摘要:

This paper studies the linear, time-invariant, multi-input multi-output unity-feedback system with possible failures in the sensor or actuator-connections. The purpose of this paper is to analyse the system with failures inkof the sensor-connections or with failures inmof the actuator-connections and develop conditions for stability, It is shown that if the system is stable for all possible failures ofkof the sensor-connections or ofmof the actuator-connections, then the plant and the controller must have certain properties explained in terms of denominator-matrices of their coprime-factorizations. These conditions imposed on the coprime-factorizations are important for design of fault-tolerant systems.

ISSN:0020-7179    

DOI:10.1080/00207179208934340

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The problem of limit cycles in decentralized relay systems is revisited. An exact method for evaluating the periods of limit cycles and determining their stability in such systems is presented. Though the necessary conditions derived in this paper are equivalent to the existing and well-known infinite series counterpart conditions, the new conditions are constructive and easier to apply since they are given in closed form. The new method is applicable to any system and uses the Z transform familiar to most control engineers and for which extensive tables can be found in most textbooks on discrete time control. Examples demonstrate the usefulness of the new conditions. The new method also reveals an interesting property of decentralized relay systems.

ISSN:0020-7179    

DOI:10.1080/00207179208934341

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The structure is addressed of time-optimal control of robotic manipulators along a specified geometric path subject to constraints on control torques. Both regular and singular (where one or more effective inertia components is/are zero on any finite time interval) cases are studied by using the extended Pontryagin's minimum principle and a parametrization method. It is shown that the structure of the time-optimal control law requires either(a) one and only onecontrol torque to be always in saturation in every finite time interval along its optimal trajectory, while the rest of them adjust their values so that the motion of the robot is guaranteed along the constrained path, or (b)at least oneof the actuators to take on its extremal values. The first form of the control law dominates the robot motion along the optimal trajectory although the second form may exist. The theoretical results are verified by various existing numerical examples.

ISSN:0020-7179    

DOI:10.1080/00207179208934342

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A novel model-following approach is developed to design reconfigurable control systems. The conventional state-space linear model-following approach to control is first re-examined with emphasis on the conditions for perfect model following and its application to reconfigurable control system design. New frequency domain necessary and sufficient conditions for perfect model following are then obtained and they are used to gain insight into the selection of the reference model and to develop a new design approach. This novel design approach yields fewer constraints on the reference model than before, and provides much greater flexibility in specifying the state trajectories of the impaired system.

ISSN:0020-7179    

DOI:10.1080/00207179208934343

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper describes the application of nonlinear quadratic regulator (NLQR) theory to the design of control laws for a typical high-performance aircraft. The NLQR controller design is performed using truncated solutions of the Hamil-ton-Jacobi-Bellman equation of optimal control theory. The performance of the NLQR controller is compared with the performance of a conventional P+I gain scheduled controller designed by applying standard frequency response techniques to the equations of motion of the aircraft linearized at various angles of attack. Both techniques result in control laws which are very similar in structure to one another and which yield similar performance. The results of applying both control laws to a high-g vertical turn are illustrated by nonlinear simulation.

ISSN:0020-7179    

DOI:10.1080/00207179208934344

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper presents an optimization-based algorithm for state estimation of multirate digital control systems. The algorithm features a predictor estimator structure and it is derived by employing a time invariant modelling approach to multirate systems. Special care is taken to ensure the causality of the derived estimation algorithm and to reduce the dimensionality inherent in multirate system modelling while maintaining a reasonably simple implementation. The proposed algorithm is developed to ensure convergence in state estimation between base sampling instants as well as between model rate sampling instants.

ISSN:0020-7179    

DOI:10.1080/00207179208934345

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper develops a new set of stability tests for differential unit memory linear repetitive processes based on plant step response data. These tests are then shown to produce, at no extra computational cost, unique computable information concerning system performance which is central to practically based control objectives. Computational aspects and open research problems are also discussed.

ISSN:0020-7179    

DOI:10.1080/00207179208934346

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Necessary and sufficient semi-algebraic conditions for (a) the stabilization of scalar transfer functions, and (b) the assignability of real poles by static output feedback, are given in terms of the Weierstrass invariants of an associated hermitian matrix pencil. An explicit graphical test for output feedback stabilizability is derived which is equivalent to the Nyquist criterion.

ISSN:0020-7179    

DOI:10.1080/00207179208934347

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Several sets (e.g. lists of integers, polynomials, etc.) which remain invariant under a group of transformations including static output feedback control of a linear dynamic system are identified. A nested feedback look decomposition of any given system is given which not only identifies the new invariants but also gives an algorithmic procedure of computing them. As is known, structural invariants such as the ones introduced here, play important roles in many theoretical studies of control theory. To show one such case, here an upper bound to the minimum order of a dynamic output feedback compensator required to stabilize a given system is calculated in terms of the newly identified invariants. This paper can be considered as an extension of the work of Morse who identified structural invariants under static-state feedback, where, as this paper identifies, there are structural invariants under static output feedback.

ISSN:0020-7179    

DOI:10.1080/00207179208934348

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We present a method for improving the tolerance of a conventional LQG controller to parameter errors in the plant model. The improvement is achieved by introducing additional terms reflecting the structure of the parameter errors into the LQR cost function, and also the process and measurement noise models. Adjusting the sizes of these additional terms permits a trade-off between robustness and nominal performance. Manipulation of some of the additional terms leads to high gain controllers while other terms lead to low gain controllers. Conditions are developed under which the high-gain approach asymptotically recovers the robustness of the corresponding full-state feedback design, and the low-gain approach makes the closed-loop poles asymptotically insensitive to parameter errors.

ISSN:0020-7179    

DOI:10.1080/00207179208934349

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor