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Control Theory and Applications, IEE Proceedings -

Issue 3 • Date May 2001

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Displaying Results 1 - 12 of 12
  • Intelligent backstepping control for linear induction motor drive

    Page(s): 193 - 202
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (840 KB)  

    The design and properties of an intelligent backstepping control system for a linear induction motor (LIM) drive to track periodic reference trajectories are studied. First, the dynamic model of a field-oriented control LIM drive is derived. Then a feedback linearisation controller is designed in the sense of the backstepping control technique. To relax the requirement for the bound of lumped uncertainty in the feedback linearisation control law, a recurrent fuzzy neural network (RFNN) uncertainty observer is proposed to estimate the lumped uncertainty in real time. In addition, an online parameter training methodology, derived using the Lyapunov stability theorem and the gradient descent method, is proposed to increase the learning capability of the RFNN. With the proposed intelligent backstepping control system, the mover position of the LIM drive possesses the advantages of good transient control performance and robustness to uncertainties for the tracking of periodic reference trajectories. The effectiveness of the proposed control scheme is verified by both simulated and experimental results View full abstract»

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  • Global output regulation with minimum information of uncertain nonlinear systems subject to exogenous signals

    Page(s): 203 - 208
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    Deals with global output regulation of uncertain nonlinear systems affected by disturbances which are generated from a known exosystem. The information needed for the control design is that the uncertain system satisfies the geometric conditions for the output feedback form with stable zero dynamics and the parameterisation is linear for unknown constant parameters and the unmeasurable disturbances. This information is minimum compared with the conditions specified in the literature for global output regulation. The proposed control design does not require any knowledge of the high-frequency gain and the bound of the uncertain parameters. The uncertainties parametrised by unknown constant parameters and by the unmeasurable disturbances are treated in a unified way in the proposed control design View full abstract»

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  • Eigenstructure assignment design for proportional-integral observers: continuous-time case

    Page(s): 263 - 267
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    A complete parametric eigenstructure assignment design approach for proportional integral observers of multivariable linear systems is proposed. Based on a complete general parametric solution to the generalised Sylvester matrix equation, complete parameterisations for all the observer gains as well as the left eigenvectors of the observer system matrix are established in terms of three sets of design parameters. The proposed approach provides all the degrees of freedom and has great potential in applications. An example shows the effect of the proposed approach View full abstract»

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  • Time-domain based design and analysis of new PID tuning rules

    Page(s): 251 - 261
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1064 KB)  

    The time domain PID analysis includes three types of first-order plus time delay (FOPTD) models: (a) zero or negligible time delay (b) low to medium long time delay and (c) very long time delay. The first part of the analysis proves that the optimum PID controller for plants having negligible time delay is a PI controller, and the corresponding PI terms based on the actuator's capacity and set-point overshoot are explicitly derived. For low to medium time delay problems, a new PID tuning scheme is then developed. The proposed tuning rule is capable of accommodating the actuator's saturation and therefore has the ability to select an optimum PID controller. By using a separate time response analysis, a new PI tuning scheme for large normalised time delay is then derived. Numerical studies are made for higher-order processes having monotonic open-loop characteristics. The performance is compared with other commonly available tuning rules. With new tuning rules, better performance is observed and the rules have the capability to cover time delays ranging from zero to any higher value View full abstract»

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  • Feedback linearisation of nonminimum singular systems

    Page(s): 213 - 216
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    Presents a solution for feedback linearisation of a class of nonlinear systems which have singularity and nonminimum phase. Traditionally, these two problems have been mentioned as shortcomings of standard feedback linearisation. In the proposed scheme, purposely introduced uncertainty under the matching condition yields stabilisable linear systems with vanishing perturbed terms. With additional Lyapunov-based control terms, the considered system is shown to be exponentially stabilised. Finally, an illustrative example for the regulation problem is provided View full abstract»

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  • LMI approach to delay-dependent robust stability for uncertain time-delay systems

    Page(s): 209 - 212
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    Stability criteria are provided for a class of uncertain linear time-delay systems with time-varying delays. Based on Lyapunov-Krasovskii functionals combined with LMI techniques, simple and improved delay-dependent robust stability criteria given in terms of quadratic forms of state and LMI are derived. Examples show the performance of the application of the results presented View full abstract»

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  • Inverse control of systems with hysteresis and creep

