Formally Verified Animation for RoboChart Using Interaction Trees

RoboChart is a core notation in the RoboStar framework. It is a timed and probabilistic domain-specific and state machine based language for robotics. RoboChart supports shared variables and communication across entities in its component model. It has a formal denotational semantics given in CSP. Interaction Trees (ITrees) is a semantic technique to represent behaviours of reactive and concurrent programs interacting with their environments. Recent mechanisations of ITrees along with ITree-based CSP semantics and a Z mathematical toolkit in Isabelle/HOL bring new applications of verification and animation for state-rich process languages, such as RoboChart. In this paper, we use ITrees to give RoboChart a novel operational semantics, implement it in Isabelle, and use Isabelle’s code generator to generate verified and executable animations. We illustrate our approach using an autonomous chemical detector model. With animation, we show two concrete scenarios when the robot encounters different environmental inputs.