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Control Systems Technology, IEEE Transactions on

Issue 4 • Date July 2007

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Displaying Results 1 - 22 of 22
  • Table of contents

    Page(s): C1 - C4
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  • IEEE Transactions on Control Systems Technology publication information

    Page(s): C2
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  • Guest Editorial Introduction to the Special Issue on Multivehicle Systems Cooperative Control With Application

    Page(s): 599 - 600
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  • Assigning Micro UAVs to Task Tours in an Urban Terrain

    Page(s): 601 - 612
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3018 KB) |  | HTML iconHTML  

    An optimization algorithm for assigning in realtime multiple unmanned aerial vehicles (UAVs) to task tours is presented and tested as part of a flight demonstration program. The scenario of interest is one where multiple microaerial vehicles are launched from a small UAV in order to investigate selected targets in an urban terrain. For path planning, we use the Dubin's car model so that the vehicles' dynamic constraint of minimum turning radius is taken into account. Due to the prohibitive computational complexity of the coupled path optimization and assignment problem, we solve the problem by ordering a set of tasks based on the Euclidean distance, utilizing a traveling salesman problem solver. We apply upper and lower bounding procedures iteratively on active subsets within the set of feasible group assignments, enabling efficient search of the solution space. The online implementation of the algorithm is discussed and simulation results confirm the efficiency of the proposed algorithm. Results from recent flight tests are also provided. View full abstract»

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  • Cooperative Tracking Using Vision Measurements on SeaScan UAVs

    Page(s): 613 - 626
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (930 KB) |  | HTML iconHTML  

    A cooperative tracking approach for uninhabited aerial vehicles (UAVs) with camera-based sensors is developed and verified with flight data. The approach utilizes a square root sigma point information filter, which takes important properties for numerical accuracy (square root), tracking accuracy (sigma points), and fusion ability (information). Important augmentations to the filter are also developed for delayed data, by estimating the correlated processes, and moving targets, by using multiple models in a square root interacting multiple model formulation. The final form of the algorithm is general and scales well to any tracking problem with multiple, moving sensors. Flight data using the SeaScan UAV is used to verify the algorithms for stationary and moving targets. Cooperative tracking results are evaluated using multiple test flights, showing excellent results. View full abstract»

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  • Distributed Robust Receding Horizon Control for Multivehicle Guidance

    Page(s): 627 - 641
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1957 KB) |  | HTML iconHTML  

    This paper presents a new distributed robust model predictive control algorithm for multivehicle trajectory optimization and demonstrates the approach with numerical simulations and multivehicle experiments. The technique builds on the robust-safe-but-knowledgeable (RSBK) algorithm, which is developed in this paper for the multivehicle case. RSBK uses constraint tightening to achieve robustness to external disturbances, an invariant set to ensure safety in the presence of changes to the environment, and a cost-to-go function to generate an intelligent trajectory around known obstacles. The key advantage of this RSBK algorithm is that it enables the use of much shorter planning horizons while still preserving the robust feasibility guarantees of previously proposed approaches. The second contribution of this paper is a distributed version of the RSBK algorithm, which is more suitable for real-time execution. In the distributed RSBK (DRSBK) algorithm, each vehicle only optimizes for its own decisions by solving a subproblem of reduced size, which results in shorter computation times. Furthermore, the algorithm retains the robust feasibility guarantees of the centralized approach while requiring that each agent only have local knowledge of the environment and neighbor vehicles' plans. This new approach also facilitates the use of a significantly more general implementation architecture for the distributed trajectory optimization, which further decreases the delay due to computation time. View full abstract»

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  • Effective Coverage Control for Mobile Sensor Networks With Guaranteed Collision Avoidance

    Page(s): 642 - 657
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1219 KB) |  | HTML iconHTML  

    This paper studies the problem of dynamically covering a given region in the plane using a set of mobile sensor agents. A novel problem formulation is proposed that addresses a number of important multiagent missions. The coverage goal, which is to cover a given search domain using multiple mobile sensors such that each point is surveyed until a certain preset level is achieved, is formulated in a mathematically precise problem statement. A control law is developed that guarantees to meet the coverage goal. This control law is modified to guarantee that a partially connected fleet also attains the coverage goal. Finally, a collision avoidance component is added to the controller to guarantee that the agents do not collide. The new controller is shown to safely achieve coverage. Several numerical examples are provided to illustrate the main results. View full abstract»

