LINEAR ACTIVE DISTURBANCE REJECTION CONTROLLER (ADRC) AND ITS APPLICATIONS IN TIME DELAY SYSTEM

Abstract

The elementary concepts of control systems have remained unchanged notably in the nearest few decades. The basic reason for the use of control systems as compared to open-loop systems is the need for improving the transient response, minimizing the steady-state errors and improving the sensitivity to fluctuations in load parameters. Improving transient response entails boosting system bandwidth. Faster response times result in faster settling of the system, which allows for better machine throughput. The systemcan endure fluctuations in both input and output parameters when the sensitivity to load parameters is made better. Examples of parameter fluctuation are the power line frequency, change in load, and unexpected disturbances. Considering all of the aforementioned factors, the ADRC technique proves to be one of the most straightforward, effective, and robust schemes. In this thesis, an attempt has been made to study the active disturbance rejection control (ADRC) technique in a detailed form. How a paradigm shift in control strategy resulted in the development of ADRC is presented along with its various forms and design procedure. The forms include LADRC, GADRC and a new design scheme ADR-TOC is proposed. Rather than using an exact mathematical model, we use an assumed mathematical model and then implement a controller that will minimize the error between the random and accurate models by actively estimating and compensating for all variation as if it were a single disturbance. The simulation study conducted demonstrates the ease of tuning the system with the help of just 2 controller parameters. Next, it demonstrates the effectiveness of the methods to handle systems with considerable time delays and also along with it the property of disturbance rejection. Finally, the advances and prospects of the ADRC scheme are suggested for the research motivation.