Robot Controller with Object Petri Net

A control component describes as a part of the control activities of a robot controller. It can represent several entities of the controller, as we decompose the controller into a set of interconnected entities, for instance Command (entity that executes a control law or a sequence control), Perception (entity in charge of sensor signal analysis, estimation etc), Event Generator ( entity that monitors event occurrences), Mode Supervisor (entity that pilots the use of a physical resource in a given mode as autonomous, teleoperation, cooperation), Mission Manger (entity that manages the execution of a given mission), etc. a control component manages and incorporates a set of representation components which define the knowledge it uses to determine the contextual state and to make its decisions.

The control of components is active entities. They can have one or more activities, and they can send messages to other control components. Internal properties of a control component are operations, attributes and an asynchronous behavior. Representation components are incorporated as attributes and as formal parameters of its operations. Each control component operation represents a context change during its execution. The asynchronous behavior of the control component is described by an OPN (Object Petri Net), that models its control logic. Tokens inside the OPN refer to representation components used by the control component are managed such as parallelism, synchronization, concurrent access to its attributes, etc. the control component operations are executed when firing OPN transitions. This OPN based behavior describes the exchanges, message reception and emission, performed by the control component, as well as the way it synchronizes its internal activities according to these messages. Thus OPN correspond to the reaction of component control according to the context evolution, received message, occurring events, etc. we chose OPN for modeling and implementation purposes. The use of Petri nets with objects is justified by the need of formalism to describe synchronizations precisely, concurrent data access and parallelism within control components, but also interaction between them.

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