摘要:

A global stability result is presented for nonlinear aircraft pitch-axis models with dynamic inversion control laws. The result is applied to the F-14 aircraft model. Using this result, we are able to sketch a stability region of the F-14 model in terms of the engine thrust and the selected pitch attitude.

ISSN:0020-7179    

DOI:10.1080/00207179608921828

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Attenuation of nonlinear uncertainties using robust control is considered. A system under investigation has a linear nominal part and a nonlinear lumped uncertainty. Robust control is designed using the Lyapunov direct method. It is shown that the proposed control is continuous, guarantees global stability without knowledge of nonlinear dynamics except their size bounding function, and ensures a finite upper bound on the attenuation performance index over an infinite horizon. That is, the proposed control is both robust and optimal. As an application, it is shown that the proposed control can be directly applied to robotic manipulators and many other nonlinear systems.

ISSN:0020-7179    

DOI:10.1080/00207179608921829

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

With the aim of controlling the motion of robots without involving complex design procedures or extensive online computations, this paper presents a strategy consisting of a linear feedback control and a self-tuning control. The main advantage of the strategy is its simplicity in design, program code and real-time implementation. The only information required in setting up the strategy is the order and the measurable states of the system, while detailed description of the model is not needed. Furthermore, uncertain effects such as static and dynamic joint frictions and external disturbances can easily be handled. In addition, all the internal signals are uniformly bounded and the control torque is smooth everywhere. These features are also verified via simulation on the GE-P50 robot.

ISSN:0020-7179    

DOI:10.1080/00207179608921830

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Nyquist stability criteria for multiple-input multiple output (MIMO) feedback systems are derived using a literal approach. In contrast to existing generalized Nyquist stability criteria, which involve the transfer function of the MIMO plant, the proposed literal approach allows the results to be expressed in terms of the poles and zeros of each of the elemental plants. Thus, explicit necessary and sufficient stability conditions for two-input and two-output and for three-input and three-output control systems are given. The results are illustrated in a flight control problem.

ISSN:0020-7179    

DOI:10.1080/00207179608921831

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The adaptive minimal control synthesis (MCS) algorithm and its extensions have been the subject of a number of analytical and implementation investigations since 1990. The purpose of this paper is to improve upon the original stability and robustness proofs for MCS, using the concept of passivity. In particular, we present a formal stability proof for the basic centralized algorithm, together with robustness proofs in the cases of plant parameter variations and external disturbances.

ISSN:0020-7179    

DOI:10.1080/00207179608921832

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Fault detection filters are a special class of observers that can generate directional residuals for the purpose of fault isolation. This paper proposes a new approach to design robust (in the disturbance de-coupling sense) fault detection filters which ensure that the residual vector, generated by this filter, has both robust and directional properties. This is done by combining the unknown input observer and fault detection filter principles. The paper proposes a new full-order unknown input observer, and gives necessary and sufficient conditions for its existence. After the disturbance de-coupling conditions are satisfied, the remaining design freedom can be used to make the residual have the directional property, based on the fault detection filter principle. A nonlinear jet engine system is used to illustrate the robust fault isolation approach presented. It is shown that linearization errors can be approximately treated as unknown disturbances and be de-coupled in the design of a robust fault detection filter. Simulation results show that mis-isolation of faults can be avoided using the robust scheme.

ISSN:0020-7179    

DOI:10.1080/00207179608921833

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

It is observed that digital versions of globally stable adaptive stabilization algorithms are, at best, locally stable due to incompatibilities between the gain adaptation algorithms and the choice of sampling rate. This fact suggests the problem of retrieving global asymptotic stability for such difficulties by modifications to the stabilization algorithms to include sampling rates as control variables and the inclusion of extra plant information to relate sampling rates to gain evolutions. In this contribution, the theoretical problem of adaptive stabilization of single-input single-output (SISO) linear systems S(A,B, C) in Rnis approached using the sampling rate as the basic adaptive mechanism, A wide range of sample interval adaptation schemes is derived that guarantees global asymptotic stability of the sampled outputs from the plant for any minimum-phase SISO systems satisfying the relative degree one constraint CB ≠ 0. The control laws are ‘universal’ in the sense that stabilization is achieved despite a lack of knowledge of the systems parameters and state dimension. They also guarantee the stability of the underlying continuous system's state response if either the system has no open-loop oscillatory unstable poles or it is under a sufficiently fast initial choice of sampling interval, or for any other generically chosen sample interval.

ISSN:0020-7179    

DOI:10.1080/00207179608921834

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A model predictive approach is used to derive a continuous-time, nonlinear feedback control law for open-loop stable, single-input single-output processes with deadtime. The derived model predictive control law minimizes a quadratic performance index in the presence of input constraints and process deadtime. A key feature of the control law is that, for its implementation, one does not need to perform an online optimization. In the absence of constraints, the control law in special cases is identical to the feedback controllers that have already been derived using a geometric approach. The connections between the derived control law and (a) the globally linearizing control and (b) the linear internal model control are established. The model predictive approach provides some insight into the problem of constraint handling in geometric control methods. The application of the theory is illustrated by a chemical reactor example.

ISSN:0020-7179    

DOI:10.1080/00207179608921835

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Two stochastic adaptive control schemes, the stochastic gradient and modified least squares, are studied. We consider these for scalar ARMAX systems with general input delays. First, when the algorithms are based on generalized minimum variance control with reference tracking, sufficient conditions for stability and optimality are found. This is done using martingale convergence analysis. Secondly, we examine parameter convergence for each of the algorithms, and establish conditions for convergence of the parameter estimates to a random multiple of the true parameters.

ISSN:0020-7179    

DOI:10.1080/00207179608921836

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We discuss the computation for ℒ2-induced norms of finite-horizon linear time-varying systems. It is well known that ℒ2-induced norm calculating problems can be converted into optimal control problems. So, with the help of optimal control algorithms, we propose a numerical technique for ℒ2-induced norm computation. Our approach is as follows. First, we present a new computational method for nonlinear optimal control problems that is numerically reliable, stable and robust, analysing the convergence property under some assumptions. Next, by modifying the presented method, we propose an algorithm for the ℒ2-induced norm calculation of finite-horizon linear time-varying systems, which is essentially different from all other existing methods. Finally, the effectiveness of our algorithm is demonstrated by simulation.

ISSN:0020-7179    

DOI:10.1080/00207179608921837

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor