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Control Systems Technology, IEEE Transactions on

Issue 1 • Date Jan. 2004

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Displaying Results 1 - 25 of 28
  • 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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  • Experimental quantitative comparison of different control architectures for master-slave teleoperation

    Page(s): 2 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB) |  | HTML iconHTML  

    A procedure for experimental evaluation and objective/quantitative comparison among the different teleoperation architectures and systems is proposed. It is based on the analysis of the different matrices that can define the teleoperated system (two-port representations) and the selection of a set of four parameters that are easy to estimate via simple experimentation: free motion impedance, position tracking in free movement, force tracking in hard contact tasks and maximum transmittable impedance. These parameters provide complete characterization of the master-slave system and have clear physical interpretation. Furthermore, they require no maneouvering of the slave robot, which is very useful in the case of heavy or nonaccessible industrial robots. The method has been applied to compare position-position (PP), force-position (FP), and four-channel (4C) controllers in a 2 DOF master-slave system. Experimental measuring for all four parameters will be shown, proving the 4C architecture clearly better than any other. View full abstract»

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  • An approach to dual-stage servo design in computer disk drives

    Page(s): 12 - 20
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    A novel design strategy is presented for a dual-stage actuator servo system in magnetic disk drives. Based on the existing decoupled-design strategy, we adopt the idea of the well-known zero-phase error tracking controller to minimize destructive effect resulting when two control loops are combined. Since the zero-phase tracking control requires previews of signals in a feedback loop, a kind of estimation scheme is suggested based on the actuators' dynamic model. The best practical advantage is that we achieve systematically a low-order DSA controller capable of high-accuracy track following as well as of high-speed short-span track seek; besides, the existing single-stage controller is fully utilized. The performance of the proposed method is analyzed and demonstrated through simulation and experiment. View full abstract»

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  • Control of a combined GTO/IGBT drive system for low torque ripple in a large permanent magnet synchronous motor

    Page(s): 21 - 35
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB) |  | HTML iconHTML  

    A control method is developed for a drive system, built of a parallel interconnection of a high-power GTO and a low-power fast-switching IGBT, feeding a large permanent magnet synchronous motor (PMSM) where torque ripple attenuation is a primary concern. The GTO is the main power supply and the IGBT is used for attenuating the current ripple due to the GTOs low switching frequency. The proposed controller combines a hierarchical, passivity-based dynamic feedback compensator, guaranteeing global exponential stability, as a well as a space vector PWM (SVM) strategy, that prevents stray, zero-sequence currents. The prevention of substantial stray currents between inverters is essential for the successful implementation of the proposed topology and is addressed by the combination of the master-slave compensator structure with the matching SVM strategy. View full abstract»

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  • Observers and feedback control for a rotating vortex pair

    Page(s): 36 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB) |  | HTML iconHTML  

    An observer is developed to estimate and to feedback-regulate the location of the vorticity centroid and the mutual distance of an interacting, same sign vortex pair. The combination of the crude approximation provided by very low-order vortex models, and high nonlinearity, even at that level, seem to make sensitive gain scheduling and high-order vector field derivatives in geometrical observer design methods, ill suited for the system at hand. This paper explores possibilities for dynamic extraction of needed information directly from leading frequencies and phasors of a sensor signal, using an extended Kalman filter. Intended advantages include simplicity, robustness, and the filtering of unmodeled dynamics. View full abstract»

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  • Development and analysis of a feedback treatment strategy for parturient paresis of cows

    Page(s): 52 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB) |  | HTML iconHTML  

    An intelligent on-line feedback treatment strategy based on nonlinear optimal control theory is presented for the parturient paresis of cows. A limitation in the development of an existing nonlinear mathematical model for the homogeneous system is addressed and further modified to incorporate a control input. A neural network based optimal feedback controller is synthesized for the treatment of the disease. Detailed studies are used to analyze the effectiveness of a feedback medication strategy and it is compared with the current 'impulse' strategy. The results show that while the current practice may fail in some cases, especially if it is carried out before the condition of a patient deteriorates, the proposed continuous medication process may be initiated at any time. Moreover the proposed on-line continuous infusion strategy never leads to severe hypercalcemic problems, thereby avoiding an associated disastrous consequence of cardiac arrest. A comparison study with linear quadratic regulator theory brings out the advantages of the nonlinear control synthesis approach. View full abstract»

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  • Fuzzy plus integral control of the effluent turbidity in direct filtration

    Page(s): 65 - 74
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB) |  | HTML iconHTML  

