摘要:

A new applications-oriented approach—individual channel design (ICD)—to multivariable feedback control—was presented in an earlier paper (O'Reilly and Leithead 1991). This paper is the final part of a three-part investigation into the performance issues raised by ICD for 2-input 2-output strongly coupled multivariable systems. Parts 1 and 2 (Leithead and O'Reilly 1991, 1992 a) respectively show that fixed stabilizing controllers exist regardless of the structure of the multivariable system and that the use of phase and gain margins and SISO Nyquist-Bode loop shaping design is justified. The three-part series of papers also develops an analytic framework for investigating and understanding the potential and limitations of the feedback design of any linear time-invariant controller. The main results of this final part are threefold. First, restriction to diagonal feedback control in ICD (O'Reilly and Leithead 1991) or elsewhere is not a significant restriction on performance. Second, non-diagonal feedback control cannot improve system structure beyond that attainable by swapping the assignment of control inputs to plant outputs. Third, lack of robustness is not alleviated by either system pre-compensation or post-compensation.

ISSN:0020-7179    

DOI:10.1080/00207179208934239

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Classical sliding mode control (SMC) uses a discontinuous control action to drive the state from an arbitrary initial state to the origin along a user-specified path and exhibits excellent robustness to disturbances and parameter uncertainty. However, the control chattering due to the discontinuity in the control law is undesirable in most processes applications. The continuous sliding mode control (CSMC) approach developed in this paper satisfies the sliding condition using a continuous control law. It therefore retains the positive properties of SMC but without the disadvantage of control chattering. The concept of boundary layer equivalence is used to show that in the presence of unknown disturbances and/or parameter uncertainty, CSMC keeps the state trajectories within a boundary layer of user-specified width. It is also shown that CSMC is equivalent to a cubic feedback control law and can be reduced to a linear form (LSMC) which provides a useful link between sliding mode control and traditional linear control. Several examples demonstrate the performance and properties of SMC, CSMC and LSMC.

ISSN:0020-7179    

DOI:10.1080/00207179208934240

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A new method is discussed which allows one to synthesize continuous-time controllers of lead/lag or PID type that are optimal both in theH∞andH2sense (equalizingH2controllers), for a restricted class of systems well suited for robotic applications. In particular, conditions on the plant are given so that the optimal controller has a lead/lag or PID structure in cascade with an additional low-pass filter. The method is applied to synthesize a PI controller for the velocity control of one joint of an electrically actuated industrial SCARA robot.

ISSN:0020-7179    

DOI:10.1080/00207179208934241

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A decentralized indirect adaptive control scheme that may be applied to both interconntected and overlapping interconnected systems is presented. With the presented scheme, indirect adaptive controllers are applied at each control station of a multi-control-station system. The adaptive controller at a given control station is designed for the subsystems connected to that station, and the controlled inputs are communicated to other selected control stations so that strong subsystem interconnections may be taken into account. The scheme is unique because key subsystem interconnections are identified and used in the controller design at each control station in order to reduce the possible detrimental effects of the interconnections. It is shown under what conditions the proposed control scheme guarantees system global stability and it is also shown that global stability limits are improved significantly by using communicated inputs in the controller design at each control station. An example is given that demonstrates the improved stability margins of the proposed scheme.

ISSN:0020-7179    

DOI:10.1080/00207179208934242

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The static output feedback control problem for discrete linear, singularly perturbed, stochastic systems is studied. A recursive algorithm is presented to solve the corresponding coupled non-linear algebraic equations. The algorithm removes the ill-conditioning by decomposing the higher order equations into lower order equations and develops a technique which enables us to obtain an arbitrary accuracy, that is,0(ϵj) (j= 1, 2, 3, …)a approximation for this problem. A numerical example is presented to support the theoretical results.

ISSN:0020-7179    

DOI:10.1080/00207179208934243

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An adaptive decoupler based on input dynamics compensation (AMiFIR) and another adaptive decoupler based on output feedback (ADaHiD) are proposed. Both schemes have advantages over previous works in terms of conceptual simplicity and computation efficiency. AMiFIR take advantage of the finite impulse response filter structure to simplify the design procedure whereas ADaHiD is an extension of the well-known SISO Dahlin-Higham controller. The minimal order of AMiFIR with exact decoupling is determined under certain conditions. Comparisons are made between the implementation aspects of the two adaptive decouplers. Examples and simulation results are given to illustrate the design and performance of the schemes.

ISSN:0020-7179    

DOI:10.1080/00207179208934244

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The design and complete stability analysis for the model reference adaptive control (MRAC) of multivariable plants with input and/or output delays are presented in this paper. A modified estimation error, which enables us to solve the non-commutativity problem and the stability issue in the multivariable case, is introduced in the adaptive law for updating the controller parameters. A generalized controller structure, which achieves stable model-plant transfer matrix matching in the presence of delays, is developed for the multivariable MRAC scheme. Based on a unified framework it is shown that the proposed adaptive control scheme guarantees the global stability and asymptotic zero tracking error for the closed-loop system.

ISSN:0020-7179    

DOI:10.1080/00207179208934245

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper describes a new multivariable adaptive decoupling controller combining a decoupling compensator with a generalized minimum variance technique. The controller can completely decouple closed-loop systems both dynamically and in the steady state. It can control an unstable and/or non-minimum phase system and it can control the process with an arbitrary time delay structure. The proof of global convergence for the algorithm is also given. Successful experimental results of the adaptive decoupling control for a pilot-scale binary distillation column demonstrate the effectiveness of the proposed adaptive decoupling algorithm.

ISSN:0020-7179    

DOI:10.1080/00207179208934246

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The input and output normal representations of stable systems are generalized for unstable systems. These are then used to reduce the order of unstable discrete-time linear multivariable systems resulting in reduced order models with the same number of unstable poles as the full order model and with an a priori upper bound on the reduction error. The generalized normal representations are then modified to include a frequency weighting resulting in frequency weighted generalized normal representations. These are used to derive frequency weighted reduced order models for unstable discrete systems with the same number of unstable poles as the full order model and with an a priori upper bound on the frequency weighted reduction error.

ISSN:0020-7179    

DOI:10.1080/00207179208934247

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The design of variable structure control schemes for uncertain discrete-time systems is considered. Previous work in this area which parallels the discrete-time sliding mode philosophy with that for the continuous-time case is reviewed. Theoretical results are presented which indicate that such a parallel approach is not necessarily desirable. A novel design methodology for discrete-time variable structure control systems is then formulated. A numerical example is given to illustrate the results described.

ISSN:0020-7179    

DOI:10.1080/00207179208934248

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor