Your browser does not support JavaScript!
http://iet.metastore.ingenta.com
1887
banner image
image of Volume 5, Issue 11
Online ISSN 1751-8652 Print ISSN 1751-8644

IET Control Theory & Applications

Volume 5, Issue 11, 21 July 2011

Volumes & issues:

Volume 5, Issue 11

21 July 2011

Show / Hide details

  • Regular Papers

    • L2-optimal identification of errors-in-variables models based on normalised coprime factors
      • Author(s): L.-H. Geng ; D.-Y. Xiao ; T. Zhang ; J.-Y. Song ; Y.-Q. Che
      • Source: IET Control Theory & Applications, Volume 5, Issue 11, p. 1235 –1242
      • DOI:  10.1049/iet-cta.2010.0012
      • Type: Article
      • + Show details - Hide details
      • p. 1235 –1242 (8)
        A frequency-domain method is proposed to cope with errors-in-variables model (EIVM) identification when the input and output noises are bounded by a certain upper bound. Based on normalised coprime factor model (NCFM) description, L2-optimal approximate models for an EIVM are first established, which consist of a system NCFM and its complementary inner factor model (CIFM) characterising the noises. Then the v-gap metric criterion is minimised to optimise a system coprime factor model, from which the system NCFM can be obtained by normalisation. During the optimisation, a priori information on the system poles can be fully used to reduce the overfitting effect caused by the noises. The associated noise CIFM can be readily constructed from the resulting estimated system NCFM by a model transformation. Compared with related identification methods, the system model can be effectively solved by linear matrix inequalities and the associated noise model can then be directly built. Finally, numerical simulations are given to demonstrate the effectiveness of the proposed method.
        Add to favourites
        Export citations
      Fault-tolerant synthesis controller design for a flight-tracking system
      • Author(s): C.-S. Liu ; B. Jiang ; S.-J. Zhang
      • Source: IET Control Theory & Applications, Volume 5, Issue 11, p. 1243 –1254
      • DOI:  10.1049/iet-cta.2010.0164
      • Type: Article
      • + Show details - Hide details
      • p. 1243 –1254 (12)
        This study presents a fault-tolerant synthesis controller design scheme for a class of non-linear systems with minimised performance index. A radial basis function (RBF) neural network with the online-updated centre and the width vector of Gaussian function is utilised to approximate the unknown non-linear dynamics. An updating rule is designed to estimate actuator failure. Based on estimated non-linear function and fault knowledge, a synthesis controller is developed with an optimal control action and a sliding-mode control action that is used to eliminate the effect of neural network approximation error. The sufficient condition for the optimal performance is given in terms of non-linear fault-dependent quadratic matrix inequality. Then, the solution of matrix inequality is reduced to solve off-line a fault-free Riccati equation. The feasibility of proposed method is demonstrated by a spacecraft model.
        Add to favourites
        Export citations
      Fault reconstruction and state estimation with sliding mode observers for Lipschitz non-linear systems
      • Author(s): K.C. Veluvolu  and  Y.C. Soh
      • Source: IET Control Theory & Applications, Volume 5, Issue 11, p. 1255 –1263
      • DOI:  10.1049/iet-cta.2010.0171
      • Type: Article
      • + Show details - Hide details
      • p. 1255 –1263 (9)
        This study considers the design of sliding mode observers for fault reconstruction and state estimations. In the sliding-mode observer design the switching terms are designed such that the faults are tracked and reconstructed from their respective sliding surfaces. As the fault reconstruction relies only on output estimation error, the reconstruction can be performed online with the state estimation. The stability condition for the reduced-order system is analysed and the feedback gain is designed such that the reduced-order system is stable. An application example to robotic manipulator is examined to demonstrate the effectiveness of the proposed method in reconstruction of unknown inputs/faults.
        Add to favourites
        Export citations
      Discretisation method and stability criteria for non-linear systems under discrete-time time delay control
      • Author(s): J.H. Jung ; P.H. Chang ; D. Stefanov
      • Source: IET Control Theory & Applications, Volume 5, Issue 11, p. 1264 –1276
      • DOI:  10.1049/iet-cta.2010.0181
      • Type: Article
      • + Show details - Hide details
      • p. 1264 –1276 (13)
        Time delay control (TDC) for non-linear systems has rapidly drawn attention as a result of its unusually robust performance and yet its extraordinarily compact form. In many real applications, TDC has been implemented digitally and the time delay, λ, was set to the sampling period of the control system, which is a constant during the control process. The existing stability analysis, however, has been made based on the assumption of the continuous-time TDC and infinitesimal time delay (λ→0). The assumption not only fails to reflect the reality that the closed-loop system (CLS) is a sampled-data system, but also leads to a stability criterion in which important parameters, such as λ, are absent. In this paper, therefore, sufficient stability criteria for a non-linear system based on the premise of discrete-time TDC and λ that is equal to the sampling period are presented. To this end, we have first proposed a discretization method to derive the approximate discrete-time model of CLS. Then by using the model and the concepts of consistency and Lyapunov stability, we have derived stability criteria for the exact discrete-time model of CLS. The suggested criteria consist of the sampling period and other parameters of TDC. These criteria have been verified by simulation results.
        Add to favourites
        Export citations
      Enumeration of lost states of a suboptimal control model of a well-known S3PR
      • Author(s): D.Y. Chao
      • Source: IET Control Theory & Applications, Volume 5, Issue 11, p. 1277 –1286
      • DOI:  10.1049/iet-cta.2010.0186
      • Type: Article
      • + Show details - Hide details
      • p. 1277 –1286 (10)
        Deadlocks halt a system completely causing a significant financial loss to a company. To resolve this problem, deadlock prevention (by adding monitors to problematic siphons) has been quite a popular research. Uzam and Zhou applied region analysis to a well-known S3PR to achieve a near-maximum permissive control policy. However, they do not list the lost states, which is essential to improve the control model. The lost states can be obtained by reachability analysis, which is a rather tedious process. Without theory, one could waste much time failing to reach more states and there is no effective solution so far in the literature. Thus, it is important to find out the condition where more states can be reached. If no more states can be reached, one should simply stop and remain satisfied with the suboptimal model obtained or employ weighted control arcs to reach more states. It is desirable to compute the gain of states without the costly reachability analysis when an alternative control policy is employed. It is interesting to explore which live states are lost in the first-met bad marking (FBM) method, which has not yet been available in the literature. This study presents the very first method to compute all lost states based on invariant without reachability analysis.
        Add to favourites
        Export citations
      Intelligent double integral sliding-mode control for five-degree-of-freedom active magnetic bearing system
      • Author(s): F.-J. Lin ; S.-Y. Chen ; M.-S. Huang
      • Source: IET Control Theory & Applications, Volume 5, Issue 11, p. 1287 –1303
      • DOI:  10.1049/iet-cta.2010.0237
      • Type: Article
      • + Show details - Hide details
      • p. 1287 –1303 (17)
        This study presents a decentralised intelligent double integral sliding-mode control (IDISMC) system, which consists of five IDISMCs, to regulate and stabilise a fully suspended five-degree-of-freedom (DOF) active magnetic bearing (AMB) system. The system structure and drive system with differential driving mode (DDM) are introduced first. Then, the decoupled dynamic model of the five-DOF AMB is analysed for the design of the decentralised control. Moreover, a decentralised integral sliding-mode control (ISMC) system is designed based on the decoupled dynamic model to control the five-DOF AMB considering the existences of the uncertainties. Furthermore, since the control characteristics of the five-DOF AMB are highly non-linear and time varying, the decentralised IDISMC system is proposed to further improve the control performance of the five-DOF AMB. In each IDISMC, the adopted double integral sliding surface reinforces the control law with the integral (I) control feature. In addition, the control gains of the IDISMC can be adjusted on-line and the system uncertainty can also be observed simultaneously by using of a modified proportional–integral–derivative neural network (MPIDNN) observer. Thus, the proposed IDISMC combines the merits of the ISMC, adaptive control and neural network (NN). Finally, the experimental results illustrate the validities of the proposed control systems using various operating conditions.
        Add to favourites
        Export citations
      Exponential stabilisation of periodic orbits for running of a three-dimensional monopedal robot
      • Author(s): K. Akbari Hamed ; N. Sadati ; W.A. Gruver ; G.A. Dumont
      • Source: IET Control Theory & Applications, Volume 5, Issue 11, p. 1304 –1320
      • DOI:  10.1049/iet-cta.2010.0292
      • Type: Article
      • + Show details - Hide details
      • p. 1304 –1320 (17)
        This study presents a motion planning algorithm to generate a feasible periodic solution for a hybrid system describing running by a three-dimensional (3-D), three-link, three-actuator, monopedal robot. In order to obtain a symmetric running gait along a straight line, the hybrid system consists of two stance phases and two flight phases. The motion planning algorithm is developed on the basis of a finite-dimensional optimisation problem with equality and inequality constraints. By extending the concept of hybrid zero dynamics to running, the authors propose a time-invariant control scheme that is employed at two levels to locally exponentially stabilise the generated periodic solution for running of the monopedal robot. The first level includes stance and flight phase feedback laws as within-stride controllers to create attractive parameterised zero dynamics manifolds. In order to render the zero dynamics manifolds hybrid invariant and stabilise the desired periodic orbit for the closed-loop hybrid system, takeoff and impact event-based controllers update the parameters of the within-stride controllers at the second level. This strategy results in a reduced-order hybrid system for which the stability analysis of the periodic orbit can be performed by a 5-D restricted Poincaré return map.
        Add to favourites
        Export citations
      Design and analysis of a continuous hybrid differentiator
      • Author(s): X. Wang  and  H. Lin
      • Source: IET Control Theory & Applications, Volume 5, Issue 11, p. 1321 –1334
      • DOI:  10.1049/iet-cta.2010.0330
      • Type: Article
      • + Show details - Hide details
      • p. 1321 –1334 (14)
        In this study, a continuous hybrid differentiator is presented based on a strong Lyapunov function. The differentiator design can not only sufficiently reduce the chattering phenomenon of derivative estimation by introducing a perturbation parameter, but the dynamical performances are also improved by adding linear correction terms to the non-linear ones. Moreover, strong robustness ability is obtained by integrating sliding-mode items and the linear filter. Frequency analysis is applied to compare the hybrid continuous differentiator with a sliding-mode differentiator. The merits of the continuous hybrid differentiator include the excellent dynamical performances, restraining noises sufficiently and avoiding the chattering phenomenon.
        Add to favourites
        Export citations
      Global practical stabilisation of large-scale hydraulic networks

Most viewed content for this Journal

Article
content/journals/iet-cta
Journal
5
Loading

Most cited content for this Journal

Print this page
This is a required field
Please enter a valid email address