Browsing by Author "Schmidt, Klaus Werner"

Now showing 1 - 20 of 52

Citation Count: Afsin, Mehmet Ertug; Schmidt, Klaus Werner; Schmidt, Ece Guran, "A configurable CAN FD controller: architecture and implementation", 2017 25th Signal Processing And Communications Applications Conference (SIU), (2017).
A configurable CAN FD controller: architecture and implementation
(IEEE, 2017) Afşin, Mehmet Ertuğ; Schmidt, Klaus Werner; Schmidt, Ece Güran
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.
Citation Count: Cakmak, Cumhur; Schmidt, Ece Guran; Schmidt, Klaus Werner, "A fast and optimal static segment scheduling method for FlexRay v3.0", 2017 25th Signal Processing And Communications Applications Conference (SIU), (2017).
A fast and optimal static segment scheduling method for FlexRay v3.0
(IEEE, 2017) Çakmak, Cumhur; Schmidt, Ece Güran; Schmidt, Klaus Werner
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.
Citation Count: Schmidt, K.W., Breindl, C. (2014). A framework for state attraction of discrete event systems under partial observation. Information Sciences, 281, 265-280. http://dx.doi.org/10.1016/j.ins.2014.05.026
A framework for state attraction of discrete event systems under partial observation
(Elsevier Science Inc., 2014) Schmidt, Klaus Werner; Breindl, Christian; 17337
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.
Citation Count: Saraçoğlu, Kıvanç; Üleş, Buğra; Schmidt, Klaus Werner (2018). "A Lane Keeping System with a Weighted Preview Measurement", 2018 26TH SIGNAL PROCESSING AND COMMUNICATIONS APPLICATIONS CONFERENCE (SIU).
A Lane Keeping System with a Weighted Preview Measurement
(2018) Saraçoğlu, Kıvanç; Üleş, Buğra; Schmidt, Klaus Werner
This paper proposes a new lane keeping system (LKS) based on a weighted preview measurement. The paper first identifies shortcomings of existing methods that use the sole measurement of lateral displacement error at a preview distance or at the center of gravity. Then, the novel idea of computing a weighted average of both measurements is proposed. The stability of the resulting LKS is analyzed and the improved performance of the resulting LKS is supported by simulation experiments.
Citation Count: Schmidt, Klaus Werner; Schmidt, E.G, "A Longest-Path Problem for Evaluating the Worst-Case Packet Delay of Switched Ethernet", 2010 International Symposium On Industrial Embedded Systems, Sies 2010 - Conference Proceedings, pp. 205-208, (2010).
A Longest-Path Problem for Evaluating the Worst-Case Packet Delay of Switched Ethernet
(2010) Schmidt, Klaus Werner; Schmidt, E. G.; 17337
In the recent years, the use of real-time Ethernet protocols becomes more and more relevant for time-critical networked industrial applications. In this context, this paper presents a method to compute the worst-case packet delays on switched Ethernet. Based on an evaluation of the packet delays at each switch port and the network topology, we construct a weighted directed graph that allows to find the worst-case end-toend packet delay by solving a conventional longest-path problem
Citation Count: Leblebicioglu, M. Kemal; Zengin, Yasin; Schmidt, Klaus Werner, "A new multi-agent decision making structure and application to model-based fault diagnosis problem", 2017 25th Signal Processing And Communications Applications Conference (SIU), (2017).
A new multi-agent decision making structure and application to model-based fault diagnosis problem
(IEEE, 2017) Leblebicioğlu, Kemal; Zengin, Yasin; Schmidt, Klaus Werner
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 Count: Moor, T.; Schmidt, K.; Wittmann, T., "Abstraction-Based Control for Not Necessarily Closed Behaviours", Ifac Proceedings Volumes (Ifac-Papersonline), Vol. 44, No. 1-1, pp. 6988-6993, (2011).
Abstraction-Based Control for Not Necessarily Closed Behaviours
(IFAC Secretariat, 2011) Moor, Thomas; Schmidt, Klaus Werner; Wittmann, Thomas
This paper addresses abstraction-based supervisory control for plant and specification behaviours that are not necessarily ω-closed, i.e. plant behaviours that exhibit eventuality properties and specifications that impose eventuality properties on the closed loop. Technically, the core idea is to combine results from previous work on abstraction-based supervision of input-output behaviours with results on supervisory control of ω-languages. As our main result, we identify a controllability condition for the plant, that ensures a nonblocking closed-loop behaviour with a controller that has been obtained for a plant abstraction.
Citation Count: Khalid, H.M.; Kirik, M.S.; Schmidt, K.W., "Abstraction-Based Supervisory Control for Recon-Gurable Manufacturing Systems?", Ifac Proceedings Volumes (Ifac-Papersonline), Vol. 4, No. 1, pp. 157-162, (2013).
Abstraction-Based Supervisory Control for Recon-Gurable Manufacturing Systems?
(2013) Khalid, Harith M.; Kırık, Mustafa Sancay; Schmidt, Klaus Werner; 271229
Reconfiguration control for discrete event systems (DES) is concerned with the realization of different system configurations by modification of the supervisory control loop. In this paper, we study the reconfiguration supervisor design for reconfigurable manufacturing systems (RMS) that comprise multiple components. We construct a modular supervisor for each configuration and system component in order to realize each active configuration and to quickly change between configurations. Different from the existing literature that is focused on monolithic design, our method is abstraction-based, and, hence applicable to large-scale DES.
Citation Count: Schmidt, K. (2010). Abstraction-based verification of codiagnosability for discrete event systems. Automatica, 46(9), 1489-1494. http://dx.doi.org/10.1016/j.automatica.2010.06.010
Abstraction-based verification of codiagnosability for discrete event systems
(Pergamon-Elsevier Science LTD, 2010) Schmidt, Klaus Werner
In this paper, we investigate the verification of codiagnosability for discrete event systems (DES). That is, it is desired to ascertain if the occurrence of system faults can be detected based on the information of multiple local sites that partially observe the overall DES. As an improvement of existing codiagnosability tests that resort to the original DES with a potentially computationally infeasible state space, we propose a method that employs an abstracted system model on a smaller state space for the codiagnosability verification. Furthermore, we show that this abstraction can be computed without explicitly evaluating the state space of the original model in the practical case where the DES is composed of multiple subsystems. (c) 2010 Elsevier Ltd. All rights reserved
Citation Count: Schmidt, K...et al. (20109. "An Experimental Study of the Flexray Dynamic Segment",Ifac Proceedings Volumes (Ifac-Papersonline), Vol. 43, No. 7, pp. 413-418.
An Experimental Study of the Flexray Dynamic Segment
(IFAC Secretariat, 2010) Schmidt, Klaus Werner; Schmidt, Ece G.; Demirci, Ali; Yürüklü, Emrah; Karakaya, Utku
It is expected that the time-triggered FlexRay bus will replace the event-triggered Controller Area Network (CAN) for the high-speed in-vehicle communication in future automobiles. To this end, FlexRay provides a static segment for the transmission of periodic messages and a dynamic segment that is suitable for exchanging event-based (sporadic) messages. In this paper, we experimentally evaluate the operation of the FlexRay dynamic segment. In particular, we study how the maximum and average message delays are affected if the length of the dynamic segment, the message payload, the utilization of the dynamic segment and the priority assignment changes. Our experiments are carried out on a FlexRay network with 6 nodes.
Citation Count: Öncü, H., Schmidt, K.W. (2013). An integrated scheduling and control model for multi-mode projects. Flexible Services And Manufacturing Journal, 25(1-2), 230-254. http://dx.doi.org/10.1007/s10696-012-9138-3
An integrated scheduling and control model for multi-mode projects
(Springer, 2013) Hazır, Öncü; Schmidt, Klaus Werner; 4168
In today's highly competitive uncertain project environments, it is of crucial importance to develop analytical models and algorithms to schedule and control project activities so that the deviations from the project objectives are minimized. This paper addresses the integrated scheduling and control in multi-mode project environments. We propose an optimization model that models the dynamic behavior of projects and integrates optimal control into a practically relevant project scheduling problem. From the scheduling perspective, we address the discrete time/cost trade-off problem, whereas an optimal control formulation is used to capture the effect of project control. Moreover, we develop a solution algorithm for two particular instances of the optimal project control. This algorithm combines a tabu search strategy and nonlinear programming. It is applied to a large scale test bed and its efficiency is tested by means of computational experiments. To the best of our knowledge, this research is the first application of optimal control theory to multi-mode project networks. The models and algorithms developed in this research are targeted as a support tool for project managers in both scheduling and deciding on the timing and quantity of control activities
Citation Count: Hazir, Ö.; Schmidt, K.W.; Eryilmaz, U.,"An Optimization Model to Coordinate Scheduling and Controling in Projects: Case With İnstantaneous Control Constraints", Opt-I 2014 - 1St International Conference On Engineering and Applied Sciences Optimization, Proceedings, pp. 2095-2110, (2014).
An Optimization Model to Coordinate Scheduling and Controling in Projects: Case With İnstantaneous Control Constraints
(National Technical University of Athens, 2014) Hazır, Öncü; Schmidt, Klaus Werner; Eryılmaz, Utkan; 17337
Today, many enterprises in different industries take part in various projects, and organizational performances depend more and more on project performances. In order to maximize performance, effective management of project functions is crucial. In this regard, we focus on scheduling and control functions and their relation. Characteristics of data sharing among them and possible integration strategies are theoretically investigated. A model base for a decision support framework that accounts for these interdependencies and supports managers is developed. To solve the formulated integrated project scheduling and control problem, a tabu search algorithm is combined with optimal control techniques. As a result, a project schedule as well as the means and timing of interventions are determined such that the project cost is minimized. The obtained results are supported by computational experiments. Integrated models and algorithms to be developed aim to fill an important theoretical gap in project management.
