针对倾转三旋翼无人机飞行模式转换中的高度保持问题进行研究，提出一种新的过渡策略，使飞机可以直接从悬停状态开始过渡转换而不需要获得一定初始速度。采用牛顿-欧拉法对过渡模式进行动力学建模分析，建立了纵向动力学模型；通过对模型进行分析给出了倾转角度和前飞速度的一一对应关系，即过渡段走廊曲线；依托倾转三旋翼无人机实验样机，按照两种不同倾转方式进行飞行试验。对地面站遥测数据分析的结果表明: 按照走廊曲线倾转，较好地解决了直接倾转时的掉高问题，从而验证了走廊曲线的有效性。

Aiming at altitude-keeping of a tilt tri-rotor UAV in flight mode conversion,a new transition strategy was proposed,by which the UAV could implement the transition directly from hovering state without requiring an initial velocity.The Newton-Euler method was adopted for dynamics modeling of the transition mode.The relationship between tilting angle and flight speed,i.e.,the corridor curve of transition mode,was obtained according to the model analysis.Flight test was made to two different tilting modes by using the experimental prototype of tilt tri-rotor UAV.Analysis to the telemetering data obtained from ground station shows that the corridor curve of transition mode is effective for altitude-keeping.