Original Date: 04/01/1993
Revision Date: 01/19/2007
Best Practice : Rapid Prototyping Simulation and Software
McDonnell Douglas Aerospace (MDA) applies over 30 years experience in simulation for design, including hardware in the loop. Guidance and control simulation reduces risk using performance assessment during design, and reduces cost by shortening development time. With the cost of a space vehicle launch, and the critical safety issues of manned space-craft, this simulation capability has become a necessity. MDA uses a spiral design process where iterative build stages are accompanied by iterative test stages.
The Rapid Prototyping and Integrated Design System (RAPIDS) was developed by MDA and Integrated Systems Inc. Using this system, build and test stages are concurrent to shorten design time. Software code is automatically generated and documented from models, providing easy traceability between requirements and design. The RAPIDS software allows for six degrees of freedom simulated performance of air vehicles. Such factors as pitch autopilot, mission time, latitude/longitude flight path, and seeker operation are monitored and controlled. Automatic analysis includes non-linear time domain simulation and frequency domain stability analysis.
Modeling begins with the System Build Block Editor. This feature provides familiar block diagrams, unlimited hierarchy, full timing control, and precise design specifications. The hierarchy allows the use of generic function blocks for high level definitions with subsequent lower and finer levels of detail as the system is designed. Each block is cataloged and may be reused any number of times in any number of system designs. The models can then be exercised to simulate performance and assess model compliance with design requirements.
After a successful simulation, the Automatic Code Generator converts the block diagrams into complete, real-time software programs. The code is directly traceable back to the System Build module, and the program is portable to any real-time computer. The AutoDoc feature provides for automatic document preparation and is compatible with FrameMaker and Interleaf.
The next determination of system performance is made by downloading the code to the guidance and control processor and exercising it with an in-circuit emulator. When all testing is satisfactorily completed, actual vehicle hardware is added to visually examine performance.
The RAPIDS has been successfully applied to full development projects such as the Single Stage Rocket Transport, with more than a two-to one-reduction in system development cost. It facilitates an integrated team approach and sharing of knowledge. While the automated code generation is not a replacement for software development, it does produce error free code and saves significant time.
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