Ilhan Mutlu

Design of signal control structures using formal methods for railway interlocking systems

Today the relay based railway interlocking systems are changing into programmable software interlocking systems. Looking at the hardware aspect, safety certified components can be used in order to satisfy the safety requirements of railway interlocking systems. But to satisfy the software requirements, the design and the programming of the interlocking system must be made by formal methods. To do this, preparing function blocks for each kind of the field equipments can be a method in order to realize a railway interlocking system. The purpose of this paper is to develop a Programmable Logic Controller (PLC) program for the signal function blocks by using formal methods and make a comparison between them.

A new test environment for PLC based interlocking systems

Interlocking systems are the core components of railway signalization systems. They ensure the safe movement of the trains on railway tracks by being the main decision making unit of the railway signalization systems. Therefore it is crucial to predetermine the errors in interlocking systems. In this work a new environment designed to test the reliability of the PLC based interlocking systems is presented.

Design of a Hardware and Software based Test Bed for Railway Signalization Systems

Abstract It is vital that an interlocking system is thoroughly tested before its deployment. The conduction of the tests of an interlocking system on the real field is cumbersome and expensive. It is necessary that fast and efficient methods are utilized to test the hardware and the software of interlocking systems before its final installation. In this manuscript, the design of hardware and software based test beds for a railway signalization system is presented.

Determination of static diagonal controllers to achieve diagonal dominance for TITO systems at fixed frequencies

Most of the multivariable control systems include interactions between different input-output pairs. The control problem becomes more complex in case of significant interactions because single loop control solutions cannot be applied directly. In such cases, reducing the interactions with a pre-compensator can be accepted as the first step of design process. In this study, two input two output systems are discussed and sufficient conditions are derived to achieve diagonal dominance in case of static diagonal controllers. Moreover, a new algorithm is proposed to determine the controller gain regions that guarantees column and row diagonal dominance. Weighting factors are applied for both row and column diagonal conditions to obtain better results. Lastly, controller gain regions are plotted for a given TITO system to verify the effectiveness of the derived theoretical results.

Automatic Interlocking Table Generation for Non-ideal Railway Yards

Abstract Interlocking systems that can be regarded as the main decision making component of fixed block railway signaling systems, are directly responsible for ensuring the safe movements of trains. Software of an interlocking system depends on the interlocking table of the related railway yard. Although there are tools for automatic interlocking table generation, these tools generally do not consider non-ideal situations like non-signaled track or non-standard use of switches or signals. In this study, an efficient automatic interlocking table generation tool was proposed considering these non-ideal situations.

Parameter space mapping for linear discrete-time systems with parametric uncertainties

Many Parameter Space Approach (PSA) based methods have been proposed previously to determine the stabilizing controller parameter spaces for discrete-time systems. The PSA approach is based on sweeping over the whole range of singular frequencies which leads to an expensive numerical computation to find the boundaries of the stability region. These PSA based methods were used for obtaining the stability boundaries for parameter uncertain discrete-time systems as well. However, this results in extremely high computational complexity in addition to other drawbacks. In this study, an approach to determine the stabilizing controller parameter regions of linear discrete-time systems with uncertain parameters is proposed. This novel procedure makes use of the Strong Kharitonov theorem for getting over the high computational complexity resulted due to the uncertainty of the system. Moreover, the asserted approach utilizes a novel Lyapunov based mapping technique for avoiding the drawbacks accompanied with the previously presented PSA based methods in literature. Two different case studies are included in the paper to illustrate the advantages and effectiveness of the proposed method.

Stability Analysis of Train Following Model with Multiple Communication Delays

Abstract In dense traffic regions, moving block railway signalization systems are utilized instead of fixed block systems. In a moving block approach, exact location of the consequent trains has to be determined which brings stability problem of keeping safe distance headway between the trains. In this study, the train following problem with multiple communication time delays between the trains and the wayside control unit is handled. The problem is modeled as a linear time invariant multiple time delay system (LTI-MTDS) for two different scenarios. Stability boundaries with respect to time delays for an appropriate following distance are obtained by using the Cluster Treatment of Characteristic Roots (CTCR) Technique with Extended Kronecker Summation Method and the results are validated via simulations.

Modelling and Control of the Qball X4 Quadrotor System based on Pid and Fuzzy Logic Structure

This work focuses on a quadrocopter model, which was developed by QuanserTM and named as Qball X4. First, mathematical model of the Qball X4 is obtained. Then, a conventional PID control technique is presented. This PID control parameters come from Qball user manual. After the presentation of conventional PID control, as an extension of the conventional PID control theory, a different fuzzy controller structure is given. The proposed fuzzy controller structure is based on fuzzy logic and its name is PID type fuzzy controller. All of the simulations are done in MATLABTM environment.

A Lyapunov equation based mapping approach to achieve controller integrity

In this study, a new approach is proposed to determine controller parameter spaces that achieve integrity for multivariable systems. Integrity refers to the property that the closed-loop system remains stable against arbitrary failures of certain subsystems in order to increase the reliability of industrial systems. The proposed approach is based on the Lyapunov equation stability mapping technique. Instead of solving 2n equations to determine the boundaries of the stabilizing regions that is required in the standard Lyapunov approach, it is necessary and sufficient to solve at most two equations with respect to the controller parameters in the proposed approach. Using this approach, an algorithm is asserted to determine non-conservative controller gain regions that guarantee the stability of the multivariable systems when any one of the controller parameters fails to operate. Lastly, two benchmark case studies are included within the scope of this study to verify the effectiveness and correctness of the derived theoretical results.

Achieving diagonal dominance for TITO systems using diagonal controllers

In this study, diagonal dominance of two input two output systems are discussed by considering the standard and weighted diagonal dominance conditions separately. In addition, sufficient conditions using static diagonal controllers are derived for fixed frequencies. Derived results can be easily extended for a given frequency range. An algorithm is proposed to determine static controller gain regions. Furthermore, by using the derived results, an optimization based method is proposed to determine dynamic diagonal controllers that achieve diagonal dominance conditions for static controllers. Lastly, case studies are included to verify the effectiveness of the proposed methods.