DARTS Shell (Dshell) is a multimission spacecraft simulator for the development, integration, and test of flight software and hardware. Dshell reduces the time and cost of developing simulation programs by enabling the development of the software in modular, reusable form and by providing a host of generic capabilities that simplify the development process and enhancing run-time usability. Dshell combines (1) the DARTS program (described in the following article), which is a computational engine that solves equations for the flexible dynamics of both spacecraft and nonspacecraft multibody systems with (2) libraries of mathematical models for such hardware items as actuators, sensors, motors, and encoders into (3) an integrated simulation-environment software system that can be easily configured and interfaced with flight software and hardware according to requirements for various real- and non-real-time simulations. Dshell is portable from desktop computer workstations to real-time, hardware-in-the-loop simulation environments. Dshell is in use by several of NASA's projects, including Cassini, Galileo, Mars Pathfinder, and several projects in the Flight System Testbed at NASA's Jet Propulsion Laboratory.
This program was written by Abhinandan Jain and Jeffrey Biesiadecki of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com under the Computer Software category, or circle no. 135on the TSP Order Card in this issue to receive a copy by mail ($5 charge).
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Software for development of spacecraft-simulation programs
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Overview
The document provides an overview of the DARTS Shell (Dshell), a sophisticated multimission spacecraft simulator developed by NASA's Jet Propulsion Laboratory (JPL). Dshell is designed for the development, integration, and testing of flight software and hardware, significantly reducing the time and cost associated with creating simulation programs. It achieves this by enabling modular and reusable software development, along with offering a range of generic capabilities that simplify the overall development process.
Dshell integrates the DARTS program, a computational engine that solves equations for the flexible dynamics of both spacecraft and non-spacecraft multibody systems. It also includes libraries of mathematical models for various hardware components such as actuators, sensors, motors, and encoders. This integrated simulation environment can be easily configured and interfaced with flight software and hardware, catering to both real-time and non-real-time simulation needs.
The simulator is portable, functioning effectively on desktop workstations as well as in real-time hardware-in-the-loop simulation environments. Dshell has been utilized in several NASA interplanetary deep space missions, including Galileo, Cassini, and Mars Pathfinder, demonstrating its reliability and effectiveness in high-stakes scenarios.
The document outlines the main goals of the Dshell environment, which include reducing the software development required for interfacing dynamics simulators and hardware models, eliminating the need for separate interface development across various testbeds, facilitating easy migration of models, supporting diverse spacecraft configurations, and promoting the reuse and customization of hardware models across different missions.
Dshell operates by allowing models to be instantiated with specific states and parameters, which can be initialized through input files. It employs the Tool Command Language (Tcl) for its command line and scripting interface, providing extensive commands to query simulation data, manipulate model states, and examine outputs. This flexibility allows for dynamic interaction with the simulation environment, making it easier for developers to adapt to changes in simulation configurations or the addition of new models.
Overall, Dshell represents a significant advancement in spacecraft simulation technology, providing a robust platform for testing and verifying flight software and hardware, ultimately contributing to the success of NASA's ambitious space exploration missions.
