Introduction to 7-DoF CoSMo-Arm: High Torque Density Manipulator based on CoSMoA and E-CoSMo

This study proposes a novel 7-DOF robotic manipulator called CoSMo-Arm for high torque density multi-link robotic platform based on a concentrically stacked modular actuator (CoSMoA) and an extended coaxial spherical joint module (E-CoSMo) introduced in previous researches. The CoSMoA is an actuator module designed to improve thermal characteristics by stacking the motor actuator parts to share the heat dissipation device of the adjacent actuator module, thereby theoretically amplifying motor performance by approximately 3.2 times. The E-CoSMo is a parallel joint mechanism connected to the end of the CoSMoA to create point-centered rotational four degrees of freedom. This joint module has a large range of motion in specific rotational directions and maximum output of approximately up to four times to the actuator output in the specific workspace. The CoSMo-Arm is designed to take advantages of these novel concept modules, having a higher payload than its own weight. To verify the benefits of the proposed mechanism, we performed kinematic analysis and dynamics simulations. From experimental verifications of the real prototype, the feasibility and validity are confirmed as a multi-DOF robotic manipulator.