摘要:

In the paper, we present the results of a study into the use ofH∞-optimisation for the design of robust feedback control laws for improving the handling qualities of high-performance helicopters. A low-speed controller was designed to give accurate control of pitch and roll attitude, yaw rate and heave velocity for a typical combat helicopter. The design was based on a linearised model obtained from a six-degree-of-freedom nonlinear model of a helicopter provided by the Royal Aerospace Establishment (RAE), Bedford, UK. Robustness was a major issue because rotor dynamics were not included in the design model. Numerical compliance of the design with handling qualities requirements was assessed by testing simulated responses against specifications from a proposed airworthiness design standard. Robust stability was assessed from singular-value plots. In addition, the qualitative features of the design were assessed in a piloted flight simulation trial held at RAE, Bedford.

DOI:10.1049/ip-d.1990.0016

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Increasingly, as flight-control laws become more complex and sample times shorten, implementation requirements are outstripping the capacity of general-purpose single-processor systems. This has prompted this investigation of the feasibility of using a parallel-processing transputer-based network, programmed in occam, for the implementation of an aircraft-flight-control algorithm. Although the problems of flight-control implementation motivated the study, the research findings have wider applicability. Three techniques to generate the concurrent realisation of a typical flight-control law are described and illustrated together with some indications of their strengths and weaknesses. On the basis of this preliminary study, one of these approaches is suggested as a practical way to tackle the problem. Software tools have been used and developed to automate the mapping of control laws onto transputerbased systems. These have proved to be effective and convenient aids, supporting real-time simulation and implementation.

DOI:10.1049/ip-d.1990.0017

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Three classes of automated tuning for PID controllers are discussed and compared. These are a Ziegler-Nichols-based autotuner, a waveform-analysis adaptive tuner and a leastsquares identification-based self-tuner. The results of a program of experiments to evaluate the relative performance of the three approaches are presented, together with a discussion of their relative merits in the light of these experiments. Two representative industrial temperature-controlled processes are used in these experiments: a plastic-onwire multizone extruder barrel and a laboratory furnace. Between them, these processes display typical characteristics such as nonlinearity and loop coupling.

DOI:10.1049/ip-d.1990.0018

出版商:IEE    

年代:1990

数据来源: IET

摘要:

In the process industries there are many cases where substantial economies could be made, if valve actuators were available with response times shorter than those presently available, with traditional spring-opposed-diaphragm units, the performance of these actuators being inhibited by built-in loading, a low working pressure and flow passages which are restricted in relation to the swept volume of the actuator. The paper presents an analysis of a pneumatic actuator system with response characteristics that are much improved compared with those available from conventional spring-opposed-diaphragm units. The equations are developed which characterise the behaviour of the pneumatic actuator, and comparisons of experimental (using a specially designed test rig) and simulated results show the accuracy of the model to be good. Linear approximate models of the pneumatic actuator system then form a basis for the application of two linear controller-design procedures. The design methods employed are the linear quadratic optimal control with extended cost functions and the Horowitz approach to sensitivity reduction. The resulting closed-loop designs are found to be robust and to achieve their required performance specifications under both emergency and normal actuator operations.

DOI:10.1049/ip-d.1990.0019

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The paper describes the design of an advanced control system for a machine used in the flexible manufacture of colliery roadway supports. Computer-aided design techniques were used extensively in the development of the system. Simulation, in particular, was important for efficiently establishing appropriate control modes and strategies. The control problem is, in essence, a co-ordinated servo control problem, and relevant high-grade robotic dynamic control techniques were used to obtain maximum performance benefits. The control system was implemented in a multiprocessor environment and worked successfully. This application is important because it demonstrates that sometimes a control system may be the deciding factor determining whether a process is possible at all.

DOI:10.1049/ip-d.1990.0020

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The paper describes the use of selftuning concepts in the classical problem of extremum control. In particular, the situation is considered whereby a recursive parameter estimator is used to determine online the parameters of a performance index. The estimates are then used to decide the directions and step lengths employed in an online extremum-seeking function. The paper considers a self-tuning extremum controller for a specific one-dimensional performance index, and demonstrates its behaviour when used in simulation and in a practical situation drawn from the automotive industry.

DOI:10.1049/ip-d.1990.0021

出版商:IEE    

年代:1990

数据来源: IET