Latest Papers

ASME Journal of Mechanisms and Robotics

  • Investigation on a Class of 2D Profile Amplified Stroke Dielectric Elastomer Actuators
    on September 24, 2024 at 12:00 am

    AbstractDielectric elastomer actuators (DEAs) have been widely studied in soft robotics due to their muscle-like movements. Linear DEAs are typically tensioned using compression springs with positive stiffness or weights directly attached to the flexible film of the DEA. In this paper, a novel class of 2D profile linear DEAs (butterfly- and X-shaped linear DEAs) with compact structure is introduced, which, employing negative-stiffness mechanisms, can largely increase the stroke of the actuators. Then, a dynamic model of the proposed amplified-stroke linear DEAs (ASL-DEAs) is developed and used to predict the actuator stroke. The fabrication process of linear DEAs is presented. This, using compliant joints, 3D-printed links, and dielectric elastomer, allows for rapid and affordable production. The experimental validation of the butterfly- and X-shaped linear DEAs proved capable of increasing the stroke up to 32.7% and 24.0%, respectively, compared with the conventional design employing springs and constant weights. Finally, the dynamic model is validated against the experimental data of stroke amplitude and output force; errors smaller than 10.5% for a large stroke amplitude (60% of maximum stroke) and 10.5% on the output force are observed.

Passive Aligning of Ribbon Cable in Sliding Surface Gripper for Assembly Task

Abstract

A passive aligning strategy for the assembly task of a ribbon cable is presented using a sliding surface gripper. Once the gripper grasps the ribbon cable, the sliding surface of the gripper pulls the cable in one direction, and at the end of the pulling process, the box-shaped structure of the fingertip of the gripper passively aligns the cable to a predictable pose. The relationship between the alignment speed of the cable on the sliding surface and the grasping force was modeled and verified by experiments. The maximum position error of the ribbon cable connector aligned by the proposed method was 0.7 mm, which was smaller than the mating tolerance between typical male and female connectors. The mating of the connectors was successfully conducted with an industrial robot whose repeatability is less than a millimeter. The entire assembly process of ribbon cable connectors, including visual recognition of the ribbon cable pose, grasping and aligning of the ribbon cable, and mating a pair of cable connectors, was successfully implemented.
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