SAGEM minimizes the Time & Cost to develop navigation functions with Esterel Technologies’ SCADE Suite
SAGEM has been using SCADE Suite since 1994 to develop helicopter autopilots, an inertial platform and an air data function. They are now deploying this new method for the development of critical software for navigation systems.
Navigation systems merge multi-sensor critical data and they use complex temporal Finite State Machines and sophisticated high order digital filtering at the sensor level; Kalman filtering with 45 to 50 states, large matrix computation and huge data flows. Furthermore, the architecture requirements are demanding in order to mix slow and fast data variations, whilst still achieving an operation frequency in the region of 2 KHz. Consequentially, system design and software architecture functions must interact closely.
As with most embedded systems, complexity increases from generation to generation and, in the case of navigation systems, this is coupled with an increase in the volume of data to be processed. With this increased sophistication come more stringent safety and certification requirements, which imply a non-linear increase in the time and cost spent on validation, verification, traceability, and justification tasks.
Moreover, evolving business drivers require a core design with several derived products so creating a necessity for efficient reuse of as much software as possible. SAGEM thus decided to implement a model driven engineering process. This powerful approach coupled with a dedicated organisation within every project resulted in several significant benefits:
- Handling the functional complexity at a more abstract level, thus giving a better understanding and overview of the design.
- Enforcement of safety-critical requirements from the beginning of the process.
- Iteration of design refinements throughout the development process.
- Creation of the certification documentation earlier.
- Automation of low level tasks.
- Improved ability to deal with time and costs constraints.
Esterel SCADE Suite minimizes the development time and cost of the targeted functions, namely: HF inertial filtering, GPS (ionospheric correction, channel state machine and parity matrix computing). With SCADE Suite, SAGEM generated 80% of the application software and also achieved the execution time vs. frequency computation optimisation that they required. Deployment is thus now in progress.