There has been increasing attention to the use of voice coil actuators (VCAs) for precision motion applications. In this paper, a detailed design of a cylindrical VCA is presented. Different options for the overall configuration are evaluated according to various criteria and design variables are defined for the chosen configuration. After that, optimization parameters are derived to maximize the performance in a precision motion application by maximizing the acceleration and minimizing the heat dissipation. Design parameters are optimized using finite element analysis to evaluate the magnetic properties. Optimization is carried out using the bulk volume of coil, which allowed electrical properties to be later characterized via the selection of wire gauge. Calculations for evaluating resistance, inductance, current drain, and voltage supply requirements for dc and dynamic cases are presented. Magnetic field predictions and formulations used in force calculations are verified in experiments.Index Terms-Coil wire gauge, finite element analysis, optimization, precision motion systems, voice coil actuator.

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Although intracardiac metastasis of germ cell tumors is rare, it can be localized in the right or left heart by disseminating spread and give their cardiac symptoms depending on the location of metastatic mass. We present a 38-year-old male patient with a preliminary diagnosis of testicular tumor who was followed by the medical oncology clinic with cerebrovascular event and heart failure symptoms.

Abstract:In this study, a precision motion stage, whose design utilizes a single shaft supported from the bottom by an air bearing and voice coil actuators in complementary double configuration, is evaluated for its dynamic properties, motion accuracy, and potential machining force response, through modal testing, laser interferometric metrology, and spectral analysis, respectively. Modal testing is carried out using two independent methods, which are both based on impact hammer testing. Results are compared with each other and with the predicted natural frequencies based on design calculations. Laser interferometry has been used with varying optics to measure the geometric errors of motion. Laser interferometry results are merged with measured servo errors, estimated thermal errors, and the predicted dynamic response to machining forces, to compile the error budget. Overall accuracy of the stage is calculated as peak-to-valley 5.7 µm with a 2.3 µm non-repeatable part. The accuracy measured is in line with design calculations which incorporated the accuracy grade of the encoder scale and the dimensional tolerances of structural components. The source of the non-repeatable errors remains mostly equivocal, as they fall in the range of random errors of measurement in laser interferometry like alterations of the laser wavelength due to air turbulence.

In this study, anti-lock brake system control using sliding-mode controller is investigated. Different alternatives for the switching function and the sliding surface, involved in the structure of the sliding-mode controller, are explored. It was aimed to reach a better controller performance with less chattering and robustness to actuator imperfections. Regarding applicability, tire force response was modeled as a uniformly distributed uncertain parameter during controller designs. Controllers are simulated for both constant and varying coefficient of friction roads, with optimized design parameters. The effects of actuator first-order dynamics and transportation delay, which come up in practical implementations, were considered. The sliding-mode control structure which employs derivative switching function with integral sliding surface is originally proposed in this study. It is found to produce less chattering and provide more robustness, which could not be achieved side by side using former designs.