Adaptive Perching and Grasping by Aerial Robot with Light-weight and High Grip-force Tendon-driven Three-fingered Hand using Single Actuator
Hisaaki Iida, Junichiro Sugihara, Kazuki Sugihara, Haruki Kozuka, Jinjie Li, Keisuke Nagato, Moju Zhao
TL;DR
This work tackles the directional limitations and payload burden of aerial-perching systems by introducing the Tri-force hand, a tendon-driven, three-finger end effector actuated by a single motor and driven through two-dimensional differential plates. Coupled with an overactuated quadrotor, the design enables pendulum-perching and multi-directional attachment and detachment, improving approach control and operational flexibility. Key contributions include the CS-TDM-based finger design, 2D differential plates for adaptive grasping, and a trajectory-planning framework for side-perching and detachment; experiments show a practical grip capacity of 27.5 kg and successful perching on cylindrical and square obstacles. The results hold practical significance for extending flight time and enabling agile aerial manipulation in cluttered environments, with future work focused on additional DoF and advanced control strategies.
Abstract
In previous research, various types of aerial robots equipped with perching mechanisms have been developed to extend operational time. However, most existing perching methods adopt either an upward or downward approach, making it difficult to perch near walls with surrounding obstacles. Additionally, perching hands are typically designed solely for attachment to objects and lack additional functionality, imposing a payload burden during flight. To address these issues, this paper proposes a lightweight robotic hand, the "Tri-force hand", capable of both perching and object grasping, as well as a new perching method called "Pendulum-perching". The Tri-force hand is a tendon-driven, three-fingered hand utilizing a spherical joint and a two-dimensional differential plate, enabling passive actuation with a single actuator. Each finger module, designed with controllable semi-tendon drive, can conform to arbitrary shapes within its operating range, allowing both perching and adaptive object grasping. By integrating this hand into a fully actuated aerial robot, the system can perform multi-directional approaches from the side and landing using gravity. This approach is similar to Crush-perching seen in researches with fixed-wing aerial robots, but it differs in its superior control over approach speed and direction, as well as its ability to achieve stable detachment and re-launch. In experiments, the fabricated Tri-force hand demonstrated the ability to withstand a total weight of up to 27.5 kg, grasp various objects ranging from simple to complex-shaped tools, and achieve a high success rate in both perching and takeoff.