Abstract
A new method for optimum shape design of variable capacitance micromotor (VCM) using Differential Evolution (DE), a stochastic search algorithm, is presented. In this optimization exercise, the objective function aims to maximize torque value and minimize the torque ripple, where the geometric parameters are considered to be the variables. The optimization process is carried out using a combination of DE algorithm and FEM analysis. Fitness value is calculated by FEM analysis using COMSOL3.4, and the DE algorithm is realized by MATLAB7.4. The proposed method is applied to a VCM with 8 poles at the stator and 6 poles at the rotor. The results show that the optimized micromotor using DE algorithm had higher torque value and lower torque ripple, indicating the validity of this methodology for VCM design.
Highlights
Variable capacitance micromotor VCM is an important MEMS actuator 1, for which several applications are envisaged, amongst medical implants, optical systems, microrobotics, Aeronautics, and Space 2
The results show that the optimized micromotor using DE algorithm had higher torque value and lower torque ripple, indicating the validity of this methodology for VCM design
In order to investigate the performance of the DE algorithm proposed here, the VCM optimization is carried out using GA with a large population size of 80 and rather large generation number of 100 with the crossover probability of 0.5 and mutation probability of 0.1
Summary
Variable capacitance micromotor VCM is an important MEMS actuator 1 , for which several applications are envisaged, amongst medical implants, optical systems, microrobotics, Aeronautics, and Space 2. The electrostatic field of VCM is analyzed using FEM method due to difficulties encountered in calculating the electric field at the edges 3. Exhaust algorithm based on 6% steps of each design parameter has been used in VCM optimization 4 for which every obtained combination made up of different variables was analyzed using FEM. A new method for VCM optimization is proposed based on Differential Evolution DE. Each individual or candidate solution is a vector that contains as many parameters as those of the problem dimensions. To get optimization shape of the micromotor, a combination of DE algorithm and FEM analysis is proposed. The paper is organized as follows: Section 2 describes the torque calculation and excitation sequence of the VCM.
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