    This paper studies the effluent turbidity control of a deep bed rapid sand filter run by direct filtration method. In spite of the highly nonlinear filter dynamics, the maximum filter run time and optimum chemical usage are achieved. The disturbances such as the filter flow rate and the influent (raw water) turbidity that directly affect the effluent turbidity are compensated successfully. The behavior of the filter is determined by on-line measuring of the influent and effluent turbidities, the bed pressure drops, the flow rate, and the temperature of the influent. The required alum is directly dosed into the filter by a dosage pump controlled by the main computer. The extraction of a mathematical model of a sand and polymer based filter is very difficult and many times impossible because of the complex nature of the system. Furthermore the filter dynamics is slightly time-dependent and quite nonlinear, making the use of linear control ineffective. Fuzzy control is proposed as most effective for this application, because of its ability to finely tune the control actions nonlinearly across different turbidity error ranges. An integral controller is added in parallel to the fuzzy controller to enhance the control performance for steady state errors. View full abstract»

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  • Optimal pulse shaping for plasma processing

    Page(s): 75 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB) |  | HTML iconHTML  

    Thin-film etching and deposition using low-pressure plasma reactors is an integral part of the fabrication of very-large-scale integrated (VLSI) circuits. Standard operation of plasma reactors uses an RF power source with constant average power to excite a plasma in the vacuum chamber. Recently, several researchers have shown empirically that operation of plasma reactors with a periodic power input has the promise to increase the flexibility of plasma processing, in the sense that a greater range of operating conditions is achievable. This paper presents a numerical analysis of a global model for an argon plasma with the aim of answering the following questions: First, can a periodic input achieve effective operating conditions that cannot be achieved using steady-state inputs? Second, if the answer to the first question is yes, what is the shape of the periodic input required to achieve a particular operating point? This technique was utilized to give answers to these questions in one particular case. It was shown that periodic operation of an argon plasma can create variations in the ratio of metastable argon density to ionized argon density beyond that achievable using constant power. In addition, strong evidence is given that arbitrarily shaped modulating waveforms have advantages over simple pulse width modulation. View full abstract»

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  • Reconfigurable flight control system design using adaptive neural networks

    Page(s): 87 - 100
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    An adaptive controller design method based on neural network is proposed for reconfigurable flight control systems in the presence of variations in aerodynamic coefficients or control effectiveness deficiencies caused by control surface damage. The neural network based adaptive nonlinear controller is developed by using the backstepping technique for command following of the angle of attack, sideslip angle, and bank angle. On-line learning neural networks are implemented to compensate the control effectiveness decrease and guarantee the robustness to the uncertainties due to aerodynamic coefficients variations. The main feature of the proposed controller is that the adaptive controller is designed by assuming that all of the nonlinear functions of the system have uncertainties, whereas most of the previous works assume that only some of the nonlinear functions are unknown. Neural networks learn through the weight update rules that are derived from the Lyapunov control theory. The closed-loop stability of the error states is also investigated. A nonlinear dynamic model of a high performance aircraft is used to demonstrate the effectiveness of the proposed control law. View full abstract»

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  • A nonlinear observer design for fuel cell hydrogen estimation

    Page(s): 101 - 110
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB) |  | HTML iconHTML  

    We present an observer design to estimate the partial pressure of hydrogen in the anode channel of a fuel cell. A precise knowledge of this pressure is of importance to ensure reliable and efficient operation of the fuel cell power system. Our design makes use of a monotonic nonlinear growth property of the voltage output on hydrogen partial pressures at the inlet and at the exit of the channel. By treating the slowly varying inlet partial pressure as an unknown parameter, an adaptive observer is developed that employs a nonlinear voltage injection term. We then study the robustness of this observer against variations in the inlet partial pressure, and analyze its sensitivity to other modeling errors. We also prove a robustness property of the observer against the parameter estimation error, which means that it can be implemented with alternative parameter estimator designs. View full abstract»

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  • H control of nonperiodic two-dimensional channel flow

    Page(s): 111 - 122
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB) |  | HTML iconHTML  

    This paper deals with finite-dimensional boundary control of the two-dimensional (2-D) flow between two infinite parallel planes. Surface transpiration along a few regularly spaced sections of the bottom wall is used to control the flow. Measurements from several discrete, suitably placed shear-stress sensors provide the feedback. Unlike other studies in this area, the flow is not assumed to be periodic, and spatially growing flows are considered. Using spatial discretization in the streamwise direction, frequency responses for a relevant part of the channel are obtained. A low-order model is fitted to these data and the modeling uncertainty is estimated. An H controller is designed to guarantee stability for the model set and to reduce the wall-shear stress at the channel wall. A nonlinear Navier-Stokes PDE solver was used to test the designs in the loop. The only assumption made in these simulations is that the flow is two dimensional. The results showed that, although the problem was linearized when designing the controller, the controller could significantly reduce fundamental 2-D disturbances in practice. View full abstract»

