# Introduction

Control theory is an interdisciplinary branch of engineering and mathematics that deals with the behavior of dynamical systems with inputs, and how their behavior is modified by feedback [1].

The objective of control theory is to design a controller so that the system has some desired characteristics. Typical objectives are [2]:

- Stabilization
- Regulation
- Tracking
- Disturbance rejection

## Feedback Control Approach

- Establish control objectives
- Qualitative
- Quantitative: step response time
- Require understanding of expected commands, disturbances and bandwitdh
- Require understanding of physical dynamics and appropriate control method

- Select sensors and actuators
- What aspect to be sensed and controlled?
- Sensor noise, cost, reliability, size ...

- Obtain system model
- First principle or system identification
- Evaluation model -> reduce size and complexity
- Accuracy? Error model?

- Design controller
- SISO or MIMO?
- Classical or state-space?
- Choose parameters (rule-of-thumb or optimization)

- Analyze closed-loop performance
- Does closed loop meet objectives?
- Analysis, simulation, experimentation and iterate.

## Declaration

This document includes basic descriptions and implementations of a Control System. The materials covered are: system modelling, controller design, classical control theory, modern control theory and C/Matlab/Simulink implementations.

This wiki site is maintained by myself at an irregularly base. Contents might be inconsistent when I am working on them. Please use it with caution as I assume no other user than myself would be using this website.

## Reference

- Control Theory - Wikipedia, link
- Jonathan How, and Emilio Frazzoli. 16.30 Feedback Control Systems. Fall 2010. Massachusetts Institute of Technology: MIT OpenCourseWare, https://ocw.mit.edu. License: Creative Commons BY-NC-SA.