摘要:

A variable structure control system (VSCS) yields total or selective invariance to system parameter variations and disturbances when in the sliding mode. In order to prescribe the system performance, a model-following approach to VSCS design is used. The required behaviour is achieved by defining a model with ideal response characteristics, and a VSCS is designed so that the error between the plant and the model is forced to exhibit a sliding mode. A parameter insensitive controller with improved disturbance rejection which achieves desired system performance results. The resulting nonlinear scheme cannot be assessed using conventional frequency domain techniques. A new analysis tool is therefore proposed and used to explore the robustness of such a nonlinear control scheme. The design technique is illustrated for lateral multimode control. The aircraft system requires a parameter insensitive control type with improved disturbance rejection if possible. In addition, the ability to prescribe flying quality requirements directly is important. The problem thus provides a suitable challenge for the technique. The robustness analysis is illustrated using the resulting VSCS applied to a range of realistic perturbation models of the fully nonlinear aircraft model.

DOI:10.1049/ip-d.1990.0045

出版商:IEE    

年代:1990

数据来源: IET

摘要:

In biotechnical processes the availability of real-time information about the biological activity is of crucial importance, and this is represented by the oxygen uptake rate (OUR). The aim of this paper is to design and evaluate a real-time estimator both for this quantity and for the related oxygen transfer rate coefficient. The design is based on linear approximations of these unknown variables and nonlinear system dynamics, and relies on a careful choice of probing signals. It is found that a maximum length binary sequence (MLBS) can be successfully used as an alternative to a switching sequence resulting from an on/off control. Later, estimation in the closed loop is considered, coupling the previous estimator with a self-tuning PID regulator. Given the nonlinear nature of the system the analysis is carried out mostly by simulation, and the results confirm that in all cases efficient estimates can be obtained. The performance compares very well with previous literature results.

DOI:10.1049/ip-d.1990.0046

出版商:IEE    

年代:1990

数据来源: IET

摘要:

An iterative least squares method with modified residuals is presented which is dedicated to the robust coefficient estimation of Walsh functions for time series contaminated with noise, some of which may even be outliers. Instead of the mean-square approximation error (MSE), a robust criterion is proposed for estimating the coefficients of the time series. It is minimised by applying the ordinary iterative Gauss-Newton approach so that an arbitrary function, which is absolutely integrable in the interval [0,T), can be properly approximated by the firstMWalsh functions. A proof of convergence of the proposed method is provided. Results of simulation confirming robustness and convergence of the robust estimates are included. This method should be of great value in real-life situations.

DOI:10.1049/ip-d.1990.0047

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The paper extends a simplified fast-model predictive control technique to a multi-variable system. The strategy is based on identifying drive combinations which will maximise the time at which predicted variables are ‘offside’, having a sign which opposes that of the drive signal. It is relevant to systems such as multi-axis robot configurations, in which each variable can be associated with an input which dominates it, so that, if driven by an input of limiting value, the variable will ultimately take the same sign as the input. Billingsley's SISO strategy is restated and the multivariable strategy, as extended by Mo, is illustrated by a simulation for which results are presented.

DOI:10.1049/ip-d.1990.0048

出版商:IEE    

年代:1990

数据来源: IET

摘要:

An expert system has been used to build an intelligent interface to a recently developed CACSD technique for the design of linear controllers. This combination allows the design to be specified in terms of time and frequency domain constraints on the closed-loop transfer functions, and provides the designer with assistance in formulating a reasonable specification and in dealing with constraint conflicts.

DOI:10.1049/ip-d.1990.0049

出版商:IEE    

年代:1990

数据来源: IET

摘要:

A novel way of tackling the problem of discontinuity and efficiency in air conditioning control is presented. The controller is split for two different conditions of operation, and the design in each case is carried out usingH∞techniques which allows for frequency response specification of the input and output variables that, ultimately, leads to a solution of the discontinuity problem. Simulations show a better performance and lower energy consumption when compared to an alternative commercial configuration.

DOI:10.1049/ip-d.1990.0050

出版商:IEE    

年代:1990

数据来源: IET

摘要:

A design technique for a single-input/single-output system with nonminimum-phase plant and large parameter variations is developed. The uncertain part is transformed into a disturbance form and the problem becomes one of attenuating the external disturbance. This method gives a much simpler design procedure.

DOI:10.1049/ip-d.1990.0051

出版商:IEE    

年代:1990

数据来源: IET

摘要:

This paper discusses the modelling of nonlinear single-input, single-output systems using a modified least-squares technique. A locally linear autoregressive moving-average model is constructed from past data, valid about the current state of the system. Weighting is applied to the past data, collected during the learning phase, according to the state-space distance between the current state and each past state. Examples demonstrate the wide applications of this technique.

DOI:10.1049/ip-d.1990.0052

出版商:IEE    

年代:1990

数据来源: IET

摘要:

This paper presents an algorithm for path tracking of two robot arms with end-effectors holding a common inertial load. The path is generated as a sequence of elementary motions. Each new position is defined as a function of the previous one. Holonomic constraints are imposed. The characteristic feature of the present algorithm is that it avoids singularities, because there is no need to use inverse kinematics.

DOI:10.1049/ip-d.1990.0053

出版商:IEE    

年代:1990

数据来源: IET