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Journal Cover Control Engineering Practice
   [12 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0967-0661
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.522]   [H-I: 59]
  • 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
       
  • Nonlinear cascade strategy for longitudinal control in automated vehicle
           guidance
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Rachid Attia , Rodolfo Orjuela , Michel Basset
      This paper deals with automatic control design for automotive driving with a special focus on the longitudinal control. The automotive vehicle is a complex system characterised by highly nonlinear longitudinal and lateral coupled dynamics. Consequently, the control design for automated driving should deal with both of these dynamic couplings. Indeed, the longitudinal control plays an important role in the automated guidance to ensure safety and comfort of automotive passengers. In this work, a nonlinear cascade longitudinal control based on inner and outer-loops design is proposed. The lateral control is handled following a model predictive approach ensuring the automated steering of the vehicle. Finally, the nonlinear longitudinal control is integrated with the lateral control in a whole architecture to perform a coupled longitudinal and lateral control. The effectiveness of the automated driving strategy is highlighted through simulation results.


      PubDate: 2014-06-14T15:55:15Z
       
  • 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
       
  • Coordinated trajectory planning for efficient communication relay using
           multiple UAVs
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Seungkeun Kim , Hyondong Oh , Jinyoung Suk , Antonios Tsourdos
      This paper investigates the use of small UAVs as communication relay nodes for expanding communication links and improving communication quality for a fleet of naval vessels. This paper firstly deals with the UAV deployment for stationary communication nodes, and then, proposes a decentralised nonlinear model predictive trajectory planning strategy for a dynamic environment. By exploiting motion estimates of vessels and states of UAVs, the trajectory planning algorithm finds a control input sequence optimising network connectivity over a certain time horizon. Numerical simulations are performed for both stationary and manoeuvring vessels to verify the feasibility and benefit of the proposed approach.


      PubDate: 2014-06-14T15:55:15Z
       
  • Nonlinear thermal system identification using fractional Volterra series
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Asma Maachou , Rachid Malti , Pierre Melchior , Jean-Luc Battaglia , Alain Oustaloup , Bruno Hay
      Linear fractional differentiation models have already proven their efficacy in modeling thermal diffusive phenomena for small temperature variations involving constant thermal parameters such as thermal diffusivity and thermal conductivity. However, for large temperature variations, encountered in plasma torch or in machining in severe conditions, the thermal parameters are no longer constant, but vary along with the temperature. In such a context, thermal diffusive phenomena can no longer be modeled by linear fractional models. In this paper, a new class of nonlinear fractional models based on the Volterra series is proposed for modeling such nonlinear diffusive phenomena. More specifically, Volterra series are extended to fractional derivatives, and fractional orthogonal generating functions are used as Volterra kernels. The linear coefficients are estimated along with nonlinear fractional parameters of the Volterra kernels by nonlinear programming techniques. The fractional Volterra series are first used to identify thermal diffusion in an iron sample with data generated using the finite element method and temperature variations up to 700K. For that purpose, the thermal properties of the iron sample have been characterized. Then, the fractional Volterra series are used to identify the thermal diffusion with experimental data obtained by injecting a heat flux generated by a 200W laser beam in the iron sample with temperature variations of 150K. It is shown that the identified model is always more accurate than the finite element model because it allows, in a single experiment, to take into account system uncertainties.


      PubDate: 2014-06-14T15:55:15Z
       
  • A highly scalable path-following controller for N-trailers with off-axle
           hitching
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Maciej Marcin Michałek
      The paper presents a highly scalable nonlinear cascaded-like path-following feedback controller for N-trailer robotic vehicles equipped with arbitrary number of off-axle hitched trailers. In contrast to the other path-following control laws proposed in the literature for N-trailer robots, the presented control approach does not require determination of the shortest distance to a reference path. By introducing the so-called segment-platooning reference paths, and under the sign-homogeneity assumption for hitching offsets, the asymptotic following is guaranteed for both constant- and varying-curvature reference paths using either backward or forward vehicle motion strategy with a guidance point fixed on the last trailer. The paper contains experimental results obtained with a 3-trailer laboratory-scale vehicle.


