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Journal Cover Control Engineering Practice
   Journal TOC RSS feeds Export to Zotero [14 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0967-0661
     Published by Elsevier Homepage  [2566 journals]   [SJR: 1.522]   [H-I: 59]
  • Measurement noise filtering for common PID tuning rules
    • Abstract: Publication date: November 2014
      Source:Control Engineering Practice, Volume 32
      Author(s): V. Romero Segovia , T. Hägglund , K.J. Åström
      Measurement noise generates undesired control activity resulting in wear of actuators and reduced performance. The effects of measurement noise can be alleviated by filtering the measurement signal. New criteria based on the trade-offs between performance, robustness, and attenuation of measurement noise are proposed for assessment of the design. Simple rules for calculating the filter time constant based on the nominal process model and the nominal controller are derived and a complete tuning procedure is proposed. The tuning procedure accounts for the effects of filtering. It is applied to well-known tuning procedures such as Lambda, SIMC, and AMIGO. The results are illustrated by experiments.


      PubDate: 2014-09-05T00:08:42Z
       
  • OBC - Autogenerate contents and barcode
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31




      PubDate: 2014-09-05T00:08:42Z
       
  • Sensor fault detection and isolation for aircraft control systems by
           kinematic relations
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): L. Van Eykeren , Q.P. Chu
      This paper presents a new approach to Fault Detection and Isolation (FDI) for sensors of aircraft. In the most general case, fault detection of these sensors on modern aircraft is performed by a logic that selects one of, or combines, the three redundant measurements. Such a method is compliant with current airworthiness regulations. However, in the framework of the global aircraft optimization for future and upcoming aircraft, it could be required, e.g., to extend the availability of sensor measurements. Introducing a form of analytical redundancy of these measurements can increase the fault detection performance and result in a weight saving of the aircraft. This can be achieved by exploiting the knowledge of the kinematic relations between the measured variables. These relations are exactly known giving the advantage that no model-mismatches need to be accounted for. Furthermore these relations are valid over the whole flight envelope and general for any type of aircraft. Two example applications will be presented, showing the applicability of the method for the FDI of air data sensors and measurements of the inertial reference unit.


      PubDate: 2014-09-05T00:08:42Z
       
  • A non-conservative H−/H∞ solution for early and robust fault
           diagnosis in aircraft control surface servo-loops
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): D. Henry , J. Cieslak , A. Zolghadri , D. Efimov
      The presented work is undertaken within the FP7-ADDSAFE (Advanced Fault Diagnosis for Sustainable Flight Guidance and Control) project, a European collaborative project that aims to propose new fault diagnosis techniques for AIRBUS aircraft that could significantly advance the aircraft performance, e.g. by optimizing the aircraft structural design (weight saving) or decreasing its environmental footprint (e.g. less fuel consumption and noise). The paper discusses the design of a model-based fault detection scheme for robust and early detection of faults in aircraft control surfaces servo-loop. The proposed strategy consists of two fault detectors: The first fault detector is based on a H − / H ∞ residual generator that maximizes sensitivity to any kind of control surface servo-loop faults whilst simultaneously minimizes the influence of unknown inputs. The second fault detector consists of a pure H ∞ residual generator that is sensitive to a restricted set of faults and robust to unknown inputs. By such a structured strategy, it is shown that it is possible to discriminate between different fault types occurring in the control surfaces servo-loop. Monte-Carlo campaigns from a highly representative simulator provided by AIRBUS as well as experimental results obtained on AIRBUS test facilities demonstrate the fault detection performance, robustness and viability of the proposed technique.


      PubDate: 2014-09-05T00:08:42Z
       
  • Bridging the gap between theory and practice in LPV fault detection for
           flight control actuators
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Bálint Vanek , András Edelmayer , Zoltán Szabó , József Bokor
      Two different approaches for fault detection, the geometric and the detection filter based methods, are compared in the paper from practical aspects, using the linear parameter-varying (LPV) framework. Presenting two designs allows a comparison of global, system level, and local component level fault detection methods with special emphasis on their relevance to aircraft industry. Practical engineering design decisions are highlighted via applying them to a high-fidelity commercial aircraft problem. The successive steps of the design, including fault modeling, LPV model generation, and LPV FDI filter synthesis, including implementation aspects, are discussed. Results are presented according to the industrial assessment perspectives phrased within the EU ADDSAFE project.


      PubDate: 2014-09-05T00:08:42Z
       
  • LPV model-based robust diagnosis of flight actuator faults
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Andreas Varga , Daniel Ossmann
      A linear parameter-varying (LPV) model-based synthesis, tuning and assessment methodology is developed and applied for the design of a robust fault detection and diagnosis (FDD) system for several types of flight actuator faults such as jamming, runaway, oscillatory failure, or loss of efficiency. The robust fault detection is achieved by using a synthesis approach based on an accurate approximation of the nonlinear actuator–control surface dynamics via an LPV model and an optimal tuning of the free parameters of the FDD system using multi-objective optimization techniques. Real-time signal processing is employed for identification of different fault types. The assessment of the FDD system robustness has been performed using both standard Monte-Carlo methods as well as advanced worst-case search based optimization-driven robustness analysis. A supplementary industrial validation performed on the AIRBUS actuator test bench for the monitoring of jamming, confirmed the satisfactory performance of the FDD system in a true industrial setting.


      PubDate: 2014-09-05T00:08:42Z
       
  • Development and application of sliding mode LPV fault reconstruction
           schemes for the ADDSAFE
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Halim Alwi , Christopher Edwards
      This paper describes the development and the evaluation of a robust sliding mode observer fault detection scheme applied to an aircraft benchmark problem as part of the ADDSAFE project. The ADDSAFE benchmark problem which is considered in this paper is the yaw rate sensor fault scenario. A robust sliding mode sensor fault reconstruction scheme based on an LPV model is presented, where the fault reconstruction signal is obtained from the so-called equivalent output error injection signal associated with the observer. The development process includes implementing the design using AIRBUS׳s the so-called SAO library which allows the automatic generation of flight certifiable code which can be implemented on the actual flight control computer. The proposed scheme has been subjected to various tests and evaluations on the Functional Engineering Simulator conducted by the industrial partners associated with the ADDSAFE project. These were designed to cover a wide range of the flight envelope, specific challenging manoeuvres and realistic fault types. The detection and isolation logic together with a statistical assessment of the FDD schemes are also presented. Simulation results from various levels of FDD developments (from tuning, testing and industrial evaluation) show consistently good results and fast detection times.


      PubDate: 2014-09-05T00:08:42Z
       
  • The European ADDSAFE project: Industrial and academic efforts towards
           advanced fault diagnosis
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Philippe Goupil , Andrés Marcos
      In this article a high-fidelity aircraft benchmark, developed by Airbus for advanced flight control related studies, is presented in relation to its evolution towards advanced fault diagnosis within a European 7th Framework Program project entitled “Advanced Fault Diagnosis for Sustainable Flight Guidance and Control (ADDSAFE)”. This European project was established to study and facilitate the transfer of model-based fault detection and diagnosis methods from Academia to Industry. The importance of the project arose on the one hand, due to the representativeness of the benchmark, and on the other hand, the industrial benchmarking and validation of the developed designs. The results presented in this article represent a quantitative measure of the success of the project since five of the developed designs were successfully validated in Airbus Verification and Validation (V&V) set-ups, and are currently undergoing further tests towards a possible real aircraft implementation.


      PubDate: 2014-09-05T00:08:42Z
       
  • Affine LPV-modeling for the ADDSAFE benchmark
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): S. Hecker , H. Pfifer
      General approaches are presented for approximating the nonlinear dynamics of a commercial aircraft model by affine linear parameter varying (LPV) models that are used for the design of fault detection and diagnosis (FDD) systems. One part of the paper deals with the approximation of the nonlinear actuator dynamics, where a simple analytic model is derived that accurately describes a given nonlinear, (partly) black-box model in the whole flight envelope. The second part presents a new two step approach for generating an affine LPV model for the nonlinear aircraft dynamics. Starting from a given trim-point in the flight envelope, the goal of the first step is to maximize the size of the region around this trim point, for which the simple affine LPV description is still valid. The second step then tries to further simplify the affine LPV model, which helps to reduce both the computational burden for FDD synthesis methods and the order of the linear fractional representations (LFRs) that are generated from these LPV models.


      PubDate: 2014-09-05T00:08:42Z
       
  • CEP special section issue on Advanced Fault Diagnosis for Sustainable
           Flight Control—The European ADDSAFE Project
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Andreas Varga , Philippe Goupil , Andrés Marcos



      PubDate: 2014-09-05T00:08:42Z
       
  • A multi-agent architecture for diagnosing simultaneous faults along water
           canals
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): João Lemos Nabais , Luís F. Mendonça , Miguel Ayala Botto
      Water is intensively used in mankind activities, in particular in agriculture. Water is commonly conveyed for agriculture purposes through water canal networks which are large-scale spatially distributed systems crossing extensive regions. In the presence of leaks, unauthorized water withdrawals, water depth sensor faults or gate faults, the quality of service can be severely compromised. A system able to diagnose which type of fault is present at a given time is of vital importance to access the current state of the water canal and proceed to restore its nominal condition. This paper proposes a multi-agent architecture to simultaneously detect, isolate and estimate lateral outflows (e.g., leaks or water withdrawals) and hardware faults (e.g., a gate obstruction or a downstream water depth sensor fault) in water canal networks. First, the main canal network is broken down into several subsystems composed of a single canal pool with the corresponding gate. Then, an agent is assigned to each subsystem aiming at its fault diagnosis. The approach is based on the generation and evaluation of residuals obtained from the comparison of model-based output signals with real data. Application to an experimental water canal bears out the proposed architecture as a valuable tool for monitoring and supervising general water canals.


      PubDate: 2014-09-05T00:08:42Z
       
  • IFC - Editorial Board / Funding body / agreements policies
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31




      PubDate: 2014-09-05T00:08:42Z
       
  • Editorial for the special section of the 8th IFAC SAFEPROCESS 2012
           Symposium
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Cristina Verde R.



      PubDate: 2014-09-05T00:08:42Z
       
  • Second order sliding mode observers for the ADDSAFE actuator benchmark
           problem
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Halim Alwi , Christopher Edwards
      This paper presents the evaluation process and results associated with two different fault detection and diagnosis (FDD) schemes applied to two different aircraft actuator fault benchmark problems. Although the schemes are different and bespoke for the problem being addressed, both are based on the concept of a second order sliding mode. Furthermore both designs are considered as ‘local’ in the sense that a localized actuator model is used together with local sensor measurements. The schemes do not involve the global aircraft equations of motion, and therefore have low order. The first FDD scheme is associated with the detection of oscillatory failure cases (OFC), while the second scheme is aimed at the detection of actuator jams/runaways. For the OFC benchmark problem, the idea is to estimate the OFC using a mathematical model of the actuator in which the rod speed is estimated using an adaptive second order exact differentiator. For the jam/runaway actuator benchmark problem, a more classical sliding mode observer based FDD scheme is considered in which the fault reconstruction is obtained from the equivalent output error injection signals associated with a second order sliding mode structure. The results presented in this paper summarize the design process from tuning, testing and finally industrial evaluation as part of the ADDSAFE project.


      PubDate: 2014-09-05T00:08:42Z
       
  • Hybrid predictive control of a coaxial aerial robot for physical
           interaction through contact
    • Abstract: Publication date: November 2014
      Source:Control Engineering Practice, Volume 32
      Author(s): Kostas Alexis , Christoph Huerzeler , Roland Siegwart
      This paper deals with the control of an unmanned coaxial helicopter designed towards active physical interaction with its environment. The system design is tailored to robust interaction through contact (e.g. docking and sliding on walls). Due to the rapid change of the dynamics from free-flight to the helicopter subject to the contact forces, a hybrid model is developed. This model captures all modes of the vehicle dynamics and is the basis for the design of a hybrid model predictive control strategy that ensures the stability of the hybrid dynamics and provides optimal maneuvering, docking on walls as well as sliding on them. The proposed control law is evaluated through experimental studies.
      Graphical abstract image Highlights

      PubDate: 2014-09-05T00:08:42Z
       
  • An application of adaptive techniques to vibration rejection in adaptive
           optics systems
    • Abstract: Publication date: November 2014
      Source:Control Engineering Practice, Volume 32
      Author(s): Riccardo Muradore , Lorenzo Pettazzi , Richard Clare , Enrico Fedrigo
      In modern Adaptive Optics (AO) systems, lightly damped sinusoidal oscillations resulting from telescope structural vibrations have a significant deleterious impact on the quality of the image collected at the detector plane. These oscillations can be observed in any mode of a generic modal representation of the AO wave-front sensor. A technique for the rejection of periodic disturbances recently presented in the literature has been adapted to the problem of rejecting vibrations in AO loops. The proposed methodology aims at estimating the harmonic disturbance together with the response of the plant at the vibration frequency. The algorithm has been tested in simulation on realistic scenarios and at the telescope.


      PubDate: 2014-09-05T00:08:42Z
       
  • Online detection of time-variant oscillations based on improved ITD
    • Abstract: Publication date: November 2014
      Source:Control Engineering Practice, Volume 32
      Author(s): Zixu Guo , Lei Xie , Taihang Ye , Alexander Horch
      An online detector for time-variant oscillations in univariate time-series is proposed. This paper is motivated by the fact that it is still an open problem to design a real-time oscillation detector which is applicable to non-linear, non-stationary and intermittent oscillations. The proposed procedure is based on intrinsic time-scale decomposition (ITD) and contains (i) an improved iteration termination condition for ITD with on-line back-redecomposition and (ii) a novel hypothesis test with a robust statistic of variation coefficient which enables online monitoring of time-variant oscillations. The proposed approach is computationally efficient, does not require a priori supervision window and is better applicable for online detection of time-variant oscillations. In addition, it preserves nonlinear features in process variables which facilitates subsequent oscillation diagnosis. Simulation examples and industrial applications are provided to demonstrate the effectiveness of the proposed online oscillation detector.


      PubDate: 2014-09-05T00:08:42Z
       
  • Multiobjective model predictive control for dynamic pickup and delivery
           problems
    • Abstract: Publication date: November 2014
      Source:Control Engineering Practice, Volume 32
      Author(s): Alfredo Núñez , Cristián E. Cortés , Doris Sáez , Bart De Schutter , Michel Gendreau
      A multiobjective-model-based predictive control approach is proposed to solve a dynamic pickup and delivery problem in the context of a potential dial-a-ride service implementation. A dynamic objective function including two relevant dimensions, user and operator costs, is considered. Because these two components typically have opposing goals, the problem is formulated and solved using multiobjective model predictive control to provide the dispatcher with a more transparent tool for his/her decision-making process. An illustrative experiment is presented to demonstrate the potential benefits in terms of the operator cost and quality of service perceived by the users.


      PubDate: 2014-09-05T00:08:42Z
       
  • Nonlinear model reference adaptive impedance control for human–robot
           interactions
    • Abstract: Publication date: November 2014
      Source:Control Engineering Practice, Volume 32
      Author(s): Mojtaba Sharifi , Saeed Behzadipour , Gholamreza Vossoughi
      Four nonlinear Model Reference Adaptive Impedance Controllers are introduced, tested, and compared for the control of the robot impedance with uncertainties in model parameters. The intended application area is human–robot interactions (HRI), particularly rehabilitation robots and haptic interfaces. All of the controllers make the closed-loop dynamics of the robot similar to the reference impedance model besides providing asymptotic tracking of the impedance model for the robot end-effector in Cartesian coordinates. The tracking and global stability are proved using Lyapunov stability theorem. Based on the simulations and experiments on a two-DOFs robot, the effectiveness of the proposed controllers is investigated.


