Gašper Mušič

University of Ljubljana · Faculty of Electrical Engineering

This paper considers a novel heuristic algorithm called “MDSA” (Minimal Deviation Strategy Algorithm) for solving Flexible Job Shop Scheduling Problems (FJSSP). In the optimization of the machine schedule, one objective function is considered - the “makespan”, i.e., the maximum completion time for all operations of all jobs is minimized. The algori...

Petri nets (PN) are a versatile modelling tool that can also be used to represent scheduling problems. In this paper, a PN-based representation of schedules is investigated in the context of optimization by genetic algorithms (GA). A new sequence repair scheme is proposed, integrated into the GA optimizer, and applied to standard benchmark instance...

Petri nets are a promising tool for development of distributed scheduling approaches and integrating these developments with state-of-the-art schedule optimization algorithms. A Petri net-based solution representation of job shop scheduling problems in a local search optimization context is studied in this paper. A novel sequence repairing scheme i...

An evolving fuzzy model for fault detection is presented in this paper. The method is based on simplified, non-parametric fuzzy model named AnYa. The novelty in this paper is the partial density estimation where only the most influential components are used. The proposed method is tested on simulated data of Tennessee Eastman Process model and furt...

This paper tackles the problem of model identification for monitoring of non-linear processes using evolving fuzzy models. To ensure a high production quality and to match the economic requirements, industrial processes are becoming increasingly complicated in both their structure and their degree of automation. Therefore, evolving systems, because...

In this paper we present an on-line evolving fuzzy cloud-based identification method. The evolving part of the algorithm is improved with new mechanisms. In the part of adding clouds (fuzzy rules) a new condition is implemented in addition to existing ones. Moreover, completely new mechanism for removing the “less active” and “less informative” clo...

In this paper we present an on-line evolving fuzzy cloud-based identification method. The evolving part of the algorithm is improved with new mechanisms. In the part of adding clouds (fuzzy rules) a new condition is implemented in addition to existing ones. Moreover, completely new mechanism for removing the " less active " and " less informative "...

In this paper we present a fuzzy cloud-based model identification method tested on realistic input/output data signals acquired from simulated Tennessee Eastman (TE) benchmark process. The cloud-based method uses simplified antecedent (IF) part based on the local density of the clouds and functional consequent (THEN) part. Number of clouds (fuzzy r...

The contribution deals with local search based optimization of schedules that are modelled by Petri nets (PNs). PN modelling of scheduling problems in manufacturing domain is addressed and a generalization of neighbour solution generation is proposed. Such a solution generator can be used to optimize schedules by standard local search optimization...

The contribution deals with an implementation of discrete control logic for a modular production line, with two main objectives pursued. Firstly, the basic ideas of PackML standard should be implemented, in particular the behaviour of the machine from the operational state viewpoint, and secondly, the implementation should be based on low-end progr...

This paper presents the prototype of an advanced platform for production analysis and optimization, referred to as ProOpter. The platform was developed to support the recently derived concept of holistic production control (HPC), which relies on model-based control. The prototype is comprised of a set of offline and on-line modules. The off-line mo...

doi:10.1201/b16529-17

The paper deals with analysis and optimization of production performance dynamics expressed by key performance indicators (KPI). The architecture of a supporting software tool that integrates into production information systems is presented. The tool is able to support efficiency indicators composition, determination of performance influential vari...

This paper presents an implementation of predictive functional control for image-based satellite attitude control. The approach considers Low Earth Orbit small satellites equipped with an on-board camera for interactive Earth observation. The control goal is to keep a target on the Earth surface in the satellite's camera field of view during orbiti...

The paper introduces an XML schema complying with PMML standard suitable for a general fuzzy model formulation. It also presents a graphical user interface that is a part of a tool for analysis and control of production dynamics, which was developed at the Competence Center for Advanced Control Technologies. The interface is used for eFuMo model id...

