From non-autonomous Petri net models to executable state machines

Petri nets have long been known as a readable and powerful graphical modelling language. In particular, Petri nets also allow the creation of high-level models of embedded controllers. These models can be translated to executable code. This possibility is already available in some tools including the IOPT Tools. Another possibility is to translate the Petri net model into a state machine, which can then be easily executed by an even larger number of platforms for cyber-physical systems. In that sense, this paper presents a tool that is able to generate a state machine from a non-autonomous class of Petri supported by the IOPT Tools framework (which is publicly available). These state machines would be too large to be manually generated, but can now be automatically created, simulated, and verified using an higher-level modelling language. The state machines can then be used for execution or even as input for additional verification tools. This paper presents the translation algorithm and an illustrative example.This work was partially financed by Portuguese Agency FCT Fundação para a Ciência e Tecnologia, in the framework of project UID/EEA/00066/2019

Control of Time-Constrained Dual-Armed Cluster Tools Using (max, +) Algebra

International audienceThe problem studied in this paper is the control of discrete event systems subject to strict temporal constraints using (max, +) algebra. Initially we sought necessary and sufficient conditions for the existence of a causal control law guaranteeing the respect of the temporal constraints. Subsequently, a method for calculating the control law, if any, is proposed. The application which we are interested in is the control of a manufacturing semiconductor wafers process subject to strict temporal constraints

Modeling and Analysis of Resource Sharing Approach in Common Platform Strategy Using Petri Net Theory

The most competitive advantages in business and manufacturing is resource-sharing.We must share common resources to produce a group of product family with using common platform strategy. This strategy helps us to increase profit and value in business. It is necessary to apply this strategy to model and analyze resource achievability in different situations. In this paper we try to develop a practical model for analyzing common resource behavioral in platform area with using Petri net theory. Petri Nets have been successfully used for modeling and control the dynamics of flexible manufacturing systems.This paper presents some important concepts about common platform and petri net theory and then presents numerical examples to show how to use Petri net for modeling and analysis in common platform. This model is very useful for common platform strategy and can be used to determine reliability of common platform systems in an effective way

A Coloured Petri Net- and D* Lite-Based Traffic Controller for Automated Guided Vehicles

Mobile robots, such as Automated Guided Vehicles (AGVs), are increasingly employed in automated manufacturing systems or automated warehouses. They are used for many kinds of applications, such as goods and material handling. These robots may also share industrial areas and routes with humans. Other industrial equipment (i.e., forklifts) could also obstruct the outlined routes. With this in mind, in this article, a coloured Petri net-based traffic controller is proposed for collision-free AGV navigation, in which other elements moving throughout the industrial area, such as humans, are also taken into account for the trajectory planning and obstacle avoidance. For the optimal path and collision-free trajectory planning and traffic control, the D* Lite algorithm was used. Moreover, a case study and an experimental validation of the suggested solution in an industrial shop floor are presented

Petri net controllers for Generalized Mutual Exclusion Constraints with floor operators

In this paper a special type of nonlinear marking specifications called stair generalized mutual exclusion constraints (stair-GMECs) is defined. A stair-GMEC can be represented by an inequality whose left-hand is a linear combination of floor functions. Stair-GMECs have higher modeling power than classical GMECs and can model legal marking sets that cannot be defined by OR–AND GMECs. We propose two algorithms to enforce a stair-GMEC as a closed-loop net, in which the control structure is composed by a residue counter, remainder counters, and duplicate transitions. We also show that the proposed control structure is maximally permissive since it prevents all and only the illegal trajectories of a plant net. This approach can be applied to both bounded and unbounded nets. Several examples are proposed to illustrate the approach

Executable models for Embedded Controllers Development -A Cloud Based Development Framework

Abstract-We present IOPT-Tools, a tool framework for the development of digital controllers based on graphical executable models. The framework supports edition, simulation, verification through state-space querying, and code generation for several hardware platforms, most notably microcontrollers (e.g. Arduino, PIC, and Raspberry Pi) and FPGAs. The tool framework uses a class of Petri nets and is cloud based: the development process is performed using a browser

Modeling next generation air traffic control system with petri net

The Federal Aviation Administration (FAA) is one of the largest Air Navigation Service Providers, managing air traffic for more than 15% of the world\u27s airspace. Today\u27s Air Traffic Control (ATC) system cannot meet the growth of the air traffic activities, which brings with more unprecedented delays. At the same time, Air Traffic Controllers are facing higher workload than ever before. The FAA has declared that the existing ATC system will transition to a new system known as “Free Flight”. “Free Flight” will change today\u27s ATC system by giving pilots increased flexibility to choose and modify their routes in real time, thereby reducing cost and increasing system capacity (Nordwall, 1995). In this work, the modules and data flow of the next generation ATC system is designed, and their Petri net models are constructed for the control module to achieve “Free Flight”