||With highly development of the quadcopter, many practical applications become even more important. The quadcopter owns advantages of high flexibility and small volume. When it is required to conduct a dangerous task or explore a region where is not accessible by humans, for the purpose of security considerations, the quadcopter is a suitable choice.|
In order to achieve trajectory control and flight operations, complex control theories are usually applied. Besides, the designed controller is only applicable to a specific trajectory or operation so the process of controller design becomes cumbersome. Therefore, this thesis employs the approach of mathematical analysis to understand the quadcopter’s flight behavior by establishing its dynamic mathematical model. The circular trajectory commonly used in exploration and investigation missions is chosen for this study. Based on repetitive characteristics and mechanics analysis of a circular motion, find the thrust planning for the quadcopter to complete the circular trajectory. Two mathematical models, without and with the aerodynamic drag are considered. For the case with the aerodynamic drag, the quadcopter is able to accomplish the designated circular task with thrust planning. Nevertheless, the quadcopter with aerodynamic drag is not easy to analyze, a simplified aerodynamic drag model is therefore proposed. Computer simulations show 10% error compared with the complete aerodynamic drag form. If this error is acceptable, the presented aerodynamic drag model can assist controller design for the quadcopter to perform the circular trajectory tasks.