Latest Papers

ASME Journal of Mechanisms and Robotics

  • Intuitive Physical Human–Robot Interaction Using an Underactuated Redundant Manipulator With Complete Spatial Rotational Capabilities
    by Audet JM, Gosselin C. on July 21, 2021 at 12:00 am

    AbstractIn this paper, the concept of underactuated redundancy is presented using a novel spatial two-degrees-of-freedom (2-DoF) gravity-balanced rotational manipulator, composed of movable counterweights. The proposed kinematic arrangement makes it possible to intuitively manipulate a payload undergoing 3-DoF spatial rotations by adding a third rotational axis oriented in the direction of gravity. The static equilibrium equations of the 2-DoF architecture are first described in order to provide the required configuration of the counterweights for a statically balanced mechanism. A method for calibrating the mechanism, which establishes the coefficients of the static equilibrium equations, is also presented. In order to both translate and rotate the payload during manipulation, the rotational manipulator is mounted on an existing translational manipulator. Experimental validations of both systems are presented to demonstrate the intuitive and responsive behavior of the manipulators during physical human–robot interactions.

  • Special Section: Mobile Robots and Unmanned Ground Vehicles
    by Reina G, Das TK, Quaglia G, et al. on July 21, 2021 at 12:00 am

    Inspired by the fifth-year anniversary celebration of the homonymous symposium at the International Mechanical Engineering Congress & Exposition (IMECE), this Special Section with ten articles shares the latest research efforts in design, theory, development, and applications for mobile robots and unmanned ground vehicles.

A Sliding-Mode Control Algorithm to Enhance In-Hand Motion Capabilities


This article reports a method for regulating the internal forces during in-hand manipulation of an unknown shaped object with soft robotic fingers. The internal forces ensure that the object does not move between the robotic fingers, thus improving the grip. It is shown that if soft fingers show bounded conformity and the finger–object interface have bounded relative slip, then the relative angular velocity between the object and the fingertip coordinate frame in contact is bounded. Detailed derivation of the proof is presented. The proof is later used to define a new metric of relative slip. The metric is used to design a sliding mode control algorithm that results in an efficient grip, which is robust toward uncertainty in object shape. The robotic fingers are assumed to be under virtual rigidity constraint, that is, the distance between the fingertips do not change. The control algorithm is attractive as it skirts requirement of information of the shape of the object or to solve optimization problems. The grip with the robust control algorithm is shown to be finite-time stable through Lyapunov’s method. The methodology is demonstrated using simulations.
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