  This paper presents a novel trajectory planning method for aerial perching.
Compared with the existing work, the terminal states and the trajectory
durations can be adjusted adaptively, instead of being determined in advance.
Furthermore, our planner is able to minimize the tangential relative speed on
the premise of safety and dynamic feasibility. This feature is especially
notable on micro aerial robots with low maneuverability or scenarios where the
space is not enough. Moreover, we design a flexible transformation strategy to
eliminate terminal constraints along with reducing optimization variables.
Besides, we take precise SE(3) motion planning into account to ensure that the
drone would not touch the landing platform until the last moment. The proposed
method is validated onboard by a palm-sized micro aerial robot with quite
limited thrust and moment (thrust-to-weight ratio 1.7) perching on a mobile
inclined surface. Sufficient experimental results show that our planner
generates an optimal trajectory within 20ms, and replans with warm start in
2ms.
