Browsing by Author "Schmidt, Klaus Werner"

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A configurable CAN FD controller: architecture and implementation
(IEEE, 2017) Afşin, Mehmet Ertuğ; Schmidt, Klaus Werner; Schmidt, Ece Güran; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
CAN FD is a new standard which provides fast. data rate while preserving the compatibility with CAN (controller area network). In this paper, a Configurable IP core architecture (A-CAN) which is compatible with the CAN FD standard, is proposed. Different than existing CAN/CAN FD controllers, the numbers and sizes of transmit and receive buffers of A-CAN can be configured in run time. To this end, A-CAN enables the best use of single controller hardware for different applications and enables improving the real time communication performance. A CAN communicates with the host device over SPI without any specific interface requirements. A-CAN is implemented on an FPGA Evaluation Board and its functionally is verified at a rate of 2 Mbps.
A fast and optimal static segment scheduling method for FlexRay v3.0
(IEEE, 2017) Çakmak, Cumhur; Schmidt, Ece Güran; Schmidt, Klaus Werner; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
We propose a novel and fast frame scheduling method for the Static Segment (SS) of the new in-vehicle network standard FlexRay v3.0 in this paper. The proposed methods assigns frames to the SS using the minimum number of time slots based on an Integer Linear Programming formulation. Different. from the existing method in the literature, the proposed method computes optimal frame schedules within miliseconds.
A new multi-agent decision making structure and application to model-based fault diagnosis problem
(IEEE, 2017) Leblebicioğlu, Kemal; Zengin, Yasin; Schmidt, Klaus Werner; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
A new hierarchical multi-agent decision-making structure has been proposed. There are two phases of the structure. The first phase is the construction phase where the decision making structure consisting of switching and classification agents is built on the training data set generated by the system scenarios. In construction phase, switching and classification agents are trained and made ready for decision making. In the decision phase, which is the second phase, the class of the new data sample is decided. This process is carried out by the transmission of the data sample to the correct classifier agent by the switching agents and the classification by the classifier agent. The proposed structure is applied to a complex fault identification problem and a successful result is obtained. The structure is also adaptable to other big data decision making problems.
Citation - WoS: 1
Citation - Scopus: 2
C3: Configurable Can Fd Controller: Architecture, Design and Hardware Implementation
(Ieee, 2017) Afsin, Mehmet Ertug; Schmidt, Klaus Werner; Schmidt, Ece Guran; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
CAN FD (Controller Area Network with Flexible Data Rate) is a new standard which provides a fast data rate while preserving the compatibility with CAN. In this paper, we propose the C-3 (Configurable CAN FD Controller) IP core architecture, which is compatible with the non-ISO CAN FD standard. C-3 supports up to 96 transmit and receive buffers. The transmit buffers are organized as mailboxes with CAN ID prioritization in frame transmission. A separate filter mask that can be configured by the user exists for each receive buffer. Different from existing CAN/CAN FD controllers, the numbers and sizes of transmit and receive buffers of C-3 can be configured at run time. To this end, C-3 enables the best use of a single controller hardware for different applications and enables improving the real-time communication performance. C-3 communicates with the host device over SPI without any specific interface requirements using the protocol that is developed in the scope of this paper. C-3 is implemented on an FPGA Evaluation Board and its functionality is verified at a data rate of 2 Mbps.
Clothoid-based Lane Change Trajectory Computation for Self-Driving Vehicles
(2017) Mohammed Ali Kahya, Ardam Haseeb; Schmidt, Klaus Werner; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
The subject of this paper is the efficient computation of lane change trajectories for self-driving vehicles. The paper first identifies that a certain type of clothoid-based bi-elementary paths can be used to represent lane change trajectories for vehicles. It is further highlighted that the curvature of such trajectories must be adjusted to the driving situation in order to obtain feasible lane change trajectories. Accordingly, the paper establishes an analytical relation between the maximum admissible curvature of the lane change trajectory and the velocity profile during a lane change. Using this relation, the paper proposes an efficient Newton iteration for computing the parameters of bi-elementary paths for lane changes. The resulting lane change trajectories are as short as possible, while meeting the constraint on the maximum curvature. Simulation experiments for various driving situations show that the computed bi-elementary paths can be computed efficiently and constitute suitable lane change trajectories.
Citation - WoS: 9
Citation - Scopus: 10
Computation of Supervisors for Reconfigurable Machine Tools
(Springer, 2015) Schmidt, Klaus Werner; 17337; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
The 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.
