Several kinematic and dynamic models of conventional motorized wheelchairs in the literature presume the wheelchair movement only on flat surfaces, disregarding the effects of gravitational forces and rolling friction. In addition, there are no many studies clearly describing how the dynamic properties of a conventional wheelchair and stair-climbing wheelchair with a track mechanism are formulated. However, the design of a good controller generally involves the formulation of a comprehensive wheelchair model. This work contributes to the modelling of the motorized wheelchair with hybrid locomotion systems (MWHLSs), which have wheel and track mechanisms to move the wheelchair, regarding the formulation of kinematic and dynamic models for each locomotion system, considering the effects of gravitational forces and rolling friction, on flat and inclined surfaces and climbing stairs. From the mathematical model for each locomotion system, the gearmotor torque control is used, since the torque provides smooth and precise driving. Thus, the open-loop and closed-loop control techniques, such as control Lyapunov function, Backstepping control, and Proportional-Integral-Derivative controller, are designed due to their well-known characteristics. The robustness analysis of these controllers, taking into account the occurrence of external disturbances, indicates which one best assists wheelchair users, providing a safer and more efficient navigation with the MWHLS.

A key problem for implementation of a collaborative and distributed production system focused on demand is the well-structured communication among productive processes. In this context there are techniques such as workflow-net (Wf-net) but they use in practical cases is not so simple. On the other side, productive Petri net (PPN) is an interpretation of Petri net which simplifies the workflow representation of the productive processes. PPN highlights different workflow patterns of productive processes, i.e., the specific information of processes stages are organized to facilitate the interpretation by a human user. Therefore this work presents a comparison of both techniques, and confirms the advantages of PPN.

Building facilities have become important infrastructures for modern productive plants dedicated to services. In this context, the control systems of intelligent buildings have evolved while their reliability has evidently improved. However, the occurrence of faults is inevitable in systems conceived, constructed and operated by humans. Thus, a practical alternative approach is found to be very useful to reduce the consequences of faults. Yet, only few publications address intelligent building modeling processes that take into consideration the occurrence of faults and how to manage their consequences. In the light of the foregoing, a procedure is proposed for the modeling of intelligent building control systems, considersing their functional specifications in normal operation and in the of the event of faults. The proposed procedure adopts the concepts of discrete event systems and holons, and explores Petri nets and their extensions so as to represent the structure and operation of control systems for intelligent buildings under normal and abnormal situations.

. The design of ACSs (Automation and Control Systems) is specific for each application, such as CNC machine, robot, machine controlled by PLC (Programmable Logic Controller), process controlled by SCADA (Supervisory Control and Data Acquisition) and equipment with FPGAs (Field Programmable Gate Arrays) for customization of their behavior. These technologies have different domains, i.e., the control solution can be implemented by hardware and software in different architectures and heterogeneous specifications. Although several engineering solutions facilitate the development for each application, the integrated design of ACS is still considered a complex task, because it is necessary to master different domains and, consequently, it involves a large number of specialists to understand the whole system. Moreover, in practice, most of ACSs are designed in a relatively short time due the competition of companies. ACSs must ensure the fulfillment of the current requirements in PSs (Productive Systems), such as flexibility, distributed architecture, and agility in response to changes imposed by the market or the inevitable occurrence of faults. In this context, one solution is a combination of techniques such as HCS (Holonic Control System) and AFTCS (Active Fault-Tolerant Control System), which allows the reuse of models, reconfigurability, autonomy, cooperation, and learning ability. Therefore, this paper proposes a procedure based on AHCS (Active Holonic Control System) concept for integrated design of the entire lifecycle of ACS: from requirement specifications to operation and maintenance, to ensure greater flexibility, efficiency and robustness of the PSs. The procedure combines bottom-up and top-down approaches using Petri net technique and its extensions - PFS (Production Flow Schema), through dynamic modeling of the system in e-PN (extended Petri Net) and the gradual refinement based on PFS. An example of application in FMS (Flexible Manufacturing System), considered a representative class of PS, is used to demonstrate the advantages of the proposal.

