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 Analysis of a Novel Reconfigurable Parallel Manipulator With Kirigami-Inspired Bennett Plano-Spherical Linkages and Angular Pouch Motors


Drawing inspiration from kirigami, this article first presents the crease pattern of a kirigami model which is kinematically equivalent to a Bennett plano-spherical linkage. In terms of the screw theory, distinct closed-loop motion branches of the linkage are revealed. This article then introduces a new reconfigurable parallel manipulator with three hybrid kinematic limbs. Each limb consists of closed-loop subchain, the Bennett plano-spherical linkage, and a R(RR) serial chain. Constraints provided by the hybrid limb are explored by analyzing constraint screws of serial limbs kinematically equivalent to the hybrid limb in different motion branches. The analysis reveals motion characteristics of the moving platform when the parallel manipulator is in different motion branches. The kinematic model provides a unified mapping between joint inputs and outputs of the reconfigurable manipulator in all three motion branches. This article further presents a new inflatable angular pouch motor and fabricated a prototype using a rectangular tile origami base and adhesive fabric. The pouch motors are then integrated with 3D printed prototypes of the Bennett plano-spherical linkage and the parallel manipulator for the purpose of reconfiguring motion branches.
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