Visual-Trace Simulation of Concurrent Finite-State Machines for Validation and Model-Checking of Complex Behaviour

Simulation of models that specify behaviour of software in robots, embedded systems, and safety critical systems is crucial to ensure correctness. This is particularly important in conjunction with modeldriven development, which is highly prevalent due to its numerous benefits. We use vectors of finite-state machines (FSMs) as our modelling tool. Our FSMs can have their transitions labeled by expressions of a common sense logic, and they are more expressive than other modelling approaches (such as Behavior Trees, Petri nets, or plain FSMs). We interpret the models using the same round-robin scheduler which is integrated into the simulator. Execution on a platform is exactly the same as in the simulator (where sensors and actuators are masqueraded by proxies) and coincides with the generator of the Kripke structure for formal modelchecking. In three ubiquitous case studies we show that our simulation discovers issues where those models were incomplete, ambiguous, or incorrect. This further illustrates that simulation and monitoring need to complement formal verification.