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Journal Cover Control Engineering Practice
  [SJR: 1.354]   [H-I: 84]   [40 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0967-0661
   Published by Elsevier Homepage  [3040 journals]
  • Damage-tolerant active control using a modal H∞-norm-based
           methodology
    • Abstract: Publication date: March 2017
      Source:Control Engineering Practice, Volume 60
      Author(s): Helói F.G. Genari, Nazih Mechbal, Gérard Coffignal, Eurípedes G.O. Nóbrega
      A new approach for vibration reduction of flexible structures subject to damage is here proposed, based on modal H ∞ -norm control. Considering that structural damage provokes different effects on each vibration mode, the proposed method concentrates the control action on modes that are indeed suffering the worst damage consequences. For this purpose, a new modal H ∞ norm is introduced, weighing each mode according to control design convenience. Based on this norm, a regular H ∞ controller design is applied, using the linear matrix inequality approach. Simulated and experimental results show significant advantages of the proposed methodology over the regular H ∞ approach, including damage tolerance.

      PubDate: 2017-01-15T00:12:35Z
       
  • Nonlinear control of coal-fired steam power plants
    • Abstract: Publication date: March 2017
      Source:Control Engineering Practice, Volume 60
      Author(s): Nahla Alamoodi, Prodromos Daoutidis
      This work proposes a nonlinear control strategy for steam power plants that efficiently controls the superheated steam temperature while accommodating large and frequent variations in power demand. The variables to be controlled are the pressure in the boiler, power generation, and superheater/reheater temperatures. The proposed strategy decomposes the overall plant into three separate subsystems and applies decoupling with deadtime compensation for each one of them. The derived strategy is implemented within a MATLAB/Simulink environment for different setpoint tracking and disturbance rejection cases, showing excellent performance and robustness.

      PubDate: 2017-01-15T00:12:35Z
       
  • Rapid development of modular and sustainable nonlinear model predictive
           control solutions
    • Abstract: Publication date: March 2017
      Source:Control Engineering Practice, Volume 60
      Author(s): Sergio Lucia, Alexandru Tătulea-Codrean, Christian Schoppmeyer, Sebastian Engell
      While computational complexity is often not anymore an obstacle for the application of Nonlinear Model Predictive Control (NMPC), there are still important challenges that prevent NMPC from already being an industrial reality. This paper deals with a critical challenge: the lack of tools that facilitate the sustainable development of robust NMPC solutions. This paper proposes a modularization of the NMPC implementations that facilitates the comparison of different solutions and the transition from simulation to online application. The proposed platform supports the multi-stage robust NMPC approach to deal with uncertainty. Its benefits are demonstrated by experimental results for a laboratory plant.

      PubDate: 2017-01-06T19:58:17Z
       
  • Closed-loop control of extracorporeal oxygen and carbon dioxide gas
           transfer
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): C. Brendle, K.-F. Hackmack, J. Kühn, M.N. Wardeh, T. Janisch, R. Kopp, R. Rossaint, A. Stollenwerk, S. Kowalewski, S. Leonhardt, M. Walter, B. Misgeld
      Additional extracorporeal gas transfer facilitates ultra-protective mechanical ventilation during treatment of severe lung disease. The proposed automation contributes to both patient safety and therapeutic success. A decentralized control system set the oxygen and carbon dioxide gas transfer rates. The controlled variables are estimated using standard measurement devices without direct blood contact. To reduce patient stress, an outer-loop integral controller adjusts the extracorporeal blood flow. The control system was first evaluated in silico and then in vivo using an animal model. Finally, the method is shown to be feasible and its response time is sufficient to meet patients' clinical needs.

      PubDate: 2016-12-28T08:18:46Z
       
  • Tracking the progression to type 2 diabetes with a proportional-derivative
           insulin secretion model
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Nor Azlan Othman, Paul D. Docherty, Nor Salwa Damanhuri, J. Geoffrey Chase
      Background Modelling insulin secretion as a function of peripheral C-peptide levels by mathematical deconvolution is widespread. However, the measurement resolution for successful deconvolution and high cost of C-peptide assays means measurement of insulin secretion can only be undertaken in small scale research endeavours. This research models the nature of insulin secretion (U N ) during the pathogenesis of type 2 diabetes. Methods A proportional-derivative U N model is based on the physiological, closed-loop insulin secretion response to increasing glucose ( ϕ D ) and glucose excursions ( ϕ P ). A total of 204 dynamic insulin sensitivity and secretion test (DISST) data sets from 68 participants in a 10-week dietary intervention trial were used to determine ϕ D and ϕ P values. The resulting gain values are used to classify subjects and thus the evaluation of U N over increasing insulin resistance. Results Participants with impaired fasting glucose (G 0 >5.56mmolL-1) had a lower median ϕ D value that becomes almost equal to ϕ P . In contrast, NGT participants (G 0 <5.56mmolL-1), ϕ D that tended to be much greater than ϕ P . Thus, as the metabolic state of a participant moves from NGT to pre-diabetes, the participant is loses first phase insulin burst secretion. The resulting gains are classified by easily measured basal glucose. Conclusions The simplicity of this PD U N model in a DISST model framework provides clear relationship between the U N profile and the readily available metabolic state of each participant. These relationships could significantly improve the cost and resolution of model-based tests like the DISST.

      PubDate: 2016-12-28T08:18:46Z
       
  • Real-time insulin bolusing for unannounced meals with artificial pancreas
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Kamuran Turksoy, Iman Hajizadeh, Sediqeh Samadi, Jianyuan Feng, Mert Sevil, Minsun Park, Laurie Quinn, Elizabeth Littlejohn, Ali Cinar
      Post-prandial hyperglycemia can occur more frequently in artificial pancreas systems without meal announcements that trigger insulin boluses. Meal announcements are manual feedforward inputs. We have developed a meal-detection and meal bolusing algorithm based on continuous glucose measurements without manual information from patients. Bergman's minimal model is modified and used in an unscented Kalman filter for state estimations. The estimated rate of appearance of glucose is used for meal detection and calculation of meal boluses. The algorithm is tested in simulation and clinical environments. The proposed algorithm decreases the frequency, duration and magnitude of hyperglycemia without causing any additional hypoglycemia.
      Graphical abstract image Highlights fx1