Citation Count: Moor, T.; Schmidt, K.; Perk, S.,"Applied Supervisory Control for A Flexible Manufacturing System",Ifac Proceedings Volumes (Ifac-Papersonline), Vol. 10, No. 1, (2010).
Applied Supervisory Control for A Flexible Manufacturing System
(2010) Moor, Thomas; Schmidt, Klaus Werner; Perk, Sebastian
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.
Citation Count: Afsin, Mehmet Ertug; Schmidt, Klaus Werner; Schmidt, Ece Guran, "C-3 : configurable CAN FD controller: architecture, design and hardware implementation", 2017 12th IEEE Internatıonal Symposium On Industrial Embedded Systems (SIES), pp.73-81, (2017).
C-3 : configurable CAN FD controller: architecture, design and hardware implementation
(IEEE, 2017) Afşin, Mehmet Ertuğ; Schmidt, Klaus Werner; Schmidt, Ece Güran
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.
Citation Count: Mohammed Ali Kahya, Ardam Haseeb; Schmidt, Klaus Werner (2017). "Clothoid-based Lane Change Trajectory Computation for Self-Driving Vehicles", Çankaya University Journal of Science and Engineering, Vol. 14, no. 2, pp. 152-179.
Clothoid-based Lane Change Trajectory Computation for Self-Driving Vehicles
(2017) Mohammed Ali Kahya, Ardam Haseeb; Schmidt, Klaus Werner
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 Count: Sülek, A.N.; Schmidt, K.W.,"Computation of Fault-Tolerant Supervisors for Discrete Event Systems ?",Ifac Proceedings Volumes (Ifac-Papersonline), Vol. 4, No. 1, pp. 115-120, (2013).
Computation of Fault-Tolerant Supervisors for Discrete Event Systems ?
(2013) Sülek, A. N.; Schmidt, Klaus Werner; 17337
Fault-tolerance addresses the problem of operating a system even in case of faults. In this paper, we study fault-tolerance in the supervisory control framework for discrete event systems (DES). We consider DES, where certain events might no longer be possible in case a fault happens. In this setting, we first identify necessary and suficient conditions for the existence of a supervisor that realizes a given behavioral specification both in the non-faulty and in the faulty case. We further show that it is possible to determine a supremal fault-tolerant sublanguage in case the existence condition is violated. Finally, we propose an algorithm for the computation of this sublanguage and prove its correctness. Different from existing work, our fault-tolerant supervisor allows fault occurrences and system repairs at any time. The concepts and results developed in this paper are illustrated by a manufacturing system example.
Citation Count: Schmidt K.,"Computation of Projections for the Abstraction-Based Diagnosability Verification",Ifac Proceedings Volumes (Ifac-Papersonline), Vol. 10, No. 1, pp. 199-204, (2011).
Computation of Projections for the Abstraction-Based Diagnosability Verification
(2011) Schmidt, Klaus Werner
The verification of language-diagnosability (LD) for discrete event systems (DES) generally requires the explicit evaluation of the overall system model which is infeasible for practical systems. In order to circumvent this problem, our previous work proposes the abstraction-based LD verification using natural projections that fulfill the loop-preserving observer (LPO) property. In this paper, we develop algorithms for the verification and computation of such natural projections. We first present a polynomial-time algorithm that allows to test if a given natural projection is a loop-preserving observer. Then, we show that, in case the LPO property is violated, finding a minimal extension of the projection alphabet such that the LPO condition holds is NP-hard. Finally, we adapt a polynomial-time heuristic algorithm by Feng and Wonham for the efficient computation of loop-preserving observers.
Citation Count: Sülek, A.N., Schmidt, K.W.,"Computation of Supervisors for Fault-Recovery and Repair for Discrete Event Systems",Advances in the Astronautical Sciences, Vol. 9, No. 3, pp. 428-433, (2014).
Computation of Supervisors for Fault-Recovery and Repair for Discrete Event Systems
(IFAC Secretariat, 2014) Sülek, Ayşe Nur; Schmidt, Klaus Werner; 17337; 107424
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.
Citation Count: Schmidt, K.W. (2015). Computation of supervisors for reconfigurable machine tools. Discrete Event Dynamic Systems-Theory And Applications, 25(1-2), 125-158. http://dx.doi.org/10.1007/s10626-014-0183-9
Computation of supervisors for reconfigurable machine tools
(Springer, 2015) Schmidt, Klaus Werner; 17337
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.
Citation Count: Schmidt, K.W...et al. (2016). Controller area network with priority queues and FIFO queues: improved schedulability analysis and message set extension. International Journal Of Vehicle Design, 71(1-4), 335-357. http://dx.doi.org/10.1504/IJVD.2016.078786
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 Güran; Karani, Duygu Culum; Karakaya, Utku; 17337
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.