中文说明：
研究了四旋翼垂直起降无人机（UAV）的建模与姿态稳定控制问题，四旋翼姿态用单位四元数代替欧拉角来表示，避免了奇异性问题。考虑电机的动态特性，忽略气动效应，设计了一种非线性的姿态稳定控制器，采用backstepping控制技术进行了控制设计，提出了一种基于科里奥利力矩和陀螺仪力矩补偿的控制律。应用Lyapunov稳定性分析证明了闭环姿态系统是渐近稳定的。此外，该控制器能保证系统在存在外部扰动力矩的情况下，所有状态一致最终有界，分析验证了该控制方法的有效性，并通过仿真研究进行了验证。
English Description：
The modeling and attitude stabilization control problems of a four-rotor vertical takeoff and landing unmanned air vehicle (UAV) known as the quadrotor are investigated.The quadrotor’s attitude is represented by the unit quaternion rather than Euler angles to avoid singularity problem. Taking dynamical behavior of motors into consideration and ignoring aerodynamic effect, a nonlinear controller is developed to stabilize the attitude.The control design is accomplished by using backstepping control technique.The proposed control law is based on the compensation for the Coriolis and gyroscope torques. Applying Lyapunov stability analysis proves that the closed-loop attitude system is asymptotic stable. Moreover, the controller can guarantee that all the states of the system are uniformly ultimately bounded in the presence of external disturbance torque.The effectiveness of the proposed control approach is analytically authenticated and also validated via simulation study.