Online ISSN
1751-8652
Print ISSN
1751-8644
IET Control Theory & Applications
Volume 5, Issue 18, 8 December 2011
Volumes & issues:
Volume 5, Issue 18
8 December 2011
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- Author(s): J. Yang ; W.-H. Chen ; S. Li
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2053 –2062
- DOI: 10.1049/iet-cta.2010.0616
- Type: Article
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p.
2053
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(10)
Robust control of non-linear systems with disturbances and uncertainties is addressed in this study using disturbance observer-based control (DOBC) technique. In this framework, the ‘disturbance’ is a generalised concept, which may include external disturbances, unmodelled dynamics and system parameter perturbations. The existing DOBC methods were only applicable for the case where disturbances and uncertainties satisfy so-called matching condition, that is, they enter the system in the same channel as the control inputs. By appropriately designing a disturbance compensation gain vector in the composite control law, a non-linear disturbance observer-based robust control method is proposed in this study to attenuate the mismatched disturbances and the influence of parameter variations from system output channels. The proposed method is applied to a missile system with non-linear dynamics in the presence of various uncertainties and external disturbances. Simulation shows that, compared with the widely used non-linear dynamic inversion control (NDIC) and NDIC plus integral action methods, the proposed method provides much better disturbance attenuation ability and stronger robustness against various parameter variations. - Author(s): A. Mohammadi ; M. Tavakoli ; H.J. Marquez
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2063 –2074
- DOI: 10.1049/iet-cta.2010.0517
- Type: Article
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2063
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(12)
Teleoperation systems are subject to different types of disturbances. Such disturbances, when unaccounted for, may cause poor performance and even instability of the teleoperation system. This study presents a novel non-linear bilateral control scheme using the concept of ‘disturbance observer-based control’ for non-linear teleoperation systems. Lumping the effects of dynamic uncertainties and external disturbances into a single disturbance term enables us to design a disturbance observer to suppress these disturbances and alleviate their adverse effects on the teleoperation system. A disturbance observer-based control law is proposed for non-linear teleoperation systems which will guarantee global asymptotic force tracking and global exponential position and disturbance tracking when the bilateral teleoperation system is experiencing slow-varying disturbances. In the case of fast-varying disturbances, the tracking errors are shown to be globally uniformly ultimately bounded, with an ultimate bound that can be made as small as desired using the design parameters. Simulations are presented to show the effectiveness of the proposed approach. - Author(s): S.-H. Hur ; R. Katebi ; A. Taylor
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2075 –2088
- DOI: 10.1049/iet-cta.2010.0557
- Type: Article
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2075
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(14)
This study reports the modelling of a plastic film extrusion process and the development and implementation of a model-based fault monitoring system. The model is mainly derived from the first-principles of chemical and mechanical engineering in addition to empirical knowledge related to the behaviour of polymer and designed to provide a safe offline platform for developing monitoring and control systems. The fault monitoring system constructs a residual via parity relations, and a multi-objective optimisation problem must therefore be solved in order that the residual can be sensitive to faults but insensitive to disturbances and modelling errors. In this study, a genetic algorithm is exploited for solving this multi-objective optimisation problem, and the resulting fault monitoring system is applied to the model. Simulation results demonstrate that various types of faults can be detected and diagnosed successfully. - Author(s): J. Qin ; W.X. Zheng ; H. Gao
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2089 –2097
- DOI: 10.1049/iet-cta.2010.0397
- Type: Article
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2089
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This study revisits the sampled-data consensus algorithm for agents modelled by double-integrator dynamics under both fixed and dynamic network topology. Totally different methods are employed to perform the convergence analysis. Under certain assumptions on the sampling period and the velocity damping gain, a necessary and sufficient condition is given for the agents under fixed network topology to reach consensus. In addition, the method employed in performing the convergence analysis for the fixed case can be further extended to achieve a similar result as that in the existing literature for the dynamical case in a more general setting. The consensus equilibria are also analysed for the system evolving under a special class of dynamic network topology. - Author(s): D. Meng and Y. Jia
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2098 –2110
- DOI: 10.1049/iet-cta.2011.0047
- Type: Article
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2098
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(13)