      PubDate: 2014-08-18T22:32:21Z
       
  • Vision-based target tracking with a small UAV: Optimization-based control
           strategies
    • Abstract: Publication date: November 2014
      Source:Control Engineering Practice, Volume 32
      Author(s): Steven A.P. Quintero , João P. Hespanha
      This paper considers the problem of a small, fixed-wing UAV equipped with a gimbaled camera autonomously tracking an unpredictable moving ground vehicle. Thus, the UAV must maintain close proximity to the ground target and simultaneously keep the target in its camera׳s visibility region. To achieve this objective robustly, two novel optimization-based control strategies are developed. The first assumes an evasive target motion while the second assumes a stochastic target motion. The resulting optimal control policies have been successfully flight tested, thereby demonstrating the efficacy of both approaches in a real-world implementation and highlighting the advantages of one approach over the other.


      PubDate: 2014-08-18T22:32:21Z
       
  • A method for detecting non-stationary oscillations in process plants
    • Abstract: Publication date: November 2014
      Source:Control Engineering Practice, Volume 32
      Author(s): Vesa-Matti Tikkala , Alexey Zakharov , Sirkka-Liisa Jämsä-Jounela
      Persistent oscillations are a common problem in process plants since they cause excessive variation in process variables and may compromise the product quality. This paper proposes a method for detecting oscillations in non-stationary time series based on the statistical properties of zero-crossings. The main development presented is a technique to remove a non-stationary trend component from a signal before applying an oscillation detection procedure. The properties and performance of the method are analyzed using simulation experiments, a comparative study using industrial benchmark data, and tests with paperboard machine data. Finally, the simulation and industrial results are analyzed and discussed.


      PubDate: 2014-08-14T22:21:33Z
       
  • Robust adaptive control for a single-machine infinite-bus power system
           with an SVC
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Yong Wan , Jun Zhao , Georgi M. Dimirovski
      In this paper, a new control synthesis framework is developed to solve a robust stabilization problem for a single-machine infinite-bus power system with a static var compensator (SVC). The uncertainties in the infinite bus voltage and the internal and external reactances to the generating station are considered. First, control inputs for the excitation and the SVC are obtained via immersion and invariance (I&I). Then, the controller is redesigned using a parameter update law and a filter using indirect I&I adaptive control and a two-time-scale technique. The transient and steady-state performances are enhanced by introducing class K functions. The simulation results show that the developed controller improves the system performance.


      PubDate: 2014-08-05T21:53:08Z
       
  • Wind turbine mechanical stresses reduction and contribution to frequency
           regulation
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): H. Camblong , I. Vechiu , A. Etxeberria , M.I. Martínez
      The aim of the present research work has been to design an optimal MIMO LQG controller to reduce the drive-train, blades and tower mechanical stresses of a wind turbine (WT), and at the same time, to involve the WT in the grid primary frequency regulation when it is operating in full load (FL) zone. To verify the effectiveness of the proposed controller, the achieved results are compared to those obtained by a base-line controller based on a PI regulator. Simulation results show that thanks to these controllers, WT can effectively contribute to the grid frequency regulation, tracking tightly the generator power reference which depends on that frequency. Compared with the base-line controller, the LQG controller significantly reduces the mechanical stresses of the WT׳s most costly components.


      PubDate: 2014-08-05T21:53:08Z
       
  • Adaptive-gain second-order sliding mode observer design for switching
           power converters
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Jianxing Liu , Salah Laghrouche , Mohamed Harmouche , Maxime Wack
      In this paper, an adaptive-gain, Second Order Sliding Mode (SOSM) observer for multi-cell converters is designed by considering it as a type of hybrid system. The objective is to reduce the number of voltage sensors by estimating the capacitor voltages from measurement of the load current. The proposed observer is proven to be robust in the presence of perturbations with unknown boundaries. As the states of the system are only partially observable, a recent concept known as Z(T N )-observability is used to address the switching behavior. Multi-rate simulation results demonstrate the effectiveness and the robustness of the proposed observer with respect to output measurement noise and system uncertainty (load variations).


      PubDate: 2014-08-05T21:53:08Z
       
  • Hierarchical optimization of boiler–turbine unit using fuzzy stable
           model predictive control
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Xiao Wu , Jiong Shen , Yiguo Li , Kwang Y. Lee
      This paper develops a hierarchical control system structure based on the Takagi–Sugeno fuzzy model to achieve an optimal control of a boiler–turbine unit. In the upper layer of the hierarchy, an optimal reference governor is designed to find the optimal operating point. A disturbance term is introduced to the fuzzy model to lump the modeling mismatch and unknown disturbance. Thus, the effect of plant behavior variation can be removed and the operating point found can be feasible to control. In the lower layer, a stable model predictive controller is developed to track the optimal set-points while guaranteeing the input-to-state stability of the system. Fuzzy Lyapunov function and appropriate slack and collection matrices are used to reduce the conservatism of stability design and improve the performance. Through the estimation of the disturbance term using an observer, the two layers in the hierarchy are coupled and the integrated system can realize a dynamic optimal control of the boiler–turbine unit, even in the case of severe plant behavior variations.