      PubDate: 2014-06-14T15:55:15Z
       
  • Gradient-based optimization algorithms for networks of reconfigurable
           sensors
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): T.H. de Groot , O.A. Krasnov , A.G. Yarovoy
      A variety of optimization algorithms has been developed for non-linear and non-convex problems in which numerous reconfigurable sensors need to be assigned to many tasks. The algorithms are based on modified gradient-search methods and inspired by centralized/distributed principles. Numerical evaluation of these algorithms on a statistically large set of optimization problems has shown that while each particular algorithm does not necessarily provide the optimal solution in all possible cases, some are very efficient in solving them. Distributed (agent-based) approaches are usually advocated because of their scalability and speed, but the developed centralized (synchronous) algorithms are shown to be better in terms of speed, and simultaneously in terms of effectiveness, and therefore, in terms of efficiency.


      PubDate: 2014-06-14T15:55:15Z
       
  • Combining extremum seeking control and tracking control for
           high-performance CVT operation
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Stan van der Meulen , Bram de Jager , Frans Veldpaus , Maarten Steinbuch
      The design of a new controller for the variator in a pushbelt continuously variable transmission (CVT) is investigated. A conventional variator controller is typically based on a variator model with large uncertainties, which results in a limited variator efficiency. The proposed controller simultaneously optimizes the variator efficiency and tracks a transmission ratio reference, for which a detailed variator model is not required. The controller, a combination of extremum seeking control and tracking control, only uses measurements from standard sensors. Experiments on the basis of a driving cycle show that a conventional variator controller is outperformed.


      PubDate: 2014-06-14T15:55:15Z
       
  • Model-based diesel Engine Management System optimization for transient
           engine operation
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Markus Grahn , Krister Johansson , Tomas McKelvey
      A recently developed strategy to calculate set points for controllable diesel engine systems is described, further developed, and evaluated. The strategy calculates set points with an aim to minimize fuel consumption for a given dynamic vehicle driving cycle, while keeping accumulated emissions below given limits. The strategy is based on existing methodology for steady-state engine operation, but extended to handle transient effects in the engine caused by dynamics in the engine air system. Using the strategy, set points for the complete operating range of the engine can be calculated off-line and stored in an Engine Management System, hence set points can be derived for any (steady-state or transient) driving scenario. The strategy has been evaluated using a simulation model of a complete diesel engine vehicle system. The model estimates fuel consumption, NO X , and soot emissions for a dynamic vehicle driving cycle depending on set points for boost pressure, oxygen fraction in the intake manifold, and injection timing, throughout the simulation. Using this simulation model, the strategy has been shown to decrease fuel consumption for the New European Driving Cycle with 0.56%, the Federal Test Procedure with 1.04%, and the Japanese JC08 cycle with 0.84% compared to a strategy based on steady-state engine operation.


      PubDate: 2014-06-14T15:55:15Z
       
  • Direct multivariable controller tuning for internal combustion engine test
           benches
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Thomas E. Passenbrunner , Simone Formentin , Sergio M. Savaresi , Luigi del Re
      Dynamical test benches are typically used in the development phase of engine systems and require tracking controllers with a high performance. Unfortunately, during such a work the components or operation parameters of the engine system are changed very frequently, making the use of classical model based control approaches very time-consuming. Against this background, this paper proposes a direct data-driven design approach for multivariable control of rotational speed and shaft torque of an internal combustion engine at a test bench based on an extended version of a recently introduced method for non-iterative direct data-driven tuning of multivariable controllers. This extension allows employing data collected in a closed-loop experiment in the direct identification of the controller parameters. The effectiveness of the proposed approach is shown on a test bench equipped with a production light duty Diesel engine. A comparison with the industrial state-of-the-art controller is provided on both a dynamically challenging test and a typical driving cycle as measured on an instrumented vehicle with the same internal combustion engine. The results confirm that the new method recovers the performance of the well-tuned industrial control, but can be developed in a fraction of the time as no explicit model of the system is needed.


      PubDate: 2014-06-14T15:55:15Z
       
  • Planar feature-based motion control for near-repetitive structures
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): J.J.T.H. de Best , M.J.G. van de Molengraft , M. Steinbuch
      This paper focuses on the motion control for machines used for the production of products that inherently consist of equal features placed in a repetitive pattern. In many cases the repetitiveness of these structures is prone to imperfections, for example due to thermal expansion, such that the distance between successive features deviates. As a consequence the metric positions of the features of such near-repetitive structures are unknown a priori such that setpoints cannot be created a priori. The considered motion task in this paper is to position a tool relative to the features of a near-repetitive structure with an accuracy of < 10 μ m . Instead of metric positions novel two-dimensional feature-based positions will be used that are obtained from a camera capturing images at 1kHz for feedback, resulting in a direct visual servoing control approach. The robustness with respect to imperfections in the repetitiveness is investigated and the design is validated on an experimental setup.


