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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Multivariable control of the Space Shuttle Remote Manipulator System using linearization by state feedback

This thesis develops and demonstrates an approach to nonlinear control system design using linearization by state feedback. The design provides improved transient response behavior allowing faster maneuvering of payloads by the SRMS. Modeling uncertainty is accounted for by using a second feedback loop designed around the feedback linearized dynamics. A classical feedback loop is developed to provide the easy implementation required for the relatively small on board computers. Feedback linearization also allows the use of higher bandwidth model based compensation in the outer loop, since it helps maintain stability in the presence of the nonlinearities typically neglected in model based designs.

Gettman, Chang-Ching LO↗
NASA NTRS1992

Dynamic analysis to evaluate viscoelastic passive damping augmentation for the Space Shuttle Remote Manipulator System

The effectiveness of constrained viscoelastic layer damping treatment designs is evaluated separately as passive control measures for low frequency joint dominated modes and higher frequency boom flexure dominated modes using a NASTRAN finite element analysis. Passive damping augmentation is proposed which is based on a constrained viscoelastic layer damping treatment applied to the surface of the manipulators's flexible booms. It is pointed out that even the joint compliance dominated modes can be damped to some degree through appropriate design of the treatment.

Alberts, Thomas E.↗
NASA NTRS2018

Human-Automation Allocations for Current Robotic Space Operations: Space Station Remote Manipulator System

NASA’s Human Research Program’s Risk of Inadequate Design of Human and Automation/Robotic Integration (HARI) delineates the uncertainty surrounding crew work with automation and robotics in spaceflight. HARI is concerned with detrimental effects of ineffective user interfaces, system designs and/or functional task allocation on crew performance, potentially compromising mission success and safety. This risk arises because of limited experience with complex automation and robotics in spaceflight. One key knowledge gap within the HARI risk is related to function allocation.

Chang, Mai Lee↗
NASA NTRS1987

A comparison of position and rate control for telemanipulations with consideration of manipulator system dynamics

Position and rate control are the two common manual control modes in teleoperations. Human operator performance using the two modes is evaluated and compared. Simulated three-axis pick-and-place operations are used as the primary task for evaluation. First, ideal position and rate control are compared by considering several factors, such as joystick gain, joystick type, display mode, task, and manipulator work space size. Then the effects of the manipulator system dynamics are investigated by varying the natural frequency and speed limit. Experimental results show that ideal position control is superior to ideal rate control, regardless of joystick type or display mode, when the manipulation work space is small or comparable to the human operator's control space. Results also show that when the manipulator system is slow, the superiority of position control disappears. Position control is recommended for small-work-space telemanipulation tasks, while rate control is recommended for slow wide-work-space telemanipulation tasks.

Kim, Won S.↗
NASA NTRS1986

The design, fabrication and delivery of a manipulator foot restraint mockup for space telescope development testing

The Manipulator Foot Restraint (MFR) is a subsystem of the Remote Manipulator System (RMS) which plays a major role in servicing the Hubble Space Telescope (HST) in orbit. Flight drawings were used to construct the MFR to guarantee that the mockup components were functionally equivalent to the flight MFR. Material surface finishes and tolerances that were compatible to the Neutral Buoyance Simulator (NBS) environment were used. Recommendation for improvements are discussed.

Hollingsworth, M. A.↗
NASA NTRS1989

A comparison of the Shuttle remote manipulator system and the Space Station Freedom mobile servicing center

The Shuttle Remote Manipulator System is a mature system which has successfully completed 18 flights. Its primary functional design driver was the capability to deploy and retrieve payloads from the Orbiter cargo bay. The Space Station Freedom Mobile Servicing Center is still in the requirements definition and early design stage. Its primary function design drivers are the capabilities: to support Space Station construction and assembly tasks; to provide external transportation about the Space Station; to provide handling capabilities for the Orbiter, free flyers, and payloads; to support attached payload servicing in the extravehicular environment; and to perform scheduled and un-scheduled maintenance on the Space Station. The differences between the two systems in the area of geometric configuration, mobility, sensor capabilities, control stations, control algorithms, handling performance, end effector dexterity, and fault tolerance are discussed.

