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Journal Cover   Control Engineering Practice
  [SJR: 1.245]   [H-I: 67]   [33 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0967-0661
   Published by Elsevier Homepage  [2586 journals]
  • Design and validation of a robust immersion and invariance controller for
           the lateral dynamics of intelligent vehicles
    • Abstract: Publication date: July 2015
      Source:Control Engineering Practice, Volume 40
      Author(s): Gilles Tagne , Reine Talj , Ali Charara
      This paper focuses on the lateral control of intelligent vehicles; the aim is to minimize the lateral displacement of the autonomous vehicle with respect to a given reference path. The control input is the steering angle and the output is the lateral displacement error. We present the design and validation of a robust lateral controller based on the Immersion and Invariance ( I & I ) principle in order to ensure robust stability and good performances with respect to parametric variations and uncertainties that are encountered in driving applications. To validate our control law, tests were performed on SCANeR Studio, a driving simulation engine, according to several real driving scenarios. Simulations were also performed using experimental data acquired by the DYNA vehicle (a Peugeot 308) belonging to the Heudiasyc laboratory. The validation demonstrates the robustness and good performances of the proposed control approach and clearly shows the improvement due to the I & I controller.


      PubDate: 2015-04-16T01:17:43Z
       
  • Multivariable system stabilization via discrete variable structure control
    • Abstract: Publication date: July 2015
      Source:Control Engineering Practice, Volume 40
      Author(s): Rodrigo R. Sumar , Antonio A.R. Coelho , Alessandro Goedtel
      This paper presents the design of an incremental discrete variable structure controller, based on the minimization of the generalized minimum variance approach, to deal with multivariable plants and to handle different time delay of control loops between the input–output pairs. Additionally, a static precompensator, to decouple the control loops in multivariable systems, is developed not only to keep a good closed-loop behavior but also to decrease the control algorithm complexity. Numerical simulation examples are shown to illustrate the dynamic performance and the closed-loop stability for three multivariable systems.


      PubDate: 2015-04-16T01:17:43Z
       
  • Detection and isolation of parametric faults in hydraulic pumps using a
           set-based approach and quantitative–qualitative fault specifications
           
    • Abstract: Publication date: July 2015
      Source:Control Engineering Practice, Volume 40
      Author(s): Daniel Hast , Rolf Findeisen , Stefan Streif
      High performance hydraulic pumps are used in many applications such as airplanes, construction machines, ships and wind turbines. Due to their relatively high power density, hydraulic pumps are subject to wear and tear that can lead to loss of efficiency and ultimately to failure. Early detection and isolation of these parametric changes which are modeled by slowly varying parameters, is of paramount importance. This is, however, challenging due to nonlinearities, noise, uncertainties, as well as the combination of qualitative and quantitative process knowledge and fault specifications. We show how such quantitative and qualitative specifications can be used to derive parameter sets defining parametric fault candidate sets. These fault candidate sets are used for detection and isolation of faults by checking the inconsistency with process measurements. To account for imprecise and qualitative specifications in the design phase and uncertainties such as noisy measurements and model-plant mismatch in the process phase, and to allow for the nonlinear models and equations, we employ a set-based framework using convex relaxations. The set-based framework allows for a comprehensive description of the faults in the parameter-space by outer approximating the parameter values which are consistent with the nonlinear model and the quantitative–qualitative specifications. The set-based approach is used for parametric fault detection and isolation and is exemplified using experimental data.
      Graphical abstract image Highlights

      PubDate: 2015-04-16T01:17:43Z
       
  • Bilateral teleoperation system stability with non-passive and strictly
           passive operator or environment
    • Abstract: Publication date: July 2015
      Source:Control Engineering Practice, Volume 40
      Author(s): Ali Jazayeri , Mahdi Tavakoli
      A bilateral teleoperation system comprises a human operator, a teleoperator, and an environment. Without exact models for the teleoperator׳s terminations (i.e., human operator and the environment), it is typically assumed that they are passive but otherwise arbitrary. Based on this assumption, the stability of the teleoperation system is investigated through Llewellyn׳s absolute stability criterion for the teleoperator. However, the assumption of passivity of the terminations is less than accurate and may be violated in practice. Using Mobius transformations, this paper develops a new powerful stability analysis tool for a two-port network coupled to a passive termination and another termination that is (a) input strictly passive (ISP), (b) output strictly passive (OSP), (c) input non-passive (INP), or (b) disc-like non-passive (DNP). While this new stability criterion is applicable to any two-port network, we apply it to bilateral teleoperation systems with position-error-based (PEB) and direct-force-reflection (DFR) controllers. Simulations and experiments are reported for a pair of Phantom haptic robots.


      PubDate: 2015-04-16T01:17:43Z
       
  • OBC - Autogenerate contents and barcode
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39




      PubDate: 2015-04-01T02:24:32Z
       
  • A framework for hybrid model predictive control in mineral processing
    • Abstract: Publication date: July 2015
      Source:Control Engineering Practice, Volume 40
      Author(s): Pablo Karelovic , Eduardo Putz , Aldo Cipriano
      Model Predictive Control (MPC) is an advanced technique for process control that has seen a significant and widespread increase in its use in the process industry since its introduction. In mineral processing, in particular, several applications of conventional MPC can be found for the individual processes of crushing, grinding, flotation, thickening, agglomeration, and smelting with varying degrees of success depending on the variables involved and the control objectives. Given the complexity of the processes normally found in mineral processing, there is also great interest in the design and development of advanced control techniques which aim to deal with situations that conventional controllers are unable to do. In this aspect, Hybrid MPC enables the representation of systems, incorporating logical variables, rules, and continuous dynamics. This paper firstly presents a framework for modeling and representation of hybrid systems, and the design and development of hybrid predictive controllers. Additionally, two application examples in mineral processing are presented. Results through simulation show that the control schemes developed under this framework exhibit a better performance when compared with conventional expert or MPC controllers, while providing a highly systematized methodology for the analysis, design, and development of hybrid MPC controllers.