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  • Coordinated Transport by Multiple Biomimetic Robotic Fish in Underwater Environment

    Page(s): 658 - 671
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4884 KB) |  | HTML iconHTML  

    This paper presents a coordination method for multiple biomimetic robotic fish in underwater transport task. Based on our robotic fish prototype, we further investigate the coordination problems of multiple robotic fish. Considering the kinematic constraints of the robotic fish, and the unstructured and dynamic characteristics of the water environment, we utilize the limit cycle approach to control the posture of the fish and realize collision avoidance. To control the transport orientation in the particular underwater environment, the fuzzy logic method is adopted. Experimental results of transportation performed by three robotic fish validate the effectiveness of the proposed method. View full abstract»

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  • Cooperative UAV Formation Flying With Obstacle/Collision Avoidance

    Page(s): 672 - 679
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (511 KB) |  | HTML iconHTML  

    Navigation problems of unmanned air vehicles (UAVs) flying in a formation in a free and an obstacle-laden environment are investigated in this brief. When static obstacles popup during the flight, the UAVs are required to steer around them and also avoid collisions between each other. In order to achieve these goals, a new dual-mode control strategy is proposed: a "safe mode" is defined as an operation in an obstacle-free environment and a "danger mode" is activated when there is a chance of collision or when there are obstacles in the path. Safe mode achieves global optimization because the dynamics of all the UAVs participating in the formation are taken into account in the controller formulation. In the danger mode, a novel algorithm using a modified Grossberg neural network (GNN) is proposed for obstacle/collision avoidance. This decentralized algorithm in 2-D uses the geometry of the flight space to generate optimal/suboptimal trajectories. Extension of the proposed scheme for obstacle avoidance in a 3-D environment is shown. In order to handle practical vehicle constraints, a model predictive control-based tracking controller is used to track the references generated. Numerical results are provided to motivate this approach and to demonstrate its potential. View full abstract»

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  • UAV as a Reliable Wingman: A Flight Demonstration

    Page(s): 680 - 688
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1341 KB) |  | HTML iconHTML  

    In this brief, we present the results from a flight experiment demonstrating two significant advances in software enabled control: optimization-based control using real-time trajectory generation and logical programming environments for formal analysis of control software. Our demonstration platform consisted of a human-piloted F-15 jet flying together with an autonomous T-33 jet. We describe the behavior of the system in two scenarios. In the first, nominal state communications were present and the autonomous aircraft maintained formation as the human pilot flew maneuvers. In the second, we imposed the loss of high-rate communications and demonstrated an autonomous safe "lost wingman" procedure to increase separation and reacquire contact. The flight demonstration included both a nominal formation flight component and an execution of the lost wingman scenario. View full abstract»

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  • Control of Resonant Acoustic Sound Fields by Electrical Shunting of a Loudspeaker

    Page(s): 689 - 703
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1596 KB) |  | HTML iconHTML  

    Low-frequency reverberant sound fields are usually suppressed by means of either adaptive feedforward control or Helmholtz resonator. Feedforward systems utilize a noise reference signal, error microphone, and loudspeaker to cancel sound propagating in one direction. Due to the requirement for multiple transducers and a powerful digital signal processor, feedforward systems are the most complex and expensive option for acoustic noise reduction. Helmholtz resonators, comprising auxiliary coupled acoustic chambers, are a popular passive technique for the control of dominant acoustic modes. Although lightly damped acoustic modes can be heavily attenuated, the resonators are difficult to tune and require unpractically large cavity volumes at frequencies below 200 Hz. This paper introduces a new technique for the control of low-frequency reverberant sound fields. By connecting an electrical impedance to the terminals of an acoustic loudspeaker, the mechanical dynamics, and hence, acoustic response can be made to emulate a sealed acoustic resonator. No microphone or velocity measurement is required. In some cases, the required electrical circuit is simply the parallel connection of a capacitor and resistor. With the addition of a single pressure microphone, a technique for online circuit adaptation is proposed. Experimental application to a closed acoustic duct results in 14-dB pressure attenuation of a single acoustic mode. Active impedances can be designed by viewing the system model from a feedback control perspective. The resulting electrical impedances, although not passive, are experimentally shown to attenuate four acoustic modes by up to 10 dB. View full abstract»