Taylor, Edith C.↗
NASA NTRS1992

Experiments in Nonlinear Adaptive Control of Multi-Manipulator, Free-Flying Space Robots

Sophisticated robots can greatly enhance the role of humans in space by relieving astronauts of low level, tedious assembly and maintenance chores and allowing them to concentrate on higher level tasks. Robots and astronauts can work together efficiently, as a team; but the robot must be capable of accomplishing complex operations and yet be easy to use. Multiple cooperating manipulators are essential to dexterity and can broaden greatly the types of activities the robot can achieve; adding adaptive control can ease greatly robot usage by allowing the robot to change its own controller actions, without human intervention, in response to changes in its environment. Previous work in the Aerospace Robotics Laboratory (ARL) have shown the usefulness of a space robot with cooperating manipulators. The research presented in this dissertation extends that work by adding adaptive control. To help achieve this high level of robot sophistication, this research made several advances to the field of nonlinear adaptive control of robotic systems. A nonlinear adaptive control algorithm developed originally for control of robots, but requiring joint positions as inputs, was extended here to handle the much more general case of manipulator endpoint-position commands. A new system modelling technique, called system concatenation was developed to simplify the generation of a system model for complicated systems, such as a free-flying multiple-manipulator robot system. Finally, the task-space concept was introduced wherein the operator's inputs specify only the robot's task. The robot's subsequent autonomous performance of each task still involves, of course, endpoint positions and joint configurations as subsets. The combination of these developments resulted in a new adaptive control framework that is capable of continuously providing full adaptation capability to the complex space-robot system in all modes of operation. The new adaptive control algorithm easily handles free-flying systems with multiple, interacting manipulators, and extends naturally to even larger systems. The new adaptive controller was experimentally demonstrated on an ideal testbed in the ARL-A first-ever experimental model of a multi-manipulator, free-flying space robot that is capable of capturing and manipulating free-floating objects without requiring human assistance. A graphical user interface enhanced the robot usability: it enabled an operator situated at a remote location to issue high-level task description commands to the robot, and to monitor robot activities as it then carried out each assignment autonomously.

Chen, Vincent Wei-Kang↗
NASA NTRS1994

A virtual work space for both hands manipulation with coherency between kinesthetic and visual sensation

This paper describes the construction of a virtual work space for tasks performed by two handed manipulation. We intend to provide a virtual environment that encourages users to accomplish tasks as they usually act in a real environment. Our approach uses a three dimensional spatial interface device that allows the user to handle virtual objects by hand and be able to feel some physical properties such as contact, weight, etc. We investigated suitable conditions for constructing our virtual work space by simulating some basic assembly work, a face and fit task. We then selected the conditions under which the subjects felt most comfortable in performing this task and set up our virtual work space. Finally, we verified the possibility of performing more complex tasks in this virtual work space by providing simple virtual models and then let the subjects create new models by assembling these components. The subjects can naturally perform assembly operations and accomplish the task. Our evaluation shows that this virtual work space has the potential to be used for performing tasks that require two-handed manipulation or cooperation between both hands in a natural manner.

Ishii, Masahiro↗
NASA NTRS1991

Manipulation strategies for massive space payloads

Motion planning and control for the joints of flexible manipulators are discussed. Specific topics covered include control of a flexible braced manipulator, control of a small working robot on a large flexible manipulator to suppress vibrations, control strategies for ensuring cooperation among disparate manipulators, and motion planning for robots in free-fall.

Book, Wayne J.↗
NASA NTRS1985

The space shuttle orbiter remote manipulator positioning mechanism

The major subassemblies of the Manipulator Positioning Mechanism (MPM) are described and illustrated. The Space Shuttle Orbiter design provides that the MPM may be mounted on either left or right sides of the payload bay, or both sides if two are flown. This MPM is provided for the purpose of securing the remote arm in stowed position during lift-off, boost, and landing. It also provides the deploy, latch and unlatch capabilities of the Remote Manipulator System arm.

Hardee, J. H.↗
NASA NTRS1972

Manipulator systems extend man's capabilities in space.

