Vasileios Deligiannis

Flatness Conservation in the n-trailer System Equipped with a Sliding Kingpin Mechanism

Nonlinear systems, which are differentially flat, have several properties that can be useful on designing effective controllers. In this paper we show that the n-trailer system equipped with a sliding kingpin mechanism is a differentially flat system, like its non-sliding kingpin counter part. The sliding kingpin technique is used to eliminate the undesired deviation of the path of each intermediate vehicle from that of the leading one (off-tracking phenomenon). The linearizing outputs of the flat system are the Cartesian coordinates of the middle of the last semi-trailers axle. The state space and the kinematic equations of the new modified system are derived and the conditions for flatness are examined. The flatness conservation is also checked relatively to several kinds of dynamic sliding feedback control.

Implementing global automata in PLCs based on the IEC 61131-3 programming norm

Global Automata are a recently proposed approach on modelling contemporary industrial systems. They are based on automata philosophy and are specially orientated for industrial use. In industry the dominant controller is the Programmable Logic Controller (PLC), which is a special aim computer suitably built for the application control tasks. The IEC 61131-3 Programming Norm describes all the well-known languages for programming PLCs and this paper presents a synthesis tool for implementing global automata in PLCs based on this programming norm. Differences on language semantics between several manufacturers are frequent since the international standard is an open frame. Due to this fact the presented synthesis tool gives an industrial engineer the general guidance to write the respective code from a global automaton.

INTRODUCING A NEW MATHEMATICAL ABSTRACTION FOR MODELING REAL TIME SYSTEMS

Abstract Due to the increasing complexity of industrial production systems, there exists a need for the development of efficient formal approaches for their analysis and control. Various methods have been proposed and examined from researchers, without being widely adopted for direct industrial use. In general, an industrial production line can be modelled as a Discrete Event System, but a more accurate representation would result, if we considered it as a real-time system. This paper presents a new mathematical abstraction for modelling real-time systems. In comparison with the conventional methods, the proposed method introduces new formulation parameters and handles variables in a different manner. It gives the opportunity to handle both discrete and real valued variables as inputs, outputs or both. A formal definition of the method is given and some examples of computations or runs of two typical examples are also presented.

A survey on automata-based methods for modelling and simulation of industrial systems

The importance of modelling and simulation for the design of high quality industrial systems in a limited amount of time is generally acknowledged. Studying industrial systems by simulation enables the designer to study their dynamic behaviour and determine characteristics of the system. Due to the increasing complexity of industrial production systems, there exists a need for the development of formal approaches for their analysis and control. While there has been intensive research effort concerning theoretical aspects on control of discrete event systems, less work has been reported on practical implementation techniques with general acceptance. This paper focuses on Automata forms of modelling considered as the primary representation scheme of industrial plants. It also presents an overview of software tools with both educational and commercial orientation, necessary on the way to real applications in modern industry.

Global automata: a new approach on modelling industrial systems

This paper introduces Global Automata as a new approach on modelling contemporary industrial systems. Global automata are based on automata philosophy and, as their name reveals, they constitute a super-set of existing automata types. Their implementation field is, therefore, wider in comparison with other available types. Their main characteristic is that they are especially oriented for industrial use. As regards to model architecture, they introduce new formulation parameters diversifying from conventional types, while they keep some common basic features. A formal definition of global automata is given as also two useful tools for system modelling, which are state aggregation and automata composition. Their use is illustrated with two representative industrial examples.

Modeling internal combustion engines using a hyper-class of hybrid automata: A case study

The reciprocating internal combustion engine is by far the most common form of engine or prime mover. As with most engines, the usual aim is to achieve a high work output with a high efficiency, and hence, control design is imperative. Subsequently, essential is the existence of a simulation model in order to give designer the ability to explore the merits of alternative designs without physically building the systems. This paper presents a new approach for modeling internal combustion engines. The modeling method is a recently proposed hyper-class of hybrid automata that provides greater modeling power compared with conventional methods, being suitable for modeling analysis of a wider variety of systems. The constructed model was implemented in an industrial software environment and simulation results were taken and presented

Automata Composition for Modeling Large Industrial Systems

Industrial production systems are usually described as discrete event systems (DESs). There are many academic methods for modeling DESs, such as Petri nets and several types of automata. All these methods did not meet great success when proposed for industrial use, primarily because they are application depended. In addition, contemporary industrial systems are hundred times more complex than typical systems found in academic papers. The dependence between application and formulation method seems to be avoided with a recently proposed new method, which is based on automata theory. Besides, the obstacle of complexity can be jumped over using composition of small systems in order to build a large systems model. The formal definitions of the new method and automatas composition are given in this paper and they are illustrated via a representative example

Automata-based modeling and control of a truck and trailer vehicle equipped with a kingpin sliding mechanism

Trailer systems consist of a steering tractor and a passive trailer linked together with rigid free joint. In this paper, we consider an active kingpin joint which is sliding on the rear axle of the tractor to compensate the off-tracking and jackknife phenomena. The backward and forward motion of the articulated vehicle is modeled in various distinct kinematic phases according to the kind of the path and braking or no condition. The scheme of a switching controller is formalized as a global automaton. The simulation results show an acceptable kinematic behavior of the vehicle and effectiveness in avoiding unstable maneuvers.

BUILDING AUTOMATA – TYPE SIMULATION MODELS FOR UNDERGRADUATE TEACHING INDUSTRIAL SYSTEMS ANALYSIS

Abstract Simulation has a significant role in control engineering. It provides the best solution for educating new engineers without expensive experimentation on real systems. This paper presents a guide for constructing simulation models based on a recently presented hyper-class of hybrid automata. New types definition is given jointly with some examples of guides use. Guide is applicable in various programming environments and is oriented for undergraduate teaching purposes.

Automata Based Modeling for Batching and Mixing Plants for Concrete

This paper deals with the modeling of a batching and mixing plant for concrete. Such plants are hybrid systems since they are described by both discrete and continuous variables. For building system model, a recently proposed hyper-class of hybrid automata was used. This method provides greater modeling power compared with conventional methods, being suitable for modeling analysis of a wider variety of systems. The model described entails a hierarchical model with an automaton as supervisor and several other automata controlling each systems part.