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  • Active Control of Sound Transmission Through Windows With Carbon Nanotube-Based Transparent Actuators

    Page(s): 704 - 714
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2661 KB) |  | HTML iconHTML  

    This paper explores the development of active sound transmission control systems for windows that can achieve a significant reduction in window noise transmission. Two major challenges need to be addressed in order to make the development of such noise blocking windows feasible. These are the need for a distributed actuation system that is optically transparent and the unavailability of a real-time reference signal that can be used by the active control system to provide advance information on the noise affecting the window. To address the first challenge, a transparent thin-film actuator (speaker) is first developed for the control system, which consists of a piezoelectric poly (vinylidene fluoride) (PVDF) thin film coated with compliant carbon nanotube-based transparent conductors on both sides. The developed thin-film speaker shows excellent acoustic response over a broadband frequency range, and has the advantages of being flexible, transparent, thin, and lightweight. To address the second challenge of providing a time-advanced reference signal from a moving noise source, a small microphone array distributed on the outside wall of the home is used. New noise source identification algorithms are employed, by which an appropriate microphone from the array can be chosen to provide a reference signal. Experimental results show that over 12 dB reduction in sound transmission is achieved globally in the case of broadband sound, which demonstrates the effectiveness of the control system in blocking sound transmission. View full abstract»

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  • A Mechanical Wave Diode: Using Feedforward Control for One-Way Transmission of Elastic Extensional Waves

    Page(s): 715 - 724
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (984 KB) |  | HTML iconHTML  

    This paper concerns the design and analysis of an active device capable of controlling mechanical waves. Its functionality is similar to that of a diode in an electrical network and, therefore, it is referred to as a mechanical wave diode. The aim is to block waves in one direction in a mechanical structure, while not affecting waves travelling in the opposite direction. The device is based on feedforward control and its design is proposed on the basis of equations that describe elastic extensional waves in bars. We present an ideal feedforward design which performs perfectly in the noise-free case. However, it has poor noise properties and is modified to be useful when measurement noise is present. Theoretical analysis and computer simulations show that the modified design is significantly less sensitive to such noise. View full abstract»

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  • On the Implementation of Supervised Control of Discrete Event Systems

    Page(s): 725 - 739
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (495 KB) |  | HTML iconHTML  

    Supervisory control theory is well developed, but its use in industrial applications can be limited by a set of problems arising when supervisors have to be implemented on common control machines. As a matter of fact, the asynchronous and undetermined nature of supervisors makes their implementation on synchronous devices like programmable logic controllers (PLCs) and PCs a complicated task. In this paper, an overview on the existing techniques about this topic is given first. Then, the supervised control approach is used to implement supervisors and the supervised control architecture consisting of a controller and a supervisor is completed by a dispatcher to obtain a closed-loop, determined behavior. The main problems occurring in implementing supervised control on synchronous devices are presented and discussed. Finally, a method is proposed to translate automata, Petri net or colored Petri net supervisors in structured text language, one of the IEC 61131-3 standard languages, by preserving their structure and the closed-loop behavior as expected from the theory. View full abstract»

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  • High-Gain Estimator and Fault-Tolerant Design With Application to a Gas Turbine Dynamic System

    Page(s): 740 - 753
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1355 KB) |  | HTML iconHTML  

    For dynamic systems with actuator faults, sensor faults, input disturbances, and measurement noises, a novel high-gain estimation technique is presented in this paper to estimate system states, actuator faults, and sensor faults simultaneously. The key idea is to represent faults as auxiliary system states so that a descriptor system representation can be formulated. By using the estimated state and fault signals, a fault-tolerant controller design approach is developed, where the closed-loop dynamic system can still be guaranteed to operate normally when actuator and sensor faults occur. It has been shown that in the proposed design framework, the actuator fault, sensor fault, input disturbance, and measurement noise can appear simultaneously and can be allowed to be in different bounded forms. Finally, the proposed algorithm is applied to the simulation study of a three-shaft gas turbine system and desired results have been obtained. View full abstract»

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  • Modeling, Estimation, and Control of Human Circulatory System With a Left Ventricular Assist Device

