Introduction to the Open-Sessame Framework

Authors:
Andrew Turner
Table of Contents

Introduction

The goal of this project is to develop an Open-Source, Extensible Spacecraft Simulation And Modeling Environment (Open-SESSAME) framework that can serve as a basis for satellite modeling and analysis. The entire collection of code provides most of the tools, libraries and structure necessary for simulating a wide-range of spacecraft while also allowing easy extension for any further desired functionality. Also, by being open-source users are able to investigate the design and operating of the code to reassure themselves of the validity of the simulator. The Open-SESSAME framework is also an active project of the large and rapidly growing open-source community. This allows new functionality to be disseminated to all current and future users of the framework as it continues to grow and mature.

Rationale

Many students and researchers of satellite dynamics and control must independently develop a software simulations each time a new research project begins. These simulations are typically built specifically for the research task at hand and not easily adaptable to future projects. Furthermore, many students have little experience developing simulations, and may not know where to begin, what to be concerned with, and how to best implement components so they can be resuable between projects and other students and engineers. The Open-Sessame framework addresses these issues by providing a common groundwork upon which students can learn how simulators are implemented and develop their own components for use in the framework for their own research.

The Space Systems Simulation Laboratory (SSSL) at Virginia Tech in Blacksburg, Virginia is working on a number of projects that work to develop new methodologies for the simulation and analysis of spacecraft and their associated systems. These projects include both hardware and software simulation techniques that are used in conjuction to better understand the interplay of satellite dynamics with novel control & sensing strategies. As a result of the various unique requirements of many of the projects, a single commercial software package has not yet fulfilled the needs of the lab. An open-source and extensible simulation framework creates a reusable basis for any future simulation projects while also allowing the students and researchers the capacity to configure the simulation to their unique specifications. Furthermore, they are able to interface the simulation software with any other analysis package they may require for their research.

Using the Framework

Here is the suggested path for using the Open-Sessame Framework.
  1. If you haven't already, download the latest source and documentation from the Sourceforge repository at http://sourceforge.net/projects/spacecraft. Download either the newest bundle (under Files), or click on the link to CVS and follow the basic instructions to get the most up-to-date release.
  2. Scroll through the Primer Presentation which gives an introduction and overview of some of the main concepts.
  3. Read the Using the Open-SESSAME Framework documentation about the general usage of the framework.
  4. Build & install the libraries by following the Installation Instructions.
  5. Follow the Tutorials
  6. Check out the forums at the Sourceforge website for discussion on development, useful links, tutorials, etc. There is a user base out there, use it.
  7. Begin contributing by checking out the todo list or talking to other uses in the forums.

Installation

See the Installation Instructions ["Installation Page"] for instructions on building & installing the Open-Sessame framework libraries.

To Do Items

To help in development, as well as learning the framework, here is a current (5/12/03) list of major todo implementation items. These consist of larger scale new feature and add-on implementation items that have been identified by the development team, which differe from the bug-fixes and small todo items found on the 'todo' page. While the small items need to be completed, if you're up to learning more about C++ coding and the framework, it is suggested you look at one of these problems.

Todo:
  1. A better, faster, powerful matrix/vector library. Should handle all typical linear algebra functionality (matrix mult, vector mult, matrix*vector mult, inverse, transpose, norm, etc). Error handling would be nice with options for command line debugging (outputting the type/size of matrix, characterization of error (wrong mult sizes, singular) and possibly where the error occured (function, code line).
  2. More force functions: solar radiation pressure, advanced atmospheric model, higher-order gravity model
  3. More torque functions: magnetic field, higher-order gravity gradient, micrometeorites
  4. Need to implement frames, both orbit & attitude.
  5. A store and restore mechanism. Needs to be cross-platform, prefer something like XML formatting. Also need to be able to export/import with MatLab, Satellite ToolKit (STK), Excel (CSV), and others.

Release Notes

release.notes

Requirements

 

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