MBD, OOT and Code Generation: A Cost-Effective Way to Speed Up HMI Certification 2012-01-2137

This white paper explains the benefits of the Model-Based Design (MBD) approach and Object-Oriented Technology (OOT) that DO-178C provides. It also specifically focuses on the usage of Models and COTS Qualifiable tools that automate or facilitate the verification and validation of avionics applications constructed from Models in order to ensure that there is no unintended function.

Software running in Aircraft cockpits has dramatically increased in complexity since DO-178B's revision in 1992. Furthermore, over the past 20 years, software development methods have made significant leaps forward and DO-178B has begun to show its age with respect to the new technology introduced to facilitate software development.

This year the newly revamped DO-178C standard sets the certification process record straight by embracing modern technology. DO-178C does not only solidify its foundation by clarifying its core document but also builds the infrastructure to support modern software development techniques already commonly used in avionics development for at least a decade. Fortunately, DO-178C upgrades and clarifies DO-178B. DO-178C therefore considers four techniques of contemporary software development practices which are published as supplements to the core document: 1. Software Tool Qualification Considerations (TQC) [DO-330]. 2. Model-Based Design and Verification Supplement (MBDV) [DO-331]. 3. Object-Oriented Technology Supplement (OOT) [DO-332]. 4. Formal Methods Supplement (FM) [DO-333].

Organizations can see gains not only in the reduction of the development cycle but also in the overall improvement of the DO-178C certification process; including reduction of schedule and costs, and improvements in the quality and reliability.

In the old school of thought, the methodology relies on textual specifications and physical prototypes. That is why the informal Text-Based Design approach is tightly associated with the waterfall methodology where all the textual requirements are manually coded, inspected, and tested on a real embedded system. In this method, changes in any part of the waterfall chain are very costly and time-consuming, leaving almost no room to iterate on the design.

By contrast, in the Model-Based Design approach, the specifications are self-contained in the Human Machine Interface (HMI) Model. The HMI requirements are defined in an unambiguous way and often captured in a formal definition language. Model-Based Design offers a collaborative approach to avionics development and allows engineers to inexpensively experiment with various concepts by deferring hardware integration until much later in the development process. Correcting problems in the early modeling phase is undeniably the strongest argument in favor of the Model-Based Design approach for developing certifiable or non-certifiable avionics applications.

This white paper is based on "MBD & Code Generation: A Cost-Effective Way to Speed up HMI Certification," by Luc Marcil, Presagis, Montréal, Québec (Canada) which was presented at the 30th Digital Avionics Systems Conference in October 18th, 2011. © 2011 IEEE.