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.

Characterization, Design, and Experimentation of a Fabric-Based Wearable Joint Sensing Device on Human Elbow

Abstract

The use of conductive fabrics (CFs) in the design of wearables for joint sensing has recently received much interest in a wide range of applications such as robotics, rehabilitation, personal wellness, and sports. However, one key limitation in the existing measurement approach is that the user’s anthropometric information is required to relate the joint parameters to the CF sensor strain reading. This paper seeks to address this limitation by evaluating a new wearable device concept that comprises a CF strain–voltage sensor embedded as part of an inverted slider-crank (ISC) mechanism for joint extension sensing. This benefits from not requiring anthropometric information from the user to relate the joint parameters to the fabric strain readings, as opposed to an existing design. We first characterize the electromechanical property of a commercially available CF. Second, we formulate the joint sensing device’s geometric synthesis procedure as a constrained revolute joint system, where the CF is designed and introduced as an RPR chain to obtain an ISC linkage. Lastly, we designed our wearable sensing device and validated against an ISC linkage fixture representing an elbow joint and an actual healthy human subject’s left elbow. The ISC linkage fixture experimental setup shows that our designed joint sensing device can track the elbow extension motion of 140 deg with a maximum error of 7.66%. The results from our human subject’s left elbow show that it can track the elbow flexion–extension at various angular motion, with error ranges between 8.24 deg and 12.86 deg, and have provided us with an acceptable average Spearman’s coefficient values rs at 0.95.
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