      PubDate: 2016-12-28T08:18:46Z
       
  • Special Section: IFAC Symposium on Biological and Medical Systems –
           BMS 2015
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Thomas Schauer, Berno J.E. Misgeld, Fabio Previdi


      PubDate: 2016-12-28T08:18:46Z
       
  • Controller design for neuromuscular blockade level tracking based on
           optimal control
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Juliana Almeida, Teresa Mendonça, Paula Rocha, Luís Rodrigues
      The contribution of this paper is to present and compare two state-feedback design methods for the automatic control of the Neuromuscular Blockade Level (NMB) based on optimal control. For this purpose a parsimoniously parameterized model is used to describe the patient's response to a muscle relaxant. Due to clinical restrictions the controller action begins when the patient recovers after an initial drug bolus. The NMB control problem, typically consisting of tracking a constant NMB reference level, can be associated with an optimal control problem (OCP) with a positivity constraint in the input signal. Due to the complexity associated with the introduction of a positivity constraint in the input, approximate solutions to this OCP will be found in this paper using two methods. In the first method, the optimal control problem is relaxed into a Semi-Definite Program (SDP) using a change of variables, whereas in the second method the OCP is approximated by an infinite horizon constrained Linear Quadratic Regulator (LQR) problem. These two controllers are compared with a classical PI controller in simulation. The PI exhibits a slightly worse performance in terms of the control magnitude but it was not optimized taking this magnitude into account. The simulation results show that the SDP relaxation and the saturated LQR methods lead to the same controller gains and therefore the same trajectory tracking using parameters from a patient's database, thus encouraging its application and validation in clinical trials. Although the performance of the proposed controllers can be compared in terms of how they work when applied to the patient's database models, the two proposed methods cannot be compared from an optimal control theoretical point of view because they correspond to the solution of two different relaxations of the original control problem using two different functions of merit.

      PubDate: 2016-12-28T08:18:46Z
       
  • Nonlinear observer design for GNSS-aided inertial navigation systems with
           time-delayed GNSS measurements
    • Abstract: Publication date: March 2017
      Source:Control Engineering Practice, Volume 60
      Author(s): Jakob M. Hansen, Thor I. Fossen, Tor Arne Johansen
      Global navigation satellite system (GNSS) receivers suffer from an internal time-delay of up to several hundred milliseconds leading to a degeneration of position accuracy in high-dynamic systems. With the increasing interest in GNSS navigation, handling of time-delays will be vital in high accuracy applications with high velocity and fast dynamics. This paper presents a nonlinear observer structure for estimating position, linear velocity, and attitude (PVA) as well as accelerometer and gyro biases, using inertial measurements and time-delayed GNSS measurements. The observer structure consists of four parts; (a) attitude and gyro bias estimation, (b) time-delayed translational motion observer estimating position and linear velocity, (c) input delays for inertial and magnetometer measurements, and (d) a faster than real-time simulator. The delayed PVA and gyro bias estimates are computed using a uniformly semiglobally exponentially stable (USGES) nonlinear observer. The high-rate inertial measurements are delayed and synchronized with the GNSS measurements in the state observer. The fast simulator integrates the inertial measurements from the delayed state estimate to provide a state estimate at current time. The sensor measurements are carefully synchronized and the estimation procedure for the GNSS receiver delay is discussed. Experimental data from a small aircraft are used to validate the results.

      PubDate: 2016-12-28T08:18:46Z
       
  • Multi-experiment state-space identification of coupled magnetic and
           kinetic parameters in tokamak plasmas
    • Abstract: Publication date: March 2017
      Source:Control Engineering Practice, Volume 60
      Author(s): B. Mavkov, E. Witrant, C. Prieur, D. Moreau
      This paper describes an identification technique for control-oriented linear time-invariant models of the coupled dynamics of the electron temperature and the poloidal magnetic flux for advanced operational tokamak scenarios. The actuators consist of two neutral beam injectors, an electron cyclotron current drive and the ohmic coil that provides the loop voltage at the plasma surface. The model is identified using a combination of subspace and output-error methods for state-space multiple-input and multiple-output system identification. This identification is applied on sets of simulated data from the METIS tokamak simulator with parameters typical of the DIII-D tokamak, and the results of the identification are presented.

      PubDate: 2016-12-28T08:18:46Z
       
  • Contents list
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59


      PubDate: 2016-12-28T08:18:46Z
       
  • An adaptive low-dimensional control to compensate for actuator redundancy
           and FES-induced muscle fatigue in a hybrid neuroprosthesis
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Naji Alibeji, Nicholas Kirsch, Nitin Sharma
      To restore walking and standing function in persons with paraplegia, a hybrid walking neuroprosthesis that combines a powered exoskeleton and functional electrical stimulation (FES) can be more advantageous than sole FES or powered exoskeleton technologies. However, the hybrid actuation structure introduces certain control challenges: actuator redundancy, cascaded muscle activation dynamics, FES-induced muscle fatigue, and unmeasurable states. In this paper, a human motor control inspired control scheme is combined with a dynamic surface control method to overcome these challenges. The new controller has an adaptive muscle synergy-based feedforward component which requires a fewer number of control signals to actuate multiple effectors in a hybrid neuroprosthesis. In addition, the feedforward component has an inverse fatigue signal to counteract the effects of the muscle fatigue. A dynamic surface control (DSC) method is used to deal with the cascaded actuation dynamics without the need for acceleration signals. The DSC structure was modified with a delay compensation term to deal with the electromechanical delays due to FES. A model based estimator is used to estimate the unmeasurable fatigue and actuator activation signals. The development of the controller and a Lyapunov stability analysis, which yielded semi-global uniformly ultimately boundedness, are presented in the paper. Computer simulations were performed to test the new controller on a 2 degrees of freedom fixed hip model after which preliminary experiments were conducted on one able-bodied male subject in the fixed hip configuration.