For model-based production control and optimisation, it is crucial to properly identify those input variables that have the strongest influence on production performance. This way, production operators can focus only on the relevant variables, and production control problems can be reduced. In order to identify previously unknown relationships amon...

This paper presents the design of the image-based control algorithm for interactive Earth observation. The image-based control algorithm is obtained from the modelling of the satellite pose in space. It is shown that the image-based control algorithm can be designed for two types of satellite attitude control problems: direction tracking and orient...

Modelling and simulation are two promising methodologies in attempts to manage the ever increasing complexity of modern technical systems. The knowledge of the inherent continuous and discrete-event dynamics of systems improves the understanding of systems operation and provides the base for designing management and control strategies. Modelling an...

Remote sensing using low-Earth orbit satellites usually needs navigation sensors as well as imaging sensors to perform required Earth observation tasks. The main purpose of the presented research is to use a visual sensor, in this case an imaging camera, as an intelligent device for remote sensing and for extracting relative attitude information ne...

Holistic production control is a concept that introduces production optimisation by employing model-based, closed-loop control of the principal production Performance Indicators (pPIs). The concept relies on the development of a simple black-box model that describes the relation between the main pPIs and the most influential input (manipulative) va...

In this paper a method for estimating the relative orbit is proposed. The method requires a minimum number of simple sensors. The design of observers for formation-flying control, which is formulated as a control problem of tracking the target satellite, is treated. If the equations of the relative motion of the target and the chaser satellites are...

The paper deals with analysis of production line performance efficiency and builds a prediction model that enables a short-term prediction of the expected performance based on the scheduled product mix. The actual schedule can be used as the model input to assist the production operators at the on-line production management. The same model can be u...

This work deals with the image-based attitude control of a satellite for remote sensing. A real Nemo HD satellite performance is simulated by the developed simulator to show feasibility of the proposed image based attitude control. This satellite is being built in a co-operation between Slovenian centre of excellence Space-SI and Space Flight Labor...

The contribution deals with simulation-optimization of schedules that are modelled by Coloured Petri nets (CPNs). CPN modelling of standard classes of scheduling problems is addressed and compact CPN representations of scheduling problems are derived. A combination of CPN representations with predefined transition sequence conflict resolution strat...

Petri nets are suitable for modelling of discrete-event systems with highly parallel and cooperating activities. In complex man-made systems, such as manufacturing systems, the systems' specific properties, such as conflicts, deadlocks, limited buffer sizes, and finite resource constraints can be easily represented in the Petri net model. Therefore...

The contribution deals with simulation-optimization of schedules that are modelled by simple Coloured Petri nets (CPNs). CPN modelling of standard classes of scheduling problems is addressed and compact CPN representations of scheduling problems are proposed. It is shown how a combination of CPN representations with predefined transition sequence c...

In this paper we describe the design of a control algorithm for MISO systems, which can be modelled as hybrid fuzzy models. Hybrid fuzzy models present a convenient approach to modelling nonlinear hybrid systems. We discuss the formulation of a hybrid fuzzy model, its structure and the identification procedure. This is followed by a derivation of t...

The paper deals with the problem of timed state space generation and exploration in the frame of simulation–optimization approach for discrete-event systems. Coloured Petri net representation of a system is considered and corresponding techniques of timed state space generation and timed simulation are addressed. It is shown that the established si...

This paper presents the use of place/transition petri nets (PNs) for the recognition and evaluation of complex multi-agent activities. The PNs were built automatically from the activity templates that are routinely used by experts to encode domain-specific knowledge. The PNs were built in such a way that they encoded the complex temporal relations...

The paper proposes a new translation algorithm that translates a hybrid system described as a discrete hybrid automaton (DHA) into an equivalent piecewise affine (PWA) system. The translation algorithm exploits, among others, a new technique for cell enumeration in hyperplane arrangement, all proposed in this paper. The new translation technique en...

The paper deals with the image-based control of a remote sensing satellite. The position of the satellite is obtained by the Simplified General Perturbations model and its orienta tion by simulating its dynamic and kinematic models. For known position and orientation of the satellite the images are obtained using Google Earth. The orientation of the...

