Mekatronik Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/255
Browse
8 results
Search Results
Conference Object Citation - Scopus: 2Computation of Supervisors for Fault-Recovery and Repair for Discrete Event Systems(Univelt Inc., 2014) Sülek, A.N.; Schmidt, K.W.In this paper, we study the fault-recovery and repair of discrete event systems (DES). To this end, we first develop a new method for the fault-recovery of DES. In particular, we compute a fault-recovery supervisor that follows the specified nominal system behavior until a fault-occurrence, that continues its operation according to a degraded specification after a fault and that finally converges to a desired behavior after fault. We next show that our method is also applicable to system repair and we propose an iterative procedure that determines a supervisor for an arbitrary number of fault occurrences and system repairs. We demonstrate our method with a manufacturing system example. © IFAC.Conference Object Citation - Scopus: 12Applied Supervisory Control for a Flexible Manufacturing System(IFAC Secretariat, 2010) Moor, T.; Schmidt, K.; Perk, S.This paper presents a case study in the design and implementation of a discrete event system (DES) of real-world complexity. Our DES plant is a flexible manufacturing system (FMS) laboratory model that consists of 29 interacting components and is controlled via 107 digital signals. Regarding controller design, we apply a hierarchical and decentralised synthesis method from earlier work in order to achieve nonblocking and safe closed-loop behaviour. Regarding implementation, we discuss how digital signals translate to discrete events from a practical point of view, including timing issues. The paper demonstrates how both, design and implementation, are supported by the open-source software tool libFAUDES.Article Citation - WoS: 8Citation - Scopus: 8Reconfigurability of Behavioural Specifications for Manufacturing Systems(Taylor & Francis Ltd, 2017) Schmidt, Klaus WernerReconfigurable manufacturing systems (RMS) support flexibility in the product variety and the configuration of the manufacturing system itself in order to enable quick adjustments to new products and production requirements. As a consequence, an essential feature of RMS is their ability to rapidly modify the control strategy during run-time. In this paper, the particular problem of changing the specified operation of a RMS, whose logical behaviour is modelled as a finite state automaton, is addressed. The notion of reconfigurability of specifications (RoS) is introduced and it is shown that the stated reconfiguration problem can be formulated as a controlled language convergence problem. In addition, algorithms for the verification of RoS and the construction of a reconfiguration supervisor are proposed. The supervisor is realised in a modular way which facilitates the extension by new configurations. Finally, it is shown that a supremal nonblocking and controllable strict subautomaton of the plant automaton that fulfils RoS exists in case RoS is violated for the plant automaton itself and an algorithm for the computation of this strict subautomaton is presented. The developed concepts and results are illustrated by a manufacturing cell example.Article Citation - WoS: 9Citation - Scopus: 9Efficient Abstractions for the Supervisory Control of Modular Discrete Event Systems(Ieee-inst Electrical Electronics Engineers inc, 2012) Schmidt, Klaus Werner; Ribeiro Cury, Jose Eduardo; Cury, José Eduardo RibeiroThe topic of this technical note is the nonblocking and maximally permissive abstraction-based supervisory control for modular discrete event systems (DES). It is shown, that an efficient abstraction technique, that was developed for the nonconflict verification of modular DES, is also suitable for the nonblocking supervisory control. Moreover, it is proved that this abstraction technique can be extended by the condition of local control consistency, in order to achieve maximally permissive supervision. Different from existing approaches, the presented abstraction does not require to preserve the shared events among the system components in the respective abstraction alphabets, and hence leads to potentially smaller system abstractions. The obtained results are illustrated by a flexible manufacturing system example.Article Citation - WoS: 17Citation - Scopus: 17A Framework for State Attraction of Discrete Event Systems Under Partial Observation(Elsevier Science inc, 2014) Schmidt, Klaus Werner; Breindl, ChristianState attraction for discrete event systems (DES) addresses the problem of reaching a desired subset of the plant state space after a bounded number of event occurrences. The problem of state attraction arises for example in fault-tolerant supervisory control or in the control of reconfigurable manufacturing systems, and is also applicable to systems biological problems such as the control of gene regulatory networks. State