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 and Analysis of a Six-Degree-of-Freedom Microsurgical Instruments Based on Rigid-Flexible Coupling Multi-Body System


In order to improve the operational accuracy of microsurgical instruments and increase the success rate of surgery, a six-degree-of-freedom microsurgical instrument is designed and analyzed based on a rigid-flexible coupling multi-body system. First, an improved kinematic modeling method is proposed based on the pseudo-rigid body theory. Second, a rigid-flexible coupling simulation system is built to analyze the error sources in terms of the remote center of motion, preload, and side load. Then, the function of motion scaling, the accuracy of kinematic modeling, and the validity of the workspace are demonstrated by analyzing the workspace. In addition, the maximum stress is analyzed to ensure the safety and reliability of the application. The analysis results show that the improved kinematic modeling method improves the positioning accuracy by more than two times, and the root mean square error at the tool tip of the microsurgical instrument does not exceed 1 μm under a side load of 0.1 N. Finally, the experimental results show that the improved kinematic modeling method has higher pointing accuracy, and the maximum error does not exceed 10 μm. The designed microsurgical instrument can meet the requirements of surgical operations.

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