Special Coverage

Transducer-Actuator Systems for On-Machine Measurements and Automatic Part Alignment
Wide-Area Surveillance Using HD LWIR Uncooled Sensors
Heavy Lift Wing in Ground (WIG) Cargo Flying Boat
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

Virtualizing Physical Measurements Using Wireless Sensor Technology

Benefits include the elimination of wired connections and having advanced signal processing capabilities within each sensor.

Virtualizing physical measurements using wireless sensor technology enables a host of new solution choices. Wireless sensors are smart devices that realize measurements without using external data acquisition (DAQ) equipment or external power sources. The hardware needed to directly digitize low-level signals resides within each sensor. The analog-to-digital converter (ADC) found in a highly integrated microcontroller is typically accompanied by a multiplexer (MUX) and programmable gain amplifier (PGA). Further inclusion of other mixed-signal peripherals such as comparators and digital-to-analog converters (DAC) promote the sensor as a complete measurement processing system.

Posted in: Briefs, Electronics & Computers, Measurements, Sensors and actuators, Sensors and actuators

Control Architecture for Robotic Agent Command and Sensing

Plans and behaviors are updated in response to changing requirements and conditions.

Control Architecture for Robotic Agent Command and Sensing (CARACaS) is a recent product of a continuing effort to develop architectures for controlling either a single autonomous robotic vehicle or multiple cooperating but otherwise autonomous robotic vehicles. CARACaS is potentially applicable to diverse robotic systems that could include aircraft, spacecraft, ground vehicles, surface water vessels, and/or underwater vessels.

Posted in: Briefs, TSP, Information Sciences, Architecture, Architecture, Robotics, Autonomous vehicles, Marine vehicles and equipment, Spacecraft, Unmanned aerial vehicles

Improved Airborne System for Sensing Wildfires

Unlike prior such systems, this system could be operated in daylight.

The Wildfire Airborne Sensing Program (WASP) is engaged in a continuing effort to develop an improved airborne instrumentation system for sensing wildfires. The system could also be used for other aerial-imaging applications, including mapping and military surveillance.

Posted in: Briefs, Electronics & Computers, Fire detection

CO₂ Sensors Based on Nanocrystalline SnO₂ Doped With CuO

Miniature CO2 sensors could be mass-produced inexpensively.

Nanocrystalline tin oxide (SnO2) doped with copper oxide (CuO) has been found to be useful as an electrical-resistance sensory material for measuring the concentration of carbon dioxide in air. SnO2 is an n-type semiconductor that has been widely used as a sensing material for detecting such reducing gases as carbon monoxide, some of the nitrogen oxides, and hydrocarbons. Without doping, SnO2 usually does not respond to carbon dioxide and other stable gases. The discovery that the electrical resistance of CuO-doped SnO2 varies significantly with the concentration of CO2 creates opportunities for the development of relatively inexpensive CO2 sensors for detecting fires and monitoring atmospheric conditions. This discovery could also lead to research that could alter fundamental knowledge of SnO2 as a sensing material, perhaps leading to the development of SnO2-based sensing materials for measuring concentrations of oxidizing gases.

Posted in: Briefs, TSP, Materials, Sensors and actuators, Sensors and actuators, Conductivity, Copper alloys, Nanotechnology, Refractory materials, Tin alloys

Algorithm for Wavefront Sensing Using an Extended Scene

The restriction to a point source has been removed.

A recently conceived algorithm for processing image data acquired by a Shack-Hartmann (SH) wavefront sensor is not subject to the restriction, previously applicable in SH wavefront sensing, that the image be formed from a distant star or other equivalent of a point light source. That is to say, the image could be of an extended scene. (One still has the option of using a point source.) The algorithm can be implemented in commercially available software on ordinary computers.

Posted in: Briefs, TSP, Information Sciences, Mathematical models, Computer software / hardware, Computer software and hardware, Remote sensing, Computer software / hardware, Computer software and hardware, Remote sensing

Onboard Data Processor for Change-Detection Radar Imaging

This system could be used to map earthquakes, landslides, floods, and wildfires.

