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.

Kinetic Analysis of Active Omni Wheel With Barrel-Shaped Rollers for Avoiding Slippage and Vibration


Omnidirectional mobility is required for the efficient movement of transport vehicles in factories and warehouses. To meet this requirement, the active omni wheel with barrel-shaped rollers (AOWBR) was previously proposed. The barrel-shaped rollers are arranged around the outer circumference of the main wheel of the AOWBR. This structure is expected to be effective in suppressing vibration during vehicle movement. The transmission roller drives the outer roller via a friction drive, which actively moves the AOWBR in the lateral direction. However, the friction drive may cause slippage between the transmission roller and the outer roller. To solve this problem, this study investigates the effects of the design parameters for an AOWBR on vibration and wheel slippage. The kinetic models of the wheel main body, transmission roller, and outer roller are established. Then, simulations are carried out using the kinetic models for various structural parameter values. The simulation results show that a softer rubber block installed in the support mechanism of the outer roller contributes to reduce wheel slippage but cause larger vibration, and that a larger setting angle between the transmission and outer rollers contributes to reduce slippage and vibration. Finally, comparison experiments are conducted on two types of prototype to verify the simulation results.

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