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.

TriRhino: A Five-Degrees-of-Freedom of Hybrid Serial–Parallel Manipulator With All Rotating Axes Being Continuous: Stiffness Analysis and Experiments


This paper studies the stiffness and experiment of a five-degrees-of-freedom (DOF) hybrid, serial–parallel, manipulator, with all rotating axes being continuous: TriRhino. First, the motion principle of the hybrid manipulator is introduced and the structural design is presented. Next, the stiffness analysis of the hybrid manipulator is carried out. Specifically, a stiffness test, based on prototype and loading device, is performed, proving that the real stiffness is lower than that obtained by the finite element analysis. Following, the main geometric parameters, involving error, are determined, while the real values of the parameters with an error are identified, through performed calibration experiments. Finally, the measurement results show that the positioning accuracy of the manipulator is significantly improved, after kinematic calibration. Moreover, machining experiments on a workpiece show the great ability of the proposed manipulator, in machining parts with curved surface; thus, great application prospects, in the machining of structural parts with complex surfaces, are quite realistic.
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