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.

A Reduced Mass-Spring-Mass-Model of Compliant Robots Dedicated to the Evaluation of Impact Forces


The introduction of intrinsic compliance in the design of robots allows to reduce the risk for humans working in the vicinity of a robotic cell. Indeed, it permits to decouple the dynamic effects of the links’ inertia from those of the rotors’ inertia, thus reducing the maximum impact force in case of a collision. However, robot designers are lacking modeling tools to help simulate numerous collision scenarios, analyze the behavior of a compliant robot, and optimize its design. In this article, we introduce a method to reduce the dynamic model of a multi-link compliant robot to a simple translational mass-spring-mass system. Simulation results show that this reduced model allows to accurately predict the maximal impact force in case of a collision with a constrained human body part. Multiple impact scenarios are conducted on two case studies, a planar serial elastic robot and the R-Min robot, an underactuated parallel planar robot, designed for collaboration.

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