Online ISSN
1751-8652
Print ISSN
1751-8644
IET Control Theory & Applications
Volume 6, Issue 3, 16 February 2012
Volumes & issues:
Volume 6, Issue 3
16 February 2012
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- Author(s): U. Rupar ; F. Lahajnar ; P. Zajec
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 341 –348
- DOI: 10.1049/iet-cta.2011.0051
- Type: Article
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p.
341
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Transverse flux motors (TFMs) are playing an increasingly important role in various drive systems owing to their high power densities, high efficiency, high torque at low speeds and reduced weight. The TFM is suitable for a variety of direct-drive applications where high efficiency and low maintenance are required. However, one of the main drawbacks of the TFM is its high parasitic torque pulsations, which severely limit its use in high-end applications where torque smoothness is very important. To overcome this limitation, an iterative learning control scheme that eliminates periodic torque-ripple effects is presented. An indirect, D-type, frequency-domain approach in a stand-alone configuration is proposed. Simulations and an experimental verification were performed, and the results obtained demonstrate the effectiveness of the proposed approach. - Author(s): S. Baromand and B. Labibi
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 349 –356
- DOI: 10.1049/iet-cta.2010.0625
- Type: Article
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349
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The main idea proposed in this study is based on converting continuous-time covariance matrix differential equations of a multivariable system into a new uncertain deterministic linear system. The closed-loop form of the new state covariance equations is derived by converting the covariance matrix Riccati equation to a new linear deterministic vector state space system. Since the new covariance system is linear and deterministic, all conventional and well-defined control strategies can be applied to it. Using a sliding mode control strategy, the uncertain interconnection terms satisfying a matching condition are nullified and the closed-loop covariance system is asymptotically stable. This is accomplished by applying a control strategy composed of sliding mode and covariance feedback control for each local subsystem. - Author(s): J.R. Huey and W. Singhose
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 357 –364
- DOI: 10.1049/iet-cta.2010.0456
- Type: Article
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p.
357
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Closed-loop feedback control and command shaping are often used together to achieve superior control performance. In many cases, the feedback control is designed and implemented first. Then, the command shaping is designed to improve the resulting closed-loop dynamics. However, there is an often-overlooked advantage of optimally combining these two control schemes. This study will show that proportional and derivative feedback control can be intelligently used to create a closed-loop system that is particularly advantageous when input shaping is used as a filter outside of the loop. Experimental results are shown to verify the theoretical developments. - Author(s): J. Luo ; X. Zou ; C. Cao
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 365 –374
- DOI: 10.1049/iet-cta.2011.0039
- Type: Article
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p.
365
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This study presents an eigenvalue assignment control architecture for a class of linear time-varying (LTV) systems in the presence of time-varying disturbances. Eigenvalue assignment architecture is presented as a way to achieve feedback stabilisation for LTV disturbed systems. With an input compensator design, the output of slowly LTV systems with disturbances can practically track the reference. Moreover, the implementation of the proposed eigenvalue assignment technique in practice has been demonstrated by using adaptive estimation of time-varying disturbances. - Author(s): F. Yan and J. Wang
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 375 –383
- DOI: 10.1049/iet-cta.2010.0745
- Type: Article
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This study deals with the non-equilibrium transient trajectory shaping problem for non-linear, strict feedback, single-input–single-output systems by a three-stage switching control method. Through this control method, the non-linear system output tracking error can be constrained within a set of properly pre-designed boundaries when it is converging to the equilibrium point. In particular, the three-stage switching control method imposes a constant bound (the first stage), two exponentially converging time-varying functions (the second stage), and a smaller constant bound (the third stage) as the tracking error boundary in each of the three stages, respectively. By designing control laws separately in the corresponding stages, the trajectory of the system tracking error can be assured within the boundaries during transient period. The bound of the control input magnitude can be determined with the respective control law at each stage and consequently establish the tradeoff between system transient performance and the available control resource. Numerical examples are utilised to show the effectiveness of the technique. - Author(s): K. Xiong ; C.Q. Zhang ; L.D. Liu
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 384 –393
- DOI: 10.1049/iet-cta.2011.0086
- Type: Article
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p.