Teleoperator components include manipulators and end effectors, sensors, a mobility unit, radio or hard-wire communications receiver and information processor, information display, man in the control loop at various levels of sophistication, the controls, and the transmitter. Possible applications of teleoperators in space cover a wide spectrum from various research and operational missions in earth orbit in conjunction with the space shuttle, space stations, and satellites to vehicles to explore the moon, planets and their moons, asteroids and comets.

Deutsch, S.↗
NASA NTRS1991

Task decomposition for a multilimbed robot to work in reachable but unorientable space

Robot manipulators installed on legged mobile platforms are suggested for enlarging robot workspace. To plan the motion of such a system, the arm-platform motion coordination problem is raised, and a task decomposition is proposed to solve the problem. A given task described by the destination position and orientation of the end effector is decomposed into subtasks for arm manipulation and for platform configuration, respectively. The former is defined as the end-effector position and orientation with respect to the platform, and the latter as the platform position and orientation in the base coordinates. Three approaches are proposed for the task decomposition. The approaches are also evaluated in terms of the displacements, from which an optimal approach can be selected.

Su, Chau↗
NASA NTRS2020

Assemblers: A Modular, Reconfigurable Manipulator for Autonomous in-Space Assembly

This paper presents a modular, reconfigurable robotic manipulator for autonomous in-space assembly. On-orbit and planetary surface assembly is a challenging domain that encompasses various technological thrusts to support human exploration, science, and technology demonstration missions. The system architecture presented here addresses the need for robotic assembly of structures in locations that prohibit constant human oversight and/or teleoperation. This system is capable of scheduling, reconfiguring itself, and executing structural assembly tasks with the ability to assess construction and correct errors during the assembly as needed. An example concept of operations is presented. Details of the mechanical and electrical design of the robotic modules as well as the dynamic modeling approach, control algorithms, and sensing and perception systems are also provided.

robotics↗
NASA NTRS1988

Minimization of spacecraft disturbances in space-robotic systems

Virtual manipulators for an arbitrary point of a real open chain space manipulator are presented. These virtual manipulators can be used to generate a disturbance map which can be used to select paths that reduce spacecraft disturbances. The present technique is applied to a simple two-link manipulator mounted on a free-floating spacecraft.

Vafa, Zia↗
NASA NTRS1988

Space-based multifunctional end effector systems functional requirements and proposed designs

The end effector is an essential element of teleoperator and telerobot systems to be employed in space in the next decade. The report defines functional requirements for end effector systems to perform operations that are currently only feasible through Extra-Vehicular Activity (EVA). Specific tasks and functions that the end effectors must be capable of performing are delineated. Required capabilities for forces and torques, clearances, compliance, and sensing are described, using current EVA requirements as guidelines where feasible. The implications of these functional requirements on the elements of potential end effector systems are discussed. The systems issues that must be considered in the design of space-based manipulator systems are identified; including impacts on subsystems tightly coupled to the end effector, i.e., control station, information processing, manipulator arm, tool and equipment stowage. Possible end effector designs are divided into three categories: single degree-of-freedom end effectors, multiple degree of freedom end effectors, and anthropomorphic hands. Specific design alternatives are suggested and analyzed within the individual categories. Two evaluations are performed: the first considers how well the individual end effectors could substitute for EVA; the second compares how manipulator systems composed of the top performers from the first evaluation would improve the space shuttle Remote Manipulator System (RMS) capabilities. The analysis concludes that the anthropomorphic hand is best-suited for EVA tasks. A left- and right-handed anthropomorphic manipulator arm configuration is suggested as appropriate to be affixed to the RMS, but could also be used as part of the Smart Front End for the Orbital Maneuvering Vehicle (OMV). The technical feasibility of the anthropomorphic hand and its control are demonstrated. An evolutionary development approach is proposed and approximate scheduling provided for implementing the suggested manipulator systems in time for space stations operations in the early 1990s.

Mishkin, A. H.↗
NASA NTRS1991

Manipulation strategies for massive space payloads

The industrial and environmental applications for robots with a relatively large workspace has increased significantly in the last few years. To accommodate the demands, the manipulator is usually designed with long, lightweight links that are inherently flexible. Ongoing research at Georgia Tech into the behavior and design of these flexible links is discussed.

Book, Wayne J.↗