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.

Fast Kinematic Calibration of a Robotic Manipulator Through a Single Continuous Motion

Abstract

The measurement step of the existing calibration approaches for robotic manipulators can take a considerable amount of time to settle a robotic manipulator down at certain static configurations, making the calibration approaches time-consuming. For applications of robotic manipulators requiring periodic recalibration (e.g., human–robot collaborative production lines and robotic inspecting systems), the time consumption of the data collection phase is a critical issue. This paper proposes a fast kinematic calibration approach for robotic manipulators, based on the measurement of a robotic manipulator tracking only a smooth and continuous time-optimal trajectory, rather than static measurement. Data samples on configurations are recorded continuously without settling the robotic manipulator down. To demonstrate and evaluate the proposed approach, experiments are performed based on a four degrees-of-freedom parallel manipulator. Experiment results show that compared to an existing calibration approach based on static measurement, the proposed approach improves the time efficiency of calibration by 93.13% with only a position accuracy loss of 1.77% and an orientation accuracy loss of 2.36%.

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