Latest Papers

ASME Journal of Mechanisms and Robotics

  • Mechanical Characterization of Supernumerary Robotic Tails for Human Balance Augmentation
    on August 31, 2023 at 12:00 am

    AbstractHumans are intrinsically unstable in quiet stance from a rigid body system viewpoint; however, they maintain balance, thanks to neuro-muscular sensory control properties. With increasing levels of balance related incidents in industrial and ageing populations globally each year, the development of assistive mechanisms to augment human balance is paramount. This work investigates the mechanical characteristics of kinematically dissimilar one and two degrees-of-freedom (DoF) supernumerary robotic tails for balance augmentation. Through dynamic simulations and manipulability assessments, the importance of variable coupling inertia in creating a sufficient reaction torque is highlighted. It is shown that two-DoF tails with solely revolute joints are best suited to address the balance augmentation issue. Within the two-DoF options, the characteristics of open versus closed loop tails are investigated, with the ultimate design selection requiring trade-offs between environmental workspace, biomechanical factors, and manufacturing ease to be made.

Numerical and Experimental Study on Caudal Fin Oscillation Mode in Hemispherical Space


Attaining multidimensional movements, such as cruising, diving, and turning, is a crucial challenge in the development of bionic robotic fish. When only focusing on caudal fin movements, the caudal fin of a tuna generates significant lateral and propulsive forces and weak lift, while in contrast, the caudal fin of a dolphin generates significant lift and propulsive forces and weak lateral forces. The paper introduces a novel caudal fin oscillation mode for the hemispherical space, which extends the caudal fin oscillation features observed in tuna and dolphin to a broader range of organisms. First, we presented the concept of hemispherical space caudal fin oscillation mode, and demonstrated the principle of lift distribution through theoretical calculations. Moreover, we detailed the force distribution obtained by the robotic fish under different caudal fin oscillation modes through numerical simulations. Finally, we experimentally validated the feasibility of the hemispherical space caudal fin oscillation mode. The results indicate that by modifying the oscillation mode of the caudal fin in bionic robotic fish, it is possible to distribute the lift generated by the fin movement to various forces that aid in achieving multidimensional movement, including propulsive, lateral, and lift forces.

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