Online ISSN
1751-8652
Print ISSN
1751-8644
IET Control Theory & Applications
Volume 5, Issue 13, 8 September 2011
Volumes & issues:
Volume 5, Issue 13
8 September 2011
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- Author(s): G. Shen ; G.-M. Lv ; Z.-M. Ye ; D.-C. Cong ; J.-W. Han
- Source: IET Control Theory & Applications, Volume 5, Issue 13, p. 1471 –1483
- DOI: 10.1049/iet-cta.2010.0198
- Type: Article
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p.
1471
–1483
(13)
This study presents a combined control strategy for electrohydraulic shaking table (EST) systems. The position frequency bandwidth of the EST system is so low that it results in a worse tracking accuracy during seismic tests, particularly when the frequency bandwidth of the desired position signal exceeds the frequency bandwidth of the EST position closed-loop system. In order to improve the position tracking accuracy, a combined control strategy is proposed, which utilises a recursive extended least square (RELS) algorithm to offline or online estimate the position closed-loop transfer function of the EST system, then uses the estimated transfer function to offline or online yield a feedforward inverse controller for extending the position frequency bandwidth, finally, employs a minimal control synthesis (MCS) algorithm to further improve the tracking performance of the EST position system. The proposed control strategy combines the merits of offline or online feedforward inverse compensation and adaptive control. The procedure of the proposed control strategy is programmed in MATLAB/Simulink, and is then compiled to a real-time PC with Microsoft Visual Studio.NET for implementation. A better tracking performance for the proposed control strategy is achieved in experiments by using actual EST. - Author(s): X. Lai ; A. Zhang ; J. She ; M. Wu
- Source: IET Control Theory & Applications, Volume 5, Issue 13, p. 1484 –1493
- DOI: 10.1049/iet-cta.2010.0210
- Type: Article
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p.
1484
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(10)
This study discusses the motion control of an underactuated 3-link gymnast robot moving in a vertical plane. The motion space of the robot is divided into two subspaces (swing-up area, attractive area), and a different type of motion control (swing-up control, balancing control) is applied to each. To enable efficient motion control, the swing-up area is further divided into two subspaces, and a different control law is designed for each. These two laws are employed sequentially and make the robot enter the attractive area with a suitable posture and energy. In the attractive area, the balancing-control law captures the robot and stabilises it at the straight-up equilibrium position. Simulations and a comparison demonstrate the validity of this control method. - Author(s): Z. Kowalczuk and J. Kozlowski
- Source: IET Control Theory & Applications, Volume 5, Issue 13, p. 1494 –1508
- DOI: 10.1049/iet-cta.2010.0310
- Type: Article
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1494
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A consequent and consistent continuous-time approach to system parameter estimation is introduced. Estimation algorithms, the underlying quality criteria and models of identified systems are described in the continuous-time domain, while suitable discretising operations are performed solely for the purpose of ultimate numerical realisation of estimation procedures. The considered indices of estimation quality take the form of integrals of absolute prediction errors rather than a common form of integrals or sums of square errors. In order to overcome the problem of analytical minimisation of such non-differentiable criteria, an approximate method is derived and applied in practical implementation of the resultant estimation schemes. Specific weighting mechanisms utilised in the algorithms allow for tracking the time-variant parameters of non-stationary systems, while with the employed instrumental variable the accuracy of estimates gets improved by means of suppression of the asymptotic bias. Following the so-called direct approach, an auxiliary discrete-time model that retains ‘physical’ parameterisation is obtained based on ‘finite-horizon’ spline-based integration of both sides of the presumed differential equation. In this aspect, application of splines makes the respective discrete-time processing resistant to cumulation of numerical errors. The attached numerical examples demonstrate the performance of the discussed estimation routines. - Author(s): M.S. Mahmoud and M.M. Hassan Hamid
- Source: IET Control Theory & Applications, Volume 5, Issue 13, p. 1509 –1522
- DOI: 10.1049/iet-cta.2010.0344
- Type: Article
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p.
1509
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(14)
Several studies have considered control theory tools for traffic control in communication networks, including congestion control in internet protocol routers. In this work, classification of congestion control schemes and their mechanisms are discussed. Buffer and queue management mechanisms are compared. Dynamic transmission control protocol (TCP) model for single and multiple routers are derived and its stability behaviour is further examined. An observer-based feedback control design method is provided to address the traffic monitoring issue in TCP/active queue management (AQM) networks. Owing to several propagation delays and the queuing delay, the set TCP/AQM is modelled as a multiple delayed system of a particular form. Simulation studies are given to illustrate the analytical development for single and multi-routers. - Author(s): M. Soodavi ; J. Ghaisari ; F. Sheikholeslam
- Source: IET Control Theory & Applications, Volume 5, Issue 13, p. 1523 –1527
- DOI: 10.1049/iet-cta.2010.0421
- Type: Article
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p.
