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Control Theory and Applications, IEE Proceedings -

Issue 1 • Date 16 Jan. 2006

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Displaying Results 1 - 16 of 16
  • Mixed H2/H PID tracking control design for uncertain spacecraft systems using a cerebellar model articulation controller

    Publication Year: 2006 , Page(s): 1 - 13
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (702 KB)  

    A mixed H2/H tracking control design method for uncertain spacecraft systems with guaranteed control performance is examined. A mixed H2/H controller incorporating a cerebellar model articulation controller (CMAC) learning method and sliding-mode control action is developed in uncertain spacecraft systems under plant uncertainties and external disturbances. The CMAC control system is used to adaptively estimate the non-linear uncertainties, yielding a controller that can tolerate a wider range of uncertainties. The sliding-mode control action is included to eliminate the effect of approximation error via CMAC control system approximation. The sufficient condition is developed for mixed H2/H performance in terms of linear matrix inequality formulations. The proposed method is simple and the PID parameters can be obtained systematically. Simulation results indicate that the mixed H2/H performance can be achieved using the proposed methods. View full abstract»

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  • Some properties of networked reset control systems

    Publication Year: 2006 , Page(s): 14 - 20
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    The dynamics and stability of reset control systems in a networked environment are studied considering the impact of network-induced delays. Lyapunov-like exponential stability and robust stability criteria for such systems are obtained. A quadratic stability condition, which is, from a practical point of view and thus more easily testable, is derived using the Kalman-Yakubovich-Popov (KYP) lemma. This result is demonstrated by examples to be applicable to the asymptotic tracking and disturbance rejection problems of such systems. View full abstract»

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  • Nonlinear flow control strategies for connection-oriented communication networks

    Publication Year: 2006 , Page(s): 21 - 28
    Cited by:  Papers (11)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (154 KB)  

    The problem of flow control in fast connection-oriented communication networks supporting traffic generated by multiple sources is addressed. The network is modelled as a dynamic system with different delay times. A nonlinear strategy governing the behaviour of the sources is proposed. The strategy combines Smith's principle with a conventional relay controller. It ensures full bottleneck link utilisation and no cell loss in the controlled network, even if the round-trip times of the connections contributing to the bottleneck link queue are not known exactly, but can only be estimated within a certain level of accuracy. Furthermore, a modified strategy with extra feed-forward compensation is proposed. This strategy also guarantees no cell loss and full bottleneck link utilisation. Moreover, it helps to achieve a favourable quality of service in the controlled network. View full abstract»

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  • Investigating the control design of the disturbance reduction system for the LISA mission

    Publication Year: 2006 , Page(s): 29 - 36
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (181 KB)  

    The Laser Interferometer Space Antenna (LISA) mission will consist of a three spacecraft formation acting as a large interferometer. The spacecraft formation will measure the distortion of space caused by passing gravitational waves. Each spacecraft will contain two shielded proof masses that define the optical arms of the interferometer. To mitigate the effects of external disturbances, the LISA Disturbance Reduction System will control the spacecraft to fly drag-free trajectories with reference to their respective proof masses. This paper investigates control design issues associated with the LISA Disturbance Reduction System (DRS). In particular, this paper presents a two degrees-of-freedom (DOF) model representing a spacecraft with a single proof mass. With this model, key control design issues are identified. A Linear Quadratic Gaussian (LQG) controller design is then presented to illustrate the feasibility of the DRS control concept. A three DOF model is used to explore the DRS implications of a spacecraft with two proof masses. View full abstract»

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  • Sliding-mode control for dc-dc converters with constant switching frequency

    Publication Year: 2006 , Page(s): 37 - 45
    Cited by:  Papers (28)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (237 KB)  

    A new approach implementing the sliding-mode controller is proposed for dc-dc converters. The equivalent control input is used as the system control input, which results in a duty cycle regulation control system. As designed, equivalent control input is maintained at a value between 0 and 1, similar to the desired duty cycle value. Thus, constant switching frequency can be achieved under changes of state conditions. Two sliding-mode controllers based on this method are designed for positive output elementary Luo converter. Traditional small-signal analysis is applied to study the close-loop system performance under proposed approach. Audio-susceptibility, control-to-output transfer functions and output impedance are derived on the basis of the small-signal model. It is shown that the proposed sliding-mode control approach retains the advantages of traditional sliding-mode control, as well as achieve constant switching frequency, which is decided by the input saw-tooth waveform. Results of the experiment are reported for both controllers and they verify the theoretical analysis. View full abstract»

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  • Design of fixed-structure controllers with frequency-domain criteria: a multiobjective optimisation approach

    Publication Year: 2006 , Page(s): 46 - 52
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    An optimisation-based iterative design of fixed-structure controllers with frequency-domain criteria is presented. An interactive multiobjective optimisation procedure is presented, which is based on a direct shaping of the frequency responses, without the need to construct explicit weighting filters. At each iteration, a constrained optimisation problem is formulated in such a way that successive improvements of the design to meet the designer's specifications are achieved. For computational efficiency, time-domain expressions consisting of linear matrix equations are used to characterise the frequency responses. View full abstract»

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  • Hydrogenerator control-loop monitoring using graphical results obtained from a principal component analysis

    Publication Year: 2006 , Page(s): 53 - 58
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (150 KB)  

    A method to concentrate information from multiple transient performance criteria into simple graphical representations for the detection and localisation of faults occurring on hydrogenerator speed control loops is presented. Simple criteria such as the ISE index, the IAE index, the ITAE index, rise time, settling time and overshoot are combined and analysed by applying principal component analysis to data containing the start-up and a step in the rotational speed reference. The results are compared to a statistical model of the normal process operation and they are graphically displayed on a selected axis that has a high relevance to the process behaviour. The graphics are simple and can therefore be easily interpreted by plant operators. Simulations of a classical hydrogenerator show that six types of faults can be successfully detected and localised. View full abstract»

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  • Actuator deadzone compensation: theoretical verification of an intuitive control strategy

    Publication Year: 2006 , Page(s): 59 - 68
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    The paper discusses the problem of actuator deadzones, and other similar nonlinearities, in otherwise linear systems. Given a linear plant, it is assumed that a nominal linear controller has been designed in ignorance of the actuator deadzone and that some form of extra compensation is needed to negate its effect. It is shown that exceptionally simple forms of add-on compensators can be used to obtain arbitrarily good performance, thereby validating a type of engineering intuition. The proposed class of compensators are also compared to the popular anti-windup compensators and the former's superiority over the latter is demonstrated. View full abstract»

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  • Coordinated passivation techniques for the dual-excited and steam-valving control of synchronous generators

    Publication Year: 2006 , Page(s): 69 - 73
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    With coordinated passivation techniques, the dual-excited and steam-valving control for synchronous generators is proposed to achieve rotor angle and voltage stability. Steam-valving controller is designed by backstepping techniques, whereas dual-excited controller is based on coordinated passivation. The passivity-based control can be obtained to ensure that the closed-loop system is asymptotically stable. Simulations have showed the effectiveness of the control designs. View full abstract»

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  • Generalised H2 controller synthesis for uncertain discrete-time fuzzy systems via basis-dependent Lyapunov functions

    Publication Year: 2006 , Page(s): 74 - 80
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (166 KB)  

    The generalised H2 control problem is investigated for a class of discrete-time fuzzy systems with uncertainties. The uncertain fuzzy dynamic model is used to represent a class of uncertain discrete-time complex nonlinear systems which include both linguistic information and system uncertainties. Using basis-dependent Lyapunov functions an H2 control design approach is developed. It is shown that the controller can be obtained by solving a set of linear matrix inequalities. It is also shown that the basis-dependent results are less conservative than the basis-independent ones. Numerical examples including a discrete chaotic Lorenz system are also given to demonstrate the applicability of the proposed approach. View full abstract»

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  • Robust digital control of a wind turbine for rated-speed and variable-power operation regime

    Publication Year: 2006 , Page(s): 81 - 91
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (343 KB)  