      PubDate: 2016-12-28T08:18:46Z
       
  • Optimal learning control of oxygen saturation using a policy iteration
           algorithm and a proof-of-concept in an interconnecting three-tank system
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Anake Pomprapa, Steffen Leonhardt, Berno J.E. Misgeld
      In this work, “policy iteration algorithm” (PIA) is applied for controlling arterial oxygen saturation that does not require mathematical models of the plant. This technique is based on nonlinear optimal control to solve the Hamilton–Jacobi–Bellman equation. The controller is synthesized using a state feedback configuration based on an unidentified model of complex pathophysiology of pulmonary system in order to control gas exchange in ventilated patients, as under some circumstances (like emergency situations), there may not be a proper and individualized model for designing and tuning controllers available in time. The simulation results demonstrate the optimal control of oxygenation based on the proposed PIA by iteratively evaluating the Hamiltonian cost functions and synthesizing the control actions until achieving the converged optimal criteria. Furthermore, as a practical example, we examined the performance of this control strategy using an interconnecting three-tank system as a real nonlinear system.

      PubDate: 2016-12-28T08:18:46Z
       
  • A low-cost high-fidelity ultrasound simulator with the inertial tracking
           of the probe pose
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Saverio Farsoni, Marcello Bonfè, Luca Astolfi
      The authors developed a versatile ultrasound simulator. The proposed system achieves the main features of a high-fidelity device exploiting low-cost rapid prototyping hardware. The hand-guided ultrasound simulator probe includes a RFID reader, a 9-DOF inertial sensor unit, consisting of an accelerometer, a magnetometer and a gyroscope, and a microcontroller that performs the real-time data acquisition, the processing and the transmission of the estimated pose information to the visualization system, so that the proper ultrasound view can be generated. Since the probe orientation is the main information involved in the pose reconstruction, this work presents and investigates several tracking methods for the probe orientation, exploiting a sensor fusion technique to filter the noisy measurements coming from inertial sensors. The performances of a Kalman filter, a nonlinear complementary filter and a quaternion-based filter as inertial trackers have been tested by means of a robot manipulator, in terms of readiness, accuracy and stability of the estimated orientation signal. The results show that the nonlinear complementary filter and the quaternion-based filter match all the application requirements (RMSE < 3 deg , variance < 1 deg 2 , and settling time < 0.3 s ), and they involve a lower computational time with respect to the Kalman filter.

      PubDate: 2016-12-28T08:18:46Z
       
  • Time-optimal flatness based control of a gantry crane
    • Abstract: Publication date: March 2017
      Source:Control Engineering Practice, Volume 60
      Author(s): Bernd Kolar, Hubert Rams, Kurt Schlacher
      This contribution deals with the flatness based control of a gantry crane, where the control objective is to transfer the load from an initial rest position to a final rest position in a minimal transition time. It is well-known that the type of crane model we consider is a differentially flat system, and that the position of the load is a flat output. We exploit this property both for the design of a tracking control as well as for planning time-optimal reference trajectories for the load. We discuss the design of the tracking control in detail, and show in particular how a standard approach which can be found in the literature can be modified systematically such that instead of measurements of certain time derivatives of the flat output we can use measurements of the state of the system. We also present a new approach for the design of time-optimal reference trajectories. In order to solve the resulting nonlinear optimization problem numerically, we use a primal-dual interior point method. Finally, we conclude with measurement results that stem from an implementation on a laboratory model.

      PubDate: 2016-12-28T08:18:46Z
       
  • Robust control for voltage and transient stability of power grids relying
           on wind power
    • Abstract: Publication date: March 2017
      Source:Control Engineering Practice, Volume 60
      Author(s): Konstantin Schaab, Jannik Hahn, Maksim Wolkov, Olaf Stursberg
      Common practice in stabilization of power grids is to refer to different stability categories (transient stability, voltage stability, rotor angle stability) and to address these by designing dedicated controllers separately based on models linearized around nominal operation points. Furthermore, the controllers of a generating unit contained in the grid are usually synthesized without considering other grid nodes. This work, in contrast, proposes a scheme for unified synthesis of controllers which conjunctively address rotor angle stability and voltage stability for grids containing synchronous generators as well as wind energy conversion systems based on doubly-fed induction generators. First, a procedure is proposed to describe the generating units by linear-parameter-varying (LPV) systems, in which fluctuations imposed by the grid or the wind are mapped into time-varying model parameters. For appropriate ranges of these parameters, decentralized robust controllers can be synthesized by semidefinite-programming, such that the power grid is stabilized for the considered fluctuations and disturbances. The effectiveness of the approach is demonstrated for a multi-bus benchmark system, where the grid oscillations are well damped and the LPV-controller stabilizes the grid after permanent changes.

      PubDate: 2016-12-21T07:47:57Z
       
  • A method for setpoint alarming using a normalized index
    • Abstract: Publication date: March 2017
      Source:Control Engineering Practice, Volume 60
      Author(s): Timothy I. Salsbury, Carlos F. Alcala
      This paper describes a normalized index for assessing the performance of PID control loops. The index was developed with a focus on ease of implementation by making use of features that are commonly found in modern control systems. Exponentially-weighted moving averages (EWMAs) or equivalent first-order infinite-impulse response (IIR) filters are found in many control system algorithm libraries and the index is developed using two EWMAs. Because the index is normalized, this paper shows how a single threshold can be derived from generic performance metrics thereby providing a solution to replace traditional setpoint alarming. Results are presented from evaluating the index using data gathered from several different loop types in a building heating, ventilating, and air-conditioning (HVAC) system.

      PubDate: 2016-12-14T07:19:34Z
       
  • Transmission support using Wind Farm controls during voltage stability
           emergencies
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Costas Vournas, Ioannis Anagnostopoulos, Theodoros Souxes
      This paper investigates the effect of reactive support by Wind Farms (WF) on the maximum power transfer, and thus the voltage stability limit of a transmission system. An insecure snapshot in a weak area of the Hellenic Interconnected System is examined, as well as a simpler test system. MV feeder characteristics and substation controls (feeder resistance and reactance, switched capacitors, LTC controls) are modelled in detail. Most importantly, the converter current limits, as well as the overvoltage limitations on the MV feeder, are taken into consideration in assessing the effect of the WF support.
      Graphical abstract image

      PubDate: 2016-12-07T13:04:31Z
       
  • Motion planning for robotic manipulators using robust constrained control
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Andrea Maria Zanchettin, Paolo Rocco
      Since their first appearance in the 1970's, industrial robotic manipulators have considerably extended their application fields, allowing end-users to adopt this technology in previously unexplored scenarios. Correspondingly, the way robot motion can be specified has become more and more complex, requiring new capabilities to the robot, such as reactivity and adaptability. For an even enhanced and widespread use of industrial manipulators, including the newly introduced collaborative robots, it is necessary to simplify robot programming, thus allowing this activity to be handled by non-expert users. Next generation robot controllers should intelligently and autonomously interpret production constraints, specified by an application expert, and transform them into motion commands only at a lower and real-time level, where updated sensor information or other kind of events can be handled consistently with the higher level specifications. The availability of several execution strategies could be then effectively exploited in order to further enhance the flexibility of the resulting robot motion, especially during collaboration with humans. This paper presents a novel methodology for motion specification and robust reactive execution. Traditional trajectory generation techniques and optimisation-based control strategies are merged into a unified framework for simultaneous motion planning and control. An experimental case study demonstrates the effectiveness and the robustness of this approach, as applied to an image-guided grasping task.

