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.

Analytic Center-Based Tension Distribution for Cable-Driven Platforms

Abstract

A redundant cable-driven platform (CDP) is composed of m cables that exceed the degree-of-freedom (DoF) of the end-effector. The choice of tension along the cables admits infinite solutions. This paper proposes the use of the analytic center to solve the tension distribution problem. Adopting this technique allows finding tensions far from the tension limits, namely, robust as well as tension profiles continuous and differentiable in time. The continuity, differentiability, and uniqueness of the solution are also proven. Moreover, the possibility of including non-linear constraints acting on the tensions (e.g., friction) is a further contribution. The computational time with the proposed approach is compared to the existing techniques to assess its real-time applicability. Finally, several simulations using several cable-driven parallel robots’ (CDPRs) architectures are reported to demonstrate the method’s capabilities.

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