This study is devoted to the finite-time consensus problem of multi-agent systems with higher-order dynamics, and presents a framework for effectively constructing distributed protocols which incorporate iterative learning control actions into output feedbacks. Using a terminal updating law, the feedback iterative learning protocols are shown with the ability to enable all agents to achieve the consensus at a finite time that can be prescribed. Furthermore, a model reference approach is employed to improve the feedback iterative learning protocols such that all agents can be guaranteed to achieve the consensus at any given desired terminal output. In both cases, necessary and sufficient conditions are provided which can also offer design criteria for the learning gains to ensure consensus. Simulation results are included to verify the effectiveness of the proposed theoretical results. - Author(s): E. Yime ; R. Saltaren ; C. Garcia ; J.M. Sabater
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2111 –2119
- DOI: 10.1049/iet-cta.2010.0622
- Type: Article
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2111
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This study deals with the dynamic modelling and task space control of the Stewart–Gough platform. The dynamic equations were obtained using the virtual work approach, and include all the 13 presented in the platform, that is, two bodies per each leg and the upper ring. The results show some similarities in the dynamic model of serial and parallel robots, making it possible to extend the control theory of serial robot to the Stewart–Gough platform. To show this, an adaptive control law is proposed to control the parallel platform. The law is obtained from the dynamical equation and its performance is tested using a sinusoidal path for position and orientation of the upper ring of parallel robot. Some additional simulations are carried out to demonstrate a well-behaved controller. - Author(s): S.I. Han and J.M. Lee
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2120 –2141
- DOI: 10.1049/iet-cta.2010.0389
- Type: Article
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2120
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(22)
A model-free control scheme with the elasto-plastic friction observer is presented for robust and high-precision positioning of a robot manipulator. The traditional model-based adaptive controller requires information on the robotic dynamics in advance and thus undergoes robustness problem because of complex dynamics and non-linear frictions of a robot system. This problem is overcome by an employed model-free recurrent cerebellar model articulation controller (RCMAC) system and friction estimator for friction and uncertainty compensation of a robot manipulator. The adaptive laws of the RCMAC networks to approximate an ideal equivalent sliding mode control law and adaptive friction estimation laws based on the elasto-plastic friction model are derived based on the Lyapunov stability analysis. To guarantee stability and increase convergence speed of the RCMAC network, the optimal learning rates are obtained by the fully informed particle swarm (FIPS) algorithm. The robust positioning performance of the proposed control scheme is verified by simulation and experiment for the Scorbot robot in the presence of the joint dynamic friction and uncertainty. - Author(s): Y. Bolea ; V. Puig ; J. Blesa
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2142 –2155
- DOI: 10.1049/iet-cta.2010.0088
- Type: Article
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(14)
Practical control problems often deal with parameter-varying uncertain systems that can be described by a first-order-plus-delay (FOPD) model. In this paper, a new approach to design gain-scheduled robust linear parameter varying (LPV) propotional–intergral derivative controllers with pole placement constraints through linear matrix inequalities (LMI) regions is proposed. The controller structure includes a Smith Predictor (SP) to deal with the delays. System parameter variations are measured online and used to schedule the controller and the SP. Although the known part of the delay is compensated with the ‘delay scheduling’ SP, the proposed approach allows to consider uncertainty in the delay estimation. This uncertainty is taken into account in the controller design as an unstructured dynamic uncertainty. Finally, two applications are used to assess the proposed methodology: a simulated artificial example and a simulated physical system based on an open canal system used for irrigation purposes. Both applications are represented by FOPD models with large and variable delays as well as parameters that depend on the operating conditions. - Author(s): Y. Luo ; H. Chao ; L. Di ; Y.Q. Chen
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2156 –2167
- DOI: 10.1049/iet-cta.2010.0314
- Type: Article
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In this study, a fractional order (PI)λ controller is developed and implemented to improve the flight control performance and robustness of a small fixed-wing unmanned aerial vehicle (UAV). The decoupled roll-channel control is realised under certain conditions and tested using the designed controllers in this study. The inner closed-loop system of the roll-channel is approximately identified as a first-order plus time delay model using the flight test data. For comparison purpose, an integer-order PI controller is designed following the modified Ziegler–Nichols (MZNs) tuning rule, based on this identified roll-channel control model. According to three design pre-specifications, the integer-order proportional integral derivative (PID), fractional-order PIλ and (PI)λ controllers are designed for the roll-channel flight control system of a small fixed-wing UAV. These three designed controllers share the same gain crossover frequency and phase margin settings for fair comparisons. From both simulation and real flight experiments, the two designed fractionalorder controllers outperform the MZNs PI and the designed integer-order PID controllers. The designed (PI)λ controller can achieve even better performance than the designed PIλ controller. - Author(s): L. Giovanini