      PubDate: 2016-12-07T13:04:31Z
       
  • A framework for simulation-based engine-control unit inspection in
           manufacturing phase
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Won K. Ham, Minsuk Ko, Sang C. Park
      This paper proposes a framework for electronic engine-control unit (ECU) inspection in manufacturing phase. Although various methodologies have been developed for the ECU verification at the development phase, the ECU verification in the manufacturing phase has rarely been brought into focus. ECUs in the manufacturing phase need the verification process in the unified way of the ECU software and hardware components by three major causes: 1) ECU software revision, 2) incomplete installation of software, and 3) quality variation of hardware. For the effective ECU verification in the manufacturing phase, we propose a simulation-based ECU testing methodology. The proposed framework configures virtual vehicle environment to simulate an ECU using a “virtual engine system (VES) model” that specifies the operations of every ECU function during a simulation. The proposed framework employs a reverse engineering approach to identify the operation state transition of an ECU function by reference vehicle states from vehicle experimental data. The main objective of this paper is to design a VES model-based inspection system that simulates an ECU without software modification in brief time for set-up and execution. The proposed framework has been implemented and successfully applied to a Korean automotive company.

      PubDate: 2016-12-07T13:04:31Z
       
  • Series Active Variable Geometry Suspension application to comfort
           enhancement
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Carlos Arana, Simos A. Evangelou, Daniele Dini
      This paper explores the potential of the Series Active Variable Geometry Suspension (SAVGS) for comfort and road holding enhancement. The SAVGS concept introduces significant nonlinearities associated with the rotation of the mechanical link that connects the chassis to the spring-damper unit. Although conventional linearization procedures implemented in multi-body software packages can deal with this configuration, they produce linear models of reduced applicability. To overcome this limitation, an alternative linearization approach based on energy conservation principles is proposed and successfully applied to one corner of the car, thus enabling the use of linear robust control techniques. An H ∞ controller is synthesized for this simplified quarter-car linear model and tuned based on the singular value decomposition of the system's transfer matrix. The proposed control is thoroughly tested with one-corner and full-vehicle nonlinear multi-body models. In the SAVGS setup, the actuator appears in series with the passive spring-damper and therefore it would typically be categorized as a low bandwidth or slow active suspension. However, results presented in this paper for an SAVGS-retrofitted Grand Tourer show that this technology has the potential to also improve the high frequency suspension functions such as comfort and road holding.

      PubDate: 2016-12-07T13:04:31Z
       
  • Experimental sensorless control for IPMSM by using integral backstepping
           strategy and adaptive high gain observer
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): M.A. Hamida, J. de Leon, A. Glumineau
      In this paper a robust sensorless control for an Interior Permanent Magnet Synchronous Motor (IPMSM) is designed. The proposed control strategy uses a backstepping controller, whose robustness is improved by using integral actions added at each step of the original algorithm, and by a Maximum-Torque-Per-Ampere strategy (MTPA) to improve its energy efficient operation. Furthermore, to implement this controller in the framework of the mechanical sensorless control from the only measurements of the currents and voltages, an adaptive interconnected high gain observer is developed for estimating the rotor speed, the position and the load torque. Moreover, sufficient conditions are given to ensure the practical stability of the Observer-Controller system even if bounded uncertainties occur. Finally, the performance and the effectiveness of the designed method are tested experimentally throw a significant benchmark including different speed references and with significant robustness tests. A comparative evaluation of the computational effort of our scheme with respect to classical motor control is given.

      PubDate: 2016-12-01T00:42:40Z
       
  • Design of univariate alarm systems via rank order filters
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Wen Tan, Yongkui Sun, Ishtiza Ibne Azad, Tongwen Chen
      Filtering is one of the techniques used in alarm system design to improve the performance of an alarm system. Due to the fact that the filtered data is no longer independent, computation of the performance indexes (false alarm rate (FAR), missed alarm rate (MAR) and expected detection delay (EDD)) is hard for filters. In this paper, rank order filters are applied in alarm system design. The output of rank order filters is restricted to one of the input samples, thus the probability density function (PDF) of the filtered data can be computed directly from the PDF of the raw data. This feature makes it possible to compute FAR and MAR for rank order filters directly. Further, a method to compute the expected detection delay is proposed for rank order filters despite the dependence of the filtered data. Simulation results shows that the order of rank order filters provide another degree-of-freedom in alarm system design besides the window size, which can be used to improve the alarm performance.

      PubDate: 2016-12-01T00:42:40Z
       
  • An agent-based Decision Support System for resources' scheduling in
           Emergency Supply Chains
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Sarah Ben Othman, Hayfa Zgaya, Mariagrazia Dotoli, Slim Hammadi
      We propose a multi-agent-based architecture for the management of Emergency Supply Chains (ESCs), in which each zone is controlled by an agent. A Decision Support System (DSS) states and solves, in a distributed way, the scheduling problem for the delivery of resources from the ESC supplying zones to the ESC crisis-affected areas. Thanks to the agents’ cooperation, the DSS provides a scheduling plan that guarantees an effective response to emergencies. The approach is applied to two real cases: the Mali and the Japan crisis. Simulations are based on real data that have been validated by a team of logisticians from Airbus Defense and Space.