attraction is investigated with the assumption of full event observation in the existing literature. This paper extends the concept of state attraction to the case of partial observation. The notion of weak attraction under partial observation (WAPO) is introduced and necessary and sufficient conditions for the existence of a supervisor under partial observation that achieves WAPO are derived. Furthermore, a solution algorithm is proposed that finds such supervisor whenever it exists. It is shown that such supervisor can always be realized as a subautomaton of the observer automaton of the DES plant. An application example from systems biology illustrates the obtained results. (C) 2014 Elsevier Inc. All rights reserved.Article Citation - WoS: 9Citation - Scopus: 10Computation of Supervisors for Reconfigurable Machine Tools(Springer, 2015) Schmidt, Klaus WernerThe rapid reconfiguration of manufacturing systems is an important issue in today's manufacturing technology in order to adjust the production to varying product demands and types. In this paper, we study the control of reconfigurable machine tools (RMTs) with the aim of fast reconfiguration and an easy controller implementation. We first formulate a particular reconfiguration problem for RMTs in a discrete event system setting, and then provide a necessary and sufficient condition for its solution. Moreover, we propose a polynomial-time algorithm for the construction of a reconfiguration supervisor as the composition of one modular supervisor for each separate RMT configuration. Each modular supervisor operates in three modes. In the first mode, it tracks the plant state if its corresponding configuration is inactive. In the second mode, it performs a configuration change if its corresponding configuration becomes active and in the third mode, it follows the specified behavior of its corresponding configuration if the configuration is active. An important property of the proposed reconfiguration supervisor is that it performs reconfigurations in a bounded number of event occurrences. In addition, the modular realization of our reconfiguration supervisor enables controller modifications such as adding or removing configurations during run-time. All results presented in the paper are illustrated by an RMT example.Article Citation - WoS: 54Citation - Scopus: 74Maximally Permissive Hierarchical Control of Decentralized Discrete Event Systems(Ieee-inst Electrical Electronics Engineers inc, 2011) Schmidt, Klaus; Breindl, ChristianThe subject of this paper is the synthesis of natural projections that serve as nonblocking and maximally permissive abstractions for the hierarchical and decentralized control of large-scale discrete event systems. To this end, existing concepts for nonblocking abstractions such as natural observers and marked string accepting (msa)-observers are extended by local control consistency (LCC) as a novel sufficient condition for maximal permissiveness. Furthermore, it is shown that, similar to the natural observer condition and the msa-observer condition, also LCC can be formulated in terms of a quasi-congruence. Based on existing algorithms in the literature, this allows to algorithmically compute natural projections that are either natural observers or msa-observers and that additionally fulfill LCC. The obtained results are illustrated by the synthesis of nonblocking and maximally permissive supervisors for a manufacturing system.Article Yeniden yapılandırılabilir üretim sistemleri için kontrolcü tasarımı(Çankaya Üniversitesi, 2013) Sülek, Ayşe Nur; Afşar, Kıvanç Uğur; Schmidt, Klaus WernerDeğişen ürün pazarlarına ve türlerine uyum sağlamak için, hızlı yeniden yapı landırılabilir üretim sistemleri (YUS) günümüz üretim teknolojisine önemli bir ¸çözüm sunmaktadır.Bu makalede, yeniden yapılanmanın hızlı olması ve kontrolcülerin kolayca gerçeklenebilmesi için yeniden yapılandırılabilir üretim sistemlerinin (YUS) kontrolü ele alınmaktadır. Makale kapsamında, bir konfigürasyon sistemin istenen bir olası operasyonu anlamına gelmektedir. Kullandığımız yöntem YUS’lerin ayrık olaylı sistem (AOS) modeli üzerine kurulmuştur ve ü sistemin herbir konfigürasyonu için kontrolcü tasarımı ile başlar. Daha sonra bu kontrolcü temel operasyonuna göre dört farklı biçimde genişletilebilir. Her kontrolcü dört biçimden birini uygulamaktadır: kendi konfigürasyonunu aktif olarak ¸calıştırır (biçim 1), kendi kon figürasyonunu bitirir ve aktif olmayan duruma geçer (biçim 2), aktif olmayan durumda bekler (biçim 3) ya da yeniden aktif olur (biçim 4). Oluşturduğumuz algoritma yalnızca bir konfigürasyonun aktif olmasını, diğer bütün konfigürasyonların ise aktif olmamasını sağlar.Ayrıca konfigürasyonlar arasında sınırlı bir sürede geçiş yapabilmeyi sağlar. Yaklaşımımız ile herbir konfigürasyon için kontrolcü hazırlandıktan sonra, ¸calışan sisteme kolaylıkla yeni bir konfigürasyon eklenebilir. Geliştirilen yöntem küçük bir üretim sistemi örneğiyle açıklanmıştır.