Special Coverage

Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space
Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines
Vibration Tables Shake Up Aerospace and Car Testing
Supercomputer Cooling System Uses Refrigerant to Replace Water
Computer Chips Calculate and Store in an Integrated Unit
Electron-to-Photon Communication for Quantum Computing

Automated Apparatus for Testing Gyroscopes

Except for initial setting of conditions, the entire testing process is automated.

The Gyroscope Automated Testbed is a computer-controlled apparatus designed primarily for automated testing of vibratory gyroscopes. It can also be used to test other devices: By changing testing-system/tested-device interface circuitry that is part of the apparatus, one can set up the apparatus to test nonvibratory gyroscopes. The apparatus can also be used as a general-purpose noise-analysis system for characterizing a variety of devices in addition to gyroscopes.

Posted in: Briefs, TSP, Test & Measurement, Automation, Test equipment and instrumentation

Electromechanical Testing of Microelectromechanical Devices

Devices would be probed at the wafer level before dicing and packaging.

A method of electromechanical testing has been proposed for general diagnosis, evaluation of performance, and burn-in (accelerated life testing) of microelectromechanical devices. The tests would ordinarily be performed at the wafer level; that is, after the devices have been fabricated on wafers but before the wafers have been diced and the dies packaged. Alternatively or in addition, the tests could be performed at other stages of the fabrication process.

Posted in: Briefs, TSP, Test & Measurement, Microelectromechanical devices, Test procedures

Mechanism for Adjusting and Measuring Tension in a Cable

Where measurement is necessary, this mechanism could be preferable to a turnbuckle.

The figure illustrates a simple mechanism designed for anchoring one end of a cable on a structure and for adjusting the tension in the cable. Unlike turnbuckles and other conventional cable-tensioning mechanisms, this mechanism also facilitates direct measurement of the tension in the cable. Several of these mechanisms are used in concert in order to suspend a structure for thermal isolation.

Posted in: Briefs, TSP, Test & Measurement, Measurements, Fittings, Mountings, Parts

Antioxidant Fiber Finishes for Polyimide-Matrix Composites

These are reactive finishes that increase thermo-oxidative stability.

Polyimide-matrix/carbon-fiber composite materials with enhanced thermo-oxidative stability can be made from carbon fibers that have been coated with suitably formulated reactive finishing materials. These finishing materials were developed out of a need to increase thermo-oxidative stability of composite materials for high-temperature applications, and in response to the observation that thermo-oxidative degradation of polyimide-matrix/carbon-fiber composites is dominated by phenomena that occur at matrix/fiber interfaces.

Posted in: Briefs, TSP, Materials, Composite materials, Fibers, Heat resistant materials, Materials properties, Polymers

Enhanced Shield Against Meteoroids and Orbital Debris

This shield significantly decreases the likelihood of loss of a crew and/or spacecraft.

NASA scientists, who are very concerned with the increasing hazard of impacts of orbital debris impact on spacecraft, have designed the "stuffed Whipple" shield — a lightweight, relatively inexpensive alternative to simple aluminum meteoroid/orbital-debris (M/OD) shield. The stuffed Whipple shield features an easily adaptable design that increases protection against hypervelocity impacts (HVIs), without significantly affecting previously formulated designs of spacecraft. The stuffed Whipple shield is critical to the continued human exploration of space, especially to the Space Station, inasmuch as the Station will be operating in low orbit around the Earth and will need shielding against HVIs in order to survive intact and for an appreciable amount of time and continue to safely support human habitation. Scientists project that the number of HVIs from detritus of artificial objects will increase from 2 to 5 percent per year— an increase that could produce devastating results.

Posted in: Briefs, Materials, Protective structures, Spacecraft

High-Performance Zn Anodes for Ag/Zn and Ni/Zn Cells

Cycle lives are increased and costs are reduced.

