mechanical and fluid systems
Lateral Kevlar Suspension Device (LKSD)
This device has the ability to maintain consistent tension by taking advantage of the Kevlars high strength and low thermal conductivity properties. In addition to Kevlar, the unit is equipped with three spring-loaded tension assemblies should the band slacken during the cooling process, the spring force directs the pulley in an outward direction taking up any slack and maintaining the tension and stiffness of the system. This provides stability and good thermal isolation to the load attached while reducing parasitic heating.
mechanical and fluid systems
A Method for Accurate Load/Position Control of Rigidly-Coupled Electromechanical Actuators
The solution rests on the idea of using homogeneous control loops to achieve heterogeneous simultaneous objectives controlling for both load and position values in this case. As a first step, the actuators are synchronized, moving in unison, so the load cell will not register any load. The proper load is then generated by calculating an offset, or virtual position, that one or both actuators can achieve in position tracking to generate the right load in the coupled system. For example, both actuators could be moved to position 50 with zero load. Then, while one is kept at 50, the other could be moved to 49 (for a tensile load) or 51 (for a compressive load). The key computation is to determine the correct virtual positions for each of the actuators that will result both in the desired actual position and the desired load. The primary benefit of the described approach is that it allows stable control of highly dynamic systems and not just static ones. Complicated position profiles can be executed while simultaneously maintaining accurate load profiles.
information technology and software
Inductive Monitoring System
The Inductive Monitoring System (IMS) software provides a method of building an efficient system health monitoring software module by examining data covering the range of nominal system behavior in advance and using parameters derived from that data for the monitoring task. This software module also has the capability to adapt to the specific system being monitored by augmenting its monitoring database with initially suspect system parameter sets encountered during monitoring operations, which are later verified as nominal. While the system is offline, IMS learns nominal system behavior from archived system data sets collected from the monitored system or from accurate simulations of the system. This training phase automatically builds a model of nominal operations, and stores it in a knowledge base. The basic data structure of the IMS software algorithm is a vector of parameter values. Each vector is an ordered list of parameters collected from the monitored system by a data acquisition process. IMS then processes select data sets by formatting the data into a predefined vector format and building a knowledge base containing clusters of related value ranges for the vector parameters. In real time, IMS then monitors and displays information on the degree of deviation from nominal performance. The values collected from the monitored system for a given vector are compared to the clusters in the knowledge base. If all the values fall into or near the parameter ranges defined by one of these clusters, it is assumed to be nominal data since it matches previously observed nominal behavior. The IMS knowledge base can also be used for offline analysis of archived data.
Measuring Optical Null Lens Aberrations
This innovation uses image-based wavefront sensing or phase retrieval which uses light traveling through the optical system in generally the same way that it will in its as-used configuration. It estimates the wavefront of the optical system using images collected on a light detector (which can be the same detector used by the optical system in its intended use). This method uses several images taken through the null optic under test, with some aspect of the test setup being systematically varied from one image to the next. Usually this variation involves somewhat out-of-focus images that are taken systematically with different amounts of defocus. The light for each diversity-defocus image passes through the optical test setup and the null lens. The resulting irradiance of the transmitted beam is measured by a light detector and this image is saved on a computer where algorithms determine an estimate of the null lens's wavefront aberrations.
electrical and electronics
Sampling and Control Circuit Board
For fast platform dynamics, it is necessary to sample the IMU at quick intervals in order to fulfill the Nyquist sampling theorem requirements. This can be difficult in cases where low size, weight, and power are required, since a primary processor may already be saturated running the navigation algorithm or other system functions. Glenn's novel circuit board was designed to handle the sampling process (involving frequent interrupt requests) in parallel, while delivering the resulting data to a buffered communication port for inclusion in the navigation algorithm on an as-available basis. The circuit operates using a universal serial bus (USB) or Bluetooth interface. A control command is sent to the circuit from a separate processor or computer that instructs the circuit how to sample data. Then, a one-pulse-per-second signal from a GPS receiver or other reliable time source is sent to trigger the circuit to perform automatic data collection from the IMU sensor. This is an early-stage technology requiring additional development. Glenn welcomes co-development opportunities.
Terahertz Quantum Cascade Laser Source
THz occupies the frequency gap between microwaves and infrared light waves. THz produces a frequency that is both coherent and spectrally broad, so such images can contain far more information than a conventional image formed with a single-frequency source. Although THz frequency can penetrate fabrics and plastics, it is non-ionizing and therefore harmless to living tissue or DNA, making it very valuable for imaging and screening applications. Scientists have attempted to find practical ways to use a QCL as a tunable source for THz frequencies for a variety of applications, but until now, have been unable to overcome obstacles in cost and fabrication. Glenn's innovation is a THz QCL source (range 1 to 5 THz) based on a passive waveguide tuning mechanism that can use the full bandwidth of a broadband THz QCL and produce a vast number of frequency channels. In Glenns process, a tunable QCL is coupled to a grating router, which consists of an appropriately configured linear dielectric array. The grating router receives a THz frequency from the QCL and generates a high density of THz frequencies. The output of the grating router enters an on/off switching waveguide controller, which is configured to select one desired THz frequency. This desired frequency is then fed into a waveguide multiplexer, which combines the output ports of the controller into a single signal for transmission. Glenn's novel technology unlocks the potential for THz frequencies to revolutionize sensing and imaging applications across a wide range of industries. This is an early-stage technology requiring additional development, and Glenn welcomes co-development opportunities.