384
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A new method is proposed to identify the parameters of the low-frequency error (LFE) of the star sensor. The LFE is one of the most dominant error sources in the high-precision attitude determination system for the satellite. It is shown that the gyroscope bias estimate, which is obtained by processing the star sensor measurement in the stellar inertial attitude determination Kalman filter, represents the variation in the LFE. As the LFE is a periodic signal, the LFE parameters can be identified from the frequency spectrum of the gyroscope bias estimate. The identified parameters are used for the LFE compensation, such that the effect of the LFE to the attitude estimate is partly eliminated. The efficiency of the proposed method is illustrated through numerical simulations with the use of the real gyroscope data. - Author(s): A.H. Tan and T.T.V. Yap
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 394 –402
- DOI: 10.1049/iet-cta.2010.0607
- Type: Article
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394
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A novel method to design perturbation signals for the identification of multivariable ill-conditioned systems is presented. The method uses multisine signals to simultaneously perturb all input–output channels of the system. The correlated harmonic component is set according to a virtual transfer function between inputs, which is defined based on the case where equal perturbation is achieved in all directions of the output state-space. This ensures that all singular values of the system, as well as the relative gain array at steady-state, are identified with a sufficiently high accuracy – a criterion important for model-based control. A case study based on a simulated multizone furnace is used to illustrate the superiority of the proposed technique over a competing design. - Author(s): N.C. Stuckey ; J.R. Vasquez ; S.R. Graham ; K.M. Hopkinson ; P.S. Maybeck
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 403 –411
- DOI: 10.1049/iet-cta.2010.0432
- Type: Article
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p.
403
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Although transmission control protocol (TCP) is a proven protocol in networks with congestion-dominated packet losses, it is a poor match for mobile networks with bit-error-dominated packet losses. This article considers a control theoretic approach for more effective flow control in reliable network transmissions. An extended Kalman filter is developed to estimate two key network state indicators: individual queue sizes and packet arrival rates to each queue. A source node estimates these parameters for each of the downstream queues currently servicing packet streams originating from itself. These estimates can be used by an linear quadratic Gaussian (LQG) ‘steady-state’ linear perturbation proportional-plus-integral (PI) controller to regulate the size of downstream queues by altering the packet rate sent towards a particular downstream queue. Although this work demonstrates the effects of a single controller, it is anticipated that a network wide deployment could achieve significant throughput and stability benefits. The primary contributions of this work include: (a) development of the necessary Kalman filter theory, (b) design of a network state estimator using a transient queue behaviour model, (c) equations for the LQG synthesis of a steady-state linear perturbation PI controller and (d) demonstration of the resulting controller performance, which shows significant improvement over traditional TCP implementations. - Author(s): S. Maza ; C. Simon ; T. Boukhobza
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 412 –419
- DOI: 10.1049/iet-cta.2011.0166
- Type: Article
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p.
412
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This study is concerned with the impact of components’ failure on the controllability of an automated system when operating. The work proposes a method based on a graph-theoretic approach to study the controllability of systems whose only the structure is known. The study focuses on the actuators’ failures and assumes that their probabilities are known. The controllability conditions are first recalled for a linear system. One study’s originality is to express the property as a Boolean equation of the actuators’ set involved in the condition. A second originality of the study is to extend the definition of the reliability to cover structural properties like the controllability and to assess the probability to conserve or to lose it from the components’ reliability. - Author(s): D. Tian ; D. Yashiro ; K. Ohnishi
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 420 –429
- DOI: 10.1049/iet-cta.2011.0164
- Type: Article
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p.
420
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Haptic transmission, which is realised by master–slave robots system, is a challenging research to extend human hands. However, the communication delay is a serious problem which degrades the performance and causes instability to the system. In this paper, a new bilateral control law with weighting control is proposed to achieve high-performance haptic transmission under varying communication delay. This method weights the force control and the position control in the master robot according to the estimation of environment stiffness in the slave one. A virtual spring is proposed and inserted into the stiffness estimation algorithm to guarantee the availability for hard environment. The stability is analysed by considering the passivity of the master–slave robots system under the proposed control law. Finally, the validity of the proposal is confirmed by experiments. - Author(s): F.-L. Sun ; Z.-H. Guan ; X.-H. Zhang ; J.-C. Chen
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 430 –436
- DOI: 10.1049/iet-cta.2010.0466
- Type: Article
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p.
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Stability of the non-linear systems with external inputs is an important problem in control theory and engineering. Input-to-state stability (ISS) is one of the stability concepts that have been introduced to non-linear systems. This study extends the ISS to a more general case, namely, exponential-weighted input-to-state stability (eλt-weighted ISS). By employing the Lyapunov function and Lyapunov–Razumikhin techniques, eλt-weighted ISS is proposed and studied for the impulsive switched hybrid systems with and without time delay. An example and simulation results are given to illustrate the effectiveness of the obtained theoretical results.
