Portable automatic calibration tracker Progress report
Portable automatic calibration tracker to improve angular calibration of antennas and radio satellite tracking systems in STADAN /Satellite Tracking Network/
Carrion, W. J.↗
SEARCH · Search NASA
Results for “AUTOMATIC TRACKING”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
High-sensitivity receiver for infrared laser communications.
Description of a high-sensitivity wide-bandwidth 10.6-micron heterodyne receiver for space and ground operational use. The receiver includes a cooled HgCdTe infrared mixer diode, a conical scanner for spatial tracking, an acquisition channel for spatial search and station alignment, and an automatic frequency-control channel to maintain a fixed laser frequency offset. The infrared mixer is designed to provide nearly quantum-noise-limited operation over an extended range of mixer temperature, bias voltage, and intermediate frequency. The resultant experimental receiver has a measured noise equivalent power of less than 10 to the minus 19th W/Hz over the 15- to 40-MHz i.f. band for mixer temperatures from 85 to 115 K, and less than 2 x 10 to the minus 19th W/Hz up to 140 K. Mixer 3-dB cutoff frequencies as high as 420 MHz were measured at a mixer temperature of 125 K. An analysis and engineering equations are given for receiver noise components, noise equivalent power, available mixer conversion gain, mixer transducer gain, and quantum-noise factor in terms of such factors as mixer parameters, quantum efficiency, mixer temperature, dynamic conductance, bias voltage, local oscillator power, and i.f. amplifier characteristics.
Peyton, B. J.↗
Characterization and measurement of phase-locked loop performance
A set of performance measures and tests are presented which can be implemented at the 'black box' level for the characterization of such statistical aspects of phase-locked loop behavior as the acquisition and tracking threshold, phase error jitter, Doppler accuracy, etc. Also presented is an automatic measurement system, designated the Statistical Loop Analyzer, which has been developed in order to undertake these phase-locked device performance measurements.
Lindsey, W. C.↗
Analog Sensor Of Large-Amplitude Displacements
Noninvasive device measures large amplitudes at low frequencies. Low-angle, light-sensitive system tracks moving leading edge of model. Applications include opening and closing of automatic doors as far and fast as needed.
Miserentino, Robert↗
Modal characterization of the ASCIE segmented optics testbed: New algorithms and experimental results
New frequency response measurement procedures, on-line modal tuning techniques, and off-line modal identification algorithms are developed and applied to the modal identification of the Advanced Structures/Controls Integrated Experiment (ASCIE), a generic segmented optics telescope test-bed representative of future complex space structures. The frequency response measurement procedure uses all the actuators simultaneously to excite the structure and all the sensors to measure the structural response so that all the transfer functions are measured simultaneously. Structural responses to sinusoidal excitations are measured and analyzed to calculate spectral responses. The spectral responses in turn are analyzed as the spectral data become available and, which is new, the results are used to maintain high quality measurements. Data acquisition, processing, and checking procedures are fully automated. As the acquisition of the frequency response progresses, an on-line algorithm keeps track of the actuator force distribution that maximizes the structural response to automatically tune to a structural mode when approaching a resonant frequency. This tuning is insensitive to delays, ill-conditioning, and nonproportional damping. Experimental results show that is useful for modal surveys even in high modal density regions. For thorough modeling, a constructive procedure is proposed to identify the dynamics of a complex system from its frequency response with the minimization of a least-squares cost function as a desirable objective. This procedure relies on off-line modal separation algorithms to extract modal information and on least-squares parameter subset optimization to combine the modal results and globally fit the modal parameters to the measured data. The modal separation algorithms resolved modal density of 5 modes/Hz in the ASCIE experiment. They promise to be useful in many challenging applications.
Carrier, Alain C.↗
Design, Development, and Flight Evaluation of Pilot Displays and Long-Track Control for Wake Surfing Applications
From April to May 2017, the National Aeronautics and Space Administration Armstrong Flight Research Center completed a series of flights with a trail C-20A airplane surfing in the wake of a Gulfstream III airplane using a commercially available datalink as the primary communication between the two aircraft. The purpose of this test was to characterize the aerodynamic benefits received by the trail airplane flying in the upwash portion of the wake generated from the lead airplane. Lateral and vertical relative position to the wake were automatically controlled through an experimental programmable autopilot on the C-20A airplane. Long-track, the separation distance between the two aircraft, was maintained by test pilots managing throttle position using customized cockpit displays. These displays provided the pilots with throttle cues for maintaining long-track position and situational awareness of the wake vortex relative to the position of the trail airplane. Flight testing demonstrated the ability of the pilots to use these displays to maintain a safe long-track distance, but found there to be trades between tracking performance and the frequency of throttle motion. The wake awareness display provided the pilots with adequate situational awareness of the wake vortex during the flight experiment. This paper presents a summary of the design, development, and flight evaluation of the pilot displays and long-track control.