      PubDate: 2014-06-14T15:55:15Z
       
  • Sea floor geometry approximation and altitude control of ROVs
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Fredrik Dukan , Asgeir J. Sørensen
      This paper presents a method for sea floor geometry approximation in a local region beneath a remotely operated vehicle (ROV) for use in altitude control. The method is based on Doppler velocity log (DVL) altitude measurements and ROV state estimates. The ROV altitude and sea floor gradient, which are obtained from the sea floor approximation, are used in a guidance law for altitude control. The altitude observer and guidance law have been implemented in the control system of NTNU׳s ROV Minerva. Results from simulations and sea trials demonstrating the performance of the proposed altitude estimation and guidance system are presented in the paper.


      PubDate: 2014-06-14T15:55:15Z
       
  • A brand new nonlinear robust control design of SSSC for transient
           stability and damping improvement of multi-machine power systems via
           pseudo-generalized Hamiltonian theory
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Bangjun Lei , Shumin Fei
      Nonlinear robust control of static synchronous series compensator (SSSC) is investigated in multi-machine multi-load power systems by using the pseudo-generalized Hamiltonian method. First, the uncertain nonlinear differential algebraic equation model is constructed for the power system. Then, the dissipative pseudo-generalized Hamiltonian realization of the system is established by means of variable transformation and prefeedback control. Finally, based on the obtained dissipative pseudo-generalized Hamiltonian realization, a brand new nonlinear robust controller is put forward. The proposed controller can effectively use the internal structure and the energy balance property of the power system. Simulation results demonstrate the effectiveness and robustness of the control scheme.


      PubDate: 2014-06-14T15:55:15Z
       
  • Assessment of gradient-based iterative learning controllers using a
           multivariable test facility with varying interaction
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Thanh V. Dinh , Chris T. Freeman , Paul L. Lewin
      A multiple input, multiple output (MIMO) experimental test facility has been developed for the evaluation, benchmarking and comparison of iterative learning control (ILC) strategies. The system addresses the distinct lack of experimental studies for the multivariable case and enables controller performance and robustness to be rigorously investigated over a broad range of operating conditions. The electromechanical facility is multi-configurable with up to 3 inputs and permits both exogenous disturbance injection and a variable level of coupling to be applied between input and output pairs. To confirm its suitability for evaluation and comparison of ILC, theoretical results are derived for two popular forms of gradient-type ILC algorithm, linking interaction with fundamental performance limitations. The test facility is then used to establish how well theoretical predictions match experimental results. The analysis is then extended to provide solutions to address this performance degradation, and these are again confirmed using the test facility.


      PubDate: 2014-06-14T15:55:15Z
       
  • Editorial: IFAC Workshop on Engine and Powertrain Control, Simulation and
           Modeling (ECOSM 2012)
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Antonio Sciarretta , Paolino Tona , Chris Manzie , Carlos Guardiola



      PubDate: 2014-06-14T15:55:15Z
       
  • Cascaded control of combustion and pollutant emissions in diesel engines
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Frédéric Tschanz , Stephan Zentner , Christopher H. Onder , Lino Guzzella
      Control of the emissions of diesel engines is an upcoming approach for complying with legislation while limiting the calibration effort. In this paper, a controller for engine-out NOx and PM is combined with a controller for the center of main combustion and the indicated mean effective pressure. The inner cascade combustion controller effectively reduces unwanted influences on the combustion. These influences are partly coupled to the outer-loop manipulated variables and partly result from disturbances which commonly appear in diesel engines. Robust stability is analyzed and holds in a wide operating range. Performance of the control structure is demonstrated with experiments.


      PubDate: 2014-06-14T15:55:15Z
       
  • Robust oxygen fraction estimation for conventional and premixed charge
           compression ignition engines with variable valve actuation
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Lyle E. Kocher , Carrie M. Hall , Karla Stricker , David Fain , Dan Van Alstine , Gregory M. Shaver
      In-cylinder oxygen fraction serves as a critical control input to advanced combustion strategies, but is extremely difficult to measure on production engines. Fortunately, the in-cylinder oxygen levels can be estimated based on accurate estimates or measurements of the oxygen fraction in the intake and exhaust manifolds, the in-cylinder charge mass, and the residual mass. This paper outlines such a physically based, generalizable strategy to estimate the in-cylinder oxygen fraction from only production viable measurements or estimates of exhaust oxygen fraction, fresh air flow, charge flow, fuel flow, turbine flow and EGR flow. While several of these flows are accurately measured or estimated, significant errors in the turbine and EGR flows are commonly observed and can highly degrade the accuracy of any calculations which utilize these flows. An EGR flow estimator was developed to improve the accuracy of this flow measurement over the stock engine control module (ECM) method and is detailed in this paper. Furthermore, the in-cylinder oxygen estimation algorithm is developed, and proven, to be robust to turbine flow errors. Regulation of in-cylinder oxygen levels is of interest for not only in conventional combustion modes but also in advanced combustion strategies such as premixed charge compression ignition. The proposed oxygen fraction estimator is designed such that its performance and stability is ensured in both conventional and advanced combustion modes. The model-based observer estimates the oxygen fractions to be within 0.5% O2 and is shown to have exponential estimator error convergence with a time constant less than 0.05s, even with turbine flow errors of up to 25%.


      PubDate: 2014-06-14T15:55:15Z
       
  • Online optimization of spark advance in alternative fueled engines using
           extremum seeking control
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Alireza Mohammadi , Chris Manzie , Dragan Nešić
      Alternative fueled engines offer greater challenges for engine control courtesy of uncertain fuel composition. This makes optimal tuning of input parameters like spark advance extremely difficult in most existing ECU architectures. This paper proposes the use of grey-box extremum seeking techniques to provide real-time optimization of the spark advance in alternative fueled engines. Since practical implementation of grey-box extremum seeking methods is typically done using digital technology, this paper takes advantage of emulation design methods to port the existing continuous-time grey-box extremum seeking methods to discrete-time frameworks. The ability and flexibility of the proposed discrete-time framework is demonstrated through simulations and in practical situation using a natural gas fueled engine.


      PubDate: 2014-06-14T15:55:15Z
       
  • Model based approach to closed loop control of 1-D engine simulation
           models
    • Abstract: Publication date: August 2014
      Source:Control Engineering Practice, Volume 29
      Author(s): Dariusz Cieslar , Paul Dickinson , Alex Darlington , Keith Glover , Nick Collings
      1-D engine simulation models are widely used for the analysis and verification of air-path design concepts to assess performance and therefore determine suitable hardware. The transient response is a key driver in the selection process which in most cases requires closed loop control of the model to ensure operation within prescribed physical limits and tracking of reference signals. Since the controller effects the system performance a systematic procedure which achieves close-to-optimal performance is desired, if the full potential of a given hardware configuration is to be properly assessed. For this purpose a particular implementation of Model Predictive Control (MPC) based on a corresponding Mean Value Engine Model (MVEM) is reported here. The MVEM is linearised on-line at each operating point to allow for the formulation of quadratic programming (QP) problems, which are solved as the part of the proposed MPC algorithm. The MPC output is used to control a 1-D engine model. The closed loop performance of such a system is benchmarked against the solution of a related optimal control problem (OCP). The system is also tested for operation at high altitude conditions to demonstrate the ability of the controller to respect specified physical constraints. As an example this study is focused on the transient response of a light-duty automotive Diesel engine. For the cases examined the proposed controller design gives a more systematic procedure than other ad hoc approaches that require considerable tuning effort.


      PubDate: 2014-06-14T15:55:15Z
       
  • Robust online roll dynamics identification of a vehicle using sliding mode
           concepts
    • Abstract: Publication date: Available online 24 April 2014
      Source:Control Engineering Practice
      Author(s): Robert Tafner , Markus Reichhartinger , Martin Horn
      This paper proposes a robust observer concept for joint estimation of system states and model parameters related to the roll dynamics of a vehicle. Using sliding mode concepts introduces robustness to parametric uncertainties and also allows reconstruction of the latter. These model parameters are of interest for vehicle dynamics assessment and estimation of the roll angle. A novel classification concept exploits these parameter estimates for assessing the roll dynamics. An additional benefit of the proposed method is the minimal requirement of measurement equipment as it only relies on cost-efficient angular rate and acceleration sensors. Evaluation of the framework is performed in simulations and real-world using an experimental vehicle.


      PubDate: 2014-04-29T06:47:05Z
       
 
 
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