Safety Instrumented Systems (SIS) are designed to prevent and / or mitigate accidents, avoiding undesirable high potential risk scenarios, assuring protection of people's health, protecting the environment and saving costs of industrial equipment. The design of these systems require formal methods for ensuring the safety requirements, but according material published in this area, has not identified a consolidated procedure to match the task . This sense, this article introduces a formal method for diagnosis and treatment of critical faults based on Bayesian network (BN) and Petri net (PN). This approach considers diagnosis and treatment for each safety instrumented function (SIF) including hazard and operability (HAZOP) study in the equipment or system under control. It also uses BN and Behavioral Petri net (BPN) for diagnoses and decision-making and the PN for the synthesis, modeling and control to be implemented by Safety Programmable Logic Controller (PLC). An application example considering the diagnosis and treatment of critical faults is presented and illustrates the methodology proposed.

Markets are becoming independent of geographic barriers and industries are seeking new manufacturing systems configurations, from centralized structures to distributed structures, moving their productive plants to countries with energy reserves and low operating costs. To allow the coordination and management of this new distributed structure, it takes advantage of the advances in mechatronics and information technologies (IT), which allow a greater cooperation between the system parties and between the involved users (clients, operators, managers, etc.). Each part of this part of disperse productive system (DPS), which is also a productive system, has a high level of operational autonomy. Thus, this kind of system presents new integration and coordination problems which must be overcome to achieve effective implementation. The recent DPS technologies use mechatronics and IT advances and explores the internet resources for components interactions, transforming them into services. The service composition is one of the components coordination challenges in DPSs. The service composition must not centralize the information exchange, as it must reduce dependence on a specific service. This work proposes a collaborative control of disperse system based service composition technique.

Distributed control systems consist of sensors, actuators and controllers, interconnected by communication networks and are characterized by a high number of concurrent process. This work presents a proposal for a procedure to model and analyze communication networks for distributed control systems in intelligent building. The approach considered for this purpose is based on the characterization of the control system as a discrete event system and application of coloured Petri net as a formal method for specification, analysis and verification of control solutions. With this approach, we develop the models that compose the communication networks for the control systems of intelligent building, which are considered the relationships between the various buildings systems. This procedure provides a structured development of models, facilitating the process of specifying the control algorithm. An application example is presented in order to illustrate the main features of this approach.

This paper presents an overview of some of the main research lines in Mechatronics, under development in Brazil and the world. Three main areas are focused: Supervision and Control, Robotics and Instrumentation. For each area, we highlight the problems and tendencies for the future. Following the paradigm of “divide to conquer”, we present distribution and communication as the key concepts for the future.

This paper presents the development of a remote monitoring and control system for a CIM plant. It discusses the main steps for the system specification. The purpose of the remote access system is to provide the user with facilities necessary to understand the system behavior, propose supervisory control strategies and test them.

This paper introduces a new approach for the modelling of hybrid productive systems. This approach is based on Petri net to represent the discrete part, differential equations to describe the continuous part and object-oriented paradigm to deal with the complexity problem in real systems. During the modelling process, the Unified Modelling Language (UML) is used in order to support the description of different aspects and identify different hybrid characteristics of the system. The proposed approach is illustrated using as an example the design of supervisory systems for air-conditioning systems.

This paper introduces a methodology for modeling and analyzing fault-tolerant manufacturing systems that not only optimizes normal productive processes, but also performs detection and treatment of faults. This approach is based on the hierarchical and modular integration of Petri nets. The modularity provides the integration of three types of processes: those representing the productive process, fault detection, and fault treatment. The hierarchical aspect of the approach allows us to consider processes on different levels of detail (i.e., factory, manufacturing cell, or machine). Case studies considering detection and treatment of faults are presented, and a simulation tool is applied to verify the models.

This paper introduces a new approach for the modelling and verification of behaviour properties in complex industrial plants that are hybrid in nature. It is based on Petri nets to represent the discrete view and differential equations to describe the continuous part. The object-oriented concepts are used to provide modularity and handle system complexity. With respect to the system analysis, the object-oriented structure allows a global analysis problem with a number of objects to be divided, into a set of local problems involving one or a few objects only. The proposed approach is applied to a cane sugar factory.

