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.

Energy-Based Footstep Planning of Biped on Uneven Deformable Terrain Using Nonlinear Inverted Pendulum


In this work, the motion of a nonlinear inverted pendulum (NIP) on deformable terrain due to foot contact forces is used for energy analysis and footstep placement. In order to include the linear and rotational motions of the NIP, the mass moment of inertia of the body is also considered in the center of mass (CoM) model. The terrain deformation is modeled using a spring-damper contact model, and based on the rigid body dynamics of the NIP, its motion is generated. The energy analysis of the system provides the regions of possible foot placement. Based on the loss of potential energy due to ground deformation, the limits of terrain stiffness are also obtained for walking on uneven deformable terrain.

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