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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A distributed multi-level current modeling method for design analysis and optimization of permanent magnet electromechanical actuators

Lim, Jung Youl 21 September 2015 (has links)
This thesis has been motivated by the growing needs for multi-degree of freedom (M-DOF) electromagnetic actuators capable of smooth and accurate multi-dimensional driving motions. Because high coercive rare-earth permanent-magnets (PMs) are widely available at low cost, their uses for developing compact, energy-efficient M-DOF actuators have been widely researched. To facilitate design analysis and optimization, this thesis research seeks to develop a general method based on distributed source models to characterize M-DOF PM-based actuators and optimize their designs to achieve high torque-to-weight performance with compact structures To achieve the above stated objective, a new method that is referred to here as distributed multi-level current (DMC) utilizes geometrically defined point sources has been developed to model electromagnetic components and phenomena, which include PMs, electromagnets (EMs), iron paths and induced eddy current. Unlike existing numerical methods (such as FEM, FDM, or MLM) which solve for the magnetic fields from Maxwell’s equations and boundary conditions, the DMC-based method develops closed-form solutions to the magnetic field and force problems on the basis of electromagnetic point currents in a multi-level structure while allowing trade-off between computational speed and accuracy. Since the multi-level currents can be directly defined at the geometrically decomposed volumes and surfaces of the components (such as electric conductors and magnetic materials) that make up of the electromagnetic system, the DMC model has been effectively incorporated in topology optimization to maximize the torque-to-weight ratio of an electromechanical actuator. To demonstrate the above advantages, the DMC optimization has been employed to optimize the several designs ranging from conventional single-axis actuators, 2-DOF linear-rotary motors to 3-DOF spherical motors. The DMC modeling method has been experimentally validated and compared against published data. While the DMC model offers an efficient means for the design analysis and optimization of electromechanical systems with improved computational accuracy and speed, it can be extended to a broad spectrum of emerging and creative applications involving electromagnetic systems.
2

Optimalizace konstrukce zvedače dutinky spřádacího stroje / Optimalization construction tube lifter of spinner machine

Jeník, Jan January 2012 (has links)
The first part of this thesis describes the current technologies of mechanical spin-ning. This is a ring, rotor and air-jet spinning. The product of spinning machines is yarn, the basic material for production textile. The next section describes in detail the current state of the node manipulator lifter tube on spinning machine TORNADO J20, by concern RIETER. It describes the structure, kinematics, duty cycle and requirements for the manipulator. The following optimization options which are described more options for solutions of individual functions of the manipulator, on the end is selected by multi-criteria analysis. The best solution that is elaborate in the next section. The author has created 3-D model optimized lifter tube. Positioning mechanism maintains the current kinematics, it is very similar. But gripper was designed as a passive, thus reduce the load positioning mechanism. Optimization was performed primarily to reduce overall production costs and to reduce weight manipulator. The conclusion is a comparison of current and new solutions. There are also eco-nomic recovery to.

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