      PubDate: 2014-08-05T21:53:08Z
       
  • Optimal control of combined heat and power units under varying thermal
           loads
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Philipp Wolfrum , Martin Kautz , Jochen Schäfer
      This paper describes a model based optimizer that allows a combined heat and power (CHP) unit to supply backup power to a Smart Grid on the one hand and minimize the cost for heat and power supply on the other hand. The model of the CHP unit is lean but nevertheless accurately represents the unit behavior, including thermal behavior of the storage as well as the aging effect of engine starts. Thanks to the small model dimension we can solve the optimal dispatch problem efficiently using dynamic programming. Two selected soft- and hard-ware in the loop tests are discussed to demonstrate the performance of the approach. A re-optimization strategy is discussed that allows reactions to wrong predictions of external influences like weather.


      PubDate: 2014-08-05T21:53:08Z
       
  • CEP special issue on power system control
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): István Erlich



      PubDate: 2014-08-05T21:53:08Z
       
  • A two-level emergency control scheme against power system voltage
           instability
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Bogdan Otomega , Mevludin Glavic , Thierry Van Cutsem
      A two-level adaptive control scheme against power system voltage instability is proposed, to deal with emergency conditions by acting on distribution transformers and/or by curtailing some loads. The lower level includes distributed controllers, each acting once the voltage at a monitored transmission bus settles below a threshold value. The upper level benefits from wide-area monitoring and adjusts in real-time the voltage thresholds of the local controllers. Emergency detection is based on the sign of sensitivities. The proposed scheme is robust with respect to communication failures. Its performance is illustrated through detailed simulations of a small but realistic 74-bus test system.


      PubDate: 2014-08-05T21:53:08Z
       
  • Optimal PMU-based monitoring architecture design for power systems
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Didier Georges
      This paper is dedicated to a new methodology for designing an optimal monitoring architecture by using a limited number of PMUs (Phasor Measurement Units) and PDCs (Phase Data Concentrators). The optimal design problem consists in defining the optimal location of both PMUs and PDCs by maximizing the expected value of the trace of the observability gramian of the power system over a large number of set point scenarios, while minimizing some communication infrastructure costs. Furthermore, a nonlinear dynamical state-observer, based on the Extended Kalman Filter, is proposed. This state-observer allows to take transient phenomena into account for wide-area power systems described by algebraic-differential equations, without needing nonlinear inversion techniques. The overall approach is illustrated with the IEEE 10 generator 39 bus New England power system.


      PubDate: 2014-08-05T21:53:08Z
       
  • IFC - Editorial Board / Funding body / agreements policies
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30




      PubDate: 2014-08-05T21:53:08Z
       
  • Hierarchical hydro power valley control: Validation on simulation platform
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Damien Faille , Frans Davelaar , Sébastien Murgey , Didier Dumur
      Hydro power valleys (HPV) are large scale interconnected systems. All plant operations have to comply with technical and environmental requirements concerning level, flow rate and power variations. A two-layer hierarchical MPC solution, designed to manage the large scale constrained and time delayed HPV, is tested on a simulation platform. The upper layer optimizes the power profiles on a one-day horizon with a coarse step size. The lower level refines the control for a shorter horizon and step size. Simulations show that the coordination is able to improve the maneuverability of the HPV.


      PubDate: 2014-08-05T21:53:08Z
       
  • OBC - Autogenerate contents and barcode
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30




      PubDate: 2014-08-05T21:53:08Z
       
  • Iterative learning control for robotic-assisted upper limb stroke
           rehabilitation in the presence of muscle fatigue
    • Abstract: Publication date: Available online 5 August 2014
      Source:Control Engineering Practice
      Author(s): Wenkang Xu , Bing Chu , Eric Rogers
      The use of iterative learning control to regulate assistive functional electrical stimulation applied to the muscles of patients undergoing robotic-assisted upper limb stroke rehabilitation has been followed through small scale clinical trials. These trials confirmed that an increase in patient ability to complete the specified task also led to a reduction in the level of electrical stimulation required. This previous work assumed that the effects of muscle fatigue could be neglected but if a patient suffers fatigue during a rehabilitation session then their the session goals are not achieved or, more likely, the session must be abandoned due to the time limits imposed by the ethical approval required to conduct such sessions. In this paper the results of the first investigation into enhancing the control scheme to remove or lessen the effects of fatigue and hence make better use of the time available for a session are given. The scheme considered adds a feedback loop around the muscle model used, where the performance results given are based on a model for the dynamics constructed using patient data collected in previous clinical trials.


      PubDate: 2014-08-05T21:53:08Z
       
  • Hedge-algebra-based voltage controller for a self-excited induction
           generator
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Dinko Vukadinović , Mateo Bašić , Cat Ho Nguyen , Nhu Lan Vu , Tien Duy Nguyen
      This paper presents an indirect rotor-flux-oriented (IRFO) control system of the self-excited induction generator (SEIG) in which excitation is achieved by means of a current-controlled voltage source inverter (CC-VSI) and a single electrolytic capacitor. In the proposed control scheme, both the iron losses and the magnetic saturation are taken into account and calculated online. The main objective is to keep the DC voltage across the capacitor constant and equal to the reference value, regardless of changes in the rotor speed and load. The study is mainly focused on the DC voltage control and, more specifically, on selection of the appropriate DC voltage controller. Besides considering widely accepted types of controllers, i.e., the classical PI controller and the fuzzy logic (FL) controller, this paper proposes an alternative solution – a new type of DC voltage controller based on hedge algebra. To our best knowledge, this is the first time that such a controller is considered for application in electrical engineering. The performance of the developed hedge algebra (HA) controller is evaluated through comparison with the optimal-tuned classical PI controller and the Sugeno-type FL controller. The simulation and experimental analysis are carried out in reasonably wide ranges of the DC voltage, load and rotor speed, including the case of a variable rotor speed. It is shown that the proposed HA controller provides superior performance in terms of tracking the reference DC voltage value as well as robustness to speed and load disturbances in the system.


