A quadcopter is considered one of the most well-known examples of unmanned aerial vehicles (UAVS), because it has more advantages than standard helicopter in terms of size, efficiency, and safety. As a result, researchers are quite interested in it. In this paper, practical applications and various control techniques of the quadcopter are presented. This article summarizes an overview of quadcopter popular control strategies such as intelligent PID techniques, feedback linearization techniques, linear quadratic LQR techniques, sliding mode control techniques, and backstepping technique, followed by analyses, pros, and cons of each control technique. Finally, our research prospects that the most important features of research and development quadcopter's future research will be directed by this focused literature. For each technique, the target and type of test of each research article are stated, making it easier for the researcher to select the research papers that best meet his objectives.
Keywords: Nonlinear Control, Quadcopter, Regulation, Tracking, Underactuated System.