pitch actuator to which is attached the roll actuator returning it to the center line of the "Z" axis arm. All three are hydraulic rotary actuators and are activated by the flow of oil through small diameter nylon tubing. Rotary potentiometers are affixed to the shaft of each actuator to indicate location or position. Small diameter wires are soldered to the leads of the potentiometers.

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

Unitized In-Line Gimbal

       The gimbal in present use in a manipulator is of an
offset configuration.  The gimbal consists of a yaw rotary actuator
mounted to the end of the "Z" axis arm.  Attached to the yaw actuator
is an "L"-shaped bracket to which the pitch actuator is attached off
to the side of the center line of the "Z" axis arm.  A bracket is
attached to the pitch actuator to which is attached the roll actuator
returning it to the center line of the "Z" axis arm.  All three are
hydraulic rotary actuators and are activated by the flow of oil
through small diameter nylon tubing.  Rotary potentiometers are
affixed to the shaft of each actuator to indicate location or
position.  Small diameter wires are soldered to the leads of the
potentiometers.

      Several problems are present in this design.  The nylon tubing
does not conform to the minimum burst pressure requirements.  This
tubing is attached externally in large loops to permit the various
turning configurations of the gimbal or wrist joint.  These large
loops present an additional hazard in that it is possible to "catch"
on to a protruding object, such as tools or fixtures, while the
machine is in motion.

      The "L"-shaped bracket tends to flex when direct downward
pressure is applied in the "Z" axis.  The tolerance accumulation of
the various mounting brackets is such that it is virtually impossible
to rotate the gimbal concentrically in the yaw mode.  The small
diameter wires attached to the potentiometers are also looped as is
the nylon tubing.  Furthermore, the constant flexing of the wires
results in frequent wire breakage.

      A unitized in-line gimbal, shown in Figs. 1, 2 and 2a through
2d, offers a solution to all of the aforementioned concerns.  All of
the oil passages P1 through P8 are contained internally.  The wiring
is imbedded in cast groove 1 (Fig. 1) and covered with a removable
plate 2 to permit access to the wiring.

      In the unitized in-line gimbal the servo valves (not shown) are
mounted atop the "Z" arm.  Metal tubing 3 is attached to the servo
valves and is inserted through...