Latest Papers

ASME Journal of Mechanisms and Robotics

  • Dynamic Modeling and Simulation of a Hybrid Robot
    by Shen N, Yuan H, Li J, et al. on May 12, 2022 at 12:00 am

    AbstractThe unique structure of hybrid robot makes its dynamic characteristic different from that of the traditional machine tools. Therefore, the dynamic model is crucial to both designing and application of hybrid robot. In this paper, a new type of five-degrees-of-freedom (5DoF) hybrid robot is introduced, and its dynamic model is established. First, the kinematic formulas are derived for all the component, and then, the inertia forces or moments are calculated. Second, the active forces or moments in the joints are assumed as variables and the number of variables is reduced by analyzing joint types. Then, an equation set of 36 equilibrium equations with 38 variables is obtained using D'Alembert's principle. Based on the spatial deformation compatibility analysis of two branches, two supplementary equations are derived to determine the solution of dynamic model of the hybrid robot with redundant constraints in its parallel mechanism. Several cases are studied by comparing with ADAMS simulation. The result shows the good accuracy of the proposed dynamic model, which provides a practical method to calculate the reaction force or moment in any joint at any instant for the hybrid robot and thus facilitates dimensional synthesis, trajectory optimization, and smoothing control.

  • Feasibility Design and Control of a Lower Leg Gait Emulator Utilizing a Mobile 3-Revolute, Prismatic, Revolute Parallel Manipulator
    by Soliman A, Ribeiro GA, Gan D, et al. on May 12, 2022 at 12:00 am

    AbstractDesign and control of lower extremity robotic prostheses are iterative tasks that would greatly benefit from testing platforms that would autonomously replicate realistic gait conditions. This paper presents the design of a novel mobile 3-degree-of-freedom (DOF) parallel manipulator integrated with a mobile base to emulate human gait for lower limb prosthesis evaluation in the sagittal plane. The integrated mobile base provides a wider workspace range of motion along the gait direction and reduces the requirement of the parallel manipulator’s actuators and links. The parallel manipulator design is optimal to generate the defined gait trajectories with both motion and force requirements using commercially available linear actuators. An integrated active force control with proportional integral derivative (PID) control provided more desirable control compared to traditional PID control in terms of error reduction. The novelty of the work includes the methodology of human data-oriented optimal mechanism design and the concept of a mobile parallel robot to extend the translational workspace of the parallel manipulator with substantially reduced actuator requirements, allowing the evaluation of prostheses in instrumented walkways or integrated with instrumented treadmills.

  • Announcing the 2021 Best Paper Award and Honorable Mention
    by Krovi V. on May 12, 2022 at 12:00 am

    Together with the Editorial Board of the Journal of Mechanisms and Robotics (JMR), I am pleased to announce the winner of the journal's 2021 Best Paper Award:P. Reinier Kuppens, Miguel A. Bessa, Just L. Herder, and Jonathan B. Hopkins, 2021, “Compliant Mechanisms That Use Static Balancing to Achieve Dramatically Different States of Stiffness,” ASME J. Mech. Robot., 13(2), p. 021010. https://doi.org/10.1115/1.4049438

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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