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.

Design of a Novel Flexible Robotic Laparoscope Using a Two Degrees-of-Freedom Cable-Driven Continuum Mechanism With Major Arc Notches

Abstract

This article presents the design, development, and motion control of a novel flexible robotic laparoscope (FRL). The main structure of the FRL includes a two degrees-of-freedom (DOFs) continuum mechanism driven by two pairs of cable-pulley-driven systems, which are actuated by four miniature linear actuators. A constant-curvature model is employed on the kinematics modeling and analysis of the continuum mechanism with designed major arc notches. The bending control strategy of the continuum mechanism is proposed and realized based on its kinematics model and a feedforward compensation method considering its nonlinearity motion calibration with a suitable initial tension of the driven cables. Besides, the continuum mechanism is made of elastic nylon material through 3D printing technology. An experimental prototype is developed to test the effectiveness and feasibility of the FRL. The experimental results indicate that the FRL has good positioning accuracy and motion performance with potential applications in robot-assisted laparoscopic surgery.

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