中文摘要：

无人直升机起降的关键是纵横向姿态保持和滑移控制,以及垂向升降速度的平稳性控制,避免纵横向滑移时受地面约束而引起倾翻和垂向近地颠簸。提出一种无人直升机自动起降控制策略,纵横向利用地面支撑力、姿态和滑移构成反馈控制,垂向利用地面支撑力判断离地和着陆,并通过高度指令牵引控制升降速度。引入地面支撑力反馈控制确保离地瞬时纵横向力和力矩平衡,使无人直升机离地时失去地面约束后能够垂直起飞,引入姿态和滑移反馈抑制无人直升机起降过程中姿态变化和滑移,两者本质上构成并联控制。该策略在某无人直升机试飞试验中获得了成功应用,为无人直升机自动起降技术发展提供有益的借鉴经验。

英文摘要：

To avoid overturning caused by ground constraints,longitudinal and lateral skidding and vertical bumping against the ground,attitude control,skidding control and vertical velocity control are the crucial considerations in an unmanned helicopter takeoff and landing. In this article an autonomous takeoff and landing control strategy for unmanned helicopters is proposed,in which the longitudinal and lateral control is based on the ground force,attitude and skidding feedbacks,and the vertical control includes takeoff and landing judgment by the ground force and velocity control based on height demand traction. Ground force feedbacks are used to keep in balance the longitudinal and lateral force and the moment so that the helicopter can take off vertically while losing the ground constraints; attitude and skidding feedbacks are used to keep the unmanned helicopter horizontal and prevent its longitudinal and lateral movement in the process of takeoff and/or landing; together they constitute an essentially parallel control mechanism. The strategy is verified successfully during the flight test of an unmanned helicopter,which provides useful experience for the development of unmanned helicopter autonomous takeoff and landing technology.