    Page(s): 754 - 767
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1179 KB) |  | HTML iconHTML  

    In this paper, a state-space model is developed through theoretical analysis and numerical solutions to approximate the response of the human circulatory system. This system model has one critical time-varying parameter: the resistance of peripheral blood vessels. A parameter estimation scheme is derived to estimate this parameter, and the parameter estimate is used to implement an adaptive observer to estimate the aortic pressure for physiological control. An optimal adaptive controller is proposed to control the estimated aortic pressure to track a reference signal updated by a nonlinear function of the pump head to meet the physiological need. A Matlab simulation program and an experimental mock human circulatory loop are employed as test environments for the human circulatory systems with a left ventricular assist device and their physiological controllers. Different physiological conditions, such as the variation of left ventricular failures, variation of activities, and collapse of the left ventricle, are evaluated to test the designed physiological control system. Simulation and experimental results consistently show that the aortic pressure estimation error is small, and that the abnormal hemodynamic variables of a congestive heart failure patient are restored back to the normal physiological range. View full abstract»

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  • Robust Inventory Control System

    Page(s): 768 - 774
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB) |  | HTML iconHTML  

    Further developments of the inventory control strategy are studied in this brief. We use high gain (sliding mode) adaptive control to handle the system uncertainties caused by modeling errors and unmeasured disturbances. It is proven that this control law makes the uncertain system globally stable. The parameters of the resulting controller are easy to tune. The simulation example and experiment studies illustrate the application of the novel method. View full abstract»

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  • A High-Integrity Multivariable Robust Control With Application to a Process Control Rig

    Page(s): 775 - 785
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (631 KB) |  | HTML iconHTML  

    This brief presents a systematic approach for the design of a robust decoupling precompensator using an approximate right inverse (ARI) of a system, where the problem of finding an ARI is presented as an L2-gain minimization problem. Furthermore, new LMIs are presented to analyze worstcase L2-gain for an uncertain system. These LMIs use extra variables to eliminate product terms between system state matrices and the Lyapunov matrix. This elimination enables the use of a parameter dependent Lyapunov function in a systematic way. These LMIs are extended to synthesis both constant and dynamic precompensators as well. Using the synthesis and the analysis LMIs, a combined genetic-LMI-algorithm is also presented to find a suitable precompensator that achieves diagonal dominance for systems with input uncertainties. Some previously presented LMIs for pole clustering are also modified to make them compatible with newly presented LMIs. The proposed approach is applied to the design of a high integrity robust multiinput multioutput controller for a process control rig which consists of a temperature and a flow rate control loop. The system has an input uncertainty of about 20%. It is shown that the closed-loop system poses a high integrity while being robust with respect to input uncertainties. The controller is also applied to the real plant to verify that the proposed algorithm and the desired results are obtained. View full abstract»

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  • Experimental Output Regulation for a Nonlinear Benchmark System

    Page(s): 786 - 793
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (944 KB) |  | HTML iconHTML  

    Research on the nonlinear output regulation problem is mainly focused on theoretical developments and studies on simulation level. In this brief, we present experimental results on the local output regulation problem for a nonlinear benchmark mechanical system, the so-called translational oscillator with a rotational actuator system. The presented results show the effectiveness of the nonlinear output regulation theory in practice. As follows from the conducted experiments, issues such as the convergence rate, stability, and performance robustness with respect to (non) parametric uncertainties, the size of the region of attraction, and actuator saturation should be accounted for in tuning the controller gains. This design problem has not been addressed in the existing literature on the nonlinear output regulation problem and it, therefore, raises a new direction for research crucial to the future application of output regulation theory in practice. View full abstract»

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  • Improving Performance Under Sampling-Rate Variations via Generalized Hold Functions

    Page(s): 794 - 797
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (271 KB) |  | HTML iconHTML  

    This paper discusses the use of actuator devices implementing the so-called generalized sample and hold functions. They will be used in order to develop state feedback controllers that tolerate significant variations in the time interval between samples, frequent in multitasking and networked computer control environments. A particular case is solved via linear matrix inequalities. An experimental DC motor setup has been used to demonstrate the applicability of the approach. View full abstract»

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  • Quality without compromise [advertisement]

    Page(s): 798
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  • IEEE Transactions on Control Systems Technology Information for authors

    Page(s): C3
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