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Release of a Stuck Solar Array or Antenna

Several options are examined that may also be useful in remotely controlled terrestrial environments. Goddard Space Flight Center, Greenbelt, Maryland Satellite launches experience approximately one deployment failure every two years. These failures include a solar array or antenna that fails to deploy because it is stuck due to a mechanism failure, or is snagged by a cable or thermal blanket. Knowledge of the exact circumstances of the deployable failure is limited. Ground commanding of the spacecraft is conducted in an attempt to free the stuck deployable.

Posted in: Briefs, Mechanical Components, Machinery & Automation

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High-Heat-Flux-Capable Boundary Layer Vortex Generator and Boundary Layer Transition Device

Lyndon B. Johnson Space Center, Houston, Texas Afixed geometry device has been developed to promote boundary layer transition and generation of streamwise vorticity, and is capable of withstanding entry heating environments for the Space Shuttle Orbiter. Designed to have a total height above the surface of the same order as the local boundary layer thickness, this device is approximately 0.25 in. (≈0.6 cm) tall and 4 in. (≈10 cm) long for the Orbiter entry application. Because temperature exposure is a key design factor for entry systems, the geometry has been optimized to establish peak heating rates and peak surface temperatures that are close to being spatially consistent on the protuberance. A relatively thin cross-section of 0.4 in. (≈1 cm) provides significant thermal radiation relief via conduction through the aft surface of the geometry. Sufficient mechanical strength to satisfy launch, ascent, entry, and landing conditions has been maintained in the design.

Posted in: Briefs, Mechanical Components, Machinery & Automation

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GEMINI Stability Control for Reducing Pointing Jitter in CubeSats and Smallsats

Pointing jitter is significantly reduced by using two reaction wheels per axis, passive vibration isolators, and differential speed control. NASA’s Jet Propulsion Laboratory, Pasadena, California Because of the cost-effectiveness of flying smallsats compared to large flagship spacecraft, there is increasing interest in boosting their capabilities for supporting precision science payloads and sophisticated instrumentation. Unfortunately, a major current drawback with using smallsats is their inability to hold the pointing line-of-sight steady without jittering. Line-of-sight jitter degrades observations made by cameras and other imaging-type instruments, and fundamentally limits the quality of science that can be obtained.

Posted in: Briefs, Mechanical Components, Machinery & Automation

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Piezoelectric-Actuated Rotary Ultrasonic Motor

This motor can be used where rotary actuation is required, particularly in cryogenic and high-temperature applications. NASA’s Jet Propulsion Laboratory, Pasadena, California This actuator was developed out of a need for a cryogenic actuator that can operate effectively in spite of the thermal mismatch involved with construction materials that have different expansion coefficients. Also, there is a need for a cryogenic motor that can drive infrared systems and produce minimal thermal energy that can interfere with their operation.

Posted in: Briefs, Mechanical Components, Machinery & Automation

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Model-Driven Innovation in Machine Design

This whitepaper discusses a Model-Driven Innovation process, an approach that makes a multidomain, system-level model the core of design activities, allowing engineers to see how individual subsystems work together. With this approach, problems can be fixed early without project delays, and designs can be validated with access to the underlying mathematics, allowing organizations seeking to mitigate system complexities to improve their ability to control costs, produce high-quality designs and move products to market more quickly. Using tools like MapleSim, the multidomain system modeling tool from Maplesoft, enables engineers to develop and test high-fidelity virtual prototypes of their complex dynamic systems.

Posted in: White Papers, Manufacturing & Prototyping, Motion Control, Machinery & Automation, Robotics

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Limboid Reconfigurable Robots for In-Space Assembly

A Limboid workforce with access to a tool crib could staff robotic space factories. NASA’s Jet Propulsion Laboratory, Pasadena, California Figure 1. A laboratory prototype of a Limbi robot autonomously builds a modular structure. This process could repeat to build a large truss or spacecraft. As shown here, the modules are small, but a similar approach would work for large modules. Many future space vehicles, planetary bases, and mining operations will be too large and heavy to launch on a single rocket. Instead, component parts would need to be launched on multiple rockets and assembled in space. To enable versatile in-space assembly, a novel class of reconfigurable robots called Limboids has been conceptualized. Limboids are robotic limbs that attach and detach from each other to form a variety of useful configurations. These configurations might be as small as a single limb, which is best for dexterous manipulation of small parts, or as large as necessary for gross manipulation. As a modular system, Limboids could be supplemented with additional tools and limbs.

Posted in: Briefs, Machinery & Automation, Robotics

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Cam Hand

This robust gripper design has applicability to both robots and as a prosthetic for the physically challenged. NASA’s Jet Propulsion Laboratory, Pasadena, California A durable gripper tool was designed for use by RoboSimian robots intended for use in disaster scenarios that demand high-force, robust manipulation. The resulting Cam Hand fills a previously unaddressed niche that emphasizes grip strength and robustness over dexterity. The design uses a number of unique features to ensure high operational flexibility. While this gripper was created for use on a robot, its basic design could be refined for other applications; in particular, as a new class of prosthetic that would exist between the traditional hook and pinch models and the dexterous models currently under development.

Posted in: Briefs, Machinery & Automation, Robotics

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