Iterative-learning-based torque-ripple compensation in a transverse flux motor
Covariance control for stochastic uncertain multivariable systems via sliding mode control strategy
Design of proportional–derivative feedback and input shaping for control of inertia plants
Eigenvalue assignment for linear time-varying systems with disturbances
Input constrained non-equilibrium transient trajectory shaping via a three-stage control method for a class of non-linear systems
Identification of star sensor low-frequency error parameters
Signal design for the identification of multivariable ill-conditioned systems using virtual transfer function between inputs
Stochastic control of computer networks
Impact of the actuator failures on the structural controllability of linear systems: a graph theoretical approach
Haptic transmission by weighting control under time-varying communication delay
Exponential-weighted input-to-state stability of hybrid impulsive switched systems
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- Author(s): M. Liu ; D.W.C. Ho ; Y. Niu
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 437 –447
- DOI: 10.1049/iet-cta.2010.0534
- Type: Article
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p.
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This study investigates the problem of observer-based control for linear time-invariant system with limited communication capacity. The system states are unavailable and the system outputs are subject to logarithmic quantisation, which can be regarded as outputs with disturbances. Traditional Luenberger observers and proportional and derivative observers are not effective to deal with such kind of estimation problems. A new estimation technique to cope with discontinuous quantised outputs is proposed such that the estimation of system states and quantisation error can be obtained simultaneously. In this design, the state variables of the derived error system are discontinuous at quantisation switching times, and traditional Lyapunov function cannot be used to perform the stability analysis. Hence, a new time-dependent Lyapunov functional and a generalised Newton–Leibniz formula are proposed to deal with this difficulty. A sufficient condition for the stability analysis of the error dynamics is established and an observer-based control scheme is proposed to stabilise the plant. Finally, a numerical example is presented to illustrate the effectiveness and applicability of the proposed technique. - Author(s): C. Peng
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 448 –453
- DOI: 10.1049/iet-cta.2011.0109
- Type: Article
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448
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This study introduces a new finite sum inequality to investigate the problem of delay-dependent stability analysis and controller synthesis for a discrete system with an interval time-varying input delay. By constructing a novel piecewise Lyapunov–Krasovskii functional and employing the proposed finite sum inequality to deal with sum items in the derivation of our results, simplified whereas improved delay-dependent stabilisation criteria are obtained with the less number of linear matrix inequalities scalar decision variables. Numerical examples show the effectiveness of the proposed method. - Author(s): S.P. Hou and C.C. Cheah
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 454 –460
- DOI: 10.1049/iet-cta.2011.0115
- Type: Article
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p.
454
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This study presents a dynamic compound shape control for a swarm of robots. A new definition of dynamic potential energy associated with the desired compound shape, which is the union of various basic shapes, is presented. Each basic shape is specified by the corresponding inequality functions. With this new definition, a variety of interesting compound shapes, which are difficult to form by the existing methods, can be easily formed. The swarm can also change their shape and size during the course of movement with the aid of a time-varying transformation matrix. A Lyapunov-like function is presented for stability analysis of the swarm systems. Simulation results are presented to illustrate the performance of the proposed method. - Author(s): R. Yu ; Q. Zhu ; G. Xia ; Z. Liu
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 461 –466
- DOI: 10.1049/iet-cta.2011.0176
- Type: Article
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p.
461
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This study concerns the robust tracking control problem for an underactuated surface vessel with parameter uncertainties. In recent work by McNinch and collegeaues, a sliding mode control (SMC) law is presented and experimentally implemented for trajectory tracking of an underactuated autonomous surface vessel. The authors believe, however, their theory formulation involves essential flaws. Motivated by the obtained result by McNinch and collegeaues, a new revised SMC law is proposed under the same assumptions. The control law is similarly developed by introducing a first-order sliding surface in terms of surge tracking errors and a second-order surface in terms of lateral motion tracking errors; however, the desired surge and sway velocities are presented as a new form to guarantee the convergence of position tracking errors. Simulation results are provided to validate their method. - Author(s): S.J. Yoo
- Source: IET Control Theory & Applications, Volume 6, Issue 3, p. 467 –473
- DOI: 10.1049/iet-cta.2011.0150
- Type: Article
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p.
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This study proposes an adaptive tracking control approach for non-linearly parameterised pure-feedback systems with completely non-affine property. Using the parameter separation technique, a state predictor is developed for deriving adaptive laws of non-linearly connected parameters. The proposed adaptive control system is designed by a combination of the backstepping and singular perturbation concept where the virtual controllers and the actual controller are defined as solutions of fast dynamic equations which accomplish the time-scale separation between the state predictor and controllers. The Lyapunov-based adaptive laws guarantee that the predictor states track the system states with bounded errors, and thus the tracking error between the system output and the desired signal is bounded. Finally, simulation results are provided to illustrate the effectiveness of the proposed control system.
Observer-based controller design for linear systems with limited communication capacity via a descriptor augmentation method
Improved delay-dependent stabilisation criteria for discrete systems with a new finite sum inequality
Dynamic compound shape control of robot swarm
Sliding mode tracking control of an underactuated surface vessel
Adaptive control of non-linearly parameterised pure-feedback systems
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