Distributed control of industrial robot systems using Petri net based multitask processing
In this paper, the methods of the modeling of the discrete event robotic manufacturing systems using Petri nets are considered, and a methodology of decomposition and coordination is presented for hierarchical and distributed control, where the cooperation of each controller is implemented so that the behavior of the overall system is the same as the centralized control system and the task specification is completely satisfied. First, a task specification is defined as a Petri net model at the conceptual level, and then transformed to the detailed Petri net representation of the subtasks. Finally, the overall Petri net is decomposed and the constituent subnets are assigned to local Petri net based controllers. The controllers are coordinated so that the decomposed transitions fire at the same time by the coordinator. System coordination algorithm through communication between the coordinator and the controllers, is presented. By the proposed method, modeling, simulation and control of large and complex manufacturing systems can be performed consistently using Petri nets.
Towards a BSN-based gesture interface for intelligent home applications
This paper presents an attempt towards the development of a hand gesture-based interface for intelligent home applications using Body Sensor Networks (BSNs). The system being developed consists of four main components namely BSN sensor gloves as the input devices, a software prototype for facilitating mappings of sensory signals onto different commands, a model for automatic gesture recognition and a relay-board for demonstrating device control output. Our current results include the first version of software prototype and real-time recognition of simple gesture commands from signals acquired using the BSN-based flex-sensor glove.
Proposal of Mark Flow Graph for Discrete System Control
The authors propose the Mark Flow Graph for the purpose of theoretical systematization of the sequential control. Sequential control systems are regarded as the event-conditon systems which are activated by mutual connections between events and conditions. These systems have such fundamental features as asynchronism, ordering, concurrency and conflict, and unsafeness and deadlock will happen to them. Petri net is one of the effective means to represent the systems with these properties and phenomena. The authors modify the concept of Petri net to develop the design and analysis tool for sequential control systems taking the safeness and notation of input/output functions into consideration. Mark Flow Graph (MFG) is proposed as such a new kind of graph. The paper deals mainly with the definitions and rules of MFG, and also with the basic subjects about its structure, structurl properties and deadlock phenomenon. Keyword: sequential control system, Petri net, Mark Flow Graph, concurrency, event-condition system