      PubDate: 2016-12-01T00:42:40Z
       
  • Fuzzy logic based adaptive admittance control of a redundantly actuated
           ankle rehabilitation robot
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Mustafa Sinasi AYAS, Ismail Hakki ALTAS
      Ankle rehabilitation robots have recently attracted great attention since they provide various advantages in terms of rehabilitation process from the viewpoints of patients and therapists. This paper presents development and evaluation of a fuzzy logic based adaptive admittance control scheme for a developed 2-DOF redundantly actuated parallel ankle rehabilitation robot. The proposed adaptive admittance control scheme provides the robot to adapt resistance/assistance level according to patients' disability level. In addition, a fuzzy logic controller (FLC) is developed to improve the trajectory tracking ability of the rehabilitation robot subject to external disturbances which possibly occur due to human-robot interaction. The boundary scales of membership functions of the FLC are tuned using cuckoo search algorithm (CSA). A classical proportional-integral-derivative (PID) controller is also tuned using the CSA to examine the performance of the FLC. The effectiveness of the adaptive admittance control scheme is observed in the experimental results. Furthermore, the experimental results demonstrate that the optimized FLC significantly improves the tracking performance of the ankle rehabilitation robot and decreases the steady-state tracking errors about 50% compared to the optimized PID controller. The performances of the developed controllers are evaluated using common error based performance indices indicating that the FLC has roughly 50% better performance than the PID controller.

      PubDate: 2016-12-01T00:42:40Z
       
  • A two-level control strategy with fuzzy logic for large-scale photovoltaic
           farms to support grid frequency regulation
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Nguyen Gia Minh Thao, Kenko Uchida
      This study proposes a two-level coordinated control strategy with fuzzy logic for appropriately adjusting the total active power supplied to a grid by large-scale photovoltaic (PV) farms in order to regulate grid frequency. For a solar farm, the strategy includes a central coordinating controller and many local controllers at PV power assemblies, treated as agents. In detail, the central controller uses a frequency regulation module based on a new automatic-tuning fuzzy-logic controller scheme to compute the appropriate reference values according to the total power needed. Then, the individual reference value for each local controller is determined. Each local controller governs all power-electronic converters installed at the PV agent to inject power into the grid according to the individual reference value received. Additionally, each local controller uses an algorithm to manage the state-of-charge of the battery bank installed at the agent so that it remains in the safe range of 20–80% while operating and close to the desired idle value of 50% at the steady state. Besides, a special control mode is developed and integrated into the overall strategy to aid rapid recovery of the grid frequency under emergency conditions. Numerical simulations demonstrate that the suggested strategy has the good response in terms of injecting an appropriate amount of power into the grid to regulate the frequency deviation into acceptable ranges of ±0.2 (Hz) in the transient state and ±0.05 (Hz) at the steady state, even when the weather conditions (solar radiation, air temperature), AC system load, and important control parameters of the grid suddenly change. Furthermore, the effectiveness in improving the grid-frequency stabilization by using the proposed strategy is validated within a four-area power system, where four PV farms are connected and the operating parameters of the grids at the areas are fairly different.

      PubDate: 2016-12-01T00:42:40Z
       
  • Robust pole location with experimental validation for three-phase
           grid-connected converters
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): Luiz A. Maccari, Humberto Pinheiro, Ricardo C.L.F. Oliveira, e Vinícius F. Montagner
      This paper provides design and experimental validation of robust current controllers for three-phase grid-connected converters. The main objectives here are: (i) to show that a simple polytopic model can be used for designing robust controllers for predominately inductive grids; (ii) to help in the choice of the control design parameter, based on a trade-off between an upper bound of the transient settling times and the control gain sizes. Linear matrix inequality based conditions are used to design the robust control gains with lower numerical complexity than similar conditions on literature. It is shown that small values the radius of pole location lead to better bounds for the transient responses, at the price of higher control gains. Good tracking of references for the grid currents is also illustrated in practice, allowing the closed-loop system to inject active and reactive power into the grid. Simulation and experimental results prove that the system connected to the grid can provide three-phase currents complying with requirements of an important international standard.

      PubDate: 2016-12-01T00:42:40Z
       
  • Gain scheduled state feedback velocity control of hydrostatic drive
           transmissions
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Joni Backas, Reza Ghabcheloo, Kalevi Huhtala
      In this paper, a velocity tracking controller for hydrostatic drive transmissions is developed. The solution is based on a state-dependent model that incorporates nonlinear characteristics of the system. A full state feedback controller is devised and the gains are scheduled on measured speed and pressures, together with approximated volumetric flow. The effects of uncertainties, especially those related to equilibrium values of pressures, are eliminated by utilizing so-called D-implementation. This technique eliminates the need for equilibrium values, which are model based and thus uncertain. To demonstrate the efficacy of the controller, the solution is implemented on a 4.5-ton wheel loader. For comparison purposes, a constant gain state feedback controller with integral action is devised, and also a linear PID controller is tuned. The results show that the benefits of the devised controller are significant when it is compared to these two controllers. Moreover, the controllability of the machine is maintained in every situation.

      PubDate: 2016-11-18T12:53:07Z
       
  • Bridging the gap between designed and implemented controllers via adaptive
           robust discrete sliding mode control
    • Abstract: Publication date: February 2017
      Source:Control Engineering Practice, Volume 59
      Author(s): M.R. Amini, M. Shahbakhti, S. Pan, J.K. Hedrick
      Bridging the gap between designed and implemented model-based controllers is a major challenge in the design cycle of industrial controllers. This gap is created due to (i) digital implementation of controller software that introduces sampling and quantization uncertainties, and (ii) uncertainties in the modeled plant's dynamics. In this paper, a new adaptive and robust model-based control approach is developed based on a nonlinear discrete sliding mode controller (DSMC) formulation to mitigate implementation imprecisions and model uncertainties, that consequently minimizes the gap between designed and implemented controllers. The new control approach incorporates the predicted values of the implementation uncertainties into the controller structure. Moreover, a generic adaptation mechanism will be derived to remove the errors in the nonlinear modeled dynamics. The proposed control approach is illustrated on a nonlinear automotive engine control problem. The designed DSMC is tested in real-time in a processor-in-the-loop (PIL) setup using an actual electronic control unit (ECU). The verification test results show that the proposed controller design, under ADC and model uncertainties, can improve the tracking performance up to 60% compared to a conventional controller design.

