Special Coverage

Soft Robot “Walks” on Any Terrain
Defense Advanced Research Projects Agency
Using Microwaves to Produce High-Quality Graphene
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

Balloon Design Software

PlanetaryBalloon Version 5.0 is a software package for the design of meridionally lobed planetary balloons. It operates in a Windows environment, and programming was done in Visual Basic 6. By including the effects of circular lobes with load tapes, skin mass, hoop and meridional stress, and elasticity in the structural elements, a more accurate balloon shape of practical construction can be determined as well as the room-temperature cut pattern for the gore shapes. The computer algorithm is formulated for sizing meridionally lobed balloons for any generalized atmosphere or planet. This also covers zero-pressure, overpressure, and super-pressure balloons. Low circumferential loads with meridionally reinforced load tapes will produce shapes close to what are known as the “natural shape.”

Posted in: Briefs, TSP, Information Sciences, CAD / CAM / CAE, CAD, CAM, and CAE, Mathematical models, Elastomers, Gases, Spacecraft

Fusing Image Data for Calculating Position of an Object

A computer program has been written for use in maintaining the calibration, with respect to the positions of imaged objects, of a stereoscopic pair of cameras on each of the Mars Explorer Rovers Spirit and Opportunity. The program identifies and locates a known object in the images. The object in question is part of a Mössbauer spectrometer located at the tip of a robot arm, the kinematics of which are known.

Posted in: Briefs, TSP, Information Sciences, Calibration, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Spacecraft

Analysis Method for Quantifying Vehicle Design Goals

A document discusses a method for using Design Structure Matrices (DSM), coupled with high-level tools representing important life-cycle parameters, to comprehensively conceptualize a flight/ground space transportation system design by dealing with such variables as performance, up-front costs, downstream operations costs, and reliability. This approach also weighs operational approaches based on their effect on upstream design variables so that it is possible to readily, yet defensibly, establish linkages between operations and these upstream variables.

Posted in: Briefs, TSP, Information Sciences, CAD / CAM / CAE, CAD, CAM, and CAE, Design processes, Systems engineering, Spacecraft

Improved Tracking of Targets by Cameras on a Mars Rover

A paper describes a method devised to increase the robustness and accuracy of tracking of targets by means of three stereoscopic pairs of video cameras on a Mars-rover-type exploratory robotic vehicle. Two of the camera pairs are mounted on a mast that can be adjusted in pan and tilt; the third camera pair is mounted on the main vehicle body. Elements of the method include a mast calibration, a camera-pointing algorithm, and a purely geometric technique for handing off tracking between different camera pairs at critical distances as the rover approaches a target of interest.

Posted in: Briefs, Information Sciences, Mathematical models, Optics, Optics, Robotics, Spacecraft

GVIPS Models and Software

Two reports discuss, respectively, (1) the generalized viscoplasticity with potential structure (GVIPS) class of mathematical models and (2) the Constitutive Material Parameter Estimator (COMPARE) computer program. GVIPS models are constructed within a thermodynamics- and potential-based theoretical framework, wherein one uses internal state variables and derives constitutive equations for both the reversible (elastic) and the irreversible (viscoplastic) behaviors of materials. Because of the underlying potential structure, GVIPS models not only capture a variety of material behaviors but also are very computationally efficient.

Posted in: Briefs, TSP, Information Sciences, Mathematical models, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Thermodynamics, Thermodynamics, Materials properties

Error Rates and Channel Capacities in Multipulse PPM

It is now possible to compare expected performances of candidate modulation schemes.

A method of computing channel capacities and error rates in multipulse pulse-position modulation (multipulse PPM) has been developed. The method makes it possible, when designing an optical PPM communication system, to determine whether and under what conditions a given multipulse PPM scheme would be more or less advantageous, relative to other candidate modulation schemes.

Posted in: Briefs, Information Sciences, Mathematical analysis, Optics, Telecommunications systems, Optics, Telecommunications systems

Simpler Adaptive Selection of Golomb Power-of-Two Codes

The selected code-parameter value is within 1 of the optimum value.

An alternative method of adaptive selection of Golomb power-of-two (GPO2) codes has been devised for use in efficient, lossless encoding of sequences of non-negative integers from discrete sources. The method is intended especially for use in compression of digital image data. This method is somewhat suboptimal, but offers the advantage in that it involves significantly less computation than does a prior method of adaptive selection of optimum codes through “brute force” application of all code options to every block of samples.

Posted in: Briefs, Information Sciences, Imaging, Imaging and visualization, Imaging, Imaging and visualization, Data management

Analysis of Performance of Stereoscopic Vision Software

A team of JPL researchers has analyzed stereoscopic vision software and produced a document describing its performance. This software is of the type used in maneuvering exploratory robotic vehicles on Martian terrain. The software in question utilizes correlations between portions of the images recorded by two electronic cameras to compute stereoscopic disparities, which, in conjunction with camera models, are used in computing distances to terrain points to be included in constructing a threedimensional model of the terrain. The analysis included effects of correlation-window size, a pyramidal image down-sampling scheme, vertical misalignment, focus, maximum disparity, stereo baseline, and range ripples. Contributions of sub-pixel interpolation, vertical misalignment, and foreshortening to stereo correlation error were examined theoretically and experimentally. It was found that camera-calibration inaccuracy contributes to both down-range and cross-range error but stereo correlation error affects only the down-range error. Experimental data for quantifying the stereo disparity error were obtained by use of reflective metrological targets taped to corners of bricks placed at known positions relative to the cameras. For the particular 1,024-by-768- pixel cameras of the system analyzed, the standard deviation of the down-range disparity error was found to be 0.32 pixel.

This work was done by Won Kim, Adnan Ansar, Robert Steele, and Robert Steinke of Caltech for NASA’s Jet Propulsion Laboratory. For further information, contact iaoffice@jpl.nasa.gov.

Posted in: Briefs, Information Sciences, Analysis methodologies, Computer software / hardware, Computer software and hardware, Imaging, Imaging and visualization, Computer software / hardware, Computer software and hardware, Imaging, Imaging and visualization

Estimating the Inertia Matrix of a Spacecraft

A paper presents a method of utilizing some flight data, aboard a spacecraft that includes reaction wheels for attitude control, to estimate the inertia matrix of the spacecraft. The required data are digitized samples of (1) the spacecraft attitude in an inertial reference frame as measured, for example, by use of a star tracker and (2) speeds of rotation of the reaction wheels, the moments of inertia of which are deemed to be known.

Posted in: Briefs, Information Sciences, Attitude control, Attitude control, Spacecraft

Spatial Coverage Planning for Exploration Robots

A report discusses an algorithm for an onboard planning and execution technology to support the exploration and characterization of geological features by autonomous rovers. A rover that is capable of deciding which observations are more important relieves the engineering team from much of the burden of attempting to make accurate predictions of what the available rover resources will be in the future. Instead, the science and engineering teams can uplink a set of observation requests that may potentially oversubscribe resources and let the rover use observation priorities and its current assessment of available resources to make decisions about which observations to perform and when to perform them.

Posted in: Briefs, Information Sciences, Robotics, Autonomous vehicles

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