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2168 –2178
- DOI: 10.1049/iet-cta.2010.0550
- Type: Article
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(11)
The supervisory control problem is analysed as an online robust design problem using switching to select the relevant models for designing the control law. The proposed supervisory control algorithm is based on the integration of concepts used in supervisory adaptive control, robust control and receding horizon control. It involves a two-stage adaptive control algorithm: (i) the identification of a time-varying set of models ℒ(k), from the set of admissible models ℒ, that explains the input–output behaviour of the system, followed by (ii) the design of the control law using a parametric linear optimisation problem. The authors show that under the proposed supervisory control algorithm, the system output remains bounded for any bounded disturbance. The use of superstability concepts, together with certain assumptions on ℒ, allows us to establish overall performance and robust stability guarantees for the supervisory scheme and to include constrains in the closed-loop variables as well as in the controller structure. The relevant features of the proposed control algorithm are demonstrated in a numerical simulation. - Author(s): S.H. Esfahani and A.K. Sichani
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2179 –2190
- DOI: 10.1049/iet-cta.2010.0480
- Type: Article
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This study is concerned with the problem of output feedback fuzzy H∞-tracking control design for non-linear systems. The non-linear system is represented by using the Takagi and Sugeno fuzzy modelling scheme. The final controller takes the form of parallel distributed compensation. The final controller results in the stability of the closed-loop system and the H∞ tracking of a bounded reference signal. Existing approaches to this problem available in the literature implement an observer-based output feedback controller. These approaches lead to a non-linear matrix inequality condition, which can be partially solved by applying a double-step algorithm. The approach presented in this study is based on a new structure for the controller. In this approach, the problem formulation and the method of finding the controller parameters involve a single-step linear matrix inequality form. Moreover, it is possible to easily find the optimal controller from the whole solution set. The approach is also extended to the case of non-linear time-delay systems. Finally, two examples are given to illustrate the effectiveness of the obtained results in comparison with the existing methods.
Non-linear disturbance observer-based robust control for systems with mismatched disturbances/uncertainties
Disturbance observer-based control of non-linear haptic teleoperation systems
Model-based fault monitoring of a plastic film extrusion process
Convergence analysis for multiple agents with double-integrator dynamics in a sampled-data setting
Finite-time consensus for multi-agent systems via terminal feedback iterative learning
Robot based on task-space dynamical model
Friction and uncertainty compensation of robot manipulator using optimal recurrent cerebellar model articulation controller and elasto-plastic friction observer
Gain-scheduled Smith proportional–integral derivative controllers for linear parameter varying first-order plus time-varying delay systems
Lateral directional fractional order (PI)α control of a small fixed-wing unmanned aerial vehicles: controller designs and flight tests
Robust adaptive control using multiple models, switching and tuning
Improvement on the problem of optimal fuzzy H∞-tracking control design for non-linear systems
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- Author(s): R. Zhang ; Y. Zhang ; C. Hu ; M.Q.-H. Meng ; Q. He
- Source: IET Control Theory & Applications, Volume 5, Issue 18, p. 2191 –2199
- DOI: 10.1049/iet-cta.2011.0194
- Type: Article
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2191
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(9)
This study is concerned with the problem of ℋ∞ filtering for two-dimensional (2-D) Markovian jump systems with delays varying in given ranges. The 2-D jump systems under consideration are described by the well-known Fornasini–Marchesini models with state delays. Different from conventional techniques using the discrete Jensen inequality which guides various delay-dependent conditions for delayed systems, a precise upper estimation is presented via a rigorous treatment of the lower bound for a linear combination of positive-definite matrices with reciprocal coefficients. By carefully selecting components of an augmented vector with algebraic constraints, a delay-range-dependent approach is proposed for the design of ℋ∞ filters such that the filtering error system is stochastically stable and has a prescribed ℋ∞ disturbance attenuation level. A numerical example is provided to illustrate the effectiveness of the developed method.
Delay-range-dependent ℋ∞ filtering for two-dimensional Markovian jump systems with interval delays
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