      PubDate: 2016-11-18T12:53:07Z
       
  • Speed tracking control for the gimbal system with harmonic drive
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Haitao Li, Xin Ning, Bangcheng Han
      This paper presents a composite controller based on a disturbance observer for the gimbal system of double-gimbal magnetically suspended control moment gyro (DGMSCMG) with harmonic drives. The controller removes the influence by coupling moments and nonlinear transmission torques. The disturbances are estimated by the designed disturbance observer. By introducing a state feedback controller, the disturbances can be eliminated from the output channel of the system. The gain selection principle of the disturbance observer is also analyzed. Both the simulation and experimental results indicate that the proposed control method can reject mismatched disturbances and improve system performance.

      PubDate: 2016-11-18T12:53:07Z
       
  • Output feedback control of a skid-steered mobile robot based on the
           super-twisting algorithm
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): I. Salgado, D. Cruz-Ortiz, O. Camacho, I. Chairez
      This paper presents the design and implementation of an output feedback controller based on the super twisting algorithm (STA) that stabilizes the trajectory tracking error of a skid steered mobile robot (SSMR). The control scheme introduces a diffeomorphism based on the mathematical model of the SSMR to transform the original problem into a third order chain of integrators. In this study, the available measurements are the position and orientation of the SSMR. A modified STA working as a step by step differentiator estimates the velocity and acceleration of the mobile robot. Then, a second STA enforces the tracking of a predefined trajectory. Numerical and experimental results comparing the STA with a state feedback controller (SFC) and a first order sliding mode controller (FOSM) justify the control proposal.

      PubDate: 2016-11-11T04:16:42Z
       
  • An observer-based blade-pitch controller of wind turbines in high wind
           speeds
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): M.L. Corradini, G. Ippoliti, G. Orlando
      The paper focuses on variable-rotor-speed/variable-blade-pitch wind turbines operating in the region of high wind speeds, where blade pitch and generator torque controllers are aimed at limiting the turbine's energy capture to the rated power value. Coupled design is described of an observer-based blade-pitch control input and a generator torque controller, both of which not requiring the availability of wind speed measurements. Closed loop convergence of the overall control system is proved. The proposed control solution has been validated on a 5-MW three-blade wind turbine using the National Renewable Energy Laboratory (NREL) wind turbine simulator FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code.

      PubDate: 2016-11-11T04:16:42Z
       
  • Implementation and test of a new autotuning method for PID controllers of
           TITO processes
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): René D.O. Pereira, Massimiliano Veronesi, Antonio Visioli, Julio E. Normey-Rico, Bismark C. Torrico
      In this paper we present a new closed-loop automatic tuning methodology for decentralised proportional–integral–derivative (PID) controllers applied to two-inputs–two-outputs (TITO) non-singular processes. The main feature of the technique is the estimation of the process parameters by evaluating two closed-loop set-point step responses with two roughly tuned PID controllers already in place. Then, once a process model has been obtained, the PID controllers can be retuned by using any rule available in the literature and suitable for the application. Simulation examples, comparative results with other works and a real application on a neonatal incubator prototype are given to illustrate the methodology and to show its effectiveness.

      PubDate: 2016-11-11T04:16:42Z
       
  • Control of a magnetic levitation system with communication imperfections:
           A model-based coupling approach
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Georg Stettinger, Martin Benedikt, Martin Horn, Josef Zehetner, Clenn Giebenhain
      This work presents a control strategy to control a magnetic levitation system under the influence of coupling imperfections (disturbances). To overcome problems arising whenever the interconnections between plant and controller have a non-negligible influence on the control-loop behavior a so-called model-based coupling approach is used. The main idea of this coupling approach is to use prediction schemes based on recursively identified plant and controller models which compensate for performance degradation due to coupling imperfections. Coupling failures such as time-delays, data-losses and noise drastically influence the control-loop performance. Especially when systems in form of real hardware (real-time systems) are present such disturbances have to be handled adequately. To demonstrate the effectiveness of the model-based coupling approach, a control-loop of a magnetic levitation system is analyzed in simulation as well as in real world laboratory setup (HiL simulation). Furthermore a first insight into the stability analysis of closed-loop systems including the model-based coupling technique is performed for a simplified configuration.

      PubDate: 2016-11-11T04:16:42Z
       
  • A backstepping high-order sliding mode voltage control strategy for an
           islanded microgrid with harmonic/interharmonic loads
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Nima Mahdian Dehkordi, Nasser Sadati, Mohsen Hamzeh
      This paper presents a new nonlinear voltage control strategy based on backstepping control and a high-order sliding mode differentiator for an islanded microgrid. The microgrid consists of multiple distributed generation (DG) units with an arbitrary configuration that can be parametrically uncertain or topologically unknown. The proposed controller robustly regulates the microgrid voltages in the presence of parametric uncertainties, unmodeled dynamics, load imbalances, and nonlinear loads with harmonic/interharmonic currents. In contrast to existing methods, the controller does not need to know the frequency of harmonic and interharmonic current of microgrid loads that lead to the reduction of the steady-state error of the voltage controller in the frequency of unknown harmonics and interharmonics. The MATLAB/SimPowerSystems toolbox has verified the proposed control strategy's performance.

      PubDate: 2016-11-11T04:16:42Z
       
  • Coal-fired utility boiler modelling for advanced economical low-NOx
           combustion controller design
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Huirong Zhao, Jiong Shen, Yiguo Li, Joseph Bentsman
      This paper focuses on developing a control-oriented coal-fired utility boiler model for advanced economical Low-NO x combustion (ELNC) controller design. Two boiler combustion models are proposed in this paper: one is a mathematical model describing the key dynamics of the real-time boiler thermal efficiency and the furnace one-dimensional NO x concentration distribution under conventional fuel and overfire air operations; the other recast from the first model is a control-oriented grey-box model with a data-driven furnace combustion submodel. Simulation studies on static and dynamic properties of the first mathematical model indicate that the model can function as a real-time simulator for both advanced boiler combustion control laws testing and generating training and validation data for the control-oriented grey-box model. At the end of this paper, the control-oriented grey-box modelling procedure as well as an optional discrete time linear state-space model are summarised to facilitate model-based advanced combustion controllers design.

