Simulink models are also software : modularity assessment

In automotive industry, more and more complex electronics and software systems are being developed to enable the innovation and to decrease costs. Besides the complex multimedia, comfort, and safety systems of conventional vehicles, automotive companies are required to develop more and more complex engine, aftertreatment, and energy management systems for their (hybrid) electric vehicles to reduce fuel consumption and harmful emissions. MATLAB/Simulink is one of the most popular graphical modeling languages and a simulation tool for validating and testing control software systems. Due to the increasing complexity and size of Simulink models of automotive software systems, it has become a necessity to maintain the Simulink models. In this paper, we defined metrics for assessing the modularity of Simulink models. A Java tool developed to measure the defined metrics on Simulink models interfaces with a visualization tool to facilitate the maintenance tasks of the Simulink models. The modularity metrics is furthermore validated in two phases. In the first phase, the modularity measurement is validated against the experts evaluation of a system. In the second phase, we studied the relationship between metric values and number of faults. We have observed that high coupling metric values frequently correspond to number of faults. Modularity metrics will be extended to architectural quality metrics for automotive systems