aircraft↗
Development of a DC propulsion system for an electric vehicle
The suitability of the Eaton automatically shifted mechanical transaxle concept for use in a near-term dc powered electric vehicle is evaluated. A prototype dc propulsion system for a passenger electric vehicle was designed, fabricated, tested, installed in a modified Mercury Lynx vehicle and track tested at the contractor's site. The system consisted of a two-axis, three-speed, automatically-shifted mechanical transaxle, 15.2 Kw rated, separately excited traction motor, and a transistorized motor controller with a single chopper providing limited armature current below motor base speed and full range field control above base speed at up to twice rated motor current. The controller utilized a microprocessor to perform motor and vehicle speed monitoring and shift sequencing by means of solenoids applying hydraulic pressure to the transaxle clutches. Bench dynamometer and track testing was performed. Track testing showed best system efficiency for steady-state cruising speeds of 65-80 Km/Hz (40-50 mph). Test results include acceleration, steady speed and SAE J227A/D cycle energy consumption, braking tests and coast down to characterize the vehicle road load.
Kelledes, W. L.↗
Techniques for detumbling a disabled space base
Techniques and conceptual devices for carrying out detumbling operations are examined, and progress in the development of these concepts is discussed. Devices which reduce tumble to simple spin through active linear motion of a small mass are described, together with a Module for Automatic Dock and Detumble (MADD) that could perform an orbital transfer from the shuttle in order to track and dock at a preselected point on the distressed craft. Once docked, MADD could apply torques by firing thrustors to detumble the passive vehicle. Optimum combinations of mass-motion and external devices for various situation should be developed. The need for completely formulating the automatic control logic of MADD is also emphasized.
Kaplan, M. H.↗
Automatic Extraction of JPF Options and Documentation
Documenting existing Java PathFinder (JPF) projects or developing new extensions is a challenging task. JPF provides a platform for creating new extensions and relies on key-value properties for their configuration. Keeping track of all possible options and extension mechanisms in JPF can be difficult. This paper presents jpf-autodoc-options, a tool that automatically extracts JPF projects options and other documentation-related information, which can greatly help both JPF users and developers of JPF extensions.
Static Analysis↗
Functional relationships among monitoring performance: Subjective report of thought process and compromising states of awareness
A biocybernetic system for use in adaptive automation was evaluated using EEG indices based on the beta, alpha, and theta bandwidths. Subjects performed a compensatory tracking task while their EEG was recorded and one of three engagement indices was derived: beta/(alpha + theta), beta/alpha, or 1/alpha. The task was switched between manual and automatic modes as a function of the subjects' level of engagement and whether they were under a positive or negative feedback condition. It was hypothesized that negative feedback would produce more switches between manual and automatic modes, and that the beta/(alpha + theta) index would produce the strongest effect. The results confirmed these hypotheses. There were no systematic changes in these effects over three 16-minute trials. Tracking performance was found to be better under negative feedback. An analysis of the different EEG bands under positive and negative feedback in manual and automatic modes found more beta power in the positive feedback/manual condition and less in the positive feedback/automatic condition. The opposite effect was observed for alpha and theta power. The implications of biocybernetic systems for adaptive automation are discussed.
Freeman, Frederick↗
Adaptive finite difference methods in fluid dynamics
An adaptive method to solve partial differential equations in fluid mechanics is presented. The approach requires internal boundary conditions that must be conservative, data structures for keeping track of several layers of fine grid patches, error estimation, and heuristics for automatic grid generation. In practical calculations gains in computer efficiency up to 10 over nonadaptive methods are observed. The whole procedure takes 3000 lines of FORTRAN code.
Berger, Marsha J.↗
Variable structure control of globally feedback-decoupled deformable vehicle maneuvers
The use of Cayley-Rodrigues attitude parameters as kinematic variables is shown to yield a globally linearized and decoupled model of the equations of motion of a deformable body, where the structural deformation state appears only in the coefficients of the inverse transformation. It is shown how commanded multiaxial attitude maneuvers can be encoded as switching surfaces for a variable-structure control implementation of the corresponding computed slew torques, automatically modulated in respnse only to detected angular rate error signs, for accurate tracking in the presence of separately damped or even uncontrolled (but stable) structural deformations.
Dwyer, T. A. W., III↗
Real Time Intelligent Target Detection and Analysis with Machine Vision
We present an algorithm for detecting a specified set of targets for an Automatic Target Recognition (ATR) application. ATR involves processing images for detecting, classifying, and tracking targets embedded in a background scene. We address the problem of discriminating between targets and nontarget objects in a scene by evaluating 40x40 image blocks belonging to an image. Each image block is first projected onto a set of templates specifically designed to separate images of targets embedded in a typical background scene from those background images without targets. These filters are found using directed principal component analysis which maximally separates the two groups. The projected images are then clustered into one of n classes based on a minimum distance to a set of n cluster prototypes. These cluster prototypes have previously been identified using a modified clustering algorithm based on prior sensed data. Each projected image pattern is then fed into the associated cluster's trained neural network for classification. A detailed description of our algorithm will be given in this paper. We outline our methodology for designing the templates, describe our modified clustering algorithm, and provide details on the neural network classifiers. Evaluation of the overall algorithm demonstrates that our detection rates approach 96% with a false positive rate of less than 0.03%.
