摘要:

Some drawbacks of existing automated urban traffic control systems are discussed. It is shown that most of them are based on deterministic algorithms and have a centralized structure. As a result, qualitative and quantitative complexity of transport processes are not taken into account effectively. To overcome this inconvenience, an approach for implementing distributed intelligence systems is proposed. It is based on multilevel and artificial intelligence techniques. Fuzzy sets theory is chosen as a tool for distributed intelligence control systems design and a specific method is presented. It is shown, however, that this method is not suitable for real time control of large scale systems and an alternative method, leading to a closed-loop fuzzy control law, is proposed. It is based on decomposition of the system into subsystems and presentation as a hierarchical two-level control structure. In this case, the controls have two components—local (calculated by the lower level) and global (calculated by the upper level). The method is used for computer simulation of an oversaturated urban traffic network and gives satisfactory results. Its main advantages are the reduction of the number of fuzzy relations and the effective accounting of constraints on state and control variables.

ISSN:0020-7721    

DOI:10.1080/00207729408929010

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A method of controlling a manipulator withn-degrees of freedom by one actuator andn— 1 brakes using fuzzy inference is described. The manipulator is reduced to have two-degrees of freedom becausen— 2 brakes are applied, so that the switching time of the brakes and the torque of the actuator are obtained. The manipulator is assumed to have uncertainty in the model and fuzzy control is determined by learning the dynamic response of the manipulator. The effectiveness of the proposed method is illustrated by a simple example.

ISSN:0020-7721    

DOI:10.1080/00207729408929011

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An approach for the design of a dead-time compensator for processes with time delays is presented. The proposed algorithm deals with multivariable state-space models instead of input-output models and utilizes not only a single delay but also distributed delays in the feedback loop. Both the continuous-time and discrete-time versions of the algorithm are derived. The design strategy of the controller is based on the approach of LQG design. It is incorporated into the dead-time compensation technique of the analytical predictor, which uses the process model directly to predict the effect of input variables on the process outputs. By introducing an integral action into the observation system, the steady-state observation error of the inaccessible load inputs converges to zero. This permits us to perform disturbance prediction and compensation within a single design. Theoretical analysis shows that this control strategy fully removes time delay elements from a system characteristic equation in the ideal situation of a system without model-plant mismatch and/or noise measurements. By the estimation and prediction of the unknown plant-input disturbances, the capability for rejecting input disturbances has also been improved. The control structure developed is shown to have the same closed-loop relationships as the linear quadratic feedback structure for a system without lime delays. The potential benefits of the proposed controller are demonstrated by the control problem of an industrial grinding system studied previously by Niemiet al.(1982) and Ylinenet al.(1987), which is a challenging problem for MPC-type algorithms.

ISSN:0020-7721    

DOI:10.1080/00207729408929012

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The main objective of this paper is to study the phenomena of the electrohydraulic servo system under the influence of the Stribeck-type friction. Owing to the nonlinear nature of this friction, a sustained oscillation, or limit cycle, might appear in the system behaviour. The system is first divided into two parts, the linear and the nonlinear. For the nonlinear Stribeck-type friction, a flexible model is proposed to represent the whole friction family, and the describing function of this nonlinear friction is generated. The system characteristic equation is established by correlating the frequency response of the linear part and the describing function of the nonlinear part. The existence and stability of the limit cycle are predicted based on the characteristic equation. Finally, by using the sinusoidal, step and ramp input, respectively, the numerical simulation is adopted to observe the system response. All predicted limit cycles can be verified by the simulation results, and the effects of stable and unstable limit cycles are clarified. The dynamic characteristics obtained in this study help to bring insight into this important engineering configuration and throw some light on the possibilities for improvement.

ISSN:0020-7721    

DOI:10.1080/00207729408929013

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The problem of balanced realization and model reduction of a singular system of the formEẋ = Ax + Bu, whereEis a singular matrix, is considered. Using coordinate transformation, which can be computed by performing singular value decomposition ofE, we derive our first approach to the balancing of singular systems. The second approach is based on standard form decomposition of singular systems to slow and fast subsystems and performing balanced realization on the decomposed model. In this sense model reduction can be established in two steps: first, by decomposing the singular system and second, by performing balancing transformation on the decomposed subsystems.

ISSN:0020-7721    

DOI:10.1080/00207729408929014

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The observer synthesis of nonlinear large-scale systems is discussed. The nonlinearities satisfy the Lipschitz conditions instead of any matching conditions and exist on the interconnection terms and local system matrices. With the aid of the solution of the Riccati-type equation, the relationship between the nonlinearity bounds and the observer gains is derived. Moreover, the existence condition and seeking algorithm for the solution of the Riccati equation are investigated. An example with simulations is given to illustrate the application of our results.

ISSN:0020-7721    

DOI:10.1080/00207729408929015

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An efficient robust adaptive control scheme is presented for nonlinear robotic arm systems with bounded time-varying parameters. Unlike other controllers for time-varying robotic models, the presented control scheme does not require the calculation of the regressor matrix and does not impose any restrictions on the rate of changes of unknown robol parameters. The controller is simple, computationally fast and provides stable trajectory tracking in the presence of a class of state-dependent disturbances. Stability analysis indicates that the tracking error will eventually converge into a closed region, which can be made arbitrarily small by adjusting the control parameters.

ISSN:0020-7721    

DOI:10.1080/00207729408929016

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The disturbance decoupling problem is addressed for a class of time-delay nonlinear systems, including linear systems as a particular case. Conditions are given for having causal control laws, and a methodology is proposed for designing the corresponding controllers. An example illustrates the design procedure.

ISSN:0020-7721    

DOI:10.1080/00207729408929017

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A sufficient condition is given for the robust stability of systems with structured uncertainty. The upper bounds measured by theH∞-norm for the sensitivity function and the closed-loop transfer function of the system are also discussed. It is shown that the upper bounds for a certain performance index derived in this paper may be used to deal with the robust stability of the system with multiplicative and additive uncertainties at the same time, as illustrated in the given example.

ISSN:0020-7721    

DOI:10.1080/00207729408929018

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A new algorithm is presented that treats the problem of systematic errors in radar measurements. These errors cannot be estimated by the usual first-order Kalman filter used in air traffic control, and this fact causes serious degradation of the accuracy of aircraft position estimates, directly affecting the aircraft minimum horizontal separation and the maximum airspace capacity. The algorithm is based on the use of distance measuring equipment (DME) measurements and is an extension of previous DME-based methods dealing with aircraft geometric height estimation. The new algorithm could be considered as part of a radar measurement fault-detection and diagnosis algorithm. Its performance is evaluated in various cases and the results are very satisfactory. The implementation of such an algorithm can reduce considerably the departure and arrival delays and the aircraft operating costs.

ISSN:0020-7721    

DOI:10.1080/00207729408929019

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor