Simulator

A simulator is a software tool designed to mimic the behavior of a real-world system, process, or environment within a virtual setting. It creates a controlled space where developers reproduce how a system will perform under various conditions without needing the actual hardware or physical environment. This is particularly valuable in safety-critical industries, where developing and testing physical prototypes can be time-consuming and expensive.

Simulators come in many forms, each tailored to specific needs. In the automotive world, you might encounter vehicle dynamics simulators that model how a car handles different road surfaces. You might also see sensor fusion simulators that replicate the input from various sensors like cameras, radar, and lidar for advanced driver-assistance systems (ADAS).

If the software is developed model based, e.g. with MATLAB/Simulink, this development environment also serves as simulator.

These tools are crucial for everything from powertrain development to testing complex autonomous driving algorithms.

Even though simulators themselves don't run on the final embedded system, they play a critical role in shaping the quality and correctness of the final product. Simulators are used to create, transform, analyze, and test the safety-critical systems, influencing the final product, even indirectly.

For instance, if a simulator used to validate a safety feature in an autonomous vehicle incorrectly simulates certain driving conditions, critical errors could go undetected, potentially leading to unsafe behavior in the real vehicle. Because of their direct influence on safety, simulators are subject to a systematic evaluation process defined in ISO 26262 Part 8, Clause 11.

For simulators, a higher level of confidence and rigorous qualification might be necessary. This ensures that the simulator accurately reflects real-world scenarios and that its results can be relied upon for safety arguments.

Similar considerations apply in different industries, with standards like IEC 61508 (general industrial), DO-178C (aerospace), and EN 50128 (rail) also requiring careful assessment of software tools.

In the automotive industry for example, ISO 26262 addresses simulators as "software tools" under Part 8. This clause outlines a clear process for evaluating and qualifying software tools to ensure they can be trusted in the safety development lifecycle. The process involves classifying tools and determining the required confidence level.