Howard, Ayanna↗
Evaluation of Decision Trees for Cloud Detection from AVHRR Data
Automated cloud detection and tracking is an important step in assessing changes in radiation budgets associated with global climate change via remote sensing. Data products based on satellite imagery are available to the scientific community for studying trends in the Earth's atmosphere. The data products include pixel-based cloud masks that assign cloud-cover classifications to pixels. Many cloud-mask algorithms have the form of decision trees. The decision trees employ sequential tests that scientists designed based on empirical astrophysics studies and simulations. Limitations of existing cloud masks restrict our ability to accurately track changes in cloud patterns over time. In a previous study we compared automatically learned decision trees to cloud masks included in Advanced Very High Resolution Radiometer (AVHRR) data products from the year 2000. In this paper we report the replication of the study for five-year data, and for a gold standard based on surface observations performed by scientists at weather stations in the British Islands. For our sample data, the accuracy of automatically learned decision trees was greater than the accuracy of the cloud masks p < 0.001.
AVHRR (ADVANCED VERY HIGH RESOLUTION RADIOMETER)↗
A new method for satellite orbit determination using an operational worldwide transponder network
The method utilizes computer programs developed for the forthcoming ATS-F/NIMBUS-F tracking and data relay experiment where the basic tracking measurements are multiple path round-trip propagation times and rates. This method of orbit computation has recently been successfully evaluated by tracking a geostationary satellite (ATS-3) using an existing VHF (150 MHz) network of automatic transponders. A master station sequentially interrogates each transponder via the ATS-3. The master site is located at Schenectady, N. Y. and four automatic transponders were located at Shannon, Reykajavik, Buenos Aires, and Seattle respectively. Data at hourly intervals were collected during a 24 hour period on April 18-19, 1973. After correcting this data for known systematic errors it was provided as input to an orbit determination program where all satellite motions during signal propagation are rigorously accounted for. The resulting estimated ATS-3 orbit yielded observational residuals on the order of 100 meters. By using more than one satellite the present scheme is further capable of accurately locating several stationary or mobile terminals as part of the overall orbital solution.
Lynn, J. J.↗
Performance of a Ka-band transponder breadboard for deep-space applications
This article summarizes the design concepts applied in the development of and advanced Ka-band (34.4 GHz/32 GHz) transponder breadboard for the next generation of space communications systems applications. The selected architecture upgrades the X-band (7.2 GHz/8.4 GHz) deep-space transponder (DST) to provide Da-band up/Ka- and X-band down capability. The Ka-band transponder breadboard incorporates several state-of-the-art components, including sampling mixers, a Ka-band dielectric resonator oscillator, and microwave monolithic integrated circuits (MMICs). The MMICs that were tested in the breadboard include upconverters, downconverters, automatic gain control circuits, mixers, phase modulators, and amplifiers. The measured receiver dynamic range, tracking range, acquisition rate, static phase error, and phase jitter characteristics of the Ka-band breadboard interfaced to the advanced engineering model X-band DST are in good agreement with the expected performance. The results show a receiver tracking threshold of -149 dBm with a dynamic range of 80 dB and a downlink phase jitter of 7 deg rms. The analytical results of phase noise and Allan standard deviation are in good agreement with the experimental results.
Mysoor, N. R.↗
Motion Tracking System
Integrated Sensors, Inc. (ISI), under NASA contract, developed a sensor system for controlling robot vehicles. This technology would enable a robot supply vehicle to automatically dock with Earth-orbiting satellites or the International Space Station. During the docking phase the ISI-developed sensor must sense the satellite's relative motion, then spin so the robot vehicle can adjust its motion to align with the satellite and slowly close until docking is completed. ISI used the sensing/tracking technology as the basis of its OPAD system, which simultaneously tracks an object's movement in six degrees of freedom. Applications include human limb motion analysis, assembly line position analysis and auto crash dummy motion analysis. The NASA technology is also the basis for Motion Analysis Workstation software, a package to simplify the video motion analysis process.
Source record↗
Multi-mode optical sensor (B) evaluation test report
An evaluation test series was performed on the unit to develop realistic specifications for a similar device for use on the orbiter vehicle. Tests included sensitivity, target dynamic range, tracking angular rate, external magnetic field effects, and photocathode uniformity. Several demonstrations of operation under automatic control were also prepared, using a desk calculator for numerical control and for subsequent reduction of data derived from the test.
Smith, R. A.↗