The Surface Attitude Position and Pointing (SAPP) software, which runs on computers aboard the Mars Exploration Rovers, tracks the positions and attitudes of the rovers on the surface of Mars. Each rover acquires data on attitude from a combination of accelerometer readings and images of the Sun acquired autonomously, using a pointable camera to search the sky for the Sun. Depending on the nature of movement commanded remotely by operators on Earth, the software propagates attitude and position by use of either (1) accelerometer and gyroscope readings or (2) gyroscope readings and wheel odometry. Where necessary, visual odometry is performed on images to fine-tune the position updates, particularly on high-wheel-slip terrain. The attitude data are used by other software and ground-based personnel for pointing a high-gain antenna, planning and execution of driving, and positioning and aiming scientific instruments.
This work was done by Khaled Ali, Charles Vanelli, Jeffrey Biesiadecki, Alejandro San Martin, Mark Maimone, Yang Cheng, and James Alexander of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Software category.
This software is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-41876.
This Brief includes a Technical Support Package (TSP).
Tracking Positions and Attitudes of Mars Rovers
(reference NPO-41876) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package (NPO-41876) from NASA's Jet Propulsion Laboratory, detailing the Surface Attitude Position and Pointing (SAPP) software used in Mars Exploration Rovers (MER). This software is essential for tracking the position and attitude of the rovers on the Martian surface, ensuring they can navigate and perform scientific tasks effectively.
SAPP software employs a combination of accelerometer readings and visual data from a pointable camera to autonomously determine the rover's attitude. It searches for the sun in the sky and monitors its movement, which is crucial for accurate positioning. The software incorporates multiple methods for attitude acquisition, enhancing its reliability compared to previous systems, such as those used in the Mars Pathfinder mission. Additionally, SAPP includes more extensive validity checks to ensure the accuracy of the data it collects.
The primary objective of the SAPP software is to solve the challenges associated with attitude and position acquisition on Mars. By utilizing both accelerometer and gyro readings, as well as wheel odometry, the software can propagate the rover's position and attitude based on the commands given by ground operators. This capability is vital for various operational tasks, including high-gain antenna (HGA) pointing, driving maneuvers, and planning for instrument deployment.
The document emphasizes the programmatic and utilization aspects of the SAPP software, highlighting its role in supporting ground operations and enhancing the overall functionality of the rovers. The advancements made in this software represent significant progress in the field of aerospace technology, with implications for future missions and broader applications in scientific and commercial sectors.
In summary, the Technical Support Package provides a comprehensive overview of the SAPP software, its unique features, improvements over previous technologies, and its critical role in the successful operation of Mars rovers. It underscores NASA's commitment to advancing space exploration through innovative software solutions that enhance the capabilities of robotic missions on other planets.