      PubDate: 2014-07-27T21:06:02Z
       
  • An effective Lagrangian relaxation approach for rescheduling a
           steelmaking-continuous casting process
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Kun Mao , Quan-Ke Pan , Xinfu Pang , Tianyou Chai
      This paper studies a steelmaking-continuous casting (SCC) rescheduling problem with machine breakdown and processing time variations. Two objectives are considered in this study: the efficiency objective and the stability objective. The former refers to the total weighted completion time and total sojourn time, whereas the latter refers to the number of operations processed on different machines in the initial and revised schedules. We develop a time-index formulation and an effective Lagrangian relaxation (LR) approach with machine capacity relaxation to address the rescheduling problem. The LR approach decomposes the relaxed problem into batch-level subproblems with variable processing times. A polynomial two-stage dynamic programming algorithm is proposed to solve the batch-level subproblems. An efficient subgradient algorithm with global convergence is presented to solve the corresponding Lagrangian dual (LD) problem. Computational experiments based on practical production data show that the proposed approach not only produces a high quality schedule within an acceptable time but also performs much better than a practical SCC rescheduling method from a large iron and steel enterprise in China.


      PubDate: 2014-07-27T21:06:02Z
       
  • A virtual yaw rate sensor for articulated vehicles featuring novel
           electro-hydraulic steer-by-wire technology
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Naseem Daher , Monika Ivantysynova
      Steer-by-wire technologies remain under rigorous research and development given the advantages that they offer over their traditional counterparts. The spectrum of steering systems encompasses applications in the automotive, construction, agricultural, and aerospace industries, to name a few. An original electro-hydraulic steer-by-wire technology based on pump displacement control actuation, an energy efficient alternative to conventional valve control, has been previously proposed by the authors. The new concept was validated and implemented on an articulated steering prototype test vehicle, and resulted in significant fuel savings and machine efficiency increase. This paper investigates the notion of virtual sensing relative to estimating the vehicle׳s yaw rate by only measuring the articulation angle and vehicle speed. Virtual sensing is a promising concept for yaw stability control and is an attractive option for vehicle manufactures as it reduces sensor cost, maintenance, and machine downtime. The designed yaw rate sensor is validated in simulation as well as on a test vehicle by devising appropriate steering maneuvers.
      Graphical abstract image

      PubDate: 2014-07-27T21:06:02Z
       
  • Two degree-of-freedom design for a send-on-delta sampling PI control
           strategy
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): M. Beschi , S. Dormido , J. Sánchez , A. Visioli
      A complete event-based two-degree-of-freedom PI controller is presented. The architecture of the control system is based on two decoupled PI controllers, one for the set-point following and one for the load disturbance rejection task. The distinctive feature of the proposed approach is that the two controllers have the same parameters and the reference tracking performance is improved by suitably modifying the reference signal applied to the set-point following controller. Examples of the technique are given. In particular, the control strategy has been applied to a distributed solar collector field.


      PubDate: 2014-07-27T21:06:02Z
       
  • Efficient solution of the diesel-engine optimal control problem by
           time-domain decomposition
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Jonas Asprion , Oscar Chinellato , Lino Guzzella
      Offline solutions of the optimal control problems relating to diesel engines provide implications for causal control strategies and serve as a tool to automate the engine calibration process. However, the numerical solution of these dynamic optimisation problems is challenging. Above all, the model evaluations are expensive, integral and local inequality constraints are present, and the time horizon to be considered is long. Generally, the continuous problem is transcribed into a nonlinear mathematical program, which has a runtime that increases superlinearly with the problem size. In the literature, the time-domain decomposition of unconstrained and control-constrained problems is proposed to alleviate this often prohibiting increase in computational time. This paper extends the decomposition approach to problems with integral inequality constraints by utilising a partially dual formulation to derive equivalence conditions. To achieve these conditions, exact and approximate iteration schemes are proposed. The time-domain decomposition is combined with an iterative mesh refinement and a parallelisation of the model evaluations, which dominate the runtime of the solution process. On a standard personal computer, an overall speedup factor of 25 is achieved for a realistically sized instance of the diesel-engine problem.


      PubDate: 2014-07-27T21:06:02Z
       
  • Modelling and control of an assembly/disassembly mechatronics line served
           by mobile robot with manipulator
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Eugenia Minca , Adrian Filipescu , Alina Voda
      The aim of this paper is to reverse an assembly line using a mobile platform equipped with a manipulator. By reversibility we mean that the line is able to perform disassembly. For this purpose, an assembly/disassembly line balancing (A/DLB) and a synchronised hybrid Petri nets (SHPN) model will be used to model and control an assembly/disassembly mechatronics line (A/DML), with a fixed number of workstations, served by a wheeled mobile robot (WMR) equipped with a robotic manipulator (RM). The SHPN model is a hybrid type, where A/DML is the discrete part, and WMR with RM is the continuous part. Moreover, the model operates in synchronised mode with signals from sensors. Disassembly starts after the assembly process and after the assembled piece fails the quality test, in order to recover the parts. The WMR with RM is used only during disassembly, to transport the parts from the disassembling locations to the storage locations. Using these models and a LabView platform, a real-time control structure has been designed and implemented, allowing automated assembly and disassembly, where the latter is assisted by a mobile platform equipped with a manipulator.
      Graphical abstract image