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  • Identification-based PID control tuning for power station processes

    Page(s): 123 - 132
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    This paper presents a new approach for PID-controller tuning based on the requirements of power station processes. It uses a novel optimization procedure based on four power process-oriented criteria. A new approach for transfer function identification of process models is also proposed as a robustness basis for the PID-control design. The tuning of PID controllers implemented on Israel Electric Corporation (IEC) steam power plant processes provides sufficiently good settings for these controller parameters and illustrates industrial applications of this approach. View full abstract»

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  • Design of a class of nonlinear controllers via state dependent Riccati equations

    Page(s): 133 - 137
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB) |  | HTML iconHTML  

    In this brief, infinite-horizon nonlinear regulation of second-order systems using the State Dependent Riccati Equation (SDRE) method is considered. By a convenient parametrization of the A(x) matrix, the state-dependent algebraic Riccati equation is solved analytically. As a result, the closed-loop system equations are obtained in analytical form. Global stability analysis is performed by a combination of Lyapunov analysis and LaSalle's Principle. Accordingly, a relatively straightforward condition for global asymptotic stability of the closed-loop system is derived. This is one of the first global results available for this class of systems controlled by SDRE methods. The stability results are demonstrated on an experimental magnetic levitation setup and are found to provide a great deal of flexibility in the control system design. View full abstract»

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  • Adaptive tracking and regulation of a wheeled mobile robot with controller/update law modularity

    Page(s): 138 - 147
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    A new adaptive controller is developed for wheeled mobile robots with parametric uncertainty in the dynamic model. The main theoretical contribution is the modular manner in which the control law and parameter update law are designed. This feature allows for design flexibility in the selection of the update law, and can be exploited to improve the transient response of the adaptive controller. The proposed controller also has the important feature of being applicable to both the tracking and regulation problems. The modularity of the adaptive controller is experimentally demonstrated on a K2A Cybermotion mobile robot that has been modified to allow for the implementation of torque-level control inputs. In particular, the adaptive controller with a gradient update law is evaluated vis-a`-vis a least-squares update law. View full abstract»

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  • Optimal sensor design and control of piezoelectric laminate beams

    Page(s): 148 - 155
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    In this paper, a new smart structure optimal design strategy is introduced and applied to robust vibration control of a piezoelectric laminate beam. The optimization of the smart material layout and the control law are performed simultaneously to extract maximum performance from the system. A homogenization approach is used to allocate sensor material, while a linear quadratic regulator (LQR) is used for the control law. The method is applied to a pinned-pinned beam where two cost functions are considered, both focusing on increasing the stability margin of the closed-loop system. The first is based on the observability gramian and the second on the control weighting parameter of the LQR cost function. Both cost functions yield optimal sensor distributions that improve the closed-loop performance as compared with uniform density distributions. In addition to investigating the effect of the cost function on the design, two different sensor design domains are considered. The first consists of five isolated patches of sensor material (a discrete sensor domain), while the second assumes the five patches cover the entire beam, but are electrically isolated (segmented distributed sensor domain). In all cases considered, the cost function based on the LQR control weighting parameter generates smoother sensor distributions that are always positively polled, an important fabrication consideration. The segmented distributed sensor approach yields the overall best performance. View full abstract»

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  • Nominal performance recovery by PID+Q controller and its application to antisway control of crane lifter with visual feedback

    Page(s): 156 - 166
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    We have recently suggested the PID+Q controller that consists of a PID controller, a stable free-parameter, and an internal model of plants. In this brief paper, we point out that the free parameter can be designed to improve the robust stability and the robust performance of the control system, and present a nominal-performance recovery problem to design the free parameter with better robust performance. Moreover, we apply the PID+Q controller to the robust antisway control of crane lifter in order to compensate the time delay caused by the vision-based measurement. After modeling the lifter system with the visual sensor as a pendulum control system with a time delay, we design a robust PD+Q controller and a PID+Q controller using the MATLAB LMI Toolbox. Finally, we implement the designed controller on a table-size lifter kit with the visual sensor to demonstrate the proposed PD PD+Q controller. View full abstract»

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  • Observer-based control for tail-controlled skid-to-turn missiles using a parametric affine model

    Page(s): 167 - 175
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB) |  | HTML iconHTML  

