For quadrotor aircraft, choosing a suitable coordinate system can make the motion equation simple and easy to analyze and solve. The fuselage coordinate system can be used to describe the rotation and motion of aircraft. The ground coordinate system must be used to determine the position of the aircraft. The coordinate system above is Cartesian right-hand rectangular coordinate system. The two defined coordinate systems are as shown in Figure 2, namely the ground coordinate system E(X, y, z) and the volume coordinate system B( Xb, Yb, Zb).