Online ISSN
1751-8652
Print ISSN
1751-8644
IET Control Theory & Applications
Volume 3, Issue 4, April 2009
Volumes & issues:
Volume 3, Issue 4
April 2009
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- Author(s): S. Bhaumik ; S. Sadhu ; T.K. Ghoshal
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 375 –382
- DOI: 10.1049/iet-cta.2008.0114
- Type: Article
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p.
375
–382
(8)
A novel method for non-linear risk-sensitive estimation based on the unscented transform has been developed. The proposed filter, referred to as risk-sensitive unscented Kalman filter (RSUKF), and would be able to overcome inherent disadvantages associated with the earlier reported extended risk-sensitive filter (ERSF). The theory and formulation of RSUKF has been presented and possible variants thereof indicated. Using two well-known non-linear examples, the superiority of RSUKF performance has been demonstrated. As the RSUKF has similar computational efficiency and better robustness as compared with the ERSF, the former may be more suitable for onboard implementation, quick exploration of risk-sensitive filtering for non-linear problems and also for generating proposal densities for more computation intensive risk-sensitive particle filters. - Author(s): B. Du ; J. Lam ; Z. Shu ; Z. Wang
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 383 –390
- DOI: 10.1049/iet-cta.2007.0321
- Type: Article
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p.
383
–390
(8)
An effective approach is introduced to study the stability of continuous systems with multiple time-varying delay components. By employing a new Lyapunov–Krasovskii functional form based on delay partitioning, delay-dependent stability criteria are established for cases with or without the information of the delay rates. The contribution of the paper is 2-fold. First, it provides an improvement, as well as generalisation, of the existing stability criteria for continuous systems with multiple time-varying delay components. Second, it is illustrated numerically that the approach can be applied to estimate the delay bound for system stability in the single delay case with reduction both in conservatism and computational complexity when compared with the existing methods. - Author(s): D.Y. Chao and Z. Li
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 391 –403
- DOI: 10.1049/iet-cta.2007.0470
- Type: Article
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p.
391
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(13)
For the purpose of deadlock control, siphons in a Petri net (PN) can be divided into elementary and dependent ones; the latter can further be distinguished by strongly and weakly dependent siphons (WDS). The computation of the elementary siphons in a PN is essential but expensive since a complete siphon enumeration is needed. The results reported in the literature show that the control of WDS is quite conservative. Li et al. present two open problems. First, for what kinds of PN, we can definitely find a set of elementary siphons such that no WDS can be derived? Secondly, could we develop an algorithm to find a set of elementary siphons that can minimise the number of WDS in a net? The aim here is to answer the first problem for an systems of simple sequential processes with resources (S3PR) by investigating its structural conditions under which there are no WDS in it. The authors address such an issue by using an incremental approach for the synthesis of subnets (to compute an strict minimal siphon) of a strongly connected resource component. At each step, the authors add a PP-handle Hi with at least one interior resource place. The structural condition for the absence of WDS is derived and show that the maximal class of S3PR is a 2c+-system. - Author(s): D. Xie and Y. Wu
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 404 –410
- DOI: 10.1049/iet-cta.2008.0135
- Type: Article
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p.
404
–410
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Exponential stabilisability of switched linear systems with time-varying delay in the detection of switching signals is investigated via state feedback by average dwell time approach incorporated with multiple Lyapunov function techniques. The feedback mechanism considered is of off-line type. Sufficient conditions for exponential stabilisability are established for three cases: some subsystems are stabilisable, all subsystems are stabilisable and all subsystems are controllable. Our results complement and generalise the results of Xie and Wang (2005) and Ji et al. (2007). - Author(s): X. Ren ; C.Y. Lai ; V. Venkataramanan ; F.L. Lewis ; S.S. Ge ; T. Liew
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 411 –418
- DOI: 10.1049/iet-cta.2008.0138
- Type: Article
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p.
