中文摘要：

针对存在复合干扰的四倾转旋翼（quad tiltrotor，QTR）无人机姿态控制问题，提出了一种结合分数阶理论、滑模变结构控制理论、新型趋近律及super twisting二阶滑模干扰观测器的分数阶滑模控制方法。首先，利用分数阶微积分算子的信息记忆和遗忘特性，把分数阶微积分理论引入滑模控制方法中，设计了分数阶比例微分积分滑模面。其次，针对传统趋近律收敛时间长、速度慢、抖震严重等不足，提出了一种具有二阶滑模特性的新型快速趋近律。最后，考虑到复合干扰的存在，采用super twisting滑模干扰观测器在线对复合干扰进行估计和补偿。通过与传统整数阶滑模控制和动态逆PID控制进行比较，仿真实验结果表明，所提控制方案具有良好的控制性能。

英文摘要：

For the attitude control of quad tilt rotor （QTR） aircraft with unknown external disturbances, a fractional order sliding mode control strategy based on the fractional order theory, sliding mode variable struc- ture control theory and the new rapid reaching law is proposed. First, using the characteristi.cs of information memory and forgetting of fractional calculus operator, the fractional calculus theory is introduced into the sliding mode control method, and a fractional order proportional integral sliding mode surface is designed. Second, in order to solve the problems of long convergence time and shake out serious of the traditional reaching law, a new fast reaching law model is put forward with characteristics of the second order sliding mode. Third, considering the existence of complex disturbances, the super twisting sliding mode disturbance observer is used to estimate and compensate the composite disturbance on line. ing mode control and dynamic inverse PID control, scheme has good control performance. Finally, by comparing with the traditional integer order slid- simulation experiment results show that the proposed control