    The design of a double-loop robust digital control algorithm for a wind turbine (WT) containing a doubly-fed induction machine is presented. The operating zone considered is that obtained when the rotational speed is limited to its rated value and the generated electricity has not reached its corresponding rated value. It is not particularly easy to find descriptions of controllers for this working zone in the existing literature. The rotational sampling effect may produce drive-train torque oscillations when a WT operates at constant speed. Consequently, its control system, which consists of two levels of control loops, has to be able to address these oscillations and be able to minimise flicker emission and dynamical loads in the drive train. These specifications, along with the robustness of the synthesised controller, lead to a reduced cost for the generated electricity and to a higher power quality, compared to those obtained using more classical WT control strategies that do not account for the peculiarities of the considered operation zone. The inner control loops govern the machine electromagnetic torque. The outer control-loop is synthesised using the discrete pole-placement with sensitivity function shaping method, to keep the rotational speed at its rated value and to reduce electromagnetic torque oscillations. The designed and synthesised control algorithms are tested on a simulation model validated using field data. Simulation results show that the proposed regulator reduces both flicker emission and dynamical drive-train loads, when compared to a classical PI regulator tuned to show an identical cut-off frequency and integral action. View full abstract»

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  • Modelling and control of agent-based power protection systems using supervisors

    Publication Year: 2006 , Page(s): 92 - 98
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    The framework of supervisory control of discrete event systems (DESs) is applied to agent-based power protection systems for achieving high reliability and selectivity. The DES-based supervisory control uses feedback information of events occurring in systems to achieve the set of desired event sequences. The large-scale and complex power systems need systematic tools for protection and control on a more abstract level. The supervisory control technique on the event-based abstract level can be used as a formal method for protection of large-scale power systems. Specifically, a design procedure of a supervisor that coordinates the behaviour of relay agents to isolate fault areas through the minimum operations of circuit breakers is presented. View full abstract»

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  • Stabilisation of uncertain singularly perturbed systems

    Publication Year: 2006 , Page(s): 99 - 103
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    This note studies the robust stabilisation problem of a linear time-invariant singularly perturbed system with nonlinear uncertainties, where the only information available for system uncertainties is their norm upper bounds, and no matching conditions are assumed. A linear stabilising control law is presented which can be determined by the solutions of two independent Lyapunov equations. The system stability bound can then be obtained by using the existing methods. Finally, a numerical example is given to illustrate the applications of the proposed results, and future work on this subject is also discussed. View full abstract»

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  • Robust stability of nonlinear singularly perturbed system with uncertainties

    Publication Year: 2006 , Page(s): 104 - 110
    Cited by:  Papers (8)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (145 KB)  

    The singularly perturbed system is easily analysed by two time-scale systems, each of which with a lower dimension than the original system. However, if uncertainties are added, then the analysis is very difficult because uncertainties change the slow manifold, the boundary layer model and the reduced model of the nominal system. Robust stability analysis of nonlinear singularly perturbed systems with vanishing uncertainties, of which the upper norm bounds only are available, is presented. The stability condition, under which the zero state equilibrium of the singularly perturbed system is exponentially stable for the sufficiently small perturbation parameter ε, is found and a stabilising controller is proposed. View full abstract»

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  • Robust recurrent-neural-network sliding-mode control for the X-Y table of a CNC machine

    Publication Year: 2006 , Page(s): 111 - 123
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    A robust recurrent-neural-network (RRNN) sliding-mode control is proposed for a biaxial motion mechanism to allow reference contour tracking. The biaxial motion mechanism is a X-Y table of a computer numerical control machine that is driven by two field-oriented control permanent-magnet synchronous motors. The single-axis motion dynamics are derived in terms of a lumped uncertainty that includes cross-coupled interference between the two-axes. A RRNN sliding-mode control system is proposed based on the derived motion dynamics to approximate the control obtained by using sliding-mode control and the motions at the X-axis and Y-axis are controlled separately. The motion tracking performance is significantly improved using the proposed control technique and robustness to parameter variations, external disturbances, cross-coupled interference and frictional torque can be obtained as well. Experimental results on circular, four-leaf, window and star reference contours are provided to show that the dynamic behaviour of the proposed control system is robust with regard to uncertainties. View full abstract»

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  • Estimate of the smallest stabilisable left-half-plane for all pole plants

    Publication Year: 2006 , Page(s): 124 - 126
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (127 KB)  

    Lower and upper bounds are given to calculate the smallest possible left-half-plane where all poles of a single-input single-output plant with no zeros can be stabilised using constant gain feedback. The results are expected to have immediate application areas in control system theory and filter design. View full abstract»

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