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Volume 142
Issue 1
IEE Proceedings - Control Theory and Applications
Volume 142, Issue 1, January 1995
Volumes & issues:
Volume 142, Issue 1
January 1995
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- Author(s): P. Stoica ; T. Soderstrom ; V. Simonyte
- Source: IEE Proceedings - Control Theory and Applications, Volume 142, Issue 1, p. 1 –6
- DOI: 10.1049/ip-cta:19951601
- Type: Article
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The paper focuses on a novel bias-free least squares (BFLS) parameter estimation approach which has received attention in the system identification and control literature. First, the BFLS parameter estimator is derived in a more general setting than in the original works. Then the paper goes on to show that any BFLS parameter estimator can be exactly realised in the well studied class of weighted instrumental variable (WIV) estimators. The paper also includes a comparative performance study of the unweighted estimators in the BFLS and IV classes. - Author(s): M.-H. Perng and K.-C. Pan
- Source: IEE Proceedings - Control Theory and Applications, Volume 142, Issue 1, p. 7 –14
- DOI: 10.1049/ip-cta:19951574
- Type: Article
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The paper presents an iterative approach for the robust performance design of basically noninteraction multivariable control (BNIC). Compared with the improved quantitative feedback theory (QFT) methodology, the present approach is attractive for two reasons; (i) the degree of overdesign can be successively reduced by iteration, and (ii) disc gain bounds are used in the problem formulation such that, in the BNIC problem, the diagonal elements of T(s) are minimum phase. An illustrative example is given to show the superiority of the present approach over the improved QFT technique for BNIC plants or plants that can be reduced to BNIC by precompensation. - Author(s): J. Xin ; H. Tsuji ; A. Sano
- Source: IEE Proceedings - Control Theory and Applications, Volume 142, Issue 1, p. 15 –22
- DOI: 10.1049/ip-cta:19951594
- Type: Article
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To improve the mean square error (MSE) of the least squares (LS) estimate of an impulse response, a new approach to signal sampling and measurement is proposed, based on decimation and interpolation. It is analytically shown that there exists an optimal sampling interval which can minimise the MSE, and this optimal sampling interval depends on the impulse response, the input power spectrum or the eigenvalues' distribution of the correlation matrix of the input signal, the noise variance and the total number of data. Furthermore, an effective data-based scheme to determine the optimal sampling interval is given by using the only accessible input-output data. The effectiveness of the presented algorithm is demonstrated through numerical examples. - Author(s): O.D.I. Nwokah ; R.E. Nordgren ; G.S. Grewal
- Source: IEE Proceedings - Control Theory and Applications, Volume 142, Issue 1, p. 23 –30
- DOI: 10.1049/ip-cta:19951227
- Type: Article
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23
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Rosenbrock's inverse Nyquist array (INA) (1970, 1974) is made robust for uncertain MIMO systems by direct application of SISO quantitative feedback theory (QFT) methodology to each element of the inverse closed loop system. This enables quantitative bounds to be generated for not only the elements of the closed loop transfer function matrix but also for the overall closed loop interaction index; thereby making precise the heuristic notion of 'sufficient' diagonal dominance used in the traditional Nyquist array. This technique will be used to convert the original MIMO problem into a series of exact robust performance problems involving both parametric and unstructured uncertainty. An illustrative example is presented comparing the solution using this new technique and a mu-synthesis solution. - Author(s): G. Lightbody and G.W. Irwin
- Source: IEE Proceedings - Control Theory and Applications, Volume 142, Issue 1, p. 31 –43
- DOI: 10.1049/ip-cta:19951613
- Type: Article
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The paper investigates in detail the possible application of neural networks to direct model reference adaptive control. The difficulties involved in training the neural controller embedded within the closed loop are discussed in detail. A training structure is suggested that removes the need for a generalised learning phase. Techniques are discussed for the backpropagation of errors through the plant to the controller. In particular, dynamic plant Jacobian modelling is proposed that uses a parallel neural forward model of the plant. The benefits of neural control are then demonstrated by comparison with Lyapunov adaptive control for a number of example plants. A continuously stirred tank reactor and a nonlinear guidance system are chosen as two realistic nonlinear case studies for the demonstration of the techniques discussed. In both cases nonlinear neural control was found to provide greatly improved performance over conventional approaches. - Author(s): A. Deb ; G. Sarkar ; S.K. Sen
- Source: IEE Proceedings - Control Theory and Applications, Volume 142, Issue 1, p. 44 –50
- DOI: 10.1049/ip-cta:19951497
- Type: Article
