This paper presents a method of designing variable structure control systems for robots. As the on-board robot computational resources are limited, but in some cases the demands imposed on the robot by the user are virtually limitless, the solution is to produce a variable structure system. The task dependent part has to be exchanged, however the task governs the activities of the robot. Thus not only exchange of some task-dependent modules is required, but also supervisory responsibilities have to be switched. Such control systems are necessary in the case of robot companions, where the owner of the robot may demand from it to
The paper presents a robotic system design methodology based on the concept of an embodied agent decomposed into communicating subsystems, whose activities are specified in terms of FSMs invoking behaviours parameterised by transition functions and terminal conditions. In the implementation phase, this specification is transformed into a system composed of a whiteboard providing communication means and logically labelled FSMs (LLFSMs) defining the system behaviour. These concepts are used to generate the code of the robot controller. The inclusion of inter-subsystem communication model completes the resulting system design with respect to our previous work that did not account for this model. Thus communication plays a central role in this presentation. The design methodology is exemplified with a rudimentary table tennis ball-collecting robot. The presented methodology and the implementation tools are suitable and beneficial for application to the design of other robotic systems.
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. INDEX TERMS Robotic system specification methodology, robotic system design methodology, communication model, hierarchical petri net.
A robot system is designed as a set of embodied agents. An embodied agent is decomposed into cooperating subsystems. In our previous work activities of subsystems were defined by hierarchical finite state machines. With their states activities were associated. In that approach communication between subsystems was treated as an implementation issue. This paper represents activities of a robot system using hierarchical Petri nets with conditions. Such net is created by specifying consecutive layers: multi-agent robot system layer, agent layer, subsystem layer, behaviour layer and communication layer. This decomposition not only organizes in a systematic manner the development of a robot system, but also introduces a comprehensive description of concurrently acting subsystems. Based on those theoretical considerations, a tool was created for producing hierarchical Petri nets defining the model of a robotic system and enabling automatic generation of the robot controller code, resulting in a significant acceleration of the implementation phase. The capabilities of the tool are presented by the development of a robot controller performing a rudimentary task.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.