Improved zinc anodes for silver/zinc and nickel/zinc rechargeable electrochemical cells have been invented. This invention will increase the usefulness and decrease cycle-life costs of Ag/Zn and Ni/Zn cells in NASA Space-Station-support applications, for which batteries with high energy densities and long cycle lives are needed; examples of these applications include extravehicular mobility unit (EMU) batteries, the EMU portable life-support subsystem (PLSS) backpack batteries, and batteries in portable tools and equipment for extravehicular activities (EVAs). Inasmuch as many of these portable tools and other items of equipment are modified versions of commercial items (portable tools, lights, cameras, recorders, camcorders, radios, communications equipment, cellular telephones, and medical equipment), this invention might also prove beneficial in numerous commercial applications. Similarly, it could offer benefits in military applications, other government applications, and other applications that involve batteries.

Posted in: Briefs, Materials, Battery cell chemistry, Nickel alloys, Zinc alloys

Tape-Spring Reinforcements for Inflatable Structural Tubes

Tape-springs and tubes help each other resist buckling.

Lightweight, inflatable tubular structural components containing tape-spring reinforcements are undergoing development. The basic (without tape-spring reinforcement) tubular components are made, variously, of aluminum laminates or composite materials and are under consideration for use in erecting structures in outer space. They could also be used to erect structures for terrestrial applications in situations in which a greater value is placed in light weight than on strength.

Posted in: Briefs, TSP, Materials, Aluminum, Composite materials, Lightweight materials

Mechanism for Planar Manipulation With Simplified Kinematics

Simple combinations of actuator motions yield purely radial or purely tangential end-effector motions.

The figure schematically illustrates three manipulator mechanisms for positioning an end effector (a robot hand or other object) in a plane (which would ordinarily be horizontal). One of these is a newer, improved mechanism that includes two coaxial, base-mounted rotary actuators incorporated into a linkage that is classified as "P4R" in the discipline of kinematics of mechanisms because it includes one prismatic (P) joint and four revolute (R) joints. The improved mechanism combines the advantages of coaxial base mounting (as opposed to noncoaxial and/or nonbase mounting) of actuators, plus the advantages of closed-loop (as opposed to open-loop) linkages in such a way as to afford a simplification (in comparison with other linkages) of inverse kinematics. Simplification of the kinematics reduces the computational burden incurred in controlling the manipulator.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Kinematics, Robotics

Improved Cable-Drive Pretensioner

Tension is adjusted easily by use of a worm gear.

An improved mechanism has been devised to facilitate the adjustment of tension in a cable in a cable-and-pulley drive. Cable-and-pulley drives are being used increasingly in robots and other high-performance, computer-controlled machines. Typically, a cable is looped around various drive pulleys with its ends anchored in proximity to each other on two coaxial cylinders (see figure). During operation of the cable drive, the cylinders are locked against rotation relative to each other to maintain a preset tension. To adjust the tension, it is necessary to unlock the cylinders and rotate them relative to each other.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Performance upgrades, Robotics, Electric drives, Flywheels

Path-Planning Program for a Redundant Robotic Manipulator

This program utilizes kinematic redundancy to find singularity-free, obstacle-avoiding paths.

The Space Station Robot Manipulator System (SSRMS) Path Planning Program is a computer program that, in comparison with software developed previously for the same purpose, supports operations of faster and more complex robots. Two especially notable features of the program are that (1) it makes for ease of description of the work space of a remote manipulator or other robot and (2) it takes advantage of redundant degrees of freedom of the manipulator by finding manipulator-link paths that avoid both mathematical singularities and physical obstacles. The program can be applied not only to space-station manipulators and other robots but also to manipulators and other robots used in remediation of waste sites and dismantling nuclear facilities. With moderate modifications, the program could even be used in reconfigurable manufacturing operations.

Posted in: Briefs, Mechanical Components, Mechanics, Architecture, Computer software and hardware, Robotics, Hazards and emergency management, Hazards and emergency operations, Spacecraft

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