Experimental design for teaching mechanical dynamics based on the amplitude-frequency characteristics of a MEMS micromirror
[Objective]Under the background of new engineering disciplines,the experimental teaching of mechanical dynamics combined with frontier technology plays an important role in promoting students'engineering practice and multidisciplinary integrating innovation abilities.To realize the combination of MEMS micromirror technology and mechanical dynamics teaching practice and achieve the purpose of design verification and parameter identification of MEMS micromirror,this study relies on a Huawei-funded project to conduct experiments on the amplitude-frequency characteristics of the MEMS micromirror.[Methods]Based on the working principle,the second-order dynamic equation of MEMS micromirror is established,and the MEMS micromirror is considered a typical second-order forced vibration problem.Therefore,its amplitude-frequency characteristics exhibit the resonance phenomenon;that is,when the driving frequency is the same as the natural frequency of the system,the angular amplitude of the micromirror reaches its maximum value.Students understand the theoretical knowledge of forced vibration combined with the experiment and use the knowledge to analyze and design the micromirror,which can promote the students'engineering practice ability.The MEMS micromirror amplitude-frequency experimental platform mainly includes an electromagnetically driven micromirror,laser source,photodetector,and signal processing board.The photodetector is realized by integrating a photodiode and a Gaussian light source.The light emitted by the Gaussian light source is reflected by the mirror attached to the back of the micromirror to the photodiodes,which are integrated with the light source into the same board.Then,the photodiodes generate an electric current through the photoelectric effect.The photodiode current passes through signal processing modules,such as amplification,low-pass filtering,and analog-to-digital conversion,to generate the output signals.When the MEMS micromirror is twisted,the light spot covering the photodiodes will be offset,resulting in the varying light intensities received by the two groups of photodiodes.As a result,the output signals corresponding to the two groups of photodiodes vary,and angle detection can be realized by calculating the difference of the output signals.The amplitude-frequency characteristic curve of the micromirror can be obtained by collecting the torsional amplitudes corresponding to different driving current frequencies.[Results]The experiment on the amplitude-frequency characteristics of the micromirror realized the precise identification of the natural frequency and quality factors of the micromirror,which lays the foundation for the formulation of the control scheme.The photodetector has the advantages of compact space and lightweight;thus,it can realize high integration with the MEMS micromirror,which has important engineering value for the product of the laser scanner.[Conclusions]The application of micromirror amplitude-frequency characteristic experiments in mechanical dynamics teaching enhances students'knowledge of engineering practice and multidisciplinary integrating innovation abilities,broadens students'understanding of frontier technologies and enhances students'desire to engage in scientific research work in the future.At the same time,Huawei's courage to break through the blockade inspired students'patriotism and craftsmanship,which had a significant effect on ideological and political lessons.
mechanical dynamicsMEMS micromirrorexperimental teachingphotoelectric detectioncurriculum ideology and politics
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