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A modification to conventional block pulse functions (BPF) is proposed by describing a set of linearly pulse-width modulated block pulse functions (LPWM-BPF) that has been utilised to develop a generalised convolution matrix of operational nature. This matrix is used to determine convolution of time-varying functions and is also employed to solve linear feedback system identification problem. Also, a recursive technique for solving the identification problem in the conventional BPF domain has been derived. Numerical examples are treated to establish the validity of the proposal. The representational error analysis has also been carried out for the LPWM-BPF to show that this kind of BPF set introduces less error than the conventional equal-width BPF. - Author(s): J.J. Hamalainen ; A. Marttinen ; L. Baharova ; J. Virkkunen
- Source: IEE Proceedings - Control Theory and Applications, Volume 142, Issue 1, p. 51 –57
- DOI: 10.1049/ip-cta:19951593
- Type: Article
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Optimal speed references were designed for a trolley crane. The path planning problem was split into five phases: vertical upward movement of the load; acceleration of the trolley while still hoisting the load; horizontal movement of the trolley with maximum velocity without hoisting; deceleration of the trolley while setting down the load; and vertical downward movement of the load. Energy optimal speed references for a given transfer time were computed for the so-called diagonal movements in which the load and trolley moved simultaneously. A dynamical model of the crane mechanics and actuators was used in the formulated optimal control problem. The transfer times for the diagonal movements were made as small as possible so that the given maximal angular velocities of the actuators were not exceeded. Speed references for the three other phases were easily obtained since they involved either hoisting only, or transfer of the trolley with constant velocity without hoisting. A pilot crane experiment with a scaled-down model has been carried out, and the results are given and discussed. - Author(s): J. Liceaga-Castro ; C. Verde ; J. O'Reilly ; W.E. Leithead
- Source: IEE Proceedings - Control Theory and Applications, Volume 142, Issue 1, p. 58 –72
- DOI: 10.1049/ip-cta:19951575
- Type: Article
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Using the multivariable analysis framework known as individual channel design (ICD), it is shown that for a typical strongly cross-coupled single main rotor helicopter at 80 knots forward flight, the standard 4-input 4-output multivariable control problem, for design purposes, decomposes without significant loss of structural (interaction) information into two simpler 2-input 2-output multivariable problems: one for the longitudinal dynamics and one for the lateral dynamics. Following on this analysis of multivariable structure, the control systems design is built up in a systematic fashion and a novel type of feedforward control is used to overcome a severe lack of robustness as well as to decouple the lateral dynamics into two SISO subsystems round crossover frequency. A diagonal (4*4) feedback controller matrix is then used, the elements of which are designed on the basis of the decoupled lateral and longitudinal dynamics. Resulting closed-loop bandwidths of all four channels are within Level 1 handling quality specifications and step responses are satisfactory with acceptably low cross-coupling. - Author(s): N. Peach
- Source: IEE Proceedings - Control Theory and Applications, Volume 142, Issue 1, p. 73 –80
- DOI: 10.1049/ip-cta:19951614
- Type: Article
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p.
73
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Bearings-only tracking using the extended Kalman filter (EKF) configured in Cartesian and modified polar coordinate systems is reviewed. A new tracking approach is proposed which consists of a set of weighted EKFs each with a different initial range estimate and this is referred to as the range-parameterised (RP) tracker. This new approach overcomes the problems exhibited with existing EKF trackers when the bearing rate is very high or near zero. In addition, it allows a more natural implementation for the prior knowledge of-the target velocity, which can allow the range to be inferred even before the first observer manoeuvre. Results are presented for a typical tracking scenario, involving a manoeuvring observer and a constant velocity target. The results show that the RP tracker gives stable, consistent and unbiased estimates in all the cases considered, whereas the same is not true for the Cartesian and modified polar EKF trackers. Although only constant velocity target trajectories have been considered in this paper, the RP tracker provides a natural framework for consideration of manoeuvring targets. The extension to include manoeuvring targets is currently under investigation.
Study of a bias-free least squares parameter estimator
Robust performance design of multivariable control systems
Optimal sampling interval for system identification based on decimation and interpolation
Inverse Nyquist array: a quantitative theory
Direct neural model reference adaptive control
Linearly pulse-width modulated block pulse functions and their application to linear SISO feedback control system identification
Optimal path planning for a trolley crane: fast and smooth transfer of load
Helicopter flight control using individual channel design
Bearings-only tracking using a set of range-parameterised extended Kalman filters
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