Fixed-root Aerial Manipulator: Design, Modeling, and Control of Multilink Aerial Arm to Adhere Foot Module to Ceilings using Rotor Thrust

Precise aerial manipulation is important for multirotor robots. For multirotors equipped with arms, the root pose error due to the floating body affects the precision at the end effector. Fixed-root approaches, such as perching on surfaces using the rotor suction force, are useful to address this problem. Furthermore, it is difficult for arm-equipped multirotors to generate large wrenches at the end effector owing to joint torque limitations. For multilink aerial robots with rotors distributed to each link, the thrust of rotors can produce large torques. Therefore, such multirotor robots can generate comparatively large wrenches at the end effector. In this paper, we introduce a rotor-distributed multilink robot that can perch on surfaces. First, we designed a root footplate and arm module for a multilink aerial robot. During perching, the joint between these two links can be passive to prevent peeling. Second, we propose a quadratic programming (QP) based controller to calculate the desired thrust for perching motion, considering the static friction and zero moment point (ZMP) conditions on the footplate. Finally, we conducted root-body perching motion tests. The manipulations of the multilink aerial robot during perching become more accurate than those during flight because the root position adheres to the environment.