Space Shuttle Remote Manipulator System Force-Torque Sensor
Flown on STS 62 in March, 1994, the Space Shuttle Remote Manpilator System
Force-Torque Sensor can detect and display forces and torques acting upon
the RMS end effector when contacting target objects.
The Shuttle RMS has already proven itself to be critical in the success
of several space missions. Until now, the detection of forces acting upon
the RMS end effector when in contact with other objects has not been available
to the astronauts operating the RMS. A force-torque sensor has been built
at JPL. It has been integrated with a magnetic end effector at JSC and
flown successfully on STS 62 in March 1994.
The FTS flight instrument serves as an enhancement to the Space Shuttle
RMS by providing the detection of forces and torques acting upon the RMS
end effector during manipulator operations involving constrained motion
when the end effector is in contact with target objects. Two major elements
comprise the RMS FTS: (i) a sensor element containing strain gauges and
data acquisition electronics is attached to the base of an RMS end effector
and (ii) data transmitted from the sensor element is received by an onboard
computer element which translates the data into graphics and numerical data
displays on a monitor screen. These displays give the astronauts a highly
accurate tool for observing imposed forces and torques acting on the RMS
end effector in each of the three translational and three rotational axes.
Keyboard commands can be input to the computer element in flight to affect
functions such as display formatting, strain gauge offset compensation,
and reference frame manipulations of translation and rotation. In-flight
engineering data can be recorded from subsequent analysis of RMS constrained
motion performance by ground personnel.
Incorporation of the FTS onto the RMS makes feasible operations requiring
small amounts of force or force increments in the range of 2 to 50 lbs.
At times when comprehensive views of the worksite are not available, the
FTS also can provide a visual "sense of touch" to augment TV camera
data in such operations as mating and demating connectors or in performing
insertion or detachment tasks. Furthermore, the magnitude and direction
of excessive forces imposed by or acting on the RMS end effector can be
detected in real time, enabling immediate corrective action. The extensive
range (configurable between 2 lbs. and 5, 000 lbs. full scale) and high
sensitivity (0.05% full scale) give the RMS FTS a wide applicability to
both Space Shuttle and Space Station based operations.
Point of Contact:
Antal Bejczy
Mail Stop 198-219
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109
818-354-4568
bejczy@telerobotics.jpl.nasa.gov
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Maintained by: Dave Lavery
Last updated: May 10, 1996