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.

Modeling of a Complete Morphing Mechanism Covered by a Paneled Morphing Skin


Presented in this paper is a method for modeling and simulation of a complete morphing mechanism. The said mechanism has a rigid panel morphing skin that morphs along with a driving mechanism. The said skin is made of segmented panels, inspired by fish scales. Since the gaps between these panels are undesirable, a gapless design is introduced in this paper by using shape-memory polymer (SMP) joints. This paper aims to solve two fundamental problems for the entire system: (1) motion control and (2) force control. The motion control is addressed through the kinematic modeling of two equations including (a) the passive rigid panels and (b) the passive rigid panels to the active mechanism. Force control is achieved through force modeling. This is to develop a relationship of the SMP deformations to the required actuator forces. The experiment is carried out to determine the SMP forces versus deformation, and simulations are conducted to investigate how a complete morphing mechanism behaves. It also reveals that the workspace and singularity of the original mechanism will change after covered by a morphing skin. The developed method sheds light on the design of a complete morphing mechanism.
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