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.

Design Framework and Clinical Evaluation of a Passive Hydraulic Patient Simulator for Biceps Spasticity Assessment Training


This article presents the framework for developing a passive (unpowered) mechanical training simulator for replication of biceps spasticity to complement current clinical assessment training. The passive training simulator was developed to mimic three main behavioral features of spasticity, i.e., abnormal muscle tone, catch-release behavior, and range of motion (ROM) reduction. The simulator can replicate varied levels of spasticity (Modified Ashworth Scale (MAS) levels 0–4) using a combination of three adjustable mechanical design features, i.e., resistance level, catch angle, and ROM selectors. Bench-top evaluation examined the performance of individual mechanical design features, as well as their combined performance. Spastic muscle resistance profiles generated by the simulator qualitatively agreed with the clinical descriptions of spasticity in the MAS. Mean peak simulated resistive torque fell within the clinical measures from actual spasticity patients for MAS 1–4, but was lower for MAS 0 (0.9, 3.5, 4.2, 6.9, 9.8 Nm for MAS 0–4, respectively). Seven clinicians were invited to validate the simulator performance. They were asked to identify the simulated MAS level during a blinded assessment and to score the realism of each simulation feature using a five-point scale, where 3 was “about right,” during a disclosed assessment. The mean percent agreement of clinicians’ judgments was 76 ± 12%. The mean realism score throughout MAS 0–4 were 2.82 ± 0.15. Preliminary results suggested good potential for this simulator in helping future healthcare practitioners learn and practice the basics of spasticity assessment.
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