      PubDate: 2016-11-11T04:16:42Z
       
  • Robust attitude control for quadrotors with input time delays
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Hao Liu, Danjun Li, Zongyu Zuo, Yisheng Zhong
      Robust attitude controller design problem is investigated for uncertain quadrotors with input delays. The vehicle model can be described as a multiple-input multiple-output nonlinear system subject to parametric uncertainties, external disturbances, and input time delays. A robust controller is proposed consisting of a nominal controller and a robust signal-based compensator. It is shown that the robust stability and the robust tracking property can be achieved. An important feature of the proposed control method is that a systematic way can be given to tune the controller parameters. Experimental results are given to demonstrate the effectiveness of the designed control system.

      PubDate: 2016-11-11T04:16:42Z
       
  • Multimode combustion in a mild hybrid electric vehicle. Part 2: Three-way
           catalyst considerations
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Sandro Nüesch, Anna G. Stefanopoulou
      This is the second of a two-part study that discusses multimode combustion in a mild hybrid electric vehicle. Homogeneous charge compression ignition (HCCI) combustion oxidizes the oxygen storage capacity (OSC) of the three-way catalyst (TWC), thereby removing the TWC's ability to convert NOx under lean conditions. Despite prolonged operation in HCCI mode, enabled by the electric motor, the depletion of the OSC causes significant penalties in fuel economy and the amounts of tailpipe NOx are substantial. Counter-intuitively, it is seen that decreasing the sizes of both HCCI regime and OSC results in reduced tailpipe NOx while maintaining fuel economy benefits.

      PubDate: 2016-11-11T04:16:42Z
       
  • Sensorless algorithm for sustaining controllability of IPMSM drive in
           electric vehicle after resolver fault
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Leszek Jarzebowicz, Krzysztof Karwowski, Wlodek J. Kulesza
      This paper presents a sensorless algorithm designated for the emergency control of an interior permanent magnet synchronous motor (IPMSM) drive in electric or hybrid vehicle. Special requirements for emergency-activated sensorless algorithms are defined, and shortcomings of state-of-the-art methods in terms of the considered application are discussed. The proposed emergency-activated algorithm is based on analysing the derivatives of motor phase currents measured over the duration of particular inverter states. The method is computationally simple and does not require additional hardware since the derivatives are measured indirectly. A lag between activating the algorithm upon an emergency flying start and re-establishing the torque controllability is defined. The proposed algorithm was implemented in the controller of a laboratory IPMSM vehicle drive and tested under varying operational conditions, including the emergency activation.

      PubDate: 2016-11-11T04:16:42Z
       
  • Trajectory planning and trajectory tracking for a small-scale helicopter
           in autorotation
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Skander Taamallah, Xavier Bombois, Paul M.J. Van den Hof
      The design of a high-performance guidance and control system for a small-scale helicopterUnmanned Aerial Vehicle (UAV), with an engine OFF flight condition (i.e. autorotation), is known to be a challenging task. It is the purpose of this paper to present a Trajectory Planning (TP) and Trajectory Tracking (TT) system, having onlinecomputational tractability. The presented Flight Control System (FCS) is anchored within the aggregated paradigms of differential flatness based optimal planning, and robust control based tracking. In particular the first real-time feasible, model-based TP and model-based TT, for a small-scale helicopter in autorotation is being demonstrated using a high-fidelity, high-order, nonlinear helicopter simulation.

      PubDate: 2016-11-11T04:16:42Z
       
  • Design and implementation of a neuro-adaptive backstepping controller for
           buck converter fed PMDC-motor
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Tousif Khan Nizami, Arghya Chakravarty, Chitralekha Mahanta
      A neuro-adaptive backstepping control (NABSC) method using single-layer Chebyshev polynomial based neural network is proposed for the angular velocity tracking in buck converter fed permanent magnet dc (PMDC)-motor. Owing to their universal approximation property, neural networks have been utilized for approximating the unknown nonlinear profile of instantaneous load torque. The inherent computational complexity of the neural network based adaptive scheme has been circumvented through the use of orthogonal Chebyshev polynomials as basis functions. A detailed stability and transient performance analysis has been conducted using Lyapunov stability criteria. The proposed control scheme is shown to yield a superior output performance with enhanced robustness for wide variations in load torque and set-point changes, compared to existing conventional approaches based on adaptive backstepping. The theoretical propositions are verified on an experimental prototype using dSPACE, Control Desk DS1103 setup with an embedded TM320F240 Digital Signal Processor proving its applicability to real-time electrical systems. The efficiency of the proposed strategy is quantified using performance measures and are evaluated against the conventional adaptive backstepping control (ABSC) methodology. Ultimately, this investigation confirms the effectiveness of the proposed control scheme in achieving an enhanced output transient performance while faithfully realizing its control objective in the event of abrupt and uncertain load variations.

      PubDate: 2016-11-11T04:16:42Z
       
  • Undulatory locomotion and effective propulsion for fish-inspired robot
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Pichet Suebsaiprom, Chun-Liang Lin, Anumat Engkaninan
      Swimming, turning, and whip-sweeping propulsion for carangiform locomotion of a fish robot are investigated by means of a 4-link planar tail and an autonomous underwater vehicle (AUV)-like model. It is observed that excellent acceleration occurs when a whip sweeping behavior has been applied to the fish tail. The forward speed can even increases twice to the nominal swimming via the simulation study. The efficient movement is thus incorporated to the fish robot for agile movement. The robot's swimming patterns realize the effect in terms of the forward swimming, turning swimming, acceleration increasing, descended swimming, ascended swimming, depth regulating, and self-stabilization. Verification is accomplished by incorporating the 4-link planar tail, AUV-like model, and a two degree-of-freedom (DOF) barycenter mechanism. The four-link planar tail and 2-DOF barycenter mechanism act, respectively, as the thrust generator and stabilizing actuator for the fish robot. Sliding mode control (SMC) has been applied for three-dimensional (3D) trajectory tracking. Simulation results illustrate satisfactory performances of the fish robot in terms of the fish-like behaviors and maneuverability, which are due to the consequence of the mimicked predator-fish behaviors and performance robustness of the SMC for trajectory tracking under ocean current perturbations and modeling uncertainties.