    This brief paper presents an observer-based control approach for the acceleration control of tail-controlled skid-to-turn (STT) missiles. The proposed approach provides a solution to overcoming the drawbacks of existing nonlinear missile controllers that it is needed to know the values of wind angles (angle of attack and sideslip angle). A nonlinear observer for wind angles is designed using a parametric affine missile model developed by the authors, where the coupling term between the lateral and longitudinal motion is also considered. Using the wind angle estimate, we can design the observer-based controller to show the desired acceleration tracking performance. The performance and stability of the resulting overall missile system are analyzed by taking into account the effects of the wind angle estimator. Simulation results are also included to show that the proposed approach provides satisfactory performance for missile dynamics. View full abstract»

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  • Data-driven control design for neuroprotheses: a virtual reference feedback tuning (VRFT) approach

    Page(s): 176 - 182
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    This paper deals with design of feedback controllers for knee joint movement of paraplegics using functional electrical stimulation (FES) of the paralyzed quadriceps muscle group. The controller design approach, virtual reference feedback tuning (VRFT), is directly based on open loop measured data and fits the controller in such a way that the closed-loop meets a model reference objective. The use of this strategy, avoiding the modeling step, significantly reduces the time required for controller design and considerably simplifies the rehabilitation protocols. Linear and nonlinear controllers have been designed and experimentally tested, preliminarily on a healthy subject and finally on a paraplegic patient. Linear controller is effective when applied on small range of knee joint angle. The design of a nonlinear controller allows better performances. It is also shown that the control design is effective in tracking assigned knee angle trajectories and rejecting disturbances. View full abstract»

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  • A note on simultaneous isolation of sensor and actuator faults

    Page(s): 183 - 192
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    Sensor and actuator self-validation is a critical step in system control and fault diagnostics. If sensors do not work properly, one cannot rely on their outputs to further deduce system status. Similarly, faulty actuators will not satisfy system performance objectives and may cause disasters in feedback control systems. In this paper, a novel method to generate structured residuals for isolating sensor and actuator failures with the least sensitivity to model-plant-mismatch (MPM) and disturbances in multivariate dynamic systems is proposed. The proposed method includes two components. The first component is the generation of the primary residuals directly from noisy input and output measurements without identifying explicitly the model of a system under consideration. The primary residuals are generated such that they have the least sensitivity to any MPM and process disturbances, but have the highest sensitivity to faults in any sensors and/or actuators. The second component of the proposed scheme is the max-min design to transform the primary residuals into a set of structured residuals for fault isolation by improving the existing structured residual approach with maximized sensitivity (SRAMS) . Since one structured residual is made immune to a specified subset of faults, but very sensitive to other faults, any faulty sensors and/or actuators can be isolated by observing the structured residuals in accordance with a predetermined isolation logic. The proposed method has been verified for detection and isolation of faulty sensors and/or actuators in an experimental pilot plant. View full abstract»

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  • Control under constraints: an application of the command governor approach to an inverted pendulum

    Page(s): 193 - 204
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    The purpose of this paper is to exhibit the relevance of command governor (CG) strategies in real control problems, where consideration has to be given to nonlinearities, model uncertainties, disturbances, input and state-related constraints and requirements of moderate computational complexity. The plant considered is a laboratory cart/rod inverted pendulum for which the control problem consists of regulating vertically its rod subject to motor voltage and rod angle constraints, while providing full-range optimized tracking performance for the cart position. The merits of the proposed CG technique in this application are investigated, and its advantages over classic linear time-invariant design methods are discussed. View full abstract»

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  • Modeling of thermal generating units for automatic generation control purposes

    Page(s): 205 - 210
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB) |  | HTML iconHTML  

    A simple discrete time model of a thermal unit has been formally developed for designing automatic generation control (AGC) controllers. This model has been developed using data obtained from specific tests and historical records. This model consists of a nonlinear block followed by a linear one. The nonlinear block consists of a dead band and a load change rate limiter, while the linear block consists of a second-order linear model and an offset. Although most of these elements have already been included in unit models for AGC presented in the literature, a certain mix up exists about which of them are necessary. This is clarified in this paper. It has been found that the unit response is mainly determined by the rate limiter, while the other model components are used for a better fitting to the real response. An identification procedure is proposed to estimate the values of the model's parameters. View full abstract»

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  • Constrained nonlinear control allocation with singularity avoidance using sequential quadratic programming

    Page(s): 211 - 216
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    Control allocation problems can be formulated as optimization problems, where the objective is typically to minimize the use of control effort (or power) subject to actuator rate and position constraints, and other operational constraints. Here we consider the additional objective of singularity avoidance, which is essential to avoid loss of controllability in some applications, leading to a nonconvex nonlinear program. We suggest a sequential quadratic programming approach, solving at each sample a convex quadratic program approximating the nonlinear program. The method is illustrated by simulated maneuvers for a marine vessel equipped with azimuth thrusters. The example indicates reduced power consumption and increased maneuverability as a consequence of the singularity-avoidance. View full abstract»

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