Robust, Flexible Motion Control for the Mars Explorer Rovers

The Mobility Flight Software, running on computers aboard the Mars Explorer Rover (MER) robotic vehicles Spirit and Opportunity, affords the robustness and flexibility of control to enable safe and effective operation of these vehicles in traversing natural terrain. It can make the vehicles perform specific maneuvers commanded from Earth, and/or can autonomously administer multiple aspects of mobility, including choice of motion, measurement of actual motion, and even selection of targets to be approached. Motion of a vehicle can be commanded by use of multiple layers of control, ranging from motor control at a low level, direct drive operations (e.g., motion along a circular arc, motion along a straight line, or turn in place) at an intermediate level to goal-position driving (that is, driving to a specified location) at a high level.

Posted in: Briefs, Software, Steer-by-wire, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Autonomous vehicles, Spacecraft
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Improved Path Planning Onboard the Mars Exploration Rovers

A revised version of the AutoNav (autonomous navigation with hazard avoidance) software running onboard each Mars Exploration Rover (MER) affords better obstacle avoidance than does the previous version. Both versions include GESTALT (Grid-based Estimation of Surface Traversability Applied to Local Terrain), a navigation program that generates local-terrain models from stereoscopic image pairs captured by onboard rover cameras; uses this information to evaluate candidate arcs that extend across the terrain from the current rover location; ranks the arcs with respect to hazard avoidance, minimization of steering time, and the direction towards the goal; and combines the rankings in a weighted vote to select an arc, along which the rover is then driven.

Posted in: Briefs, Software, Computer software / hardware, Computer software and hardware, Navigation and guidance systems, Computer software / hardware, Computer software and hardware, Navigation and guidance systems, Autonomous vehicles, Spacecraft
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Inertial Measurements for Aero-assisted Navigation (IMAN)

IMAN is a Python tool that provides inertial sensor-based estimates of spacecraft trajectories within an atmospheric influence. It provides Kalman filterderived spacecraft state estimates based upon data collected onboard, and is shown to perform at a level comparable to the conventional methods of spacecraft navigation in terms of accuracy and at a higher level with regard to the availability of results immediately after completion of an atmospheric drag pass. A benefit of this architecture is that this technology is conducive to onboard data processing and estimation and thus can compute near realtime spacecraft state estimates making it suitable for autonomous operations and/or closed-loop guidance, navigation, and control strategies.

Posted in: Briefs, TSP, Software, Architecture, Spacecraft guidance, Architecture, Spacecraft guidance
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Solar Sail Spaceflight Simulation

The Solar Sail Spaceflight Simulation Software (S5) toolkit provides solar-sail designers with an integrated environment for designing optimal solar-sail trajectories, and then studying the attitude dynamics/ control, navigation, and trajectory control/ correction of sails during realistic mission simulations. Unique features include a high-fidelity solar radiation pressure model suitable for arbitrarily-shaped solar sails, a solarsail trajectory optimizer, capability to develop solar-sail navigation filter simulations, solar-sail attitude control models, and solar-sail high-fidelity force models.

Posted in: Briefs, Software, Computer simulation, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Solar energy, Spacecraft
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Deep Space Network Antenna Logic Controller

The Antenna Logic Controller (ALC) software controls and monitors the motion control equipment of the 4,000- metric-ton structure of the Deep Space Network 70-meter antenna. This program coordinates the control of 42 hydraulic pumps, while monitoring several interlocks for personnel and equipment safety. Remote operation of the ALC runs via the Antenna Monitor & Control (AMC) computer, which orchestrates the tracking functions of the entire antenna.

Posted in: Briefs, Software, Antennas, Computer software / hardware, Computer software and hardware, Electronic control systems, Antennas, Computer software / hardware, Computer software and hardware, Electronic control systems
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Modeling Magnetic Properties in EZTB

A software module that calculates magnetic properties of a semiconducting material has been written for incorporation into, and execution within, the Easy (Modular) Tight-Binding (EZTB) software infrastructure. [EZTB is designed to model the electronic structures of semiconductor devices ranging from bulk semiconductors, to quantum wells, quantum wires, and quantum dots. EZTB implements an empirical tight-binding mathematical model of the underlying physics.]

Posted in: Briefs, Software, Mathematical models, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Conductivity, Semiconductors
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Modeling Carbon and Hydrocarbon Molecular Structures in EZTB

A software module that models the electronic and mechanical aspects of hydrocarbon molecules and carbon molecular structures on the basis of first principles has been written for incorporation into, and execution within, the Easy (Modular) Tight-Binding (EZTB) software infrastructure, which is summarized briefly in the immediately preceding article. Of particular interest, this module can model carbon crystals and nanotubes characterized by various coordinates and containing defects, without need to adjust parameters of the physical model.

Posted in: Briefs, Software, Simulation and modeling, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Hydrocarbons, Nanomaterials
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BigView Image Viewing on Tiled Displays

BigView allows for interactive panning and zooming of images of arbitrary size on desktop PCs running Linux. Additionally, it can work in a multi-screen environment where multiple PCs cooperate to view a single, large image. Using this software, one can explore — on relatively modest machines — images such as the Mars Orbiter Camera mosaic [92,160×33,280 pixels].

Posted in: Briefs, Software, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Displays, Displays
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Rapid Analysis of Mass Distribution of Radiation Shielding

Radiation Shielding Evaluation Toolset (RADSET) is a computer program that rapidly calculates the spatial distribution of mass of an arbitrary structure for use in ray-tracing analysis of the radiation-shielding properties of the structure. RADSET was written to be used in conjunction with unmodified commercial computer-aided design (CAD) software that provides access to data on the structure and generates selected three-dimensional-appearing views of the structure. RADSET obtains raw geometric, material, and mass data on the structure from the CAD software.

Posted in: Briefs, Software, CAD / CAM / CAE, CAD, CAM, and CAE, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Radiation protection, Spacecraft
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Software Compensates Electronic-Nose Readings for Humidity

A computer program corrects for the effects of humidity on the readouts of an array of chemical sensors (an “electronic nose”). To enable the use of this program, the array must incorporate an independent humidity sensor in addition to sensors designed to detect analytes other than water vapor. The basic principle of the program was described in “Compensating for Effects of Humidity on Electronic Noses” (NPO- 30615), NASA Tech Briefs, Vol. 28, No. 6 (June 2004), page 63. To recapitulate: The output of the humidity sensor is used to generate values that are subtracted from the outputs of the other sensors to correct for contributions of humidity to those readings. Hence, in principle, what remains after corrections are the contributions of the analytes only.

Posted in: Briefs, Software, Computer software / hardware, Computer software and hardware, Sensors and actuators, Computer software / hardware, Computer software and hardware, Sensors and actuators, Water
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