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 Biomimetic Masticating Robot for Food Texture Analysis

Abstract

Assessing the food texture via mastication is important for advancing knowledge of food properties so as to develop favorable and healthy food products. Oral processing of food by robots can enable an in vitro assessment of food texture by simulating human mastication objectively. In this study, a chewing robot is developed to mimic the rhythmic motion of the molars to enable controllable chewing kinematics and a biomimetic oral environment. The robotic chewing is realized using a 3 degree-of-freedom (DOF) linkage mechanism, which recreates the molar grinding movement based on molar trajectories and chewing cycle durations previously reported in the literature. Moreover, a soft pneumatically actuated cavity is developed to provide a space to contain and reposition the food between occlusions. To regulate the robotic chewing having variable molar trajectories and chewing durations, the mathematical relationship of the linkage’s actuators and molar movements is investigated for the purpose of motion analysis and control. Accordingly, the design of the robot in terms of linkage, oral cavity, and mechatronics system is performed. The built robot is validated by tracing a planned variable molar trajectory while chewing peanuts. The performance of robot chewing is validated by demonstrating the ability of the robot to chew the peanuts similar to that by human through comparison of peanut particle size distributions (PSDs) and particle median size diameters.

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