Robotic System Specification Methodology Based on Hierarchical Petri Nets

The paper presents a methodology of creating a Hierarchical Petri Net modelling the activities of a multi-agent robotic system. The methodology follows the separation of concerns approach to the design of robot control software, thus five layers resulted, representing: the system composed of agents, agents' subsystems, behaviours of subsystems, behaviour pattern, and finally inter-subsystem communication and transition function calculation. Blocking and non-blocking communication modes are taken into account. The robotic system structure and its activities are specified using the developed Robotic System HPN Tool. It facilitates modeling HPNs, verification of the activities of a robotic system through the HPN simulation and automatic code generation of an equivalent ROS based system. The specification methodology is presented on a simple example of designing a controller for the LWR4+ robot.