An integrated environment for computer-aided control engineering

This thesis considers the construction of a system to support the total design cycle for control systems. This encompasses modelling of the plant to be controlled, specification of the final objectives or performance, design of the required controllers and their implementation in hardware and software. The main contributions of this thesis are : its development of a model for CAD support for controller design, evaluation of the software engineering aspects of CAD development, the development of an architecture to support a control system design through its full design cycle and the implementation of this architecture in a prototype package. The research undertakes a review of general design theory to develop a model for the computeraided controller design process. Current state-of-the-art packages are evaluated against this model, highlighting their shortcomings. Current research to overcome these shortcomings is then reviewed. The software engineering aspects to the design of a CAD package are developed. The characteristics of CAD software are defined. An evaluation of Fortran, Pascal, C, C++, Ada , Lisp and Prologue as suitable languages to implement a CAD package is made. Based on this, Ada was selected as the most suitable, mainly because of its encapsulation of many of the modern software engineering concepts. The architecture for a computer-aided control engineering (CACE) package is designed using an object-oriented design method. This architecture defines the requirements for a complete CACE package including control-oriented data structures and schematic capture of plant models. The details of a prototype package using Ada are given to provide detailed knowledge in the problems of implementing this architecture. Examples using this prototype package are given to demonstrate the potential of a complete implementation of the architecture

Multi-objective scheduling and control of a nonlinear automotive powertrain

The automotive industry is faced with the challenge of ever-increasing emission legislation. This study demonstrates the effective use of nonlin­ear techniques in automotive control for the problem of fuel and emission minimisation. A review of previous work highlights the inadequacy of traditional optimisation formulations. The conflicting requirements of both low fuel and emissions is a design problem for which compromise and trade-offs are unavoidable. This study attacks the problem through powertrain scheduling, an approach ideally suited to both S.I. and diesel engines, and demonstrates how the novel application of multi-objective optimisation methods provides a solution more akin to the real physical problem. The modern control theory approach presented is a three stage pro­cess : formulation of the mathematical model, including the essential dy­namics, constraints, and objectives of the physical problem; optimisation of the control strategy with respect to the relevant performance criteria; and synthesis of the optimal control design. The optimisation model is finite-dimensional and nonlinear, the use of which demands a knowledge of nonlinear systems and available methods. These are classified. Re­sults for single and multi-objective optimisations are compared and fully demonstrate the advantages of the latter for the scheduling problem. Op­timal schedules are generated and from them, implementable rule-based control laws are derived. Performance, in terms of the ability to track a legislative test cycle and to retain the optimal design specification, is demonstrated through dynamic simulation, as is their driveability and robustness. This study specifically considers a diesel-engined vehicle incorporating a CVT. The methods tire widely applicable however, to other engine and transmissions types, and to other automotive control problems