Design and Experimental Validation of a Macro-Micro Robot With Cable-Driven and Underactuated Joints

This letter presents the design, modeling, and experimental validation of a macro-micro robot featuring a 2-degrees-of-freedom (DOF) serial underactuated mechanism mounted on a cable-driven pulley. The main contribution consists in demonstrating that, by ensuring a specific mass distribution, the system achieves differential flatness, enabling accurate point-to-point and via-point trajectory planning without feedback from the passive joint. The dynamic model incorporates damping effects and is validated both numerically and experimentally. Results confirm the feasibility and benefits of the proposed system in terms of dexterity, trajectory control, and reduction of workspace occupation, particularly when obstacles are present.