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.

One-Step Solving the Robot-World and Hand–Eye Calibration Based on the Principle of Transference

Abstract

Principle of transference is very important in the kinematic analysis of spatial mechanisms, which enables the extension of point transformations to line transformations inbuilt with the dual mapping. An ideal conceptualization for applying kinematic calibration is to extend the solution of the rotational equations to the kinematic equations via dual mapping. However, this necessitates an analytic representation of the rotational solution, a task that is typically unachievable. Duffy and his coauthors used the principle of transference to generate the spatial equations from the spherical equations. Therefore, the application of the principle of transference to kinematic calibration allows one to start with the process of deriving and solving the equations of kinematics. In this article, the kinematic calibration problem is used as an application to discuss the implementation process of principle of transference in detail. First, the process of transforming the rotational equations into a linear null-space computational system based on quaternion matrix operators is reviewed. Then, fusing the dual matrix operators converts the kinematic equations into the dual linear system of equations, which reflects the forward process of principle of transference. Finally, eliminating the dual operations in the dual linear system of equations turns it into a high-dimensional linear null-space computational system, which embodies the inverse process of principle of transference. This article provides a new closed-form solution for the AX=YB problem.

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