The Controllability Prefix for Supervisory Control Under Partial Observation With an Application To Fault-Tolerant Control
(Elsevier, 2017) Moor, Thomas; Schmidt, Klaus Werner; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
The controllability prefix is known as a useful concept for the discussion and solution of synthesis problems in supervisory control of cp-languages, i.e., formal languages of infinite-length words. There, the controllability prefix is defined as the set of all finite-length prefixes that can be controlled to satisfy prescribed liveness and safety properties. In this paper, we discuss a variation of the controllability prefix to address supervisory control under partial observation for regular *-languages, i.e., formal languages of finite-length words. We derive algebraic properties that are useful for a quantitative analysis on how an upper-bound language-inclusion specification affects achievable lower-bound specifications. Our study is motivated by the synthesis of fault-tolerant supervisory controllers, where the possible occurrence of a fault may restrict the achievable pre-fault behaviour so severe, that a relaxation of the upper-bound specification becomes a practical option. As our study shows, such a relaxation can be systematically constructed in terms of the controllability prefix. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 6
Controller Area Network With Priority Queues and Fifo Queues: Improved Schedulability Analysis and Message Set Extension
(inderscience Enterprises Ltd, 2016) Schmidt, Klaus Werner; Alkan, Burak; Schmidt, Ece Guran; Karani, Duygu Culum; Karakaya, Utku; 17337; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
Controller area network (CAN) enables communication of electronic control units (ECUs) via messages using priority-based arbitration, which requires the implementation of priority queues (PQs) in the ECU device driver. Nevertheless, it is possible that not all ECUs on a CAN support PQs but use FIFO queues (FQs) instead. In this case, the classical CAN scheduling model with PQs is not suitable for the computation of message worst-case responsetimes (WCRTs) that are essential for verifying the correct vehicle operation. This paper considers an existing scheduling model for CAN with both PQs and FQs. First, an improved algorithm for speeding up the WCRT computation is proposed. Second, the practical case where an existing CAN message set is extended by new messages is addressed. An original algorithm for assigning priorities to new messages while keeping the priority order of existing messages is developed. Both algorithms are evaluated by computational experiments.
Controller Design for Cacc With Time-Varying Communication Delays
(Ieee, 2023) Soysal, Gokhan; Schmidt, Klaus Werner; Bingol, Hilal; 218795; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
Cooperative Adaptive Cruise Control (CACC) aims at the safe and comfortable travel of vehicles at short distances in the form of platoons. Hereby, it is generally desired to attenuate disturbances along vehicles in a platoon, which is captured by different string stability conditions. In this paper, we focus on L-infinity string stability. This condition ensures reducing the magnitude of the acceleration signal along the platoon, which helps to avoid actuator saturation and increases driving comfort. Since the performance of CACC is adversely affected by time-varying communication and actuator delays, we develop the first controller design method for L-infinity-string stability, combining the Lyapunov-Krasovskii method and our custom bisection algorithm. Simulation experiments demonstrate the effectiveness of our method.
Citation - WoS: 4
Citation - Scopus: 4
Discrete Event Supervisor Design and Application for Manufacturing Systems With Arbitrary Faults and Repairs
(Ieee, 2015) Schmidt, Klaus Werner; Acar, Ayse Nur; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
This paper considers the supervisory control of discrete event systems (DES) that are subject to faults. To this end, an existing method for the fault-recovery and repair of single faults is extended to the case of different faults. As a result, we obtain a supervisor that follows the specified nominal system behavior in the fault-free case, converges to a desired degraded behavior for each fault type and recovers the nominal behavior after repair. The results of the paper are illustrated by a small example.
Citation - WoS: 15
Citation - Scopus: 17
Distributed Real-Time Protocols for Industrial Control Systems: Framework and Examples
(Ieee Computer Soc, 2012) Schmidt, Klaus Werner; Schmidt, Ece Guran; 17337; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
The automation of today's large-scale industrial systems relies on the operation of distributed controller devices that perform local computations and exchange information via communication networks. The subject of this paper is the development of a family of shared-medium industrial communication protocols that support the transmission of real-time (RT) and nonreal-time (nRT) data among distributed controller devices. Different from existing protocols, we suggest to incorporate information that is available from the control application in the protocol definition. As a result, our protocols dynamically change the bandwidth allocation on the shared medium according to the instantaneous communication requirements while ensuring hard RT guarantees. Following the recent developments in industrial automation, our protocols can be realized as software layers on top of low-cost conventional Ethernet.
Citation - WoS: 9
Citation - Scopus: 9
Efficient Abstractions for the Supervisory Control of Modular Discrete Event Systems
(Ieee-inst Electrical Electronics Engineers inc, 2012) Schmidt, Klaus Werner; Ribeiro Cury, Jose Eduardo; 17337; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
The 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.
Citation - WoS: 1
Eyleyici Doyumu Altında Dizi Kararlı Kooperatif Otomatik Seyir Kontrolü
(2016) Çankaya, Erkam; Bingöl, Hilal; Schmidt, Klaus Werner; 218795; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
Kooperatif otomatik seyir kontrolü (CACC), araçtan araca haberleşme yöntemiyle veri iletilmesini ve uzaklık ölçümlerine göre yoğun trafikte güvenilir araç takibinin yapılmasını sağlar. Kullanılan CACC dizaynları dizi kararlılığının temel özelliklerini sorunsuz bir şekilde yerine getirirken doğrusal araç modelleri için sınırlıdır. Bu makalede ise, doğrusal olmayan araç modeli kullanıldığında ve lider araca uygulanan giriş sinyali doyuma uğramadığında dizi kararlılığının korunabildiği gösterilmiştir.
Citation - WoS: 5
Citation - Scopus: 6
Fault-Tolerant Control of Discrete-Event Systems With Lower-Bound Specifications
(Elsevier, 2015) Moor, Thomas; Schmidt, Klaus Werner; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
Fault-tolerant control addresses the control of dynamical systems such that they remain functional after the occurrence of a fault. To allow the controller to compensate for a fault, the system must exhibit certain redundancies. Alternatively, one may relax performance requirements for the closed loop behaviour after the occurrence of a fault. To achieve fault tolerance for a hierarchical control architecture, a combination of both options appears to be advisable: on each individual level of the hierarchy, the controller may compensate the fault as far as possible, and then pass on responsibility to the next upper level. This approach, when further elaborated for discrete-event systems represented by formal languages, turns out to impose a hard lower-bound inclusion specification on the closed-loop behaviour. The present paper discusses the corresponding synthesis problem and presents a solution. (C) 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
Citation - WoS: 61
Citation - Scopus: 67
Feedforward Strategies for Cooperative Adaptive Cruise Control in Heterogeneous Vehicle Strings
(Ieee-inst Electrical Electronics Engineers inc, 2018) Al-Jhayyish, Ahmed M. H.; Schmidt, Klaus Werner; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
String stability is an essential property to ensure that the fluctuations are attenuated along vehicle strings. This paper focuses on the fulfillment of string stability in the practical case of heterogeneous vehicle strings that comprise vehicles with different dynamic properties. Using the idea of predecessor following, acceleration feedforward, predicted acceleration feedforward, and input signal feedforward are considered as different possible feedforward strategies. For all strategies, the parameter ranges of predecessor vehicles that ensure string stability of a given vehicle are characterized, computed, and validated by simulation.
Citation - WoS: 17
Citation - Scopus: 17
A Framework for State Attraction of Discrete Event Systems Under Partial Observation
(Elsevier Science inc, 2014) Schmidt, Klaus Werner; Breindl, Christian; 17337; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
State 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.
Citation - WoS: 41
Citation - Scopus: 49
Fuzzy Discrete Event Systems for Multiobjective Control: Framework and Application To Mobile Robot Navigation
(Ieee-inst Electrical Electronics Engineers inc, 2012) Schmidt, Klaus Werner; Boutalis, Yiannis S.; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
Fuzzy discrete event systems (FDESs) have been introduced in recent years to model systems whose discrete states or discrete state transitions can be uncertain and are, hence, determined by a possibility degree. This paper develops an FDES framework for the control of sampled data systems that have to fulfill multiple objectives. The choice of a fuzzy system representation is justified by the assumption of a controller realization that depends on various potentially imprecise sensor measurements. The proposed framework consists of three basic steps that are performed at each sampling instant. First, the current fuzzy state of the system is determined by a sensor evaluation. Second, the fuzzy state in the future sampling instant is predicted for all possible control actions of the system. Finally, an original multiobjective weighting strategy is proposed to determine the control action to be applied in the current sampling instant. The features of the proposed approach are demonstrated by a detailed mobile robot example, which includes a simulation study.
Hierarchical Control With Partial Observations: Sufficient Conditions
(IEEE, 2011) Boutin, Olivier; Komenda, Jan; Masopust, Tomas; Schmidt, Klaus Werner; Van Schuppen, Jan H.; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
In this paper, hierarchical control of both monolithic and modular discrete-event systems under partial observations is studied. Two new conditions, called observation consistency and local observation consistency, are proposed. These conditions are sufficient for the preservation of observability between the original and the abstracted plant. Moreover, it is shown that both conditions are compositional, that is, they are preserved by the synchronous product. This property makes it possible to use hierarchical and decentralized supervisory control for discrete-event systems with partial observations.
IEEE
(2013 Ieee 52Nd Annual Conference On Decision and Control (Cdc), 2013) Schmidt, Klaus Werner; 271229; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
Reconfigurable manufacturing systems (RMSs) are designed to quickly adapt to new products and production requirements. To this end, RMSs need to be able to perform fast changes between different configurations. This paper investigates the reconfiguration of RMSs in a supervisory control framework. Different from previous work, we formulate and solve a reconfiguration problem that allows to start a newly requested configuration before the previously active configuration has been completed. Our solution is optimal in the sense that there is no other solution that enables an earlier start of the new configuration. The practicability of the proposed solution is demonstrated by a small RMS example.
Citation - WoS: 1
Citation - Scopus: 1
Improved Load Distribution for Controller Area Network
(Ieee, 2017) Batur, Ahmet; Schmidt, Klaus Werner; Schmidt, Ece Guran; 06.08. Mekatronik Mühendisliği; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
The main requirement for the design of the controller are network (CAN) is to guarantee that each message response time is smaller than their specified deadline. In practical in-vehicle applications, messages on CAN are released with offsets in order to avoid message bursts that lead to undesirably large response times. In this paper, new algorithms for the choice of suitable message offsets are developed and it is shown that these algorithms outperform existing algorithms.