      PubDate: 2015-04-01T02:24:32Z
       
  • Flight control of tethered kites in autonomous pumping cycles for airborne
           wind energy
    • Abstract: Publication date: July 2015
      Source:Control Engineering Practice, Volume 40
      Author(s): Michael Erhard , Hans Strauch
      Energy harvesting based on tethered kites benefits from exploiting higher wind speeds at higher altitudes. The setup considered in this paper is based on a pumping cycle. It generates energy by winching out at high tether forces, driving an electrical generator while flying crosswind. Then it winches in at a stationary neutral position, thus leaving a net amount of generated energy. The focus of this paper is put on the flight control design, which implements an accurate direction control towards target points and allows for a flight with an eight-down pattern. An extended overview on the control system approach, as well as details of each element of the flight controller, is presented. The control architecture is motivated by a simple, yet comprehensive model for the kite dynamics. In addition, winch strategies based on an optimization scheme are presented. In order to demonstrate the real world functionality of the presented algorithms, flight data from a fully automated pumping-cycle operation of a small-scale prototype are given. The setup is based on a 30m2 kite linked to a ground-based 50kW electrical motor/generator by a single line.
      Graphical abstract image Highlights

      PubDate: 2015-04-01T02:24:32Z
       
  • Second-order consensus predictive control for 360MN extrusion machine
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39
      Author(s): Xiwei Zhao , Qianchuan Zhao , Wanzhou Li , Hongbing Yang
      A new consensus predictive control protocol is proposed in this paper. It significantly speeds up the convergence rate comparing to traditional consensus mechanism and has been proved working well in simulation platform. A mathematical model is built by simplifying the hydraulic cylinders to single-DOF agents distributed evenly around 360MN extrusion machine׳s main table. With this model, a theoretical analysis of the mechanism is given and the validity of the consensus predictive control protocol for strong coupling multi-agent system on ADAMS–EASY5 simulation platform is illustrated. The machine׳s main table balance problem is well solved and the convergence rate is increased. These results are meaningful for increasing productivity.


      PubDate: 2015-04-01T02:24:32Z
       
  • IFC - Editorial Board / Funding body / agreements policies
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39




      PubDate: 2015-04-01T02:24:32Z
       
  • Semi-physical mean-value NOx model for diesel engine control
    • Abstract: Publication date: July 2015
      Source:Control Engineering Practice, Volume 40
      Author(s): C. Quérel , O. Grondin , C. Letellier
      A semi-physical model has been developed to predict nitrogen oxide (NO x ) emissions produced by diesel engines. This model is suitable for online NO x estimation and for model-based engine control. It is derived from a zero-dimensional thermodynamic model which was simplified by only retaining main phenomena contributing to NO x formation. The crank angle evolution of the burned gas temperature, which has a strong impact on NO x formation rate, is described by a semi-empirical model whose key variable is the maximum burned gas temperature. This variable presents a good correlation with the molar fraction of NO x at the end of combustion and can be expressed as a function of the intake burned gas ratio and the start of combustion. The maximum burned gas temperature sub-model is then coupled to an averaged NO x formation kinetic model (based on the Zeldovich mechanism) to form a mean-value model for NO x computation. This latter model was validated using data sets recorded in two diesel engines for steady-state operating conditions as well as for several driving cycles including parametric variations of the engine calibration.


      PubDate: 2015-04-01T02:24:32Z
       
  • Gain-scheduling control of vapor compression cycle for transient heat-flux
           removal
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39
      Author(s): Zehao Yang , Daniel T. Pollock , John T. Wen
      Two-phase cooling is attractive for high heat-flux applications arising in high-power electronics such as LEDs, all-electric vehicles, and radar systems. A key challenge is critical heat-flux that could cause device damage due to dryout. This paper discusses a systematic design of robust and gain-scheduled controls for dryout avoidance in vapor compression cycles. Linear models from various operating points (OP) are clustered to reduce model nonlinearity. H ∞ controllers are synthesized to reach local robust stability. The gain-scheduled controller combining local controllers and OP switching shows excellent disturbance rejection performance in experimental comparison with the open-loop operation.


      PubDate: 2015-03-16T19:20:48Z
       
  • Output feedback motion control system for observation class ROVs based on
           a high-gain state observer: Theoretical and experimental results
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39
      Author(s): Daniel de A. Fernandes , Asgeir J. Sørensen , Kristin Y. Pettersen , Décio C. Donha
      This paper proposes a motion control system for observation class ROVs. It is essentially an output feedback control system composed of a MIMO PID controller, which is aided by reference feedforward, and a high-gain observer. Feedback linearisation of the plant dynamics is also performed. Four degrees-of-freedom are controlled (surge, sway, heave, and yaw). Stability and satisfactory performance are attained under suitable and smooth reference trajectories, despite the presence of unmodelled plant dynamics, plant parameter variations, measurement errors and noise, and environmental disturbances. Results from full-scale sea trials based on NTNU׳s ROV Minerva are presented and discussed.