This paper introduces a methodology for modeling and analyzing fault-tolerant manufacturing systems that not only optimizes normal productive processes, but also performs detection and treatment of faults. This approach is based on the hierarchical and modular integration of Petri Nets. The modularity provides the integration of three types of processes: those representing the productive process, fault detection, and fault treatment. The hierarchical aspect of the approach permits us to consider processes on different levels of detail (i.e. factory, manufacturing cell, or machine). Case studies considering detection and treatment of faults are presented, and a simulation tool is applied for verifying the models.

Several different types of modeling approaches of discrete-event dynamic systems (DEDS) have been presented in the literature, leading to a proliferation of related modeling and analysis tools. This paper presents a discussion on how some suitable modeling linguistic features can grant uniformity to the computational treatment of heterogeneous models. This uniformity aims at making the representation of models and, consequently, the operation of modeling and analysis tools follow a common pattern across all types of models, reducing, for example, the need to learn new user interfaces as new types of models and tools appear. This is an important feature as a computational system with these characteristics can handle the increasing variety of system features and requirements of modern production systems.

The aim of this article is to present an algorithm for interpreting condition/event Petri Nets for real-time control of discrete event systems. A brief exposition of the new challenges in manufacturing systems is made, explaining some features of multiprocessing, resource sharing, and reducing product life cycles, which increase the complexity of the related control programs. Next, it is shown that the programming languages in IEC 61131-3 are unsuitable for dealing with this complexity problem, and the condition/event Petri Net is presented as a possible solution. Then, the concept of condition/event Petri Nets is briefly explained, to introduce the algorithm itself afterwards. This algorithm is object-oriented, which increase its reuse/improvement potential. Finally, a runtime analysis of the algorithm is presented.

The design of supervisory system for automated environments can be seen as a task involving techniques and methods of two main areas: software and control engineering. In this context, the purpose of this work is to introduce a new approach for open distributed supervisory system design based on the merging of traditional techniques of software engineering (such as object-oriented concepts) with formal models of discrete events dynamic systems- (such as Petri nets). In this first level of abstraction, the reference model of open distributed processing (RM-ODP) is used as a standard architectural framework for the construction of open distributed system. Based on the RM-ODP, the unified modeling language (UML) diagrams are built as a second level of abstraction. Finally, the Petri nets (the third level of abstraction) are used throughout the process in order to guarantee the coherence among the UML models from requirement analysis to implementation, and to provide formal models of the system.

This paper introduces a new approach for the verification of behaviour properties in hybrid systems. By using Petri nets and object oriented concepts the proof of a system property is reduced from a complex proof involving the overall model to a set of simpler proofs involving the model of one or a few objects. Each local proof is made considering a set of hypotheses that should then be proven. Particularly, this paper considers the case of proving safety properties

In this paper, a methodology for considering detection and treatment of faults in automated machines is introduced. This methodology is based on the integration of Petri nets for diagnosis (BPN) and Bayesian networks. After that, the integration among detection/treatment of faults and the "normal" processes (represented by Petri nets, PN) is possible. This integration allows us to develop a fault tolerant supervisor, which considers all the processes in the same structure. A case study of fault tolerant AGV is considered. Finally, a simulation tool for edition and analysis of models with these characteristics is introduced.

Presents a framework for a supervisor in balanced automation systems (BAS). The concept of BAS is based on an appropriate technological level considering human factors and highly automated machines. The supervisor not only considers a normal process but also detection and treatment of failures. The framework is based on distributed Petri nets (DPNs). DPNs permit the integration of several modules of Petri nets , where each module represents a particular process such as, normal processes, detection and treatment of failures. A case study of detection and treatment of failure in machining operations is considered, in which, the normal process, the detection and treatment of failures in a BAS are integrated through modules based on DPNs.

In this paper, a Petri Net approach is introduced for modelling and simulation of control strategies in Intelligent Building. In this context, it is claimed that integration with other building systems can be achieved in a more systematic way considering a mechatronic approach (i.e. multidisciplinary concepts applied to the development of systems). The case study is the Ambulatory Building of Medical School Hospital of University of São Paulo. Particularly, the developed methodology is applied to the elevator system and to the HVAC (Heating, Ventilation and Air Conditioning) system. It is shown that using this approach, the control systems could be integrated, improving performance.