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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Advanced teleoperators

Advanced teleoperators are discussed, with emphasis on the remote manipulation system designed to perform such actions as grasping, orienting, moving, placing, and inserting objects. Geometrical performance dimensions are considered, indicating that a manipulator is limited to three-orders-of-magnitude ratio of workspace extension to positioning accuracy. The control system is examined, showing that a manipulative task requires coordination of several joints, with the relationship between the task definers and the joint variables given by complex trigonometrical transformations. Control modes developed in the last 30 years are noted, including program controlled industrial 'robots' which can endlessly repeat a fixed sequence of motions without operator intervention, and the sensor-referenced/computer-controlled mode manipulators. Advanced proximity sensor systems are taken into account, with emphasis on the applications of the force-torque and slip models. The proximity sensor system for the shuttle-size manipulator is described.

Bejczy, A. K.↗
NASA NTRS1984

Memory-Metal Electromechanical Actuators

Electrically controlled actuator produces predetermined force, torque, or displacement without motors, solenoids, or gears. Using memory-metal elements, actuator responds to digital input without electronic digitalto-analog conversion. To prevent overheating and consequent loss of hotformed shape, each element protected by thermostat turns off current when predetermined temperature is exceeded. Memory metals used to generate fast mechanical response to electric signals.

Ruoff, C. F.↗
NASA NTRS1986

Electromagnetic scattering theory

Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.

Bird, J. F.↗
NASA NTRS1987

The flight demonstration program and selection process

The Orbital Refueling System (ORS); force torque sensor; Plasma Motor/Generator (PMG) proof of function; voice controlled system; infrared intercommunications; superfluid helium on orbit transfer; laser docking sensor; and the Small Expendable Deployment System (SEDS) are summarized.

Levin, G. M.↗
NASA NTRS1989

Flight telerobot mechanism design: Problems and challenges

Problems and challenges of designing flight telerobot mechanisms are discussed. Specific experiences are drawn from the following system developments: (1) the Force Reflecting Hand Controller, (2) the Smart End Effector, (3) the force-torque sensor, and a generic multi-degrees-of-freedom manipulator.

Dahlgren, John B.↗
NASA NTRS1987

Nonlinear feedback control of multiple robot arms

Multiple coordinated robot arms are modeled by considering the arms: (1) as closed kinematic chains, and (2) as a force constrained mechanical system working on the same object simultaneously. In both formulations a new dynamic control method is discussed. It is based on a feedback linearization and simultaneous output decoupling technique. Applying a nonlinear feedback and a nonlinear coordinate transformation, the complicated model of the multiple robot arms in either formulation is converted into a linear and output decoupled system. The linear system control theory and optimal control theory are used to design robust controllers in the task space. The first formulation has the advantage of automatically handling the coordination and load distribution among the robot arms. In the second formulation, by choosing a general output equation, researchers can superimpose the position and velocity error feedback with the force-torque error feedback in the task space simultaneously.

Tarn, T. J.↗
NASA NTRS1988

New nonlinear control algorithms for multiple robot arms

Multiple coordinated robot arms are modeled by considering the arms as closed kinematic chains and as a force-constrained mechanical system working on the same object simultaneously. In both formulations, a novel dynamic control method is discussed. It is based on feedback linearization and simultaneous output decoupling technique. By applying a nonlinear feedback and a nonlinear coordinate transformation, the complicated model of the multiple robot arms in either formulation is converted into a linear and output decoupled system. The linear system control theory and optimal control theory are used to design robust controllers in the task space. The first formulation has the advantage of automatically handling the coordination and load distribution among the robot arms. In the second formulation, it was found that by choosing a general output equation it became possible simultaneously to superimpose the position and velocity error feedback with the force-torque error feedback in the task space.

Tarn, T. J.↗
NASA NTRS1989

ROTEX-TRIIFEX: Proposal for a joint FRG-USA telerobotic flight experiment

The concepts and main elements of a RObot Technology EXperiment (ROTEX) proposed to fly with the next German spacelab mission, D2, are presented. It provides a 1 meter size, six axis robot inside a spacelab rack, equipped with a multisensory gripper (force-torque sensors, an array of range finders, and mini stereo cameras). The robot will perform assembly and servicing tasks in a generic way, and will grasp a floating object. The man machine and supervisory control concepts for teleoperation from the spacelab and from ground are discussed. The predictive estimation schemes for an extensive use of time-delay compensating 3D computer graphics are explained.

