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.

Design and Evaluation of a Parallel Cable-Driven Shoulder Mechanism With Series Springs


Upper limb paralysis and movement disorders resulting from neurologic injuries can be treated with an upper limb exoskeleton robot that assists with movement retraining. Cable-driven exoskeletons have been widely studied because of their lightness, compact structure, and low cost. However, the problems of shoulder squeeze force and system stability have not been solved. In this article, we present a prototype parallel cable-driven shoulder mechanism with series springs. The theoretical analysis suggests that the stability of the mechanism is improved compared with that of the previous mechanism, and the effects of stiffness, upper limb weight, and mechanism parameters on the shoulder joint extrusion pressure are analyzed by simulation and experimental results. The results show that this mechanism plays an important role in reducing or eliminating the shoulder squeeze pressure and improving the stability of the mechanism. Moreover, the mechanism has good portability and can be combined with other exoskeletons to facilitate various robot-assisted upper limb rehabilitation training.

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