The synthesis of plant-wide control structures is recognised as one of the most important production-management design problems in the process industries. This article proposes a closed-loop control structure utilising production performance indicators (pPIs) as a possible solution to simplify this problem. pPIs represent the translation of operati...

Process manufacturing has a number of characteristics that make it different from other types of manufacturing. These characteristics are reflected in the design of process production control. This article addresses some features of process manufacturing that have to be taken into account during the design of a production control system in the proc...

In this paper we study a self-adaptive predictive functional control algorithm as an approach to control of temperature in an exothermic batch reactor. The batch reactor is situated in a pharmaceutical company in Slovenia and is used in the production of medicines. Due to mixed discrete and continuous inputs the reactor is considered as a hybrid sy...

The paper deals with Petri net based scheduling approach, where constructive heuristics in the form of dispatching rules is combined with a meta-heuristic embedded within the local search optimization algorithm. The approach is tested on some standard job shop benchmark problems.

This paper proposes an approach for reducing the computational complexity of a model-predictive-control strategy for discrete-time hybrid systems with discrete inputs only. Existing solutions are based on dynamic programming and multi-parametric programming approaches, while the one proposed in this paper is based on a modified version of performan...

This paper addresses the problem of verifying the discrete control logic that is typically implemented by programmable controllers. Not only are the logical properties of the controller studied during verification, the behaviour of the overall controlled system is also examined. An approach that combines the calculation of the safety-oriented inter...

The paper deals with model predictive control (MPC) of nonlinear hybrid systems with discrete inputs based on reachability analysis. In order to implement a MPC algorithm, a model of the process that we are dealing with is needed. In the paper, a hybrid fuzzy modelling approach is proposed. The hybrid system hierarchy is explained and the Takagi–Su...

The paper deals with modelling and simulation of scheduling and sequencing problems based on Petri nets. In particular, the Petri-net models are simulated over the time domain and a simulation-based optimisation is implemented to optimise the input sequences. A new conflict resolution is implemented and a sophisticated way of defining firing sequen...

Processes in industry, such as batch reactors, often demonstrate a hybrid and non-linear nature. Model predictive control (MPC) is one of the approaches that can be successfully employed in such cases. However, due to the complexity of these processes, obtaining a suitable model is often a difficult task. In this paper a hybrid fuzzy modelling appr...

Model predictive control (MPC) has become an important area of research and is also an approach that has been successfully used in many industrial applications. In order to implement a MPC algorithm, a model of the process we are dealing with is needed. Due to the complex hybrid and nonlinear nature of many industrial processes, obtaining a suitabl...

During the development of a production control system, an appropriate model of the production process is needed to evaluate the various control strategies. This paper describes how to apply timed Petri nets and existing production data to the modelling of production systems. Information concerning the structure of a production facility and the prod...

Timed Petri nets can be used for the modelling and analysis of a wide range of concurrent discrete-event systems, e.g. production systems. The present paper describes how to do so while starting from the information about the structure of a production facility and about the products usually given in production-data management systems. We describe a...

This paper describes a control logic implementation approach, which is based on discrete event models in form of finite state machines and Petri nets. Such models may be derived during supervisory control synthesis. The approach defines a transformation of the models into an IEC 61131-3 compliant code that can be translated and downloaded into a st...

The paper deals with model predictive control (MPC) of systems with discrete inputs based on reachability analysis. The basic algorithm is - due to its MPC nature - suitable for controlling a wide spectrum of systems, provided that they have discrete inputs only, therefore its advantages are especially evident when dealing with relatively complex s...

This paper proposes and discusses a model predictive control approach to hybrid systems with discrete inputs only. The algorithm, which takes into account a model of a hybrid system, described as a mixed logical dynamical system, is based on a performance-driven reachability analysis. The algorithm abstracts the behavior of the hybrid system by bui...