Hirzinger, G.↗
NASA NTRS1991

A new active virtual pivot six-degree-of-freedom hand controller for aerospace applications

During 1989 a new six-degree-of-freedom (6-DOF) active hand controller concept was designed and constructed based on the concept of a virtual pivot. This concept, labeled VPHC, was first demonstrated in a 1985 study and a patent was issued in 1990. Operator control input occurs via a force/torque sensor rigidly mounted to the handgrip. Sensed force/torque signals are used by microprocessors to generate motor drive control for each of six independently controlled motors mounted on the three-legged mechanism. The control microprocessor uses input biasing and rate-feedback motor controllers to generate the sensed feel of virtual springs and deadbands found in more conventional designs. An important advantage of this design is that the location of the virtual pivots, reflective forces and torques, breakout force levels, sensed spring rates, and operating modes, can be changed simply by changing the software. This approach yields an autonomous VPHC that can easily adapt itself to an individual operator (by software extension). A proof-of-concept version has been demonstrated, and further improvements are currently being studied and implemented.

Marshall, William C.↗
NASA NTRS1985

Bearing Tester Data Compilation Analysis, and Reporting and Bearing Math Modeling

The magnitude and direction of fluid induced torques and forces on the 57 mm bearing cage is considered to be a contributing factor in possible cage instabilities that can produce intermittent high heating in the bearing. Analyses of the fluid forces and torques are presented. Heat generated by viscous fluid work was estimated for two flow diverter configurations and a coolant flow of 10 lbs/sec to support the thermal evaluation of the LOX Bearing Materials Tester. Results of the analysis of the LOX turbopump turbine end bearings are discussed. Coolant velocities for the no. 4 LOX turbopump turbine end bearings were estimated as a function of shaft speed and coolant flow rate. Contact angles and track width data were developed for the 57 mm bearing as functions of shaft speed, and axial and radial loads. The Advanced Dynamics of Rolling Elements (ADORE) computer program was installed on the MSFC UNIVAC 1100 and a test case successfully run. Both the text output and the plotting output were verified. The Bearing Seal and Materials Tester - Test Condition Data Base was developed. The parametric analysis of the operating characteristics of the LOX turbopump pump end bearing using the 45 mm bearing thermal model was begun.

Source record↗
NASA NTRS1991

Infrastructure for deployment of power systems

A preliminary effort in characterizing the types of stationary lunar power systems which may be considered for emplacement on the lunar surface from the proposed initial 100-kW unit in 2003 to later units ranging in power from 25 to 825 kW is presented. Associated with these power systems are their related infrastructure hardware including: (1) electrical cable, wiring, switchgear, and converters; (2) deployable radiator panels; (3) deployable photovoltaic (PV) panels; (4) heat transfer fluid piping and connection joints; (5) power system instrumentation and control equipment; and (6) interface hardware between lunar surface construction/maintenance equipment and power system. This report: (1) presents estimates of the mass and volumes associated with these power systems and their related infrastructure hardware; (2) provides task breakdown description for emplacing this equipment; (3) gives estimated heat, forces, torques, and alignment tolerances for equipment assembly; and (4) provides other important equipment/machinery requirements where applicable. Packaging options for this equipment will be discussed along with necessary site preparation requirements. Design and analysis issues associated with the final emplacement of this power system hardware are also described.

Sprouse, Kenneth M.↗
NASA NTRS1993

Quantitative Tester And Reconditioner For Hand And Arm

Apparatus measures torques, forces, and motions of hand, wrist, forearm, elbow, and shoulder and aids in reconditioning muscles involved. Used to determine strengths and endurances of muscles, ranges of motion of joints, and reaction times. Provides quantitative data used to assess extent to which disuse, disease, or injury causes deterioration of muscles and of motor-coordination skills. Same apparatus serves as exercise machine to restore muscle performance by imposing electronically controlled, gradually increasing loads on muscles. Suitable for training and evaluating astronauts, field testing for workers' compensation claims, and physical therapy in hospitals. With aid of various attachments, system adapted to measure such special motions as pinching, rotation of wrist, and supination and pronation of the forearm. Attachments are gloves, wristlets, and sleeves.

Engle, Gary↗
NASA NTRS1991

Proximity operations considerations affecting spacecraft design

Proximity operations can be defined as the maneuvering of two or more spacecraft within 1 nautical mile range, with relative velocity less than 10 feet per second. The passive vehicle is nontranslating and should provide for maintenance of the desired approach attitude. It must accommodate the active (translating) vehicle induced structural loads and performance characteristics (mating hardware tolerances), and support sensor compatibility (transponder, visual targets, etc.). The active vehicle must provide adequate sensor systems (relative state information, field-of-view, redundancy), flight control hardware (thruster sizing, minimal cross-coupling, performance margins, redundancy) and software (reconfigurable, attitude/rate modes, translation and rotation fine control authority) characteristic, and adequate non-propulsive consumables such as power. Operational concerns must be considered. These include the following: (1) the desired approach trajectory and relative orientation; (2) the active vehicle thruster plume effects (forces, torques, contamination) on the passive vehicle; and (3) procedures for contingencies such as loss of communications, sensor or propulsion failures, and target vehicle loss of control.

