ATOM: A Tendon-Driven Aerial Manipulator Achieving High Stiffness, High Torque, and Low Coupling Disturbance

Aerial manipulator systems (AMSs) have significantly progressed in air-ground collaborative tasks. Deploying high-stiffness and high-torque manipulators in AMSs can enhance operational robustness, enabling the execution of more demanding tasks such as high-altitude platforms operation, post-disaster rapid response and assisted rescue. However, this is challenging due to the significant coupling disturbance (CPD) induced by the substantial mass and inertia of high-torque joint actuators. To address this issue, we introduce the aerial tendon-driven manipulator (ATOM), which integrates a multirotor with a 4-DOF anthropomorphic tendon-driven serial manipulator. This design minimizes CPD while preserving high-stiffness and high-torque. Our approach begins with an analysis of the CPD model inherent in AMSs, guiding the development of our design concept. In detail, the joints incorporate a tension-amplification-tendon mechanism, significantly enhancing overall stiffness and torque. The links are optimized using finite element topology and lattice optimization techniques, mimicking the radially graded structure found in bone. This bio-inspired design effectively reduces weight and inertia while maximizing structural rigidity. To ensure consistent performance, we have also developed a novel pretension mechanism that allows for adjustable cable tension, preventing unwanted cable relaxation. Experimental validation demonstrates that the ATOM can achieve high-stiffness and high-torque with minimal CPD while exhibiting robust waterproof performance, showcasing its potential for advanced air-ground collaborative tasks.