Schema for Spacecraft-Command Dictionary

An Extensible Markup Language (XML) schema was developed as a means of defining and describing a structure for capturing spacecraft command-definition and tracking information in a single location in a form readable by both engineers and software used to generate software for flight and ground systems. A structure defined within this schema is then used as the basis for creating an XML file that contains command definitions. The schema is divided into three sections:

Posted in: Briefs, Information Sciences, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Terminology, Spacecraft
Read More >>

Self-Adjusting Hash Tables for Embedded Flight Applications

A common practice in computer science to associate a value with a key is to use a class of algorithms called a hash-table. These algorithms enable rapid storage and retrieval of values based upon a key. This approach assumes that many keys will need to be stored immediately. A new set of hash-table algorithms optimally uses system resources to ideally represent keys and values in memory such that the information can be stored and retrieved with a minimal amount of time and space. These hash-tables support the efficient addition of new entries. Also, for large data sets, the look-up time for large data-set searches is independent of the number of items stored, i.e., O(1), provided that the chance of collision is low.

Posted in: Briefs, TSP, Information Sciences, Embedded software, Embedded software
Read More >>

Efficient Algorithm for Rectangular Spiral Search

The search pattern is automatically expanded as needed.

An algorithm generates grid coordinates for a computationally efficient spiral search pattern covering an uncertain rectangular area spanned by a coordinate grid. The algorithm does not require that the grid be fixed; the algorithm can search indefinitely, expanding the grid and spiral, as needed, until the target of the search is found. The algorithm also does not require memory of coordinates of previous points on the spiral to generate the current point on the spiral.

Posted in: Briefs, Information Sciences, Mathematical models, Surveillance, Surveillance
Read More >>

Algorithm-Based Fault Tolerance Integrated With Replication

In a proposed approach to programming and utilization of commercial off-the-shelf computing equipment, a combination of algorithm-based fault tolerance (ABFT) and replication would be utilized to obtain high degrees of fault tolerance without incurring excessive costs. The basic idea of the proposed approach is to integrate ABFT with replication such that the algorithmic portions of computations would be protected by ABFT, and the logical portions by replication.

Posted in: Briefs, Information Sciences, Failure analysis, Mathematical models, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware
Read More >>

Targeting and Localization for Mars Rover Operations

A design and a partially developed application framework were presented for improving localization and targeting for surface spacecraft. The program has value for the Mars Science Laboratory mission, and has been delivered to support the Mars Exploration Rovers as part of the latest version of the Maestro science planning tool. It also has applications for future missions involving either surface-based or low-altitude atmospheric robotic vehicles.

Posted in: Briefs, Information Sciences, Architecture, Architecture, Ground vehicle operations, Robotics, Spacecraft
Read More >>

Terrain-Adaptive Navigation Architecture

A navigation system designed for a Mars rover has been designed to deal with rough terrain and/or potential slip when evaluating and executing paths. The system also can be used for any off-road, autonomous vehicles. The system uses more sophisticated terrain analysis, but also converges to computational complexity similar to that of currently deployed navigation systems when the terrain is benign. The system consists of technologies that have been developed, integrated, and tested onboard research rovers in Mars analog terrains, including goodness maps and terrain triage, terrain classification, remote slip prediction, path planning, high-fidelity traversability analysis (HFTA), and slip-compensated path following.

Posted in: Briefs, Information Sciences, Adaptive control, Adaptive control, Terrain, Ground vehicle operations, Spacecraft
Read More >>

An Efficient Reachability Analysis Algorithm

A document discusses a new algorithm for generating higher-order dependencies for diagnostic and sensor placement analysis when a system is described with a causal modeling framework. This innovation will be used in diagnostic and sensor optimization and analysis tools. Fault detection, diagnosis, and prognosis are essential tasks in the operation of autonomous spacecraft, instruments, and in-situ platforms. This algorithm will serve as a power tool for technologies that satisfy a key requirement of autonomous spacecraft, including science instruments and in-situ missions.

Posted in: Briefs, TSP, Information Sciences, Mathematical models, Sensors and actuators, Sensors and actuators, Diagnostics, Prognostics, Spacecraft, Unmanned aerial vehicles
Read More >>

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
Read More >>

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
Read More >>

XML-Based SHINE Knowledge Base Interchange Language

The SHINE Knowledge Base Interchange Language software has been designed to more efficiently send new knowledge bases to spacecraft that have been embedded with the Spacecraft Health Inference Engine (SHINE) tool. The intention of the behavioral model is to capture most of the information generally associated with a spacecraft functional model, while specifically addressing the needs of execution within SHINE and Livingstone. As such, it has some constructs that are based on one or the other.

Posted in: Briefs, TSP, Information Sciences, Communication protocols, Computer software / hardware, Computer software and hardware, Data exchange, Communication protocols, Computer software / hardware, Computer software and hardware, Data exchange
Read More >>

The U.S. Government does not endorse any commercial product, process, or activity identified on this web site.