Staas, Steven K.↗
NASA NTRS1991

Magnetic end effectors for space operations

The Magnetic End Effector (MEE) to be flown as part of the Dexterous End Effector (DEE) flight experiment was designed to operate with the Shuttle Remote Manipulator System (SRMS). Grappling or attachment of payloads is accomplished magnetically with two fault tolerant operations. The small magnetic grapple plate weighs far less than the standard grapple fixture; allows stacking and close spacing of payloads; and eliminates secondary release mechanisms. In addition to specifics regarding the MEE, the DEE project, Magnetic Attachment Tool (MAT), RMS-Force Torque Sensor (RMS-FTS), and Targeting and Reflective Alignment Concept (TRAC) are discussed.

Monford, Leo↗
NASA NTRS1990

Flight telerobotic servicer

Viewgraphs on the Space Station Flight Telerobotic Servicer (SSFTS) are presented. Topics covered include: SSFTS design; SSFTS elements; FTS mission requirements; FTS general requirements; flight telerobotic servicer - telerobot; FTS manipulator; force-torque transducer; end effector changeout mechanism; flight telerobotic servicer - end-of-arm tooling; user interfaces; FTS data management and processing; control subsystem; FTS vision subsystem and camera positioning assembly; FTS workstation display assembly panel; mini-master hand controller; and FTS NASREM system architecture.

Haley, Dennis↗
NASA NTRS1994

Dexterous end effector flight demonstration

The Dexterous End Effector Flight Experiment is a flight demonstration of newly developed equipment and methods which make for more dexterous manipulation of robotic arms. The following concepts are to be demonstrated: The Force Torque Sensor is a six axis load cell located at the end of the RMS which displays load data to the operator on the orbiter CCTV monitor. TRAC is a target system which provides six axis positional information to the operator. It has the characteristic of having high sensitivity to attitude misalignment while being flat. AUTO-TRAC is a variation of TRAC in which a computer analyzes a target, displays translational and attitude misalignment information, and provides cues to the operator for corrective inputs. The Magnetic End Effector is a fault tolerant end effector which grapples payloads using magnetic attraction. The Carrier Latch Assembly is a fault tolerant payload carrier, which uses mechanical latches and/or magnetic attraction to hold small payloads during launch/landing and to release payloads as desired. The flight experiment goals and objectives are explained. The experiment equipment is described, and the tasks to be performed during the demonstration are discussed.

Carter, Edward L.↗
NASA NTRS1995

Simulating the dynamic interaction of a robotic arm and the Space Shuttle remote manipulator system

Industrial robots are usually attached to a rigid base. Placing the robot on a compliant base introduces dynamic coupling between the two systems. The Vehicle Emulation System (VES) is a six DOF platform that is capable of modeling this interaction. The VES employs a force-torque sensor as the interface between robot and base. A computer simulation of the VES is presented. Each of the hardware and software components is described and Simulink is used as the programming environment. The simulation performance is compared with experimental results to validate accuracy. A second simulation which models the dynamic interaction of a robot and a flexible base acts as a comparison to the simulated motion of the VES. Results are presented that compare the simulated VES motion with the motion of the VES hardware using the same admittance model. The two computer simulations are compared to determine how well the VES is expected to emulate the desired motion. Simulation results are given for robots mounted to the end effector of the Space Shuttle Remote Manipulator System (SRMS). It is shown that for fast motions of the two robots studied, the SRMS experiences disturbances on the order of centimeters. Larger disturbances are possible if different manipulators are used.

Garrahan, Steven L.↗
NASA NTRS1995

Some mechanical design aspects of the European Robotic Arm

The European Robotic Arm (ERA) is a contribution to the Russian Segment of the International Space Station Alpha. It will start operating on the Russian Segment during the assembly phase. ERA is designed and produced by a large industrial consortium spread over Europe with Fokker Space & Systems as prime contractor. In this paper, we will describe some of the overall design aspects and focus on the development of several mechanisms within ERA. The operation of ERA during the approach of its end effector towards the grapple interface and the grapple operation is discussed, with a focus on mechanisms. This includes the geometry of the end effector leading edge, which is carefully designed to provide the correct and complete tactile information to a torque-force sensor (TFS). The data from this TFS are used to steer the arm such that forces and moments are kept below 20 N and 20 N.m respectively during the grappling operation. Two hardware models of the end effector are built. The problems encountered are described as well as their solutions. The joints in the wrists and the elbow initially used a harmonic drive lubricated by MoS2. During development testing, this combination showed an insufficient lifetime in air to survive the acceptance test program. The switch-over to a system comprising planetary gearboxes with grease lubrication is described. From these development efforts, conclusions are drawn and recommendations are given for the design of complex space mechanisms.

Lambooy, Peter J.↗