Ales Polic

Closed-loop matrix based model of discrete event systems for machine logic control design

This paper deals with modeling, dynamic description, and control of discrete event systems (DES) for production systems and machines control logic design. The control logic of such systems is considered as DES, which is then modeled by a matrix representation of Petri net graph. The dynamics of a DES is described by a well known algebraic Petri net next-state equation and a novel logical firing event selecting equation. The control of the DES dynamics is introduced by logical signals, which represent conditions for occurrence of events. Such a presentation enables closed-loop modeling of DES, which is important for simulation of the systems and analysis of their performance before the target system is actually built. The proposed method is illustrated with a cutting machine application. Using the proposed method, the correct functionality as well as faults response can be simulated with Matlab/Simulink.

Matrix based logic controller

This paper deals with the modelling, dynamic description and control of the discrete event systems within the scope of flexible manufacturing systems and machines control logic design. The modelling of discrete event systems is based on a matrix description of Petri nets. The matrix representation is supplemented with PN next-state function and discrete event controller equation which enables the dynamic description of the discrete event system. The control of the discrete event system is ensured by introducing the transition condition inputs. Such a description of discrete event system enables the simulation of the system and analysis of its performances before the target system is actually built. The target system in this paper is a cutting machine transport system. Using the proposed method, the fault response properties of target system are simulated and analyzed.

Modeling and logic control design for production system: a matrix based approach

This paper introduces a novel, more systematic approach to the modeling and control design of machine logic control. The machine logic control is considered to be an event-driven system. A matrix representation of Petri nets is used, for modeling the structure of discrete event-driven system. Its dynamics is described by state-transition equations. The control of discrete event system is introduced by drawing a clear distinction between the plant and the controller model. The proposed approach is illustrated by simulation and experimental results for the lab-scale linear drive position initialization procedure.

FPGA Based Discrete Event Current Control Strategy for a Three Phase Inverter

This paper investigates the possibilities of the design of current control for VSI from the discrete event point of view. Event-driven control approach determines the transistor switching pattern directly from the current error logic signals and is designed using a novel matrix based approach for the description of the discrete event systems. A new approach for description of event-driven systems is introduced. It is based on matrix description of Petri Nets, supplemented with a combination of logic and algebraic equations. The control algorithms designed by proposed approach can be easily implemented on modern DSP an FPGA devices. The approach is illustrated with the design of direct current controller for a three phase inverter fed Permanent Magnet Synchronous Machine and is examined with simulations and experimentally confirmed.

Rapid Control Prototyping of Mechatronic Systems

This paper presents a new approach to the rapid prototyping of mechatronic control devices. The mechatronic control device as found in practice can be considered as a hybrid system: it is composed of a time-driven subsystem and an event-driven subsystem. For modeling of such a system a unified recursive approach is presented in this paper. The rapid logic control prototyping paradigm is illustrated by a simple case study that involves implementation on an in-house developed high-performance DSP/FPGA experimental platform

Rapid embedded control prototyping by Petri nets

This paper presents rapid prototyping approach of control devices in mechatronics. The logic control device is considered as an embedded event-driven system. For modeling of the structure of such a system the paper proposes the use of a matrix representation of Petri nets. The dynamics are described by state-transition logic equations. The control concept for discrete event system resembles the conventional closed-loop concept of continuous and discrete time systems. The paper focuses on rapid logic control prototyping paradigm with Petri nets that is illustrated by the case study of a linear drive initialization procedure.

A matrix based approach to design of logic control functions for a production system

Contemporary production systems and machines contain extended technology, functionality and communication features. Consequently, the size of control and steering of such machines increases. To cover the advanced functionality and to design the control in shorter development cycle a systematic approach is necessary. This paper introduces a new, systematic approach to the modeling of the machine control logic. The machine control logic is considered as event-driven system. Modeling of the structure of discrete event-driven system is based on matrix representation of Petri nets. The discrete dynamics of such a system is described by transferring the system between its specific discrete states. This is denoted using combination of algebraic and logic equations. To show the application of proposed approach, simulation results for the cutting machine transport system are presented. Connecting introduced modeling approach with the continuous system theory, overall functionality of the system was described. This is important for the simulation, analysis and implementation of rare and expensive systems, where the target system does not allow the traditional try and fix implementation approach or the target system is not available for testing of the control logic

A Recursive Description of Mixed Time- and Event-driven Dynamics in Mechatronic Systems

This paper introduces a recursive systematic approach for design of event-and data-flow control structures in mechatronic systems. The key idea, illustrated in this paper, is to widen the idea of well known state space description of time-driven systems to the field of event-driven systems, which results in a unified recursive modeling approach for both kinds of processes. The interaction between the time-driven and event-driven processes is introduced by converting continuous values into the logical conditions on one side, and by converting discrete logic states into the appropriate continuous reference values on the other side. Proposed approach is illustrated by simulation and experimental results for the lab-scale single axis drive position homing sequence procedure.

Rapid Prototyping of Mechatronic Systems with Mixed Continuous and Discrete-Event Dynamics

This paper presents rapid prototyping approach for control devices in mechatronics with special attention paid to the unified description and interaction of continuous and discrete-event processes. Traditionally, different dynamics of continuous processes one hand, and logical discrete event processes on the other hand, requires a different theoretical approaches for the description of both kind of processes. However, a complete functionality of the mechatronic system is achieved by settling interaction between both kinds of processes. In this paper, the idea of well known state space description of continuous systems is widened to the field of event driven systems, which results in a unified recursive modeling approach for both kinds of processes. The interaction between the continuous and event-driven processes is introduced by converting continuous values into the logical conditions on one side, and by converting discrete logic states into the appropriate continuous reference values on the other side. The interaction process is illustrated on the single axis drive position initialization procedure. The experiment is implemented using a high performance DSP/FPGA experimental board, supported with graphical programming environment

VSS Current Control Strategy for a Three Phase VSI

This paper introduces a new current control principle for three phase VSI. The transistor switching vector for the current control is determined directly from the Lyapunov stability condition in order to select the most effective transistor switching vector. To reduce the switching frequency of the proposed current control algorithm, sequential switching among the transistor switching vectors is introduced, which is described using a novel recursive matrix logic controller approach for description of the discrete event systems. Next to the systematic control design procedure, simplified implementation is major benefit of the proposed approach. Instead of traditional coding, the control algorithms are loaded in the form of logical matrices. The approach is illustrated by the design of event-driven current controller for a three phase inverter fed Permanent Magnet Synchronous Machine. The design is examined by simulations and experimentally confirmed.