Quantitative Stability Of Quadrotor Unmanned Aerial Vehicles

Quadrotor Unmanned Aerial Vehicle have broad application area in bomb attacking, atmospheric detecting, goods transporting due to their excellent comprehensive properties, such as small volume, high flexibility, vertical take-off and landing. However, the atmospheric disturbance, the gyroscopic effect and other unpredictable effects due to the complicated airflow in near-earth space, which easily results in the stability problems, such as out of control, shaking and loss accuracy of command tracking. The present study the motion stability of three main methods: describing function method, Lyapunov stability theory, and the PID control theory, but in the face of these methods multivariable and high coupling, quadrotor unmanned aerial vehicles nonlinear underactuated system, there is a certain difficulty, complex dynamics equation is difficult to solve the problems, the Lyapunov function is difficult to build. The qualitative analysis as the main methods to investigate of the systems stability of quadrotor unmanned aerial vehicle at present is hard to reveal the quantitative analysis indicators of the systems stability. This paper builds a quantitative relationship between control input or structural parameter of aerial vehicles and their system stability based on Lyapunov exponent theory from viewpoint of structural parameter design.By analyzing the dynamics modeling and stability during take-off, landing and yawing stage of the unmanned aerial vehicles respectively, it was found that structural parameter variations of the system is conductive to improving the systematic stability. The attitude controller and the position controller are designed based on the system dynamics model. The feasibility of promoting the systems stability is verified by changing the control input parameters and the mechanical structural parameters.