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At least 163 records · Page 9

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NASA NTRS1979

Proposed smart integrated-optical preprocessor using holographic subtraction

The paper presents a proposed integrated-optical preprocessor with a holographic subtraction. It is based on an optical analog of a set of N analog voltages formed by passing an optical plane wave, confined in an electrooptic waveguide, under a set of N electrodes to which the voltages are applied; in the limit in which diffraction is ignored, the wavefront of the emerging guided wave will have superimposed upon it N discrete phase shifts. Processors which operate upon voltages encoded in this manner are being fabricated; they include a comparator in which incoming data are compared to a holographic record of the optical analog of a reference set, and a 'smart' system based upon holographic self-subtraction, in which the processor can independently adapt to changes in background information. The preprocessor operation is described in the screening, identification, and the self-subtraction modes, and implementation of devices in an integrated optical configuration is discussed.

Verber, C. M.↗

NASA NTRS1981

The SMART MIL-STD-1553 bus adapter hardware manual

The SMART Multiplexer Interface Adapter, (SMIA) a complete system interface for message structure of the MIL-STD-1553, is described. It provides buffering and storage for transmitted and received data and handles all the necessary handshaking to interface between parallel 8-bit data bus and a MIL-STD serial bit stream. The bus adapter is configured as either a bus controller of a remote terminal interface. It is coupled directly to the multiplex bus, or stub coupled through an additional isolation transformer located at the connection point. Fault isolation resistors provide short circuit protection.

Ton, T. T.↗

NASA NTRS1980

Programmable performance - One aspect of smart sensing systems

Programmable performance is the ability to flexibly alter basic spatial, spectral, and radiometric system response as a function of time. In this paper programmable performance is defined as a functional element of smart sensor systems for the 1990's. The uses and benefits of these classes of sensor systems are discussed with reference to multispectral scanners of the earth's surface. An overall technology trend is identified which couples a high degree of sensor performance flexibility to a need for advanced device technology developments.

Jobson, D. J.↗

NASA NTRS1983

Linking "Smart" Modules by a Single Channel

System architecture brings order to potentially chaotic situation. New configuration allows many "smart" modules (each containing memory and microprocessor) to be linked by common data channel. Architecture allows each module to carry on operations at own data rate within block of time, while communications between modules occur in strict synchronism.

Kohl, W. H.↗

NASA NTRS1986

Multipurpose aircraft monitoring with a smart recorder

This paper describes a microprocessor-based flight recorder the 'Smart Recorder' - which was developed and installed on a King Air aircraft used for commercial charter service. The recorder is used as a research tool for developing monitoring strategies and processing algorithms to: (1) characterize the typical flight environment encountered by the host aircraft, (2) develop technology for automated engine trend monitoring, and (3) implement a crash recording capability. Initially the recorder was used as an adaptive data acquisition system, monitoring engine sensors and flight instruments and then modifying its data acquisition in response to the perceived aircraft situation. Data collected in this manner were stored in a removable bubble memory and subsequently analyzed in the laboratory. Later, on-board processing was implemented to better utilize the available storage capacity.

White, J. H.↗

NASA NTRS1988

Development of a multipurpose smart recorder for general aviation aircraft

An intelligent flight recorder, called the Smart Recorder, was fabricated and installed on a King Air aircraft used in standard commercial charter service. This recorder was used for collection of data toward two objectives: (1) the characterization of the typical environment encountered by the aircraft; and (2) research in the area of trend monitoring. Data processing routines and data presentation formats were defined that are applicable to commuter size aircraft. The feasibility of a cost-effective, multipurpose recorder for general aviation aircraft was successfully demonstrated. Implementation of on-board environmental data processing increased the number of flight hours that could be stored on a single data cartridge and simplified the data management problem by reducing the volume of data to be processed in the laboratory. Trend monitoring algorithms showed less variability in the trend plots when compared against plots of manual data.

White, J. H.↗

NASA NTRS1988

Smart command recognizer (SCR) - For development, test, and implementation of speech commands

The SCR, a rapid prototyping system for the development, testing, and implementation of speech commands in a flight simulator or test aircraft, is described. A single unit performs all functions needed during these three phases of system development, while the use of common software and speech command data structure files greatly reduces the preparation time for successive development phases. As a smart peripheral to a simulation or flight host computer, the SCR interprets the pilot's spoken input and passes command codes to the simulation or flight computer.

Simpson, Carol A.↗

NASA NTRS1989

Distributed ice accretion sensor for smart aircraft structures

A distributed ice accretion sensor is presented, based on the concept of smart structures. Ice accretion is determined using spectral techniques to process signals from piezoelectric sensors integral to the airfoil skin. Frequency shifts in the leading edge structural skin modes are correlated to ice thickness. It is suggested that this method may be used to detect ice over large areas with minimal hardware. Results are presented from preliminary tests to measure simulated ice growth.

Gerardi, J. J.↗

NASA NTRS1990

Improved "Smart" Robot Hand

Improved version of developmental "smart" robot hand equipped with bidirectional, wide-band optical-fiber link for transmission of digitized strain-gauge force- and torque-sensor signals from hand and for transmission of command signals to motor drive unit on hand. Collection of sensor data speeded hundredfold. Higher data-collection speed makes possible to perform advanced processing of sensor data in host processor.

Szakaly, Zoltan F.↗

NASA NTRS1990

Rate-based congestion control in networks with smart links, revision

The author uses a network simulator to explore rate-based congestion control in networks with smart links that can feed back information to tell senders to adjust their transmission rates. This method differs in a very important way from congestion control in which a congested network component just drops packets - the most commonly used method. It is clearly advantageous for the links in the network to communicate with the end users about the network capacity, rather than the users unilaterally picking a transmission rate. The components in the middle of the network, not the end users, have information about the capacity and traffic in the network. The author experiments with three different algorithms for calculating the control rate to feed back to the users. All of the algorithms exhibit problems in the form of large queues when simulated with a configuration modeling the dynamics of a packet-voice system. However, the problems are not with the algorithms themselves, but with the fact that feedback takes time. If the network steady-state utilization is low enough that it can absorb transients in the traffic through it, then the large queues disappear. If the users are modified to start sending slowly, to allow the network to adapt to a new flow without causing congestion, a greater portion of the network's bandwidth can be used.

Heybey, Andrew Tyrrell↗

NASA NTRS1989

A fast lightstripe rangefinding system with smart VLSI sensor

The focus of the research is to build a compact, high performance lightstripe rangefinder using a Very Large Scale Integration (VLSI) smart photosensor array. Rangefinding, the measurement of the three-dimensional profile of an object or scene, is a critical component for many robotic applications, and therefore many techniques were developed. Of these, lightstripe rangefinding is one of the most widely used and reliable techniques available. Though practical, the speed of sampling range data by the conventional light stripe technique is severely limited. A conventional light stripe rangefinder operates in a step-and-repeat manner. A stripe source is projected on an object, a video image is acquired, range data is extracted from the image, the stripe is stepped, and the process repeats. Range acquisition is limited by the time needed to grab the video images, increasing linearly with the desired horizontal resolution. During the acquisition of a range image, the objects in the scene being scanned must be stationary. Thus, the long scene sampling time of step-and-repeat rangefinders limits their application. The fast range sensor proposed is based on the modification of this basic lightstripe ranging technique in a manner described by Sato and Kida. This technique does not require a sampling of images at various stripe positions to build a range map. Rather, an entire range image is acquired in parallel while the stripe source is swept continuously across the scene. Total time to acquire the range image data is independent of the range map resolution. The target rangefinding system will acquire 1,000 100 x 100 point range images per second with 0.5 percent range accuracy. It will be compact and rugged enough to be mounted on the end effector of a robot arm to aid in object manipulation and assembly tasks.

Gruss, Andrew↗

NASA NTRS1990

Adaptivity and smart algorithms for fluid-structure interaction

This paper reviews new approaches in CFD which have the potential for significantly increasing current capabilities of modeling complex flow phenomena and of treating difficult problems in fluid-structure interaction. These approaches are based on the notions of adaptive methods and smart algorithms, which use instantaneous measures of the quality and other features of the numerical flowfields as a basis for making changes in the structure of the computational grid and of algorithms designed to function on the grid. The application of these new techniques to several problem classes are addressed, including problems with moving boundaries, fluid-structure interaction in high-speed turbine flows, flow in domains with receding boundaries, and related problems.

Oden, J. Tinsley↗

NASA NTRS1990

Piezoceramic devices and artificial intelligence time varying concepts in smart structures

The problem of development of smart structures and their vibration control by the use of piezoceramic sensors and actuators have been discussed. In particular, these structures are assumed to have time varying model form and parameters. The model form may change significantly and suddenly. Combined identification of the model from parameters of these structures and model adaptive control of these structures are discussed in this paper.

Hanagud, S.↗

NASA NTRS1989

Dynamic and structural control utilizing smart materials and structures

An account is given of several novel 'smart material' structural control concepts that are currently under development. The thrust of these investigations is the evolution of intelligent materials and structures superceding the recently defined variable-geometry trusses and shape memory alloy-reinforced composites; the substances envisioned will be able to autonomously evaluate emergent environmental conditions and adapt to them, and even change their operational objectives. While until now the primary objective of the developmental efforts presently discussed has been materials that mimic biological functions, entirely novel concepts may be formulated in due course.

Rogers, C. A.↗

NASA NTRS1992

Spacecraft attitude control using a smart control system

Traditionally, spacecraft attitude control has been implemented using control loops written in native code for a space hardened processor. The Naval Research Lab has taken this approach during the development of the Attitude Control Electronics (ACE) package. After the system was developed and delivered, NRL decided to explore alternate technologies to accomplish this same task more efficiently. The approach taken by NRL was to implement the ACE control loops using systems technologies. The purpose of this effort was to: (1) research capabilities required of an expert system in processing a classic closed-loop control algorithm; (2) research the development environment required to design and test an embedded expert systems environment; (3) research the complexity of design and development of expert systems versus a conventional approach; and (4) test the resulting systems against the flight acceptance test software for both response and accuracy. Two expert systems were selected to implement the control loops. Criteria used for the selection of the expert systems included that they had to run in both embedded systems and ground based environments. Using two different expert systems allowed a comparison of the real-time capabilities, inferencing capabilities, and the ground-based development environment. The two expert systems chosen for the evaluation were Spacecraft Command Language (SCL), and NEXTPERT Object. SCL is a smart control system produced for the NRL by Interface and Control Systems (ICS). SCL was developed to be used for real-time command, control, and monitoring of a new generation of spacecraft. NEXPERT Object is a commercially available product developed by Neuron Data. Results of the effort were evaluated using the ACE test bed. The ACE test bed had been developed and used to test the original flight hardware and software using simulators and flight-like interfaces. The test bed was used for testing the expert systems in a 'near-flight' environment. The technical approach, the system architecture, the development environments, knowledge base development, and results of this effort are detailed.

Buckley, Brian↗

NASA NTRS1993

Development of Miniaturized Optimized Smart Sensors (MOSS) for space plasmas

The cost of space plasma sensors is high for several reasons: (1) Most are one-of-a-kind and state-of-the-art, (2) the cost of launch to orbit is high, (3) ruggedness and reliability requirements lead to costly development and test programs, and (4) overhead is added by overly elaborate or generalized spacecraft interface requirements. Possible approaches to reducing costs include development of small 'sensors' (defined as including all necessary optics, detectors, and related electronics) that will ultimately lead to cheaper missions by reducing (2), improving (3), and, through work with spacecraft designers, reducing (4). Despite this logical approach, there is no guarantee that smaller sensors are necessarily either better or cheaper. We have previously advocated applying analytical 'quality factors' to plasma sensors (and spacecraft) and have begun to develop miniaturized particle optical systems by applying quantitative optimization criteria. We are currently designing a Miniaturized Optimized Smart Sensor (MOSS) in which miniaturized electronics (e.g., employing new power supply topology and extensive us of gate arrays and hybrid circuits) are fully integrated with newly developed particle optics to give significant savings in volume and mass. The goal of the SwRI MOSS program is development of a fully self-contained and functional plasma sensor weighing 1 lb and requiring 1 W. MOSS will require only a typical spacecraft DC power source (e.g., 30 V) and command/data interfaces in order to be fully functional, and will provide measurement capabilities comparable in most ways to current sensors.

Young, D. T.↗

NASA NTRS1991

Search-based model identification of smart-structure damage

This paper describes the use of a combined model and parameter identification approach, based on modal analysis and artificial intelligence (AI) techniques, for identifying damage or flaws in a rotating truss structure incorporating embedded piezoceramic sensors. This smart structure example is representative of a class of structures commonly found in aerospace systems and next generation space structures. Artificial intelligence techniques of classification, heuristic search, and an object-oriented knowledge base are used in an AI-based model identification approach. A finite model space is classified into a search tree, over which a variant of best-first search is used to identify the model whose stored response most closely matches that of the input. Newly-encountered models can be incorporated into the model space. This adaptativeness demonstrates the potential for learning control. Following this output-error model identification, numerical parameter identification is used to further refine the identified model. Given the rotating truss example in this paper, noisy data corresponding to various damage configurations are input to both this approach and a conventional parameter identification method. The combination of the AI-based model identification with parameter identification is shown to lead to smaller parameter corrections than required by the use of parameter identification alone.

Glass, B. J.↗

NASA NTRS1991

Control systems using modal domain optical fiber sensors for smart structure applications

Recently, a new class of sensors has emerged for structural control which respond to environmental changes over a significant gauge length; these sensors are called distributed-effect sensors. These sensors can be fabricated with spatially varying sensitivity to the distributed measurand, and can be configured to measure a variety of structural parameters which can not be measured directly using point sensors. Examples of distributed-effect sensors include piezoelectric film, holographic sensors, and modal domain optical fiber sensors. Optical fiber sensors are particularly attractive for smart structure applications because they are flexible, have low mass, and can easily be embedded directly into materials. In this paper we describe the implementation of weighted modal domain optical fiber sensors. The mathematical model of the modal domain optical fiber sensor model is described and used to derive an expression for the sensor sensitivity. The effects of parameter variations on the sensor sensitivity are demonstrated to illustrate methods of spatially varying the sensor sensitivity.

Lindner, Douglas K.↗