Development of Hiryu-II: A Long-Reach Articulated Modular Manipulator Driven by Thrusters

Robotic manipulators using thrusters for weight compensation are an active research topic due to their potential to exceed the limits of maximum length. However, existing manipulators that use thrusters have limitations of maximum length because the hardware design is not sufficiently refined. This letter focuses on overcoming these limitations and realizing an articulated manipulator more than twice the length of conventional ones. To cancel the moment for each link, we performed static analysis considering the torsional deformation around the link axis to derive the thruster position. Weight compensation and joint angle control of the manipulator can be realized with simple proportional integral derivative control for each link by numerical simulation. Consequently, we demonstrated the feasibility of the proposed manipulator by lifting a 0.6 kg payload at the arm end with a prototype of length 6.6 m. Theoretically, each thrust force control input was almost constant, regardless of link attitude. This suggests modular properties that contribute to the practicality of the proposed manipulator for various tasks.