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.

Development of a Novel Compact Robotic Exoskeleton Glove With Reinforcement Learning Control

Abstract

This paper presents the design, optimization, control, and experimental evaluation of a novel compact exoskeleton glove aiming to assist patients with brachial plexus injuries in grasping daily used objects. The finger mechanism is based on a rigid coupling hybrid mechanism concept, which utilizes a serially connected rack-and-pinion mechanism and an offset slider-crank mechanism to couple the motions of different finger joints. The glove dimensions are synthesized based on the natural grasping motion of human hands. To better control the glove and enhance the grasping capabilities, a simulation environment was developed and reinforcement learning techniques were applied. This learning-based control trained an agent to perform different grasp types with appropriate force. The trained agent was then applied in real-world experiments with the developed exoskeleton glove. The results validated the effectiveness of the mechanical design and the real-time self-adjustable control policy, which demonstrated the glove’s functionality and capability to grasp various objects relevant to activities of daily living.

Read More

Journal of Mechanisms and Robotics Open Issues