A Design Methodology for Uncertain, Unstable Plants with Hard Actuator Saturation

点击翻译按钮获取中文摘要

The major objectives of this research project are to develop a transparent and practical set of design tools for synthesizing controllers for guaranteeing acceptable performance in uncertain, unstable plants under hard actuator saturation; to develop a methodology that removes the need for integral control and more generically the need for imbedding an internal model inside a control loop for a large class of problems; and to demonstrate the applicability of the developed methodologies on two laboratory systems; one a single flexible link attached to a rigid hub and the other a flexible link driven by a worm gear transmission. In order to achieve the objective of developing a design methodology, first stable, uncertain singleinput single- output (SISO) plants under saturating control is considered. Next, SISO, linear, uncertain plants with poles in the closed left half plane subjected to actuator saturation are enclosed and finally linear, uncertain plants with poles in the right half plane subjected to actuator saturation are investigated. Preliminary results indicate that using local feedback around the saturation nonlinearity such that the closed loop system has an impulse response of one sign allows the system to gracefully come out of a saturation state so that feedback remains active for the most part. Both time domain and frequency domain methods are considered. To demonstrate the feasibility of the proposed design methodology two laboratory scale systems currently available in the PI's lab at Texas A&M University are used. Both systems are fully instrumented to be controlled by a PC. One of the systems has a model linearized about a trajectory characterized by poles on the imaginary axis and the other has a linearized model characterized by poles in the right half plane. The key goal of the demonstration are to let the driving d.c. motors saturate and to compare the performance with a controller design that does not explicitly consider hard saturation.