Ripples is a computer program that makes it possible to specify arbitrarily complex space-flight systems in an easy-tolearn, high-level programming language and to have the specification automatically translated into LibSim, which is a textbased computing language in which such simulations are implemented. LibSim is a very powerful simulation language, but learning it takes considerable time, and it requires that models of systems and their components be described at a very low level of abstraction. To construct a model in LibSim, it is necessary to go through a time-consuming process that includes modeling each subsystem, including defining its fault-injection states, input and output conditions, and the topology of its connections to other subsystems. Ripples makes it possible to describe the same models at a much higher level of abstraction, thereby enabling the user to build models faster and with fewer errors. Ripples can be executed in a variety of computers and operating systems, and can be supplied in either source code or binary form. It must be run in conjunction with a Lisp compiler.
This program was written by Mark James of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free online 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-42532.
This Brief includes a Technical Support Package (TSP).
Cross-Compiler for Modeling Space-Flight Systems
(reference NPO-42532) is currently available for download from the TSP library.
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Overview
The document titled "Ripples: A Cross-Compiler to LibSim for Modeling Subsystems of Space Flight Systems" (NPO-42532) presents a novel capability designed to simplify the simulation of complex spacecraft systems. Traditionally, spacecraft simulation is a labor-intensive and error-prone process that requires extensive investment from organizations like NASA. The existing practice involves using complex simulation languages, which necessitate detailed modeling of each subsystem, including defining input and output conditions and establishing connective topologies.
The Ripples tool addresses these challenges by allowing users to specify models in a high-level programming language, which can then be automatically translated into the LibSim simulation language. LibSim, while powerful, has a steep learning curve and requires users to work at a low level of abstraction. By enabling higher-level model descriptions, Ripples significantly accelerates the model-building process and reduces the likelihood of errors.
The primary motivation for developing this cross-compiler was to create a simulation testbed environment that meets the end-to-end testing needs for autonomy flight software design, development, testing, integration, and mission operations, particularly for the Deep Space 1 (DS-1) mission. The testbed is designed to be reconfigurable, accommodating various flight software development and testing requirements that were previously managed by multiple testbeds. It supports closed-loop simulation needs and can handle different configurations, including various computational hardware setups and functional configurations for testing subsystems like guidance and control (G&C) and autonomy.
The document also highlights the capabilities of LibSim, which allows for defining the connectivity between subsystems, simulating their execution, and incorporating fault injection. However, the process of defining these connections and managing constraints can be time-consuming. The Ripples tool aims to streamline this by providing an easy way to define the connective topology, verify connections, and cross-compile into LibSim instructions.
Additionally, the software is versatile, running on various platforms, including SUN, HP, Intel, and Apple MACs, and can be distributed in source or binary form. It requires a LISP compiler to operate, with several options available commercially or as shareware. Overall, the document outlines a significant advancement in the field of spacecraft simulation, promising to enhance efficiency and reduce errors in the modeling of space-flight systems.
