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 of a Morphing Compliant Mechanism With Separate Grippingand Retraction Modes Using a Single Actuation


A key aspect of robotics and automation is continuous repetition of predefined travel and actions. One such example is a robotic gripper, gripping an object, retracting, and displacing it. Usually, two separate actuations are needed to implement the decoupled gripping and retraction modes. In this article, a morphing compliant gripper is proposed that grips an object (X displacement) and retracts it linearly (Y displacement) based on one single actuation, to reduce the input efforts. The mechanism is first designed by the rigid body replacement method and is based on the double-slider mechanism. Morphing is successfully achieved through the use of contact-aided features and a pseudo spring beam to decouple the X and Y displacements. The design is comprehensively analyzed through the nonlinear finite element analysis method and is optimized using the integrated design exploration tools. Simulation results closely match an ideal X and Y displacement path and a displacement-activated transition from X displacement to Y displacement while minimizing the input actuation force. Finally, a 3D-printed prototype is made and preliminarily tested to verify the design.

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