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.

A Reconfigurable 6 R Linkage With Six Motion Modes and Three Topological Structures

Abstract

In this paper, a new reconfigurable 6R linkage is obtained by combining two identical equilateral Bennett linkages arranged in a plane-symmetric manner, and a detailed kinematic analysis is conducted which shows that there are six distinct motion modes and three topological structures of the derived mechanism without changing the types of kinematic joints. Explicit relationships among the kinematic variables are obtained with D–H method and various modes are discussed in detail. Bifurcation points are derived and the reconfigurations are analyzed. The result shows that the mechanism has six motion modes which contain a special case of a plane-symmetric 6R mode and a special case of a two-fold symmetric 6R mode, an X-shaped motion mode, and two V-shaped motion modes. A physical prototype is fabricated to verify the derivation and it shows that the mechanism can transform among all the motion modes without the need of reassembling.

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