Midori Maki

Robust control with adaptation mechanism for improving transient behaviour

This paper deals with the problem of designing a robust controller with adaptation mechanisms for the purpose of improving transient performance in time-response. The controlled object is a linear system with unknown parameters which vary within certain prescribed bounds. In the proposed method, a target model with adjustable parameters is constructed in order to obtain on-line information on parameter uncertainty and to improve transient time-response. A robust controller is established in a parameter-dependent form, in which parameters are adjusted on-line on the boundary surface of the possible parameter space according to the error between the state trajectory of the plant and that of the target model.

A Stability Guaranteed Active Fault-Tolerant Control System

In this paper, we focus on the problem of active management of actuator redundancy for fault-tolerant control of linear systems in the presence of both parameter uncertainty and actuator failures. In the proposed method, multiple controllers are designed based on the concept of quadratic stablizing control, in which each controller is determined under the assumption that one specified actuator, named the main actuator, is failure-free. During the course of system operation, the best controller is selected automatically based on the result of fault detection and isolation process. The significance of the proposed active fault-tolerant control system is that the stability of the closed-loop system is always guaranteed even in the presence of fault isolation errors. Such errors only affect control performance. Therefore, the scheme provides a good trade-off among the conflicting requirements on stability and performance. This control starategy has been demonstrated on a lateral-directional dynamics of a McDonnel F-4C airplane by simulation.