      PubDate: 2015-03-16T19:20:48Z
       
  • IFC - Editorial Board / Funding body / agreements policies
    • Abstract: Publication date: May 2015
      Source:Control Engineering Practice, Volume 38




      PubDate: 2015-03-13T08:46:39Z
       
  • OBC - Autogenerate contents and barcode
    • Abstract: Publication date: May 2015
      Source:Control Engineering Practice, Volume 38




      PubDate: 2015-03-13T08:46:39Z
       
  • A toolkit for nonlinear model predictive control using gradient projection
           and code generation
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39
      Author(s): Jouko Kalmari , Juha Backman , Arto Visala
      Nonlinear model predictive control (NMPC) is a control strategy based on finding an optimal control trajectory that minimizes a given objective function. The optimization is recalculated at each control cycle and only the first control values are actually used. The dynamics of the system can be nonlinear and there can be constraints on states and controls. A new toolkit called VIATOC has been developed that can be used to automatically generate the code needed to implement NMPC. The generated code is self-contained ANSI C and the compiled program has a small footprint. In VIATOC, the gradient projection method is used to solve the nonlinear optimization problem. Barzilai–Borwein type step length selection for the gradient method has also been implemented. The performance of the controllers generated with the toolkit is compared with those solved with the ACADO toolkit and HQP. The performance of the optimization is compared with two different test cases with different numbers of controls and states. The first one is based on a model of a pendulum hanging freely on a movable platform. The second one is a more complex model of a chain of three masses connected by springs. Seven different prediction horizons between 10 and 100 steps are used. When the time to achieve a near optimum solution is measured, VIATOC is in most cases the fastest one when the length of the prediction horizon is shorter than 70 steps.


      PubDate: 2015-03-13T08:46:39Z
       
  • Enlarging parallel robot workspace through Type-2 singularity crossing
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39
      Author(s): Georges Pagis , Nicolas Bouton , Sebastien Briot , Philippe Martinet
      In order to increase the reachable workspace of parallel robots, a promising solution consists of the definition of optimal trajectories that ensure the non-degeneracy of the dynamic model in the Type 2 (or parallel) singularity. However, this assumes that the control law can perfectly track the desired trajectory, which is impossible due to modeling errors. This paper proposes a robust multi-model approach allowing parallel robots to cross Type 2 singularities. The main idea is to shift near singularities to a simplified dynamic model that can never degenerate. The two main contributions are the definition of an optimal trajectory crossing Type 2 singularities and the multi-model control law allowing to track this trajectory. The proposed control law is validated experimentally through a Five-bar planar mechanism.


      PubDate: 2015-03-09T08:40:24Z
       
  • Robust microscale grasping through a multimodel design: synthesis and real
           time implementation
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39
      Author(s): Mokrane Boudaoud , Marcelo Gaudenzi De Faria , Yassine Haddab , Sinan Haliyo , Yann Le Gorrec , Philippe Lutz , Stéphane Régnier
      This paper deals with robust force control at the microscale for safe manipulation of deformable soft materials. Since mechanical properties of micrometer sized objects are highly uncertain, instability often occurs during a gripping task. This leads to object damage or destruction due to excessive gripping force. In this paper we propose the design of a robust dynamic output feedback controller that is able to insure desired performances for a set of 65 soft and resilient microspheres whose diameter ranges from 40μm to 80μm and stiffness varies from 2.8N/m to 15.7N/m. The degrees of freedom of the controller are managed by the use of a set of elementary observers. Robustness with respect to parametric uncertainties is satisfied thanks to an iterative procedure alternating between multimodel closed loop eigenstructure assignment and worst case analysis. The developed controller is of low order and can be implemented in real time. Robust gripping force control is for the first time demonstrated experimentally when dealing with the manipulation of a large number of variable deformable soft materials at the microscale. Both simulations and experimental results validate the interest of such control design approach.


      PubDate: 2015-03-09T08:40:24Z
       
  • Stable Queue Management in communication networks
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37
      Author(s): Sajjad Pourmohammad , Afef Fekih , Dmitri Perkins
      Since Active Queue Management (AQM) was recommended by the Internet Engineering Task Force (IETF) as an efficient way to overcome performance limitations of Transmission Control Protocol (TCP), several studies have proven control theory to be a promising field for the design and analysis of congestion control in homogenous communication networks. AQM is gaining increased importance due to reports of buffer-induced latencies throughout the Internet. The increasing volume and diversity of traffic types (i.e., data, voice, and video) suggests that traffic management mechanisms, in general, and AQM schemes, specifically, must not only focus on the critical issue of congestion control but must also consider the QoS demands of heterogeneous traffic. However, to combine quality-of-service provisioning with congestion control, AQM design needs to be reconsidered. In this paper, we propose a state feedback controller design scheme for heterogeneous networks preserving the closed-loop system stability. Delay dependant stability conditions of the closed loop system are derived based on the Lyapunov-Krasovskii method. The proposed approach offers flexible choice of control parameters allowing the network administrator to control fairness and response time for each individual source node in a network of multiple links with different delay properties. The performance and robustness of the proposed controller were illustrated and analyzed using event-based computer simulations.


      PubDate: 2015-03-09T08:40:24Z
       
  • Active vibration isolation using negative stiffness and displacement
           cancellation controls: Comparison based on vibration isolation performance
           
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37
      Author(s): Mhia Md. Zaglul Shahadat , Takeshi Mizuno , Yuji Ishino , Masaya Takasaki
      Two vibration control techniques, negative stiffness and displacement cancellation, are characterized and employed to achieve active vibration isolation. A horizontal vibration isolation system is developed and then used to investigate each of these techniques theoretically and experimentally. The respective responses of the developed system are measured separately while closed-loop poles of the system are kept unchanged; these measured responses are compared. The developed system is based on a series combination of two isolators and consists of two moving tables; one of the moving tables is mounted on the series-connected isolators and the other is placed between the isolators. Using the negative stiffness technique, the isolators are controlled so that one of them has a negative stiffness and the other has a positive stiffness of equal absolute magnitude; using the displacement cancellation technique, one isolator is set to cancel displacement while the other behaves as a positive-stiffness isolator. The active negative, positive, and displacement cancellation isolators are created using voice-coil motors guided by a negative stiffness controller, proportional derivative controller and integral-proportional derivative controller, respectively.


