The propulsion of nano-ferromagnetic objects by means of MRI gradients is a promising approach to enable new forms of therapy. In this work, necessary techniques are presented to make this approach work. This includes path planning algorithms working on MRI data, ferromagnetic artifact imaging and a tracking algorithm which delivers position feedback for the microdevice and a propulsion sequence to enable interleaved magnetic propulsion and imaging. Using a dedicated software environment integrating path-planning methods and real-time tracking, a clinical MRI system is adapted to provide this new functionality for potential controlled interventional targeted therapeutic applications. Through MRI-based sensing analysis, this paper aims to propose a framework to plan a robust pathway to enhance the navigation ability to reach deep locations in human body. The proposed approaches are validated with different experiments.
We report here a peculiar dynamically ordered state of clustering droplets of a mixture of organic solvent. There droplets are driven by the solutal Marangoni effect on the surface of aqueous surfactant solution. They form temporal ring clusters which start collapsing immediately after its formation. This process is repeated for more than several hours with the period of 5--20 minutes. We propose an inhomogeneous force model to phenomenologically understand the basic mechanism of this dynamics, where the forces acting on each particle are controlled differently. This droplet system offers a simple, non-biological experimental model for the study of complex dynamical states realized by a group of self-propelled particles.
It is one of the important factors in the design of a pneumatic convyor to sellect appropriate bend pipes so that the deposition and the crushing of the solid particles to be conveyed are avoided as much as possible with as the minimum pressure drop.First, this paper deals with the fundamental analysis on the velocity distribution of the flow of air and the pressure drop in two-dimensional bend pipes by the finite element method.Secondary, it shows the relationships among the shape of the bend pipe, the behavior of the particles and the prssure drop in it experimentelly.It finally shows the appropriate shape of the bend pipe in the pneumatic conveyor for granular materials.
Snakes change their gait patterns in response to the environment. Elucidating the mechanism underlying this behavior lead to the development of robots that work in a wide range of environments. We have previously modeled the snake locomotion on the basis of autonomous decentralized control and demonstrated through simulations that the gait transition could be achieved only via a change in a small number of parameters. However, the previous model could not reproduce concertina and rectilinear locomotion, which are observed when snakes move in narrow space. In this study, we demonstrate through the simulation that concertina locomotion can be reproduced by an autonomous decentralized control scheme in which curvature derivative control is combined with a simple local reflexive mechanism.
Autonomous decentralized control is an attractive concept for designing robots that can exhibit highly adaptive animal-like behaviour. However, despite its appeal, previous robots based on this scheme could only adapt to a limited number of environments. Our hypothesis it that this problem can be overcome by simply implementing a scaffold-exploitation mechanism. We draw our inspiration from flatworms, which move over various terrains using their two-dimensional sheet-like body, and we design an autonomous decentralized control scheme for a similar robot based on the scaffold-exploitation mechanism. Simulation results show that a robot with the proposed control scheme can move efficiently over various irregular terrains. Our control scheme is not specific to a certain environment, but will be applicable in any environment; it could thus form the basis for developing a multi-terrestrial robot whose working area covers land, sea and even air.