      PubDate: 2014-07-27T21:06:02Z
       
  • Automated synthesis of hybrid Petri net models for robotic cells in the
           aircraft industry
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Francesco Basile , Fabrizio Caccavale , Pasquale Chiacchio , Jolanda Coppola , Alessandro Marino , Diego Gerbasio
      The use of robots in the aircraft structural assembly is a challenge. The presence of human operators, auxiliary systems and industrial robots makes hybrid the dynamic behavior of a robotic cell in this context. Here, the focus is on the automated synthesis of a model for the sequencing of the activities of a robotic cell in the aircraft industry. The cell model is obtained from a simple specification of resources and tasks, considered the main cell components, running the algorithm presented in this paper. The effectiveness of the model is shown using a case study defined by the ongoing European project LOCOMACHS (LOw COst Manufacturing and Assembly of Composite and Hybrid Structures, http://www.locomachs.eu/).


      PubDate: 2014-07-27T21:06:02Z
       
  • Active carbody roll control in railway vehicles using hydraulic actuation
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Edoardo F. Colombo , Egidio Di Gialleonardo , Alan Facchinetti , Stefano Bruni
      Carbody tilting is used in railway vehicles to reduce the exposure of passengers to lateral acceleration in curves, allowing these to be negotiated at higher speeds with the same level of comfort. This, however, requires a rather complex actuation system that increases vehicle weight and reduces space for passengers. This paper introduces a new concept that provides a limited amount of carbody tilt using hydraulic actuation. The device consists of interconnected hydraulic actuators attached to the carbody and bogies, replacing the passive anti-roll bar used in railway vehicles and in addition permitting active tilt control. Three control strategies for the active hydraulic suspension are proposed, and the regulator gains are defined using Genetic Algorithm optimisation, based on numerical simulation of the running behaviour of the actuated railway vehicle in a high-speed curve. Finally, the performance of the actuated vehicle is assessed on the basis of numerical simulations, showing it is possible to increase significantly the vehicle׳s running speed in fast curves compared with a vehicle equipped with passive suspension.


      PubDate: 2014-07-27T21:06:02Z
       
  • Quality prediction and analysis for large-scale processes based on
           multi-level principal component modeling strategy
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Zhiqiang Ge
      This paper proposed a multi-level principal component regression (PCR) modeling strategy for quality prediction and analysis of large-scale processes. Based on decomposition of the large data matrix, the first level PCR model divides the process into different sub-blocks through uncorrelated principal component directions, with a related index defined for determination of variables in each sub-block. In the second level, a PCR model is developed for local quality prediction in each sub-block. Subsequently, the third level PCR model is constructed to combine the local prediction results in different sub-blocks. For process analysis, a sub-block contribution index is defined to identify the critical-to-quality sub-blocks, based on which an inside sub-block contribution index is further defined for determination of the key variables in each sub-block. As a result, correlations between process variables and quality variables can be successfully constructed. A case study on Tennessee Eastman (TE) benchmark process is provided for performance evaluation.


      PubDate: 2014-07-27T21:06:02Z
       
  • An experimental assessment of finite-state Predictive Torque Control for
           electrical drives by considering different online-optimization methods
    • Abstract: Publication date: October 2014
      Source:Control Engineering Practice, Volume 31
      Author(s): Fengxiang Wang , Zhenbin Zhang , Alireza Davari , José Rodríguez , Ralph Kennel
      Finite-State Predictive Torque Control (FS-PTC) is experimentally investigated based on different online-optimization methods by using a two-level voltage source inverter for an induction machine. The calculation time and the switching frequencies are important research points for FS-PTC industrial applications. Long-step FS-PTC methods are expected to improve the performance of the system. However, the calculation time will increase exponentially with the increase of the prediction horizon. A reduced switching frequency PTC (RSF-PTC) method by considering the reductions of the switching frequency and the calculation time is tested. Based on this algorithm, an extended prediction horizon is proposed and verified on a common test bench. A torque-band based PTC (TB-PTC) method is proposed and discussed in this paper. The TB-PTC method pre-calculates the torque error between the predicted torque and the torque reference. The optimization method focuses on the flux error and the switching frequency for switching states which constrain the torque error within the torque-band. The conventional FS-PTC method, the RSF-PTC method with one-step and two-step horizons and the TB-PTC method are developed and experimentally compared in this work. The results confirm that conventional FS-PTC, RSF-PTC and TB-PTC methods can work well in the full speed range. When the switching frequencies and the calculation effort are taken into consideration, the RSF-PTC algorithm shows the better performance. However, the conventional FS-PTC method and the TB-PTC method have better current performance.


      PubDate: 2014-07-27T21:06:02Z
       
  • Experimental implementation of distributed flocking algorithm for multiple
           robotic fish
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Yongnan Jia , Long Wang
      This paper presents the experimental implementation of a flocking algorithm for multiple robotic fish governed by extended second-order unicycles. Combing consensus protocols with attraction/repulsion functions, a flocking algorithm is proposed to make the agents asymptotically converge to swim with consistent velocities and approach the equilibrium distances to their neighbors. The LaSalle–Krasovskii invariance principle is applied to verify the stability of the system. Besides numerical simulations, platform simulations involving robotic fish kinematic constraint and control mechanism are shown. An experiment with three robotic fish is implemented to illustrate the effectiveness of the proposed flocking algorithm in the presence of external disturbance and boundary collision.