      PubDate: 2015-03-09T08:40:24Z
       
  • Input–output feedback linearizing control of linear induction motor
           taking into consideration the end-effects. Part I: Theoretical analysis
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Francesco Alonge , Maurizio Cirrincione , Marcello Pucci , Antonino Sferlazza
      This first part of a paper, divided into two parts, deals with the theoretical formulation of the input–output feedback linearization (FL) control technique as to be applied to linear induction motors (LIMs). Linear induction motors, differently from rotating induction motors (RIMs), present other strong non-linearities caused by the so-called dynamic end effects, leading to a space-vector model with time-varying inductance and resistance terms and an additional braking force term. This paper, starting from a dynamic model of the LIM taking into consideration its dynamic end effects, previously developed by the same authors, defines a feedback linearization (FL) technique suited for LIMs, since it inherently considers its end effects. It further emphasizes the role of the LIM dynamic end effects in the LIM control formulation, highlighting the differences with respect to the corresponding technique for RIMs. It describes the control design criteria, taking also into consideration the constraints on the control and controlled variables, arising from the application of such control technique in a real scenario. The second part of this paper describes the set of tests, both in numerical simulations and experiments, performed to assess the correctness of the proposed control technique.


      PubDate: 2015-03-09T08:40:24Z
       
  • Observer-based backstepping control of a 6-dof parallel hydraulic
           manipulator
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Sung-Hua Chen , Li-Chen Fu
      In this paper, a backstepping control strategy is proposed to control the 6-dof parallel hydraulic manipulator (Stewart platform) while incorporating an observer-based forward kinematics solver. Different from conventional control methods, the proposed control considers not only the platform dynamics but also the dynamics of the hydraulic actuator. One feature of this work is employing the observer-based forward kinematics solution to achieve the posture tracking goal successfully only with the measurement of actuators lengths. When designing the controller of hydraulic actuators, the friction compensation is applied to improve the performance. The stability of the whole system is thoroughly proved to ensure convergence of the control errors. Simulations and experimental results are presented to validate the hereby proposed results.


      PubDate: 2015-03-09T08:40:24Z
       
  • Stable recursive canonical variate state space modeling for time-varying
           processes
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Liangliang Shang , Jianchang Liu , Kamuran Turksoy , Quan Min Shao , Ali Cinar
      An adaptive recursive process modeling approach is developed to improve the accuracy of modeling time-varying processes. We adopt the exponential weighted moving average approach to update the covariance and cross-covariance of past and future observation vectors. Forgetting factors are adjusted in the recursive modeling process based on the residual of model outputs. To ensure the stability of the identified model, we introduce a constrained nonlinear optimization approach and propose a stable recursive canonical variate state space modeling (SRCVSS) method. The performance of the proposed method is illustrated with an open-loop numerical example and simulation with the closed-loop data from a continuous stirred tank heater (CSTH) system. The results indicate that the accuracy of proposed SRCVSS modeling method is higher than that of state space modeling with traditional canonical variate analysis.


      PubDate: 2015-03-09T08:40:24Z
       
  • Nonlinear model predictive energy management controller with load and
           cycle prediction for non-road HEV
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Johannes Unger , Martin Kozek , Stefan Jakubek
      The energy management system (EMS) in hybrid electric vehicles is used to control the battery׳s state of charge, while the efficiency of the powertrain is subject to maximization. Due to the nonlinearities of hybrid powertrains, achieving an optimal control performance amounts to a nonlinear optimization problem to be solved in the EMS in real time. Finding an optimal solution is challenging, since controller complexity and real time capability are in general conflicting objectives. In this paper, a real time capable model predictive control concept is proposed that considers nonlinearities of the electrical system and complies with the constraints of the system. Additionally, novel data based methodologies to predict the future load demand are introduced. A short term load prediction based on Bayesian inference and a cycle detection based on correlation analysis are proposed to improve the controller performance as well as to take advantage of the full capabilities of the electrical system. A stability analysis and the implementation of the EMS on a real testbed show the feasibility of the concept. Fuel consumption and raw exhaust emissions are significantly reduced by the proposed concept, while phlegmatisation and downspeeding strategies are considered without limiting the performance of the powertrain.


      PubDate: 2015-03-09T08:40:24Z
       
  • Robust distributed attitude synchronization of multiple three-DOF
           experimental helicopters
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Bo Zhu , Hugh Hong-Tao Liu , Zhan Li
      Multiple experimental three-degrees-of-freedom (three-DOF) helicopters that are equipped with active disturbance systems constitute an attractive platform to validate robust control strategies. In this paper, a distributed synchronization controller is developed for such a platform, where each helicopter is subjected to unknown model uncertainties and external disturbances, and the desired trajectories are generated online, communicated through a network and not accessible by all helicopters. The controller is composed of a continuous tracker and a continuous uncertainty and disturbance estimator (UDE). The tracker makes the nominal closed-loop system globally asymptotically stable, and the UDE output is used to reject total uncertainties. The conditions that ensure zero-error tracking for each helicopter are identified; for the case with nonzero error, explicit relationship inequalities between the involved design parameters and the ultimate bound of error are revealed. Experimental results of four cases demonstrate improved tracking and synchronization accuracy of using the UDE with small parameters.