mechanical and fluid systems
Compact Vibration Damper
Structural vibrations frequently need to be damped to prevent damage to a structure. To accomplish this, a standard linear damper or elastomeric-suspended masses are used. The problem associated with a linear damper is the space required for its construction. For example, if the damper's piston is capable of three inches of movement in either direction, the connecting shaft and cylinder each need to be six inches long. Assuming infinitesimally thin walls, connections, and piston head, the linear damper is at least 12 inches long to achieve +/-3 inches of movement. Typical components require 18+ inches of linear space. Further, tuning this type of damper typically involves fluid changes, which can be tedious and messy. Masses suspended by elastomeric connections enable even less range of motion than linear dampers. The NASA invention is for a compact and easily tunable structural vibration damper. The damper includes a rigid base with a slider mass for linear movement. Springs coupled to the mass compress in response to the linear movement along either of two opposing directions. A rack-and-pinion gear coupled to the mass converts the linear movement to a corresponding rotational movement. A rotary damper coupled to the converter damps the rotational movement. To achieve +/- 3 inches of movement, this design requires slightly more than six inches of space.
Gas Composition Sensing Using Carbon Nanotube Arrays
An array of carbon nanotubes (CNTs) in a substrate is connected to a variable-pulse voltage source. The CNT tips are spaced appropriately from the second electrode maintained at a constant voltage. A sequence of voltage pulses is applied and a pulse discharge breakdown threshold voltage is estimated for one or more gas components, from an analysis of the current-voltage characteristics. Each estimated pulse discharge breakdown threshold voltage is compared with known threshold voltages for candidate gas components to estimate whether at least one candidate gas component is present in the gas. The procedure can be repeated at higher pulse voltages to estimate a pulse discharge breakdown threshold voltage for a second component present in the gas. The CNTs in the gas sensor have a sharp (low radius of curvature) tip; they are preferably multiwall carbon nanotubes (MWCNTs) or carbon nanofibers (CNFs), to generate high-strength electrical fields adjacent to the current collecting plate, such as a gold plated silicon wafer or a stainless steel plate for breakdown of the gas components with lower voltage application and generation of high current. The sensor system can provide a high-sensitivity, low-power-consumption tool that is very specific for identification of one or more gas components. The sensors can be multiplexed to measure current from multiple CNT arrays for simultaneous detection of several gas components.
mechanical and fluid systems
Full-Size Reduced Gravity Simulator For Humans, Robots, and Test Objects
The Active Response Gravity Offload System (ARGOS) provides a simulated reduced gravity environment that responds to human-imparted forces. System capabilities range from full gravity to microgravity. The system utilizes input/feedback sensors, fast-response motor controllers, and custom-developed software algorithms to provide a constant force offload that simulates reduced gravity. The ARGOS system attaches to a human subject in a gimbal and/or harness through a cable. The system then maintains a constant offload of a portion of the subjects weight through the cable to simulate reduced gravity. The system supports movements in all 3 dimensions consistent with the selected gravity level. Front/back and left/right movements are supported via a trolley on an overhead runway and bridge drive system, and up/down movements are supported via a precisely positioned cable. The system runs at a very high cycle rate, and constantly receives feedback to ensure the human subjects safety.
mechanical and fluid systems
Feedthrough for Severe Environments and Temperatures
Space and ground launch support related hardware often operate under extreme pressure, temperature, and corrosive conditions. When dealing with this type of equipment, it is frequently necessary to run wiring, tubes, or fibers through a barrier separating one process from another with one or both operating in extreme environments. Feedthroughs used to route the wiring, tubes, or fibers through these barriers must meet stringent sealing and leak tightness requirements. This affordable NASA feedthrough meets or exceeds all sealing and leak requirements utilizing easy-to-assemble commercial-off-the-shelf hardware with no special tooling. The feedthrough is a fully reconfigurable design; however, it can also be produced as a permanent device. Thermal cycling and helium mass spectrometer leak testing under extreme conditions of full cryogenic temperatures and high vacuum have proven the sealing capability of this feedthrough with or without potting (epoxy fill) on the ends. Packing material disks used in the construction of the device can be replaced as needed for rebuilding a given feedthrough for another job or a different set of feeds if potting is not used for the original feedthrough build. (Potting on one or both sides of the sleeve provides double or triple leak sealing protection). Variable Compression Ratio (VCR) connectors were adapted for the pressure seal on the feedthrough; however, any commercial connector can be similarly adapted. The design can easily be scaled up to larger (2" diameter) and even very large (12" or more) sizes.