Timed Petri nets can be used for the modeling and analysis of a wide range of concurrent discrete-event systems, e.g. production systems. This paper describes how to apply production management data and timed Petri nets to the modeling of production systems. Information about the structure of a production facility and about the products that can be...

This paper addresses the problem of optimally selecting the production plan for a Multiproduct Batch Plant. The proposed approach can also be applied to a broader class of optimal control problems for systems with discrete inputs. The plant is modelled as a Discrete Hybrid Automaton (DHA) using the high level modelling language, HYbrid System DEscr...

The paper proposes a model predictive control algorithm that can be applied to discrete-time hybrid systems with discrete inputs. The algorithm is based on performance driven reachability analysis. The algorithm abstracts the behavior of the hybrid system by building a tree of evolution. Nodes of the tree represent reachable state of process, and t...

The paper describes a software support for Petri net modelling and Petri net based supervisory control synthesis that was developed as a toolbox for popular MATLAB engineering computational tool. Basic functionality of the toolbox is described and analysis and synthesis capabilities are presented through a simple manufacturing machine example.

The paper proposes a model predictive control approach to the hybrid systems with discrete inputs only. The algorithm, which takes into account a model of a hybrid system described as MLD (mixed logical dynamical) system, is based on performance driven reachability analysis. The algorithm abstracts the behavior of the hybrid system by building a tr...

Synthesis and verification of discrete control logic by a combined application of automata based supervisory control theory and Petri nets is addressed. While supervisory control theory is well suited to specification and design of the interlock part of the control logic, the sequencing part can be more easily described by Petri net models. The bas...

This paper addresses the issue of an optimal selection of the production and delivery plan for an asphalt base process. The process is modeled as a DHA (Discrete Hybrid Automaton) using the high level modeling language HYSDEL (HYbrid System DEscription Language) that allows converting the DHA model into an MLD (Mixed Logical Dynamical) model. The p...

The paper proposes a solution to a class of scheduling problems where the goal is to minimize the schedule (production) time. The algorithm. which takes into account a model of a hybrid system described as MLD (mixed logical dynamical) system, is based on performance driven reachability analysis. The algorithm abstracts the behavior of the hybrid s...

Paper deals with modelling methods for the purpose of control of hybrid systems, a class of dynamic systems where the behaviour of interest is determined by interacting time continuous and discrete-event dynamics. Different modelling approaches are discussed and compared. Then the model with the interface is selected and illustrated by an example o...

In the paper we present an implementation method for controllers designed by discrete event control theory. Controllers are implemented by standard programmable logic controller and IEC 61131-3 compliant programming software.

The paper presents a methodology of designing control logic that is implemented by industrial programmable logic controllers. The approach is based on discrete-event model of a plant to be controlled and a set of interlock and sequential specification models. Supervisory control theory is used to test the controllability of the specifications and i...

The paper presents the design of an algorithm used in control of a sequencing batch reactor (SBR) for wastewater treatment. The algorithm is used for the on-line optimization of the batch phases duration which should be applied due to the variable input wastewater. Compared to an operation with fixed times of batch phases, this kind of a control st...

A new approach to predictive control of highly nonlinear processes based on Takagi-Sugeno fuzzy model is proposed. It is investigated how the Takagi-Sugeno fuzzy models can be linked to a special type of model based predictive control algorithm, the generalized predictive control (GPC). In original GPC design purely linear transfer function model i...

Combined discrete event and continuous views of production processes are important in designing computer control systems for both process industries and manufacturing. The paper presents an extension of the popular Matlab–Simulink simulation tool to facilitate the simulation of the discrete sequential control logic applied to continuous processes....

A systematic approach to the design of sequential control is presented. It is illustrated by a case study of a two level hierarchical and distributed control design for a laboratory scale modular production system. The authors' first goal is to show how Petri net models can be used as a tool for sequential control specification that enables systema...

In the paper we present an implementation method for controllers designed by discrete event control theory. Controllers are implemented by standard pro-grammable logic controller and IEC 61131-3 compliant pro-gramming software.