      PubDate: 2016-11-11T04:16:42Z
       
  • Dynamic modeling and optimal control of goethite process based on the
           rate-controlling step
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Yong-fang Xie, Shi-wen Xie, Yong-gang Li, Chun-hua Yang, Wei-hua Gui
      The iron removal process is an important technology in zinc hydrometallurgy. Due to its complicated reaction mechanism, it is difficult to highly control the performance of process solely relying on manual experience. Therefore, this paper focuses on the dynamic modeling for the goethite process and its optimal control method. In different reactors, different operating conditions will influence the rate-controlling step of process reactions, as well as the kinetic model. We determine the rate-controlling step of reactions in each reactor according to the reaction conditions, and subsequently the dynamic model has been developed based on the rate-controlling step. Then an optimal control method for the goethite process has been proposed, which satisfies the technical requirements with minimal process consumption. The proposed optimal control includes pre-setting of descent gradient of outlet ferrous ion concentration and optimal control of oxygen and zinc oxide. The simulation results demonstrate that the proposed dynamic model exhibits greater performance comparing with the process model without considering rate-controlling step, and the proposed control strategy has a higher satisfactory than the nonlinear model predictive control. Then, the proposed optimal control is validated by the industrial experiment, which the average oxygen and zinc oxide consumptions decreased by 568m3/day (6.22%) and 3.09t/day (5.16%) and the qualified rate of outlet ferrous ion concentrations increased by 5.5%, compared with the manual control.

      PubDate: 2016-11-11T04:16:42Z
       
  • Friction compensation in control valves: Nonlinear control and usual
           approaches
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Matheus Cammarosano Hidalgo, Claudio Garcia
      This work presents different approaches to reduce the control valve friction effect on a process. One is to use the sliding mode control in different conditions and then to compare this controller to widely used algorithms and devices that reduce the control loop variability. The experiments were performed in the Flow Pilot Plant of Polytechnic School of the University of São Paulo with a pneumatic control valve with high friction in a flow control loop. The sliding mode controller yielded promising results, which can represent new horizons with respect to friction compensation in control valves.

      PubDate: 2016-11-11T04:16:42Z
       
  • Ensemble modified independent component analysis for enhanced non-Gaussian
           process monitoring
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Chudong Tong, Ting Lan, Xuhua Shi
      As a multivariate statistical tool, the modified independent component analysis (MICA) has drawn considerable attention within the non-Gaussian process monitoring circle since it can solve two main problems in the original ICA method. Despite the diversity in applications, the determination logic for non-quadratic functions involved in the iterative procedures of MICA algorithm has always been empirical. Given that the MICA is an unsupervised modeling method, a direct rational study that can conclusively demonstrate which non-quadratic function is optimal for the general purpose of fault detection is inaccessible. The selection of non-quadratic functions is still a challenge that has rarely been attempted. Recognition of this issue and motivated by the superiority of ensemble learning strategy, a novel ensemble MICA (EMICA) modeling approach is presented for enhancing non-Gaussian process monitoring performance. Instead of focusing on a single non-quadratic function, the proposed method combines multiple base MICA models derived from different non-quadratic functions into an ensemble one, and the Bayesian inference is employed as a decision fusion method to form a unique monitoring index for fault detection. The enhanced fault detectability of the EMICA method is also illustrated on two industrial processes.

      PubDate: 2016-11-11T04:16:42Z
       
  • An intelligent control system for traffic lights with simulation-based
           evaluation
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Junchen Jin, Xiaoliang Ma, Iisakki Kosonen
      This paper introduces an intelligent control system for traffic signal applications, called Fuzzy Intelligent Traffic Signal (FITS) control. It provides a convenient and economic approach to improve existing traffic light infrastructure. The control system is programmed on an intermediate hardware device capable of receiving messages from signal controller hardware as well as overriding traffic light indications during real-time operations. Signal control and optimization toolboxes are integrated into the embedded software in the FITS hardware device. A fuzzy logic based control has been implemented in FITS. In order to evaluate the effects of FITS system, this study attempts to develop a computational framework to evaluate FITS system using microscopic traffic simulation. A case study is carried out, comparing different commonly used signal control strategies with the FITS control approach. The simulation results show that the control system has the potential to improve traffic mobility, compared to all of the tested signal control strategies, due to its ability in generating flexible phase structures and making intelligent timing decisions. In addition, the effects of detector malfunction are also investigated in this study. The experiment results show that FITS exhibits superior performance than several other controllers when a few detectors are out-of-order due to its self-diagnostics feature.

      PubDate: 2016-11-11T04:16:42Z
       
  • Explicit hidden coupling terms handling in gain-scheduling control design
           via eigenstructure assignment
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): H. Lhachemi, D. Saussié, G. Zhu
      This paper presents a novel method for the design of gain-scheduled output feedback controllers in the presence of hidden coupling terms, which naturally arise when endogenous signals are used as scheduling parameters. In this case, the controller gains vary with respect to system variables, leading to inner loops between the system and the linearized gain-scheduled controller dynamics. Such effects, also known as parasitic feedbacks, are inherently difficult to handle in classic gain-scheduling control design and are often omitted, which might result in performance degradations or even destabilization of the closed-loop system. This paper shows how such a pitfall can be avoided through the application of self-scheduling and eigenstructure assignment techniques. In this context, the main contribution of the present work is the extension of eigenstructure assignment-based self-scheduling techniques for explicit hidden coupling terms handling. The viability of the proposed method is illustrated through a pitch-axis missile autopilot benchmark problem.

      PubDate: 2016-11-11T04:16:42Z
       
  • A Light-Weight Fault Injection Approach to Test Automated Production
           System PLC Software in Industrial Practice
    • Abstract: Publication date: January 2017
      Source:Control Engineering Practice, Volume 58
      Author(s): Susanne Rösch, Birgit Vogel-Heuser
      A light-weight software-implemented fault injection (SWIFI) testing approach is introduced, focusing on technical process faults and system faults. The reaction of automated production systems (aPSs) and their programmable logic controller (PLC) software to these faults is tested. In order to tailor the testing approach to the aPS domain in industrial practice, our test generation is based on a classification of possible deviations, i.e. a classification of possible technical process and system faults as the PLC perceives them. As a result, both specification and test execution become more efficient for practitioners. Furthermore, the test specification is tailored for execution on IEC 61131-3 programming environments. In this, the execution of test cases both against simulation or the real aPS, is enabled.

      PubDate: 2016-11-11T04:16:42Z
       
 
 
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