A computer system denoted a change-detection onboard processor (CDOP) is being developed as a means of processing the digitized output of a synthetic-aperture radar (SAR) apparatus aboard an aircraft or spacecraft to generate images showing changes that have occurred in the terrain below between repeat passes of the aircraft or spacecraft over the terrain. When fully developed, the CDOP is intended to be capable of generating SAR images and/or SAR differential interferograms in nearly real time. The CDOP is expected to be especially useful for understanding some large-scale natural phenomena and/or mitigating natural hazards: For example, it could be used for near-real-time observation of surface changes caused by floods, landslides, forest fires, volcanic eruptions, earthquakes, glaciers, and sea ice movements. It could also be used to observe such longer-term surface changes as those associated with growth of vegetation (relevant to estimation of wildfire fuel loads).

Posted in: Briefs, TSP, Semiconductors & ICs, Computer software / hardware, Computer software and hardware, Imaging, Imaging and visualization, Radar, Computer software / hardware, Computer software and hardware, Imaging, Imaging and visualization, Radar, Terrain, Weather and climate

System for Measuring Flexing of a Large Spaceborne Structure

An optoelectronic metrology system is used for determining the attitude and flexing of a large spaceborne radar antenna or similar structure. The measurements are needed for accurate pointing of the antenna and correction and control of the phase of the radar signal wavefront. The system includes a dual-field-of-view star tracker; a laser ranging unit (LRU) and a position-sensitive-detector (PSD)-based camera mounted on an optical bench; and fiducial targets at various locations on the structure.

Posted in: Briefs, Electronics & Computers, Calibration, Measurements, Antennas, Radar, Antennas, Radar

VHF Wide-Band, Dual-Polarization Microstrip-Patch Antenna

A dual-stacked-patch design incorporates several improvements over a basic design.

The figure depicts selected aspects of a very-high-frequency (VHF) microstrip-patch antenna designed and built to satisfy requirements specific to an airborne synthetic-aperture radar system for measuring the thickness of sea ice. One of the requirements is that the antenna be capable of functioning over the relatively wide frequency band of 127 to 172 MHz — corresponding to a fractional bandwidth of about 30 percent relative to a nominal mid-band frequency of 149.5 MHz. Another requirement is that the antenna be capable of functioning in either or both of two orthogonal linear polarizations. In addition, the antenna is required to be as compact and lightweight as possible.

Posted in: Briefs, Electronics & Computers, Antennas, Architecture, Radar, Antennas, Architecture, Radar, Weather and climate

Using LDPC Code Constraints To Aid Recovery of Symbol Timing

Performance would approach within ≈ 0.2 dB of that of perfect timing.

A method of utilizing information available in the constraints imposed by a low-density parity-check (LDPC) code has been proposed as a means of aiding the recovery of symbol timing in the reception of a binary-phase- shift-keying (BPSK) signal representing such a code in the presence of noise, timing error, and/or Doppler shift between the transmitter and the receiver. This method and the receiver architecture in which it would be implemented belong to a class of timing-recovery methods and corresponding receiver architectures characterized as pilotless in that they do not require transmission and reception of pilot signals.

Posted in: Briefs, Electronics & Computers, Architecture, Architecture

Integrated Formation Optical Communication and Estimation System

Formation estimation couples estimation algorithms, sensing topology, and communication topology.

An architecture has been designed that integrates formation estimation methodologies, precision formation sensing, and high- bandwidth formation communication into a robust, strap-on system that meets knowledge and communication requirements for the majority of planned, precision formation missions. Specifically, the integrated system supports (a) sub- millimeter metrology, (b) multiple >10 Mbps communication channels over a large, 10° field-of-view (FOV), and (c) generalized formation estimation methodologies. The sensing sub-system consists of several absolute, metrology gauges with up to 0.1 mm precision that use amplitude-modulated lasers and a LISA-heritage phase meter. Since amplitude modulation is used, inexpensive and robust diode lasers may be used instead of complex, frequency-stabilized lasers such as for nanometer-level metrology. The metrology subsystem laser transceivers consist of a laser diode, collecting optics, and an avalanche photo diode (APD) for detecting incoming laser signals. The APD is necessary since received power is small due to the large (for optical applications) FOV. The phase meter determines the phase of the incoming amplitude modulations as measured by the APD. This phase is equivalent to time-of-flight and, therefore, distance.

Posted in: Briefs, Electronics & Computers, Architecture, Communication protocols, Lasers, Architecture, Communication protocols, Lasers

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