Mechanical Components

Implementation of a Non-Metallic Barrier in an Electric Motor

Electric motors that run in pure oxygen must be sealed, or “canned,” for safety reasons to prevent the oxygen from entering into the electrical portion of the motor. The current canning process involves designing a metallic barrier around the rotor to provide the separation. This metallic barrier reduces the motor efficiency as speed is increased. In higher-speed electric motors, efficiency is greatly improved if a very thin, non-metallic barrier can be utilized. The barrier thickness needs to be approximately 0.025-in. (≈0.6-mm) thick and can be made of a brittle material such as glass. The motors, however, designed for space applications are typically subject to high-vibration environments.

Posted in: Mechanics, Mechanical Components, Briefs

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Thermionic Power Cell To Harness Heat Energies for Geothermal Applications

Possible uses include geothermal exploration, automotive, and renewable energy applications. A unit thermionic power cell (TPC) concept has been developed that converts natural heat found in high-temperature environments (460 to 700 ºC) into electrical power for in situ instruments and electronics. Thermionic emission of electrons occurs when an emitter filament is heated to “white hot” temperatures (>1,000 ºC) allowing electrons to overcome the potential barrier and emit into the vacuum. These electrons are then collected by an anode, and transported to the external circuit for energy storage.

Posted in: Mechanics, Mechanical Components, Briefs

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Space Mirror Alignment System

An optical alignment mirror mechanism (AMM) has been developed with angular positioning accuracy of ±0.2 arcsec. This requires the mirror’s linear positioning actuators to have positioning resolutions of ±112 nm to enable the mirror to meet the angular tip/tilt accuracy requirement. Demonstrated capabilities are ±0.1 arc-sec angular mirror positioning accuracy, which translates into linear positioning resolutions at the actuator of ±50 nm.

Posted in: Mechanics, Mechanical Components, Briefs

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Spacesuit Soft Upper Torso Sizing Systems

This system has application in medical devices for immobilizing injured limbs or applying controlled pressure to areas of the body of a burn victim. The passive sizing system consists of a series of low-profile pulleys attached to the front and back of the shoulder bearings on a spacesuit soft upper torso (SUT), textile cord or stainless steel cable, and a modified commercial ratchet mechanism. The cord/cable is routed through the pulleys and attached to the ratchet mechanism mounted on the front of the spacesuit within reach of the suited subject. Upon actuating the ratchet mechanism, the shoulder bearing breadth is changed, providing variable upper torso sizing.

Posted in: Mechanics, Mechanical Components, Briefs

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Graph Theory Roots of Spatial Operators for Kinematics and Dynamics

These concepts can be applied to modeling, simulation, and control of robots and other mechanisms. Spatial operators have been used to analyze the dynamics of robotic multibody systems and to develop novel computational dynamics algorithms. Mass matrix factorization, inversion, diagonalization, and linearization are among several new insights obtained using such operators. While initially developed for serial rigid body manipulators, the spatial operators — and the related mathematical analysis — have been shown to extend very broadly including to tree and closed topology systems, to systems with flexible joints, links, etc. This work uses concepts from graph theory to explore the mathematical foundations of spatial operators. The goal is to study and characterize the properties of the spatial operators at an abstract level so that they can be applied to a broader range of dynamics problems.

Posted in: Mechanics, Mechanical Components, Briefs

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Umbilical Deployment Device

NASA’s next-generation Mars rover encompasses this novel landing technique. The landing scheme for NASA’s next-generation Mars rover will encompass a novel landing technique (see figure). The rover will be lowered from a rocket-powered descent stage and then placed onto the surface while hanging from three bridles. Communication between the rover and descent stage will be maintained through an electrical umbilical cable, which will be deployed in parallel with structural bridles.

Posted in: Mechanical Components, Briefs

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Modular Rake of Pitot Probes

Individual probes can be replaced more easily than was possible before. The figure presents selected views of a modular rake of 17 pitot probes for measuring both transient and steady-state pressures in a supersonic wind tunnel. In addition to pitot tubes visible in the figure, the probe modules contain (1) high-frequency dynamic-pressure transducers connected through wires to remote monitoring circuitry and (2) flow passages that lead to tubes that, in turn, lead to remote steady-state pressure transducers.

Posted in: Mechanics, Mechanical Components, Briefs

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