Development and analysis of car rearlights in accordance with the standard ISO26262

The purpose of this thesis is to implement the lifecycle, according to the ISO26262, for the concept, system and hw parts of the development of a car rearlight in order to point out how the safety process impacts on the electrical and electronic parts of a car item. The car item chosen for this project is the car rearlight and its functionalities of stopping, turning and tailing. This work includes the safety analysis, both quantitative and qualitative, that provide an evaluation of the robustness of the system. Since the preliminary requirements and the applied analysis are based on mathematical criteria and verified at model level, without the possibility of an implementation in a real system (car), V cycle results completed and confirmed only for the verification section (test branch, model level, ..). The validation (including on board tests) is out of scope for this work. The resources used are the following: standard ISO26262:2018, schematics and BOMs relating to examples of existing car rearlights, the desired functional requirements to which the device must be compliant with, simulation tool as Matlab and Simulink, Isograph Reliability Workbench tool. Expected outcomes: writing of a Technical Safety Concept from functional specifications; writing of system-level technical requirements; development of a system-level block architecture; writing of hardware-level technical requirements; development of a hardware-level block architecture; development of a detailed circuit diagram (starting from pre-existing diagrams); Safety Analyses at the hardware level (FTA, FMEDA). In order to satisfy the desired goals, the project started with the analysis of the assigned Safety Goals and their respective ASIL levels in order to understand the approach to be used in accordance with ISO26262. From the Safety Goals, the Functional Safety Requirements were derived. Thus the project system architecture was developed remaining at the system level. Then, in order to keep track of the main information concerning the project, a Technical Safety Concept has been drawn. The TSC also contains the Technical Safety Requirements which translate the FSRs at technical level and assigns a given issue to the field of competence capable of resolving it (HW or SW department). Referring to this project, only the HW requirements have been treated and specified into another document named Hardware Safety Concept (HWSC). For what concern the HW design, a single one was created to satisfy both safety and non-safety requirements so that only one development process was involved to handle both. After the HW design development the verification was needed to ensure the compliance of it with the hardware safety requirements. The verification was made both qualitative (FTA) and quantitative (FMEDA) as requested by the ISO. At the end of the verification, the computation of the parameters’ value proved that the direct development of the design in accordance with the requirements does not need any adjustment as the parameter values fall within the required range by the ISO for the assigned ASIL levels. This result showed that the development of the car item of the project was optimized by reference to the standard at the beginning of the development itself and not making the a posteriori analysis.