    Page(s): 185 - 192
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    Since the beginning of the 1990s, hysteresis operators have been employed on a larger scale for the linearisation of hysteretic transducers. One reason for this is the increasing number of mechatronic applications that use solid-state actuators based on magnetostrictive or piezo-electric material or shape memory alloys. All of these actuator types show strong hysteretic effects. In addition to hysteresis, piezo-electric actuators show strong creep effects. Thus, the objective of the paper is to enlarge the operator-based methodology of hysteresis operators by elements that allow the description of systems with hysteresis and creep. To reach this objective, following the procedure used for hysteretic systems, creep operators are introduced to form, together with the hysteresis operators, a system operator for the simultaneous consideration of both phenomena. With regard to applications in control and measurement technology, the existence, uniqueness, Lipschitz continuity and thus input-output stability of its inverse operator are theoretically supported by functional analytical methods. Subsequently, the efficiency of this new concept is demonstrated, in practice, by a real-time inverse feedforward controller for piezo-electric actuators. Using this control concept, the tracking errors caused by hysteretic and creep effects are reduced by approximately one order of magnitude View full abstract»

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  • Adaptive stabilisation of extended nonlinear output feedback systems

    Page(s): 268 - 272
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    The paper deals with the adaptive stabilisation for a class of uncertain nonlinear systems whose nonlinear terms are functions of two state variables. The uncertainty is parametrised by an unknown constant parameter vector affined to smooth nonlinear functions. The model format considered in the paper can be viewed as an extension to the standard output feedback systems with nonlinear terms of the single output which has been extensively studied recently. Based on the principle of adaptive backstepping design, an adaptive control algorithm is proposed to stabilise the system in a feasibility region, using the feedback of the system output which is a vector containing the two state variables View full abstract»

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  • Control of free length when coiling a helical spring

    Page(s): 239 - 244
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    The problem of controlling the free-length of a helical spring while it is being manufactured on an automatic coiling machine is examined. This is a disturbance rejection problem, and the feedback system is designed to reject disturbances caused by variation of the wire properties and disturbances generated by the coiler. Fixed, self-tuning and fuzzy self-tuning control are used to reduce the variance of the coiled and free length of a helical spring. Friction feedforward is proposed to compensate for the varying coefficients of friction of different materials View full abstract»

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  • Temperature control in liquid helium cryostat using self-learning neurofuzzy controller

    Page(s): 233 - 238
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    Describes the development and practical application of a neurofuzzy controller that learns online to follow a time-varying set-point. It is shown that, during training, the control action is similar to that of a proportional plus integral plus derivative controller. A method for selecting the parameters of the learning scheme is proposed that does not require precise information about the open-loop behaviour of the system. Experimental results are presented that demonstrate that the self-learning controller is able to regulate the temperature inside a liquid helium cryostat over a wider operating range than was previously possible View full abstract»

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  • Nonlinear decoupled control for linear induction motor servo-drive using the sliding-mode technique

    Page(s): 217 - 231
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (976 KB)  

    Presents a design for nonlinear decoupled control of a linear induction motor (LIM) servo-drive. An ideal feedback linearisation control (IFLC) system is first adopted in order to decouple the thrust force and the flux amplitude of the LIM. However, the control performance of the LIM is influenced seriously by the uncertainties of the plant, such as electrical and mechanical parameter variation, external force disturbance and unmodelled dynamics in practical applications. Hence, to increase the robustness of the LIM drive for high-performance applications, a sliding-mode feedback linearisation control (SMFLC) system, that comprises a sliding-mode flux controller and a sliding-mode position controller, is proposed to decouple the thrust force and the flux amplitude of the LIM. The control laws of the SMFLC system are derived in the sense of the Lyapunov stability theorem, such that the asymptotic stability of the control system can be guaranteed under the occurrence of system uncertainties. Moreover, to relax the requirement of the secondary flux in the SMFLC system, an adaptive flux observer is proposed to estimate the secondary flux, considering all possible uncertainty in practical applications. In addition, the effectiveness of the proposed control scheme is verified by some simulated results View full abstract»

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  • Lyapunov-based controller design for bounded dynamic stochastic distribution control

    Page(s): 245 - 250
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    Following developments in the modelling and control of the output probability density function of dynamic stochastic systems, an approach for the controller design is presented using square root approximation, where a set of B-spline functions are used to approximate the square root of the measured output probability density function to guarantee its positiveness. A performance function is defined which measures the tracking error of the output probability density function with respect to a given distribution. Instead of finding an optimal control which minimises this performance function and then analysing the stability of the closed loop system, the new approach directly uses the performance function as a Lyapunov function to design the required controller. As a result, the controller obtained not only guarantees the decreasing of the performance function with respect to time, but also stabilises the closed-loop system, realising an asymptotically tracking performance of the output probability density function with respect to its target distribution. The algorithm described has been tested on a simulated example and desired results have been achieved View full abstract»

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