1523
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(5)
State-dependent switched systems constitute a major group of hybrid systems. ℒ2-gain property for these systems is analysed in this study. A theorem is proposed, which can be used to determine an upper-bound for the ℒ2-gain of such systems. Multiple Lyapunov functions play a key role in applying the theorem. By using the sum of squares technique, a practical method is provided to compute these functions. ℒ2-gain analysis of switched linear systems is performed based on linear matrix inequalities, as well. Illustrative examples indicate the effectiveness of the results. - Author(s): N. Sadati ; G.A. Dumont ; K.Akbari Hamed ; W.A. Gruver
- Source: IET Control Theory & Applications, Volume 5, Issue 13, p. 1528 –1543
- DOI: 10.1049/iet-cta.2010.0512
- Type: Article
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1528
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This study presents an online motion planning algorithm for generating reference trajectories during flight phases of a planar monopedal robot to transfer the configuration of the mechanical system from a specified initial pose to a specified final one. The algorithm developed in this research is based on the reachability and optimal control formulations of a time-varying linear system with input and state constraints. A two-level control scheme is developed for asymptotic stabilisation of a desired period-one orbit during running of the robot. Within-stride controllers, including stance and flight phase controllers, are employed at the first level. The flight phase controller is a feedback law to track the reference trajectories generated by the proposed algorithm. To reduce the dimension of the full-order model of running, the stance phase controller is chosen to be a parameterised time-invariant feedback law that produces a family of two-dimensional finite-time attractive and invariant submanifolds. At the second level, the parameters of the stance phase controller are updated by an event-based update law to achieve hybrid invariance and stabilisation. To illustrate the analytical results developed for the behaviour of the closed-loop system, a detailed numerical example is presented. - Author(s): J. Qiu ; M. Ren ; Y. Zhao ; Y. Guo
- Source: IET Control Theory & Applications, Volume 5, Issue 13, p. 1544 –1550
- DOI: 10.1049/iet-cta.2010.0519
- Type: Article
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The problem of active fault-tolerant control for vehicle active suspension systems in finite-frequency domain is investigated. First, a linear model of vehicle active suspension systems is given. With an observer-based fault estimator, a new H∞ controller in generalised internal model control architecture is proposed. By using the Kalman–Yakubovich–Popov lemma, sufficient conditions ensuring simultaneous finite-frequency estimation and control performance are derived. In terms of the linear matric inequalities, fault compensation is also proposed. Finally, simulation results are given to illustrate the effectiveness of the proposed results. - Author(s): C.-H. Huang ; W.-J. Wang ; C.-H. Chiu
- Source: IET Control Theory & Applications, Volume 5, Issue 13, p. 1551 –1560
- DOI: 10.1049/iet-cta.2010.0530
- Type: Article
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p.
1551
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This study proposes the motion control design of a real self-balancing transporter (SBT) which is fabricated in the laboratory. Based on the system-on-a-programmable-chip (SoPC) developmental architecture, two controls are implemented to achieve the objectives of balanced standing and moving with a constant velocity for the SBT. Based on the Takagi–Sugeno (T–S) fuzzy model of the SBT, the parallel distributed compensation (PDC) controller is employed to achieve the mentioned controls. Then an extra Mamdani If–Then fuzzy rule base (FRB) is built to cooperate with the PDC control such that the SBT not only can stand with balance, but can also move forward with a desired constant velocity ‘quickly’. The maximum emphasis is that there is a novel idea in the design of the If–Then FRB which is the relationship between the moving velocity error and the desired inclination angle of the SBT. Owing to the aids of the extra If–Then FRB, the time of the controlled response to reach the desired state is obviously shortened. This is the significant contribution of the study. Finally, both the fuzzy PDC and the If–Then FRB are realised in the SoPC platform for the real SBT. The performance and merit of the proposed control scheme is exemplified by conducting computer simulations and practical experiments.
Implementation of electrohydraulic shaking table controllers with a combined adaptive inverse control and minimal control synthesis algorithm
Motion control of underactuated three-link gymnast robot based on combination of energy and posture
Non-quadratic quality criteria in parameter estimation of continuous-time models
Feedback control methods for router management
ℒ2-gain analysis for switched systems with a state-dependent switching signal
Two-level control scheme for stabilisation of periodic orbits for planar monopedal running
Active fault-tolerant control for vehicle active suspension systems in finite-frequency domain
Velocity control realisation for a self-balancing transporter
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- Author(s): Z. Zhou ; C. Yang ; Q. Zhang ; M. Cai
- Source: IET Control Theory & Applications, Volume 5, Issue 13, p. 1561 –1567
- DOI: 10.1049/iet-cta.2010.0483
- Type: Article
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p.
1561
–1567
(7)
This study considers input-to-state stability (ISS) for descriptor systems with non-linear perturbations. The linear parts of the systems are allowed to be unstable. By using Lyapunov stability theory and linear matrix inequality (LMI), an LMI-based ISS criterion is derived. Furthermore, the trajectory boundedness of descriptor systems with non-linear perturbations is discussed by the newly developed result. Finally, an example is given to show the effectiveness of the proposed methods. - Author(s): A. Alenany ; H. Shang ; M. Soliman ; I. Ziedan
- Source: IET Control Theory & Applications, Volume 5, Issue 13, p. 1568 –1576
- DOI: 10.1049/iet-cta.2010.0585
- Type: Article
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p.
1568
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(9)
Subspace identification incorporating prior information has been proven to be effective in obtaining state-space models with improved accuracy. Available algorithms, however, can require prohibitively demanding computations. The incorporation of prior information, for example, steady-state gain, time constant and zero transfer functions, in subspace identification is investigated using constrained least squares (CLS). The method exploits the interpretation of subspace identification as an optimal multi-step ahead predictor and reduces the identification to solve an optimisation problem with equality constraints describing the prior information. The standard multivariable output-error state-space subspace algorithm is further examined using the same CLS approach to incorporate dc gain information. Simulation results show that the proposed algorithm provides computationally efficient approach for subspace identification with satisfactory parameter variances, and the method is equally applicable to both single-input single-output and multiple-input multiple-output systems.
Input-to-state stability for descriptor systems with non-linear perturbations
Improved subspace identification with prior information using constrained least squares
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