摘要:

In this paper we study the problem of maximizing the complex stability radius of a linear time-invariant state-space system by linear state feedback, We show that the supreme achievable stability radius can be characterized via parametrized Riccati equations. The dependency on the parameters is examined and the limiting behaviour described. Finally, the relationship between the supremum of the achievable stability radii and the distance of a system from non-stabilizabilky is investigated.

ISSN:0020-7179    

DOI:10.1080/00207179008953567

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The mathematical inconsistencies and hence the unsuitability of the only algorithm available so far in the literature (Sinha et al. 1980) for the identification of non-linear distributed parameter systems via orthogonal functions are critically reviewed. A modified algorithm is proposed and its practical limitations are discussed in detail. In order to illustrate the ideas and to confirm the theoretical predictions, a numerical example is included.

ISSN:0020-7179    

DOI:10.1080/00207179008953568

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This paper presents a proof of a connection between the strong solutions to three algebraic Riccati equations which are associated with the solution of a discrete-timeH∞-optimal control problem. Of these solutions, denoted X∞, Y∞" and Z∞, two parametrize a generator of all γ-suboptimal output-feedback controllers and one is associated with a dual state-feedback problem. The relationship is proved by establishing the existence of a similarity transformation between two symplectic matrix pencils which are associated with two of the Riccati equations. A similar result is known to exist in the continuous-time setting.

ISSN:0020-7179    

DOI:10.1080/00207179008953569

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The problem of tracking time-varying trajectories in non-linear systems is considered. These trajectories could be generated on-line by a reference model. The problem is tackled by considering the overall system as a set of decentralized linear sub-systems which can be modelled as a set of double integrators and treating the non-linearities as uncertainties with known bounds on their magnitudes. A variable structure controller is designed based on the theory of uncertain dynamical systems. The system is shown to track a class of trajectories generated by the reference mode! (a set of double integrators) to within a specified tolerance. Some analysis is presented to explain the dynamic behaviour of the closed-loop system and bounds are derived linking the rate of convergence and the tracking ability to system parameters such as available control and magnitude of the uncertainty. Simulation results are presented to validate the conclusions.

ISSN:0020-7179    

DOI:10.1080/00207179008953570

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The iterative learning control system (ILCS) has attracted considerable research interest in recent years. However the theoretical results on some fundamental properties of the ILCS have not yet been established. One of the common drawbacks shared by current approaches is lack of a suitable mathematical model which can clearly describe both the dynamics of the control system itself and the behaviour of the learning process as well. In this paper, a class of iterative learning control systems is analysed from the point of view of two-dimensional (2-D) system theory. The 2-D model for a class of ILCS is established in the form of‘Roessor's model’, based on which a general type of learning controller is proposed. Analysis of the 2-D error equation shows that the 2-D asymptotic stability of the 2-D model guarantees the learning convergence of an ILCS. Design criteria for a learning controller is also suggested. The learning gain matrices are obtained from a recursive 2-D identifier using the input and output of the controlled plant in previous operations; the model transformation method is discussed. An example of applying the proposed learning control method to a parallel link robotic manipulator is given.

ISSN:0020-7179    

DOI:10.1080/00207179008953571

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A recursive algorithm is derived to compute the generalized frequency response functions for a large class of non-linear integro-differential equations. Applications to Duffing's equation and a modified Van der Pol model are discussed.

ISSN:0020-7179    

DOI:10.1080/00207179008953572

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Severe safety concerns in man-made systems require that some variables remain within very strict limits. Even though there is a rich literature on probabilistic and on ‘energy’ bounds, results on hard constraints are scarce. Hard constraint bounding results are summarized here with additional new results. Novel and existing bounding techniques for the outputs and the states of systems disturbed either by uncertain inputs or modelling errors are derived, using either boxes or ellipsoids as the constraint sets. The bounding results are summarized, based on both the concept of matrix measures and Schweppe's ellipsoid bounds. Bounds for large-scale systems and non-linear systems are presented, with some of the theoretical results being applied to a simplified model of a physically meaningful system, namely a steam boiler model, with encouraging results. For the class of non-linear systems represented by the boiler model, it is concluded that even though a box bound based control system may produce more conservative results, as compared to Schweppe's ellipsoid bounding approach, it can be more attractive because of certain practical implementation issues, such as the limitation on realizable actuator bandwidths. Furthermore, for a linear system with a Metzler system matrix, box bounds are the tightest that can actually be attained.

ISSN:0020-7179    

DOI:10.1080/00207179008953573

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A weighted least-squares algorithm is examined for continuous-time linear deterministic systems. The convergence of the algorithm is discussed from several viewpoints. The necessity of the persistently exciting condition is stressed for the exponential convergence of the algorithm. The need and the effect of introducing the normalizing factor into the algorithm are also considered in relation to the global stability of the adaptive feedback control. Adaptive pole placement control by means of an adaptive observer is considered as a typical example of the application of the algorithm.

ISSN:0020-7179    

DOI:10.1080/00207179008953574

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A control approach is proposed for robust accurate trajectory tracking of manipulators based on the computed torque technique and variable-structure systems (VSS) theory. The computed torque structure of the control scheme, most importantly, provides greater insight to the control of manipulators and serves as a unifying framework for control law development. Looking at the control structure from a computed torque perspective also enables the extension of the technique from joint space to direct end-effector control of both non-redundant and redundant robots in task or operational space. The technique, perhaps, may be further augmented to incorporate force control to achieve hybrid force/position control. The use of sliding modes in the control scheme, in its idealized form, ensures accurate tracking while achieving insensitivity to parameter variations/uncertainties and bounded disturbances. In the development of the control laws, some useful properties of the robot dynamics, viz., positive definiteness of the inertia matrix, and its (dynamics structure) linear form with respect to its parameters, are exploited to make the control laws simple for real-time implementation and reflect the explicit inter-dependence of control non-linearity and structured dynamic model uncertainty. The control algorithms obtained by various researchers for manipulator control using VSS theory may be interpreted from the approach given, which thus to a certain extent unifies the VSS techniques suggested in the literature for robot control.

ISSN:0020-7179    

DOI:10.1080/00207179008953575

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A design methodology is presented which applies projective controls to the disturbance attenuation problem for large flexible structures. Through this method, low-order strictly proper controllers are designed which improve the disturbance attenuation properties of the system. A new parameterization of the closed-loop system in terms of free parameters in the projective controller leads to an auxiliary minimization problem which determines the parameters of the controller. A flexible structure example demonstrates the use of this methodology.

ISSN:0020-7179    

DOI:10.1080/00207179008953576

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor