Controller Design For Large-scale Systems Research Articles

Distributed Networked Controller Design for Large-Scale Systems Under Round-Robin Communication Protocol

This article studies the distributed L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -gain control problem for continuous-time large-scale systems under Round-Robin communication protocol. In this protocol, each subcontroller obtains its own subsystem's state information continuously while communicating with neighbors at discrete-time instants periodically. Distributed controllers are designed such that the closed-loop system is exponentially stable and that the prescribed L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -gain is satisfied. The design condition is obtained based on a time-delay approach and given in terms of linear matrix inequalities. Finally, three numerical examples are presented to illustrate the efficiency of the proposed scheme.

A Decomposition Result in Linear-Quadratic Coordinated Control

Scalability is a fundamental requirement in control design for large-scale systems. Typically, it needs to be considered explicitly at the expense of performance degradation and more complicated design procedures. In this paper, we present a class of large scale systems where scalability is an inherent property of the optimal centralized solution. More specifically, we study a coordination problem where a group of identical subsystems are required to satisfy an equality constraint on the sum of their inputs. We show that the problem can be completely decomposed in terms of the unconstrained problems associated with each subsystem. In particular, the computational effort required to obtain the optimal solution is independent of the number of subsystems and the only global information processing required to execute the optimal control law is a simple summation, which scales well when the number of subsystems grows large.

Model Following Controller Design for Large-Scale Systems With Time-Delay Interconnections and Multiple Dead-Zone Inputs

The model following control problem is addressed for a class of nonlinearly interconnected systems with time delays. The subsystems are with multiple dead-zone actuators and mismatched time-varying disturbances. To deal with the multiple unknown dead-zone inputs, we decompose the system properly based on the input matrix. By using the adaptive method to compensate the unknown parameters, we design a new and simple memoryless controller. The stability of the resultant closed-loop error system is proved by employing a new Lyapunov Krasovskii functional. The designed controller is tolerant to any dead-zone inputs and general time delays. Finally, the simulations are performed and the results show the potential of the proposed method.

Decentralized control design for large-scale systems with strong interconnections using neural networks

We propose a decentralized neural network (NN) controller for a class of large-scale nonlinear systems with the strong interconnections. The NNs are used to approximate the unknown subsystems and interconnections. Due to the functional approximation capabilities of NNs, the additional precautions are not required to be made for avoiding the possible control singularity problems. Semiglobal asymptotic stability results are obtained and the tracking error converges to zero. Furthermore, the issue of transient performance of the subsystems is also addressed under an analytical framework.

Predictive control design for large-scale systems

The design of a model-based generalised predictive controller (GPC) for large-scale systems is reported. A two-level decentralised Kaiman filter is used to locally estimate the states of each subprocess, and an optimal coordination strategy then improves this filtering solution. A two-level optimisation strategy then decomposes the global GPC problem into manageable subproblems. The GPC solution for each low level subprocess is independently found and sent to update the values of a high-level optimal coordinator. This procedure is repeated until an optimal solution is found. Simulation results for a power generation plant demonstrate the improvement achieved by using the proposed technique.

Decentralized H∞ controller design for large-scale systems

The problem of disturbance attenuation for large-scale systems using decentralized control is considered. The design procedure developed here involves constructing H∞ local state feedback controls via the Riccati equation approach, and a complete solution to this problem is carried out merely by iteratively solving a set of local algebraic Riccati equations. It is shown that when all the states are available, the H∞ norm of the closed-loop transfer function over all linear constant decentralized control laws is not imrpoved by allowing feedback to be dynamic. With successively smaller values of the prespecified disturbance level, the local state feedback H∞ suboptimal control problem can be solved and the controller can be chosen to be static.

Decentralized adaptive controller design for large-scale systems with higher order interconnections

Decentralized robust adaptive controller designs for large-scale interconnected systems are investigated. Motivated by real mechanical systems, the authors consider a general representation of interconnections when the strength of the interconnections is bounded by a pth-order polynomial in states. This is in contrast to other studies which have made simpler assumptions about the strength of the interconnections. The authors investigate several scenarios as the control computations become more distributed until the controllers are completely decentralized. The possible bound of the interconnections is assumed to be known for the decentralized semiadaptive controller. Without the knowledge of these bounds, two adaptive controllers are designed: a decentralized adaptive controller with partially centralized compensation and a fully adaptive decentralized controller.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Decentralized Control Design of Large-Scale Systems

Some recent and new results on decentralized control design for large scale dynamic systems are surveyed. The decomposition of systems and the decentralization of the design task are characterized. The results concern the methods for the design of serially interconnected systems including complete decentralization, multi-controller configurations and simultaneous stabilization, sequential design, aggregation and overlapping-decomposition design techniques, singularly perturbed systems, decentralized PI-control with integrity property and symmetric composite systems. The methods are presented with an emphasis on the robustness against model errors which are given by upper bounds. The design task comprises also the requirement on the I/O-behaviour of the closed-loop system.

New multilevel control design for large-scale systems

A new multilevel control design for interconnected dynamical systems is presented based upon a two-level controller configuration with constraints. The design is computationally attractive and involves the solution of existing Riccati-Lyapunov matrix equations. Examples are provided to illustrate the method.

Singular perturbation approach to near-optimum control with a prescribed degree of stability

The paper presents a singular perturbation approach to the design of near-optimal controllers with a prescribed degree of stability. All the poles of the resulting closed-loop system are constrained to lie in a half plane Re(s) 0 and α e (0, α0). The approach presented overcomes difficulties associated with the optimal control design For large-scale systems and does not require a knowledge of the perturbation parameter ϵ. The results are verified through an illustrative numerical example.

Variable Structure Control Design for Large-Scale Systems

A new approach to the control design of large-scale systems using variable structure systems theory is presented. Graph-theoretic concepts are used for tearing up a large system into a set of hierarchically decomposed subsystems. The control design for such subsystems is then greatly simplified. A numerical example is presented to illustrate the design technique.

On stabilization of large-scale control systems using variable structure systems theory

A new approach to control design for large-scale systems using variable structure systems (VSS) theory is presented. Multilevel control concepts arc used to decompose a large control problem into a two-level algorithm such that each subsystem is stabilized with local discontinuous controllers and higher level corrective control is designed to take into account the effect of interactions among the subsystems. Two numerical examples are discussed as illustrations.