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Volume 136
Issue 4
IEE Proceedings D (Control Theory and Applications)
Volume 136, Issue 4, July 1989
Volumes & issues:
Volume 136, Issue 4
July 1989
Decentralised PD and PID robotic regulators
- Author(s): Y. Bestaoui
- Source: IEE Proceedings D (Control Theory and Applications), Volume 136, Issue 4, p. 133 –145
- DOI: 10.1049/ip-d.1989.0020
- Type: Article
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p.
133
–145
(13)
The paper presents a new method of robotic manipulator control based on decentralised pole-placement feedback deduced from the computed torque method. An anticipatory action is included in the controller by ensuring subsequent desired joint positions, velocities and accelerations in the Newton-Euler equations of motion. The desired torques and the coordination parameters are computed in the first level (discrete) when the torques coming from the decentralised PD or PID regulators are computed in the second level (continuous). The parameters of the decentralised PD and PID regulators are given by simple laws. Decentralised control is appropriate for this control scheme because it is very easy to share calculations among the micro-processors with few interconnections. Then the stability of the regulator is investigated. Finally, the simulation results obtained for the PD and PID regulators are presented.
Fuzzy systems identification
- Author(s): Chen-Wei Xu
- Source: IEE Proceedings D (Control Theory and Applications), Volume 136, Issue 4, p. 146 –150
- DOI: 10.1049/ip-d.1989.0021
- Type: Article
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146
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(5)
The paper deals with fuzzy system identification. A general identification approach for multi-input/single-output fuzzy systems is presented, which includes structure identification, parameter (fuzzy relation) estimation, and the associated self-learning algorithm. Zadeh's possibility distribution plays an important role in identification and the use of fuzzy models thus constructed. Numerical examples are provided which show the advantages of the proposed identification algorithm and the effectiveness of the self-learning algorithm. Comparison shows that the proposed method can produce the fuzzy model with higher accuracy than previously achieved in other work. In the application example, the proposed identification approach has been used to construct fuzzy models for a fluidised catalytic cracking unit in a big refinery. The resultant fuzzy models are accurate enough for industrial application purpose.
Model reduction of continuous-time systems using a modified Routh approximation method
- Author(s): C.-S. Hsieh and C. Hwang
- Source: IEE Proceedings D (Control Theory and Applications), Volume 136, Issue 4, p. 151 –156
- DOI: 10.1049/ip-d.1989.0022
- Type: Article
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151
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A modified Routh approximation method is presented for obtaining stable reduced models of continuous-time systems. The reduced models give good approximates of the initial transient response and the steady-state response of the original system. Both the frequency-domain and time-domain reduced-order modelling procedures using the modified Routh approximants are given. An example is included.
General hybrid orthogonal functions and some potential applications in systems and control
- Author(s): Amit Patra and Ganti Prasada Rao
- Source: IEE Proceedings D (Control Theory and Applications), Volume 136, Issue 4, p. 157 –163
- DOI: 10.1049/ip-d.1989.0023
- Type: Article
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157
–163
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A framework for a system of general hybrid orthogonal functions (GHOF) is introduced in the paper. The system of GHOF is shown to be more relevant to many practical situations than the conventional systems of orthogonal functions. The proposed framework of definition combines the natural features of discontinuity of the class of piecewise-constant systems and the inherent characteristics of continuity and differentiability of the systems of continuous systems of polynomial and sinusoidal functions, leading to a general, flexible and piecewise-continuous (and differentiable) system of GHOF. The powerfulness of the proposed system is demonstrated in the representation of functions with discontinuities, solution of the state equation with discontinuous inputs and prediction of the limit cycle of a highly nonlinear van der Pol's oscillator. The results amply demonstrate the value of the GHOF as a potential basis for function expansion in a large class of real-world problems.
Robust control of discrete systems
- Author(s): C.S. Berger
- Source: IEE Proceedings D (Control Theory and Applications), Volume 136, Issue 4, p. 165 –170
- DOI: 10.1049/ip-d.1989.0024
- Type: Article
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165
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A robust controller is designed by minimising the deviation of the frequency response of perturbed plant at selected frequencies. The plant perturbations are generated by uncertainty in the coefficients of the plant transfer function.
Simplified design approach for decentralised controllers of large-scale systems
- Author(s): Gang Feng
- Source: IEE Proceedings D (Control Theory and Applications), Volume 136, Issue 4, p. 171 –175
- DOI: 10.1049/ip-d.1989.0025
- Type: Article
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171
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In the design of decentralised controllers of large-scale systems, the performance of the system is not usually good enough, sometimes the system may be unstable if all the interactions between the subsystems are neglected, while the solution of a problem of high dimension (equal to the order of the whole system) is met if the interactions are considered fully. A simplified approach is proposed here, i.e. the decentralised controller of a subsystem is designed using the reduced-order model for the rest of the system. In other words, the subsystem and the reduced-order model are taken to comprise an approximated low-order system, on which the decentralised controller for the subsystem is designed. The balanced model reduction method and gradient optimisation technique are used in the paper. And it is shown that the approach could greatly simplify the design of decentralised controllers for high-dimension systems and achieve high performance.
Cost of uncertainty about controlled objects
- Author(s): O.L.R. Jacobs
- Source: IEE Proceedings D (Control Theory and Applications), Volume 136, Issue 4, p. 177 –187
- DOI: 10.1049/ip-d.1989.0026
- Type: Article
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p.
177
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(11)
The paper aims to quantify, in terms of closed-loop performance, the cost of uncertainty about behaviour of controlled objects. Formulations are introduced to make explicit the dependence of a scalar measure of cost on how the controlled object actually behaves, on what information is available about its behaviour and on how the information is used. A by-product is the definition of two distinct control system properties: ‘information variability’ and ‘object variability’, characterising aspects of system sensitivity and robustness. General analytic results about the cost of uncertainty are not obtainable for conventional systems, so numerical results are presented for simple first-order LQ systems. A graphical format provides explicit and novel insight into determinants of closed-loop performance. Conclusions are summarised which may be applicable to other more general systems.
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