411
–418
(8)
A feedforward control based on neural networks to attenuate the effect of external vibrations on the positioning accuracy of hard disk drives (HDDs) is presented. The adaptive neural network compensator utilises accelerometer signals to detect external vibrations. No information on the plant, sensor and disturbance dynamics is needed in the design of the adaptive neural network compensator. The stability of the proposed scheme is analysed by the Lyapunov criterion. Experimental results show that the tracking performance of HDDs can be improved significantly by using the feedforward controller when compared with the case without compensation. - Author(s): N.R. Abjadi ; J. Soltani ; J. Askari ; G.R. Arab Markadeh
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 419 –427
- DOI: 10.1049/iet-cta.2008.0118
- Type: Article
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p.
419
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(9)
A sliding-mode (SM) feedback linearisation control system is designed for a multi-motor web-winding system. First, an ideal feedback linearisation control system is adopted in order to decouple the tensions and velocity of the web-winding system; then to enhance the performance of the control system in the presence of uncertainties, an SM feedback linearisation control system is applied, which consists of an SM velocity controller and two SM tension controllers; a decentralised version of the proposed controller is developed. Two tension observers are suggested to eliminate the need of load cells in a web-winding system. Finally, the effectiveness and capability of the proposed control strategy is verified by computer simulation. - Author(s): P. Melba Mary and N.S. Marimuthu
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 428 –436
- DOI: 10.1049/iet-cta.2007.0334
- Type: Article
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p.
428
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An improvement over the existing conventional fuzzy logic approach, based on a self-tuning fuzzy logic controller (FLC), for the design of a temperature control process, capable of providing optimal performance over the entire operating range of the process, was proposed. Since an optimum response of the FLC can be expected only for a limited range of inputs, tuning the input and output gains is done here for various range of inputs. The proposed control system has the advantages of self-tuning FLC schemes. To evaluate the performance of the proposed control system methods, the results from the simulation of the process are presented. - Author(s): Q. Huang ; Z. Huang ; H. Zhou
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 437 –444
- DOI: 10.1049/iet-cta.2007.0367
- Type: Article
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p.
437
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Design of a nonlinear optimal and robust controller for a lightweight all-electric vehicle is presented. An electric vehicle driven by a DC motor is modelled. A controller is designed with differential-geometric approach and linear quadratic regulator techniques, to guarantee optimal performance. Then the uncertainties of the system are considered. A nonlinear robust controller that can tolerate multi-parametric uncertainties is designed. The model and controllers are implemented in Simulink® environment and numerical simulations are performed. To compare the performance of the controllers, two regular PID controllers are designed. The performance of the designed controllers are compared with that of PID controllers and a driving cycle test is performed to test the control performance and energy consumption. The controller designed here demonstrates much better performance than that of regular PID controller under tests. - Author(s): Z. Sangelaji and S.P. Banks
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 445 –451
- DOI: 10.1049/iet-cta.2007.0318
- Type: Article
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p.
445
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The stabilisation of a class of nonlinear systems is studied using the angular form of a differential equation to reduce the problem to the control of the radial component of the state. In this method, the system is converted into two subsystems: one is a nonlinear equation on a sphere and the other is a radial differential equation. A stabilising control can be designed based on the one-dimensional radial system dynamics. The radial control may be continuous or discontinuous depending on the structure of the input map. Whenever the input map of the radial subsystem is zero, the radial control is not accessible. A method is presented to remove this obstacle. The control is designed using an appropriate weighting function. - Author(s): J. Toledo ; L. Acosta ; M. Sigut ; J. Felipe
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 452 –464
- DOI: 10.1049/iet-cta.2008.0028
- Type: Article
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p.