      PubDate: 2014-06-14T15:55:15Z
       
  • Dynamic surface control of a piezoelectric fuel injector during rate
           shaping
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Dat Le , Bradley W. Pietrzak , Gregory M. Shaver
      Fuel injection rate shaping is a strategy to improve fuel efficiency and reduce harmful emissions in diesel engines. Due to their fast response, piezoelectric fuel injectors are capable of rate shaping operation. This paper describes a model-based closed-loop controller of injection flow rate for a piezoelectric fuel injector. This within-an-engine-cycle control strategy utilizes a dynamic surface control scheme and shows an injection flow rate tracking capability. Practical issues with LabVIEW FPGA control implementation are also addressed. The performance of the controller is verified with simulation and experimental results at different rail pressures and desired injection rates. The experiments show a maximum error of total fuel per one injection event of 2.5%. A stability analysis is also included.


      PubDate: 2014-06-14T15:55:15Z
       
  • Supervisory control of air–fuel ratio in spark ignition engines
    • Abstract: Publication date: September 2014
      Source:Control Engineering Practice, Volume 30
      Author(s): Denis V. Efimov , Vladimir O. Nikiforov , Hossein Javaherian
      The problem of air–fuel ratio stabilization in spark ignition engines is addressed in this paper. The proposed strategy consists of proper switching among two control laws to improve quality of the closed-loop system. The first control law is based on an a priori off-line identified engine model and ensures robust and reliable stabilization of the system at large, while the second control law is adaptive, it provides on-line adaptive adjustment to the current fluctuations and improves accuracy of the closed-loop system. The supervisor realizes a switching rule between these control laws providing better performance of regulation. Results of implementation on two vehicles are reported and discussed.


      PubDate: 2014-06-14T15:55:15Z
       
  • IFC - Editorial Board / Funding body / agreements policies
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29




      PubDate: 2014-06-14T15:55:15Z
       
  • Probability density function of bubble size based reagent dosage
           predictive control for copper roughing flotation
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Jianyong Zhu , Weihua Gui , Chunhua Yang , Honglei Xu , Xiaoli Wang
      As an effective measurement indicator of bubble stability, bubble size structure is believed to be closely related to flotation performance in copper roughing flotation. Moreover, reagent dosage has a very important influence on bubble size structure. In this paper, a novel reagent dosage predictive control method based on probability density function (PDF) of bubble size is proposed to implement the indices of roughing circuit. Firstly, the froth images captured in the copper roughing are segmented by using a two-pass watershed algorithm. In order to characterize bubble size structure with non-Gaussian feature, an entropy based B-spline estimator is hence investigated to depict the PDF of the bubble size. Since the weights of B-spline are interrelated and related to the reagent dosage, a multi-output least square support vector machine (MLS-SVM) is applied to depict a dynamic relationship between the weights and the reagent dosage. Finally, an entropy based optimization algorithm is proposed to determine reagent dosage in order to implement tracking control for the PDF of the output bubble size. Experimental results can show the effectiveness of the proposed method.


      PubDate: 2014-06-14T15:55:15Z
       
  • Set-membership methods applied to identify high-frequency elements of EMI
           filters
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Nacim Meslem , Vu Tuan Hieu Le , Cécile Labarre , Stéphane Lecoeuche , Jean-Luc Kotny , Nadir Idir
      In order to enhance the performance of electromagnetic interference (EMI) filters, it is necessary to identify high-frequency parasitic elements of their passive components, mainly those related to the coupled inductors. Motivated by this issue, in this work a realistic high-frequency model is proposed for the coupled inductors. Actually, using interval analysis in particular the forward–backward contractor, a set-membership algorithm has been developed to estimate systematically the parasitic elements linked with the magnetic components. The main advantages of this algorithm compared to the fitting methods are the values of the estimated parameters are always positive and the corrupted data are taken into account. The comparison of the simulation results and the experimental data allows us to validate the proposed method.


      PubDate: 2014-06-14T15:55:15Z
       
  • Data-based automated diagnosis and iterative retuning of
           proportional-integral (PI) controllers
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Tim Spinner , Babji Srinivasan , Raghunathan Rengaswamy
      This work presents a new look at the existing data-based and non-intrusive PI (proportional-integral) controller tuning assessment methods for SISO (single-input single-output) systems under regulatory control. Poorly tuned controllers are a major contributor to performance deterioration in process industries both directly and indirectly, as in the case of actuator cycling and eventual failure due to aggressive tuning. In this paper, an extensive review and classification of performance assessment and automated retuning algorithms, both classical and recent is provided. A subset of more recent algorithms that rely upon classification of poor tuning into the general categories of sluggish tuning and aggressive tuning are compared by their diagnostic performance. The Hurst exponent is introduced as a method for diagnosis of sluggish and aggressive control loop tuning. Also, a framework for more rigorous definitions than previously available of the terms “sluggish tuning” and “aggressive tuning” are provided herein. The performance of several tuning diagnosis methods are compared, and new algorithms for using these tuning diagnosis methods for iterative retuning of PI controllers are proposed and investigated using simulation studies. The results of these latter studies highlight the possible problem of loop instability when retuning based upon the diagnoses provided by data-based measures.


      PubDate: 2014-06-14T15:55:15Z
       
 
 
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