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Das, H.

Publications and source records attributed to Das, H..

28 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Evaluation of a telerobotic system to assist surgeons in microsurgery

A tool was developed that assists surgeons in manipulating surgical instruments more precisely than is possible manually. The tool is a telemanipulator that scales down the surgeon's hand motion and filters tremor in the motion. The signals measured from the surgeon's hand are transformed and used to drive a six-degrees-of-freedom robot to position the surgical instrument mounted on its tip. A pilot study comparing the performance of the telemanipulator system against manual instrument positioning was conducted at the University of Southern California School of Medicine. The results show that a telerobotic tool can improve the performance of a microsurgeon by increasing the precision with which he can position surgical instruments, but this is achieved at the cost of increased time in performing the task. We believe that this technology will extend the capabilities of microsurgeons and allow more surgeons to perform highly skilled procedures currently performed only by the best surgeons. It will also enable performance of new surgical procedures that are beyond the capabilities of even the most skilled surgeons. Copyright 1999 Wiley-Liss, Inc.

Microsurgery/instrumentation/methods↗
NASA NTRS1998

A Telerobot to Extend the Skill of Microsurgeons

The engineering details of the Robot Assisted MicroSurgery (RAMS) telerobotic system designed to assist microsurgeons improve the precision and dexterity with which they can position surgical instruments is described in this paper.

telerobotics microsurgery precise positioning of s↗
NASA NTRS1997

Robot Assisted Microsurgery Development at JPL

A team of engineers at JPL, working in collaboration with MicroDexterity Systems, Inc., and Dr. Steve Charles, recently developed a telerobotic workstation to assist microsurgeons perform surgery.

Microsurgery JPL telerobotic MicroDexterity System↗
NASA NTRS1994

Telerobotic Tending of Space Based Plant Growth Chamber

The kinematic design of a telerobotic mechanism for tending a plant growth space science experiment chamber is described. Ground based control of tending mechanisms internal to space science experiments will allow ground based principal investigators to interact directly with their space science experiments.

space science experiment chamber plant growth↗
NASA NTRS1993

Integrated tools for teleoperated satellite repair

Tools and tool handling techniques designed for demonstrating the use of the Advanced Teleoperation System at JPL in satellite repair operations are described in this paper. Our model for the repair demonstration is the Main Electronics Box (MEB) replacement on the Solar Maximum Satellite Repair (SMSR) procedure developed by NASA and successfully performed by the crew of Space Shuttle STS-13 in 1984. A summary of the repair procedure consists of uncovering thermal protection blankets on the satellite, removing screws from the MEB panel, opening the panel and clamping it in place, then removing electrical connectors from their sockets, cutting cords that hold electrical cables to the MEB panel, replacing the panel, and finally reversing the previous procedures. Methods for handling tools used in our SMSR procedure, along with details of the tool designs are discussed in this paper.

Das, H.↗
NASA NTRS1992

Performance experiments with alternative advanced teleoperator control modes for a simulated solar maximum satellite repair

Experiments are described which were conducted at the JPL Advanced Teleoperator Lab to demonstrate and evaluate the effectiveness of various teleoperator control modes in the performance of a simulated Solar Max Satellite Repair (SMSR) task. THe SMSR was selected as a test because it is very rich in performance capability requirements and it actually has been performed by two EVA astronauts in the Space Shuttle Bay in 1984. The main subtasks are: thermal blanket removal; installation of a hinge attachment for electrical panel opening; opening of electrical panel; removal of electrical connectors; relining of cable bundles; replacement of electrical panel; securing parts and cables; re-mate electrical connectors; closing of electrical panel; and reinstating thermal blanket. The current performance experiments are limited to thermal blanket cutting, electrical panel unbolting and handling electrical bundles and connectors. In one formal experiment even different control modes were applied to the unbolting and reinsertion of electrical panel screws subtasks. The seven control modes are alternative combinations of manual position and rate control with force feedback and remote compliance referenced to force-torque sensor information. Force-torque sensor and end effector position data and task completion times were recorded for analysis and quantification of operator performance.

Das, H.↗
NASA NTRS1992

Operator performance with alternative manual control modes in teleoperation

Recent experiments conducted at the JPL comparing alternative manual control modes using the JPL Advanced Teleoperator system are described. Of particular interest were control modes that provide force reflection to the operator. The task selected for the experiment is a portion of the Solar Maximum Satellite Repair procedure we developed to demonstrate the repair of the Solar Maximum Satellite with teleoperators. The seven manual control modes evaluated in the experiment are combinations of manual position or resolved motion rate control with alternative control schemes for force reflection and remote manipulator compliance. Performance measures used were task completion times, average force and torque exerted during the execution of the task, and cumulative force and torque exerted. The results were statistically analyzed and they show that, in general, force reflection significantly improves operator performance and indicate that a specific force-reflecting scheme may yield the best performance among the control modes we tested. Also, our experiment showed that, for the selected task, the position control modes were preferable to the rate control modes and slave manipulator compliance reduced task interaction forces and torques.

Das, H.↗