452
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The lifting methodology can be used for simplifying the closed-loop stability study of a system in which the measurement data are acquired at different frequencies. This is because the lifting operators allow treating this kind of systems as if there is only one control frequency, which reduces the complexity of the problem in a very important way. The four-rotor microhelicopter designed by the authors, whose control is faced, is a nonlinear plant with sensors operating at two different frequencies. First, the system is linearised cancelling the rotors dynamics. Then, the authors implement a model reference adaptive control structure for identifying the gains of the linear reference plant and performing the adaptive control of the microhelicopter. At this point, the system stability study is carried out by just computing the eigenvalues of the closed-loop states matrix thanks to the lifting operators. - Author(s): J. Kim ; D.G. Bates ; I. Postlethwaite
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 465 –472
- DOI: 10.1049/iet-cta.2007.0391
- Type: Article
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p.
465
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A new problem formulation for the structured singular value μ in the case of purely real (possibly repeated) uncertainties is presented. The approach is based on a geometrical interpretation of the singularity constraint arising in the μ lower bound problem. An interesting feature of this problem formulation is that the resulting parametric search space is independent of the number of times any parameter is repeated in the structured uncertainty matrix. A corresponding lower bound algorithm combining randomisation and optimisation methods is developed, and some probabilistic performance guarantees are derived. The potential usefulness of the proposed approach is demonstrated on two high-order real μ analysis problems from the aerospace and systems biology literature. - Author(s): M.J. Robertson and W.E. Singhose
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 473 –480
- DOI: 10.1049/iet-cta.2007.0276
- Type: Article
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p.
473
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Properly shaped reference commands can greatly improve the performance of flexible systems. However, command profiles that move a system without residual vibration while simultaneously limiting transient deflection are very challenging to create. If the command generation problem is formulated and solved in the continuous-time domain, then a non-linear optimisation will generally be required to produce the command. The authors describe a method for creating deflection-limiting commands in the discrete-time domain. The major advantage of this method is that the problem is solved via linear optimisation. This reduces the computational complexity required to create deflection-limiting commands. Additionally, linear robustness constraints can be formulated, allowing for the development of robust deflection-limiting commands. The characteristics of the command profiles are presented as a function of transient deflection limit and the move distance. Experiments performed with an industrial bridge crane verify the usefulness of the proposed approach. - Author(s): C. Louembet ; F. Cazaurang ; A. Zolghadri ; C. Charbonnel ; C. Pittet
- Source: IET Control Theory & Applications, Volume 3, Issue 4, p. 481 –491
- DOI: 10.1049/iet-cta.2008.0054
- Type: Article
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p.
481
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(11)
Path planning for satellite slew manoeuvres is considered as an optimal control problem. The goal is to design rapid manoeuvres with the resting time vibrational modes as short as possible in order to provide more time for space imagery. This problem of optimal time and control effort is addressed using differential flatness and B-spline collocation. The flatness allows for reformulating the original optimal control problem as a tractable geometric programming problem with no numerical integration, and with a minimal number of decision variables. A direct consequence of flatness is that the transformed constraints describe generally a non-convex subspace. In the proposed approach, a flat suboptimal convex problem is derived by means of offline convex approximations of the feasible space and a measure of its conservatism is given. Numerical results are discussed and compared with the results generated from an in-service industrial path planner available at the French Space Agency, CNES.
Risk-sensitive formulation of unscented Kalman filter
A delay-partitioning projection approach to stability analysis of continuous systems with multiple delay components
Structural conditions of systems of simple sequential processes with resources nets without weakly dependent siphons
Stabilisability of switched linear systems with time-varying delay in the detection of switching signals
Feedforward control based on neural networks for disturbance rejection in hard disk drives
Nonlinear sliding-mode control of a multi-motor web-winding system without tension sensor
Design of self-tuning fuzzy logic controller for the control of an unknown industrial process
Nonlinear optimal and robust speed control for a light-weighted all-electric vehicle
Stabilisation of nonlinear systems using weighted angular method
Stabilisation and altitude tracking of a four-rotor microhelicopter using the lifting operators
A geometrical formulation of the μ-lower bound problem
Robust discrete-time deflection-limiting commands for flexible systems
Path planning for satellite slew manoeuvres: a combined flatness and collocation-based approach
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