      PubDate: 2015-03-09T08:40:24Z
       
  • Supervisory controller for reduction of wind turbine loads in curtailed
           operation
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Vedrana Spudić , Mate Jelavić , Mato Baotić
      There are situations in which wind turbines must curtail their power, i.e. produce less power than is available from the wind. In such cases the wind turbine power can be increased or decreased if required. This gives an opportunity to strike a balance between varying power production and reducing wind turbine structural loading. To that end, a supervisory controller is designed that issues power references to the wind turbine and can be easily installed on already operational wind turbines. The wind turbine with a supervisory controller produces the required mean power, while reducing wind turbine loads by adding power variations. The extensive, realistic simulations are done to evaluate the influence of the proposed controller on the fatigue loads, extreme loads and the overall wind turbine operation. The results indicate that a significant reduction of fatigue loads can be achieved, which can increase the operating life of the structure. Furthermore, the proposed supervisory controller can be utilized as the main building block of a wind farm controller, which meets the grid code requirements and can be easily installed on very large wind farms due to minimal requirements on the farm-wide communication.


      PubDate: 2015-03-09T08:40:24Z
       
  • Control strategy of a dual induction motor: Anti-slip control application
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Tahar Achour , Mustapha Debbou , Maria Pietrzak-David
      The paper deals with a Dual Induction Motor control. A control strategy based on the Average Differential Control (ADC) is developed and adapted to work as an anti-slip control in a railway traction system. In addition to cancel the behaviour deviation between the motors supplied by a single inverter in case of an adhesion loss (or an unbalanced load), the proposed control strategy permits an action on the torque control to cancel the differential torque between the two motors. The control strategy is validated on a laboratory test bench with a Mechanical Railway Traction Load Emulator.


      PubDate: 2015-03-09T08:40:24Z
       
  • Double-model adaptive fault detection and diagnosis applied to real flight
           data
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Peng Lu , Laurens Van Eykeren , Erik-Jan van Kampen , Coen de Visser , Qiping Chu
      The existing multiple model-based estimation algorithms for Fault Detection and Diagnosis (FDD) require the design of a model set, which contains a number of models matching different fault scenarios. To cope with partial faults or simultaneous faults, the model set can be even larger. A large model set makes the computational load intensive and can lead to performance deterioration of the algorithms. In this paper, a novel Double-Model Adaptive Estimation (DMAE) approach for output FDD is proposed, which reduces the number of models to only two, even for the FDD of partial and simultaneous output faults. Two Selective-Reinitialization (SR) algorithms are proposed which can both guarantee the FDD performance of the DMAE. The performance is tested using a simulated aircraft model with the objective of Air Data Sensors (ADS) FDD. Another contribution is that the ADS FDD using real flight data is addressed. Issues related to the FDD using real flight test data are identified. The proposed approaches are validated using real flight data of the Cessna Citation II aircraft, which verified their effectiveness in practice.


      PubDate: 2015-03-09T08:40:24Z
       
  • Mooring system diagnosis and structural reliability control for position
           moored vessels
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Shaoji Fang , Mogens Blanke , Bernt J. Leira
      Early diagnosis and fault-tolerant control are essential for safe operation of floating platforms where mooring systems maintain vessel position and must withstand environmental loads. This paper considers two critical faults, line breakage and loss of a buoyancy element and employs vector statistical change detection for timely diagnosis of faults. Diagnosis design is scrutinised and a procedure is proposed based on specified false alarm probability and estimation of the distribution of the test statistics on which change detection is based. A structural reliability index is applied for monitoring the safety level of each mooring line and a set-point chasing algorithm accommodates the effects of line failure, as an integral part of the reliability-based set-point chasing control algorithm. The feasibility of the diagnosis and of the fault-tolerant control strategy is verified in model basin tests.


      PubDate: 2015-03-09T08:40:24Z
       
  • Experimental investigation of stochastic parafoil guidance using a
           graphics processing unit
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Nathan Slegers , Andrew Brown , Jonathan Rogers
      Control of autonomous systems subject to stochastic uncertainty is a challenging task. In guided airdrop applications, random wind disturbances play a crucial role in determining landing accuracy and terrain avoidance. This paper describes a stochastic parafoil guidance system which couples uncertainty propagation with optimal control to protect against wind and parameter uncertainty in the presence of impact area obstacles. The algorithm uses real-time Monte Carlo simulation performed on a graphics processing unit (GPU) to evaluate robustness of candidate trajectories in terms of delivery accuracy, obstacle avoidance, and other considerations. Building upon prior theoretical developments, this paper explores performance of the stochastic guidance law compared to standard deterministic guidance schemes, particularly with respect to obstacle avoidance. Flight test results are presented comparing the proposed stochastic guidance algorithm with a standard deterministic one. Through a comprehensive set of simulation results, key implementation aspects of the stochastic algorithm are explored including tradeoffs between the number of candidate trajectories considered, algorithm runtime, and overall guidance performance. Overall, simulation and flight test results demonstrate that the stochastic guidance scheme provides a more robust approach to obstacle avoidance while largely maintaining delivery accuracy.


      PubDate: 2015-03-09T08:40:24Z
       
  • OBC - Autogenerate contents and barcode
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37




      PubDate: 2015-03-09T08:40:24Z
       
  • IFC - Editorial Board / Funding body / agreements policies
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36




      PubDate: 2015-03-09T08:40:24Z
       
  • LFT modelling and identification of anaerobic digestion
    • Abstract: Publication date: March 2015
      Source:Control Engineering Practice, Volume 36
      Author(s): Alessandro Della Bona , Gianni Ferretti , Elena Ficara , Francesca Malpei
      In this paper, a reduced order model of anaerobic digestion is first proposed, with the main goal to develop an efficient tool for process monitoring and control. Then, in order to perform parameter estimation, the model has been rewritten in a linear fractional transformation (LFT) formulation, using a symbolic tool originally developed for linear models and modified for the processing of nonlinear models. Two different test cases have been considered. In a first case, the data used for parameter identification have been generated by simulating the well known and more complex ADM1 model, considering waste activated sludge as substrate. In a second case, experimental data were collected on a laboratory scale equipment, operated in a semi-batch experiment, performing the anaerobic digestion of ultra-filtered cheese-whey.


      PubDate: 2015-03-09T08:40:24Z
       
  • Cascade force control for autonomous beating heart motion compensation
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37
      Author(s): Michel Dominici , Rui Cortesão
      Robotic-assisted heart surgeries do not allow autonomous compensation of cardiac motion. This paper tackles this problem, based on a robotic control architecture that relies on force feedback, without requiring vision data. The algorithm merges two cascade loops. The inner one is based on the Kalman active observer (AOB) for model-reference adaptive control and the outer one based on a model predictive control (MPC) approach generates control references for beating heart motion compensation. A 4-DoF surgical robot generates desired surgical forces and a 3-DoF robot equipped with an ex vivo heart at the end-effector reproduces realistic heart motion.
      Graphical abstract image Highlights

      PubDate: 2015-03-09T08:40:24Z
       
  • Delay-dependent wide-area damping control for stability enhancement of
           HVDC/AC interconnected power systems
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37
      Author(s): Yong Li , Fang Liu , Yijia Cao
      In this paper, a delay-dependent wide-area damping control strategy associated with a high-voltage direct current (HVDC) supplementary controller is presented to enhance the overall stability of parallel HVDC/AC interconnected systems. First, the HVDC/AC interconnected systems are linearized into a nominal delay-dependent linear model using varying-delay characteristics. Next, the robust H ∞ design approach is used to solve the optimal state-feedback-type controller parameters. All of the controller design problems are formulated in the framework of linear matrix inequalities (LMIs), which is convenient for converting the controller design problem into a standard nonlinear optimization problem represented as an optimization objective with a set of LMIs constraints. An iterative algorithm is presented to solve the optimization problem. The effects of the varying-delay of the wide-area signal on the damping performance are considered during the controller design. Additionally, the state observer is used to convert the state-feedback control into an output-feedback control that is convenient for practical applications. Two case studies are conducted on the Kundur׳s 4-machine 2-area system and the New England/New York interconnected system to validate the presented control concept and the designed HVDC wide-area damping controller.


      PubDate: 2015-03-09T08:40:24Z
       
  • Controller design and experimental validation of a very low frequency
           high-voltage test system
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37
      Author(s): W. Kemmetmüller , S. Eberharter , A. Kugi
      This paper presents the design of a quasi optimal controller for a new type of very low frequency (VLF) high-voltage test system for on-site cable tests. The test system is based on the differential resonance technology (DRT), which allows a light weight and compact construction. The high requirements regarding quality and accuracy of VLF test voltages can only be achieved with a suitable control concept. In this work, a two degrees-of-freedom control strategy comprising a feedforward and a feedback control in combination with an estimator for the unknown cable capacitance is proposed. The controller design is based on an envelope model which describes the (nonlinear) envelope dynamics of the occurring amplitude modulated signals. The feasibility of the proposed control strategy is verified by a number of measurements on a prototype system for cable tests up to 200kVrms. The measurement results show that the generated test voltage has a total harmonic distortion (THD) of less than 0.1%, which is significantly better than the requirements of sinusoidal VLF test voltages. Moreover, the control strategy has the ability to cover a wide range of cable capacitances, desired amplitudes of the output voltage and desired test frequencies.


      PubDate: 2015-03-09T08:40:24Z
       
  • Computation of transfer function data from frequency response data with
           application to data-based root-locus
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37
      Author(s): R. Hoogendijk , M.J.G. van de Molengraft , A.J. den Hamer , G.Z. Angelis , M. Steinbuch
      This paper describes the computation and use of transfer function data (TFD) computed from frequency response data of a system. TFD can be regarded as a sampled, data-based representation of the transfer function. TFD can be computed from frequency response data for stable, lightly damped systems using a Cauchy integral. Computational accuracy and complexity are extensively discussed. As a use-case of TFD it is shown that a root-locus can be computed in a data-based way, using only frequency response data of a system. Experiments on a benchmark motion system demonstrate the use of TFD in minimizing the settling time.


      PubDate: 2015-03-09T08:40:24Z
       
  • Iterative motion feedforward tuning: A data-driven approach based on
           instrumental variable identification
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37
      Author(s): Frank Boeren , Tom Oomen , Maarten Steinbuch
      Feedforward control can significantly enhance the performance of motion systems through compensation of known disturbances. This paper aims to develop a new procedure to tune a feedforward controller based on measured data obtained in finite time tasks. Hereto, a suitable feedforward parametrization is introduced that provides good extrapolation properties for a class of reference signals. Next, connections with closed-loop system identification are established. In particular, instrumental variables, which have been proven very useful in closed-loop system identification, are selected to tune the feedforward controller. These instrumental variables closely resemble traditional engineering tuning practice. In contrast to pre-existing approaches, the feedforward controller can be updated after each task, irrespective of noise acting on the system. Experimental results confirm the practical relevance of the proposed method.


      PubDate: 2015-03-09T08:40:24Z
       
  • Call for papers for Special Issue on Industrial Practice of Fault
           Diagnosis and Fault Tolerant Control
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37




      PubDate: 2015-03-09T08:40:24Z
       
  • Optimal maintenance planning for sustainable energy efficiency lighting
           retrofit projects by a control system approach
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37
      Author(s): Xianming Ye , Xiaohua Xia , Lijun Zhang , Bing Zhu
      The energy savings achieved by implementing energy efficiency (EE) lighting retrofit projects are sometimes not sustainable and vanish rapidly given that lamp population decays as time goes by if without proper maintenance activities. Scope of maintenance activities refers to replacements of failed lamps due to nonrepairable lamp burnouts. Full replacements of all the failed lamps during each maintenance interval contribute to a tight project budget due to the expense for the lamp failure inspections, as well as the procurement and installation of new lamps. Since neither “no maintenance” nor “full maintenance” is preferable to the EE lighting project developers (PDs), we propose to design an optimal maintenance plan that optimises the number of replacements of the failed lamps, such that the EE lighting project achieves sustainable performance in terms of energy savings whereas the PDs obtain their maximum benefits in the sense of cost–benefit ratio. This optimal maintenance planning (OMP) problem is aptly formulated as an optimal control problem under control system framework, and solved by a model predictive control (MPC) approach. An optimal maintenance plan for an EE lighting retrofit project is designed as a case study to illustrate the effectiveness of the proposed control system approach.


      PubDate: 2015-03-09T08:40:24Z
       
  • IFC - Editorial Board / Funding body / agreements policies
    • Abstract: Publication date: April 2015
      Source:Control Engineering Practice, Volume 37




      PubDate: 2015-03-09T08:40:24Z
       
  • Adaptive sliding mode observer for sensor fault diagnosis of an industrial
           gas turbine
    • Abstract: Publication date: May 2015
      Source:Control Engineering Practice, Volume 38
      Author(s): Sandy Rahme , Nader Meskin
      Sensors are one of the crucial components in gas turbines and the failure in sensor measurements can lead to serious problems in maintaining their safety and performance requirements. Our aim in this paper is to develop an adaptive sliding mode observer for sensor fault diagnosis in an industrial gas turbine. The proposed observer has a robustness against gas turbine parameter uncertainties caused by degradations without any priori knowledge about the bounds of faults and parameter uncertainties. The efficiency of the proposed fault diagnosis approach is validated with Matlab/Simulink simulations and the realistic gas turbine data extracted from the PROOSIS software.


      PubDate: 2015-03-09T08:40:24Z
       
  • Qualitative event-based diagnosis applied to a spacecraft electrical power
           distribution system
    • Abstract: Publication date: May 2015
      Source:Control Engineering Practice, Volume 38
      Author(s): Matthew J. Daigle , Indranil Roychoudhury , Anibal Bregon
      Quick, robust fault diagnosis is critical to ensuring safe operation of complex engineering systems. A fault detection, isolation, and identification framework is developed for three separate diagnosis algorithms: the first using global model; the second using minimal submodels, which allows the approach to scale easily; and the third using both the global model and minimal submodels, combining the strengths of the first two. The diagnosis framework is applied to the Advanced Diagnostics and Prognostics Testbed that functionally represents spacecraft electrical power distribution systems. The practical implementation of these algorithms is described, and their diagnosis performance using real data is compared.


      PubDate: 2015-03-09T08:40:24Z
       
  • Digital versus analog control of bilateral teleoperation systems: A task
           performance comparison
    • Abstract: Publication date: May 2015
      Source:Control Engineering Practice, Volume 38
      Author(s): Ting Yang , Yili Fu , Mahdi Tavakoli
      Controller discretization has the potential to jeopardize the stability of a bilateral teleoperation system. As reported in the literature, stability conditions impose bounds on the gains of the discrete-time controller and the sampling period and also a trade-off between the two. This paper shows a choice of task for which large sampling periods, necessitating low control gains for maintaining stability, lead to low teleoperation transparency and unacceptable task performance. It continues to show that users can successfully perform the same task if the controller is implemented using analog components. This highlights the advantages of analog haptics in tasks involving the display of highly stiff environments. The paper also highlights the constraints in designing analog haptic teleoperation controllers and proposes design guidelines to address them.


      PubDate: 2015-03-09T08:40:24Z
       
  • Optimal motion control for energy-aware electric vehicles
    • Abstract: Publication date: May 2015
      Source:Control Engineering Practice, Volume 38
      Author(s): Tao Wang , Christos G. Cassandras , Sepideh Pourazarm
      We study two problems of optimally controlling how to accelerate and decelerate a non-ideal energy-aware electric vehicle so as to (a) maximize its cruising range and (b) minimize the traveling time to a specified destination under a limited battery constraint. Modeling an electric vehicle as a dynamic system, we adopt an electric vehicle power consumption model (EVPCM) and formulate two respective optimal motion control problems. Although the full solutions can only be obtained numerically, we propose approximate controller structures such that the original optimal control problems are transformed into nonlinear parametric optimization problems, which are much easier to solve. Numerical examples illustrate the solution structures and support their accuracy.


      PubDate: 2015-03-09T08:40:24Z
       
  • Super-twisting sliding-mode traction control of vehicles with tractive
           force observer
    • Abstract: Publication date: May 2015
      Source:Control Engineering Practice, Volume 38
      Author(s): Suwat Kuntanapreeda
      This paper utilizes the super-twisting algorithm (STA) to obtain a traction controller for road vehicles. The control objective is to operate the vehicles such that a desired wheel slip ratio is achieved. The controller comprises a STA-based sliding-mode control law and a nonlinearity observer. Simulation and experimental studies illustrate the success of the controller. The controller successfully drove the vehicle to operate at the desired wheel slip ratio and efficiently handled the sudden changes of tire–road frictions. The results are compared to those obtained with a conventional sliding-mode controller. It is shown that the STA-based controller yields better control performance.


      PubDate: 2015-03-09T08:40:24Z
       
  • Experimental evaluation of decentralized cooperative cruise control for
           heavy-duty vehicle platooning
    • Abstract: Publication date: May 2015
      Source:Control Engineering Practice, Volume 38
      Author(s): Assad Alam , Jonas Mårtensson , Karl H. Johansson
      In this paper, we consider the problem of finding decentralized controllers for heavy-duty vehicle (HDV) platooning by establishing empiric results for a qualitative verification of a control design methodology. We present a linear quadratic control framework for the design of a high-level cooperative platooning controller suitable for modern HDVs. A nonlinear low-level dynamical model is utilized, where realistic response delays in certain modes of operation are considered. The controller performance is evaluated through numerical and experimental studies. It is concluded that the proposed controller behaves well in the sense that experiments show that it allows for short time headways to achieve fuel efficiency, without compromising safety. Simulation results indicate that the model mimics real life behavior. Experiment results show that the dynamic behavior of the platooning vehicles depends strongly on the gear switching logic, which is confirmed by the simulation model. Both simulation and experiment results show that the third vehicle never displays a bigger undershoot than its preceding vehicle. The spacing errors stay bounded within 6.8m in the simulation results and 7.2m in the experiment results for varying transient responses. Furthermore, a minimum spacing of −0.6m and −1.9m during braking is observed in simulations and experiments, respectively. The results indicate that HDV platooning can be conducted at close spacings with standardized sensors and control units that are already present on commercial HDVs today.


      PubDate: 2015-03-09T08:40:24Z
       
  • Design of remotely located and multi-loop vibration controllers using a
           sequential loop closing approach
    • Abstract: Publication date: May 2015
      Source:Control Engineering Practice, Volume 38
      Author(s): U. Ubaid , S. Daley , S.A. Pope
      In some applications, vibration control objectives may require reduction of levels at locations where control system components cannot be sited due to space or environmental considerations. Control actuators and error sensors for such a scenario will need to be placed at appropriate locations which are potentially remote from the points where ultimate attenuation is desired. The performance of the closed loop system, therefore, cannot be assessed simply by the measurement obtained at this local error sensor. The control design objective has to take into account the vibration levels at the remote locations as well. A design methodology was recently proposed that tackles such problems using a single-loop feedback control architecture. The work in this paper describes an extension of this control design procedure to enable the systematic design of multiple decentralised control loops. The approach is based upon sequential loop closing and conditions are provided that ensure that closed loop stability is maintained even in the event of failure in some control loops. The design procedure is illustrated through its application to a laboratory scale slab floor that replicates the problems associated with human induced vibration in large open-plan office buildings. The experimental results demonstrate the efficacy of the approach and significant suppression of the dominant low frequency modes in the floor is achieved using two independent acceleration feedback control loops.


      PubDate: 2015-03-09T08:40:24Z
       
  • Event-driven receding horizon control for energy-efficient container
           handling
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39
      Author(s): Jianbin Xin , Rudy R. Negenborn , Gabriel Lodewijks
      The performance of container terminals needs to be improved to adapt the growth of containers while maintaining sustainability. This paper provides a methodology for determining the trajectory of interacting machines that transport containers between the quayside area and the stacking area in an automated container terminal. The behaviors of the interacting machines are modeled as a combination of discrete-event dynamics and continuous-time dynamics. An event-driven receding horizon controller (RHC) is proposed for achieving energy efficient container handling. The underlying control problems are hereby formulated as a collection of small optimization problems that are solved in a receding horizon way. Simulation studies illustrate that energy consumption of container handling can indeed be reduced by the proposed methodology. Moreover, an assessment is made of performance of the proposed RHC controller under different types of uncertainties.


      PubDate: 2015-03-09T08:40:24Z
       
  • Fault detection and isolation of bearings in a drive reducer of a hot
           steel rolling mill
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39
      Author(s): Marcello Farina , Emanuele Osto , Andrea Perizzato , Luigi Piroddi , Riccardo Scattolini
      Defective bearings are a major concern in rotating machinery. In this work we propose a two-step scheme, relying on two complementary data-driven techniques, for fault detection and isolation for a drive reducer in a hot steel rolling mill. A preliminary fault detection phase is based on a computationally lightweight time-domain multivariate statistical technique. Secondly, a more computationally intensive frequency-domain analysis method is used to confirm the fault detection and provide information on its frequency characteristics. Automatic procedures are sketched for the application of both techniques. Bearing defect models are employed to test their fault detection and isolation capabilities.


      PubDate: 2015-03-09T08:40:24Z
       
  • Detection of stiction in flow control loops based on fuzzy clustering
    • Abstract: Publication date: June 2015
      Source:Control Engineering Practice, Volume 39
      Author(s): M.A. Daneshwar , Norlaili Mohd Noh
      In the presence of stiction, the control valves may present an oscillatory behaviour that affects the regulatory control performance, thereby causing a loss of product quality and increasing energy consumption. Detection of stiction in the early phase is a crucial key for process control to avoid major disruptions to the plant operations. In this paper, a novel technique based on a well-developed fuzzy clustering approach is proposed. Based on a dramatic change of the slope of the lines obtained from successive cluster centres in the presence of stiction, a new performance index to distinguish the cause of oscillation is proposed. The simulation, experimental and industrial results are provided.


      PubDate: 2015-03-09T08:40:24Z
       
 
 
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