Mechanical singularity

Abstract: The induced magnetic fields generated by a line mechanical singularity in a magnetized elastic half plane are investigated in this paper. One version of linear theory for soft ferromagnetic elastic solids which has been developed by Pao and Yeh (1973) is adopted to analyze the plane strain problem undertaken. By applying the Fourier transform technique, the exact solutions for the generated magnetic inductions due to various mechanical singularities such as a single force, a dipole, and single couple are obtained in a closed form. The distributions of the generated inductions on the surface are shown with figures.

Abstract: We speculate that the universe may be filled with a kind of fluid which may be called aether or tao. Thus, Newton's law of gravitation is derived by methods of hydrodynamics based on a sink flow model of particles.

Abstract: The multilinked or modular structure is one of the state-of-the-art topics in aerial robot field. One type of the multilinked aerial robot called DRAGON containing a two degree-of-freedom (DoF) force vectoring apparatus in each link has been developed in our previous work to augment both maneuvering and manipulation ability. However, several types of invalid robot poses, which are due to the mechanical structure, the previous control method and the interrotor aerodynamic interference, significantly reduce the region of deformation. Thus, enhanced modeling and control methods are necessary to overcome these problems. In this letter, we first develop an integrated thrust and vectoring control method with a rigorous allocation to solve the control singularity. Second, we present a vectoring configuration planning method, which solves the mechanical singularity by locking one of the axes in the two DoF vectoring apparatus. Finally, we propose an estimation method and an active compensation control regarding the aerodynamic interference to improve the flight stability. In the end, simulation studies and experiments involving the hovering and deformation along a vertical plane are performed to evaluate the whole modeling and control framework.

Abstract: To introduce a passive compliant mechanism for robot joints is an effective way for impact absorption. However, because robot joints also require high torque transmission characteristic, the simultaneous implementation of stiffness and softness is a significant issue. In this paper, we develop a torque transmission mechanism with nonlinear passive stiffness that realizes from zero to extremely high stiffness based on mechanical singularity. The analysis of nonlinear stiffness is established and the experimental evaluation is shown. A four- legged robot with the proposed mechanism is designed and the effectiveness of high nonlinearity of the proposed mechanism is shown by simulation.