Model validation and performance prediction in the design of micro systems

Abstract

Micro Electro Mechanical Systems are among the new and emerging technologies of the future and have many applications in different disciplines. Predicting the performance of such systems early in the design process can significantly impact the design cost and also improve the quality of the design. This study presents the model validation techniques integrated with some design methodologies to predict the performance of the micro systems. A two-dimensional micro scanner mirror was chosen as the case study to demonstrate the developed methodologies. The model validation methodology includes the verification of the finite element model using an experimental modal analysis setup for measuring the out-of-plane vibrations of the micro devices. The setup includes a laser doppler vibrometer, a microscope, a camera, a laser positioning system, and a data acquisition system to acquire the data. An experimental procedure was developed to collect the vibration data and then modal analysis was performed to determine the modal frequencies, mode shapes, and modal damping coefficients. The finite element analysis and experimental results were compared to identify the inaccuracies in the modeling assumptions. A validated finite element model was used to obtain the state space representation of the micro scanner mirror to proceed further with additional design studies. The state space model was used for disturbance analