Design, Control, and Motion-Planning for a Root-Perching Rotor-Distributed Manipulator
Takuzumi Nishio, Moju Zhao, Kei Okada, Masayuki Inaba
TL;DR
This work addresses the limited end-effector wrench and reach in aerial manipulators by introducing a minimal rotor-distributed manipulator (RDM) with root-perching capability. It develops a quasi-steady model with a rotor-allocation matrix $\mathbf{Q}(\mathbf{q})$, and a QP-based perching controller that enforces friction and ZMP constraints while respecting rotor limits. A planning framework based on differential kinematics generates end-effector and foot trajectories under joint, thrust, and contact constraints. Experimental results on flight and ceiling-perching confirm improved end-effector stability and wrench capacity, enabling complex ceiling-based tasks such as drilling, painting, and valve operation. The approach offers a scalable path to enhance manipulation performance of aerial robots in confined spaces, leveraging fixed-root perching to reduce joint-load and expand reach.
Abstract
Manipulation performance improvement is crucial for aerial robots. For aerial manipulators, the baselink position and attitude errors directly affect the precision at the end effector. To address this stability problem, fixed-body approaches such as perching on the environment using the rotor suction force are useful. Additionally, conventional arm-equipped multirotors, called rotor-concentrated manipulators (RCMs), find it difficult to generate a large wrench at the end effector due to joint torque limitations. Using distributed rotors to each link, the thrust can support each link weight, decreasing the arm joints' torque. Based on this approach, rotor-distributed manipulators (RDMs) can increase feasible wrench and reachability of the end-effector. This paper introduces a minimal configuration of a rotor-distributed manipulator that can perch on surfaces, especially ceilings, using a part of their body. First, we design a minimal rotor-distributed arm considering the flight and end-effector performance. Second, a flight controller is proposed for this minimal RDM along with a perching controller adaptable for various types of aerial robots. Third, we propose a motion planning method based on inverse kinematics (IK), considering specific constraints to the proposed RDMs such as perching force. Finally, we evaluate flight and perching motions and \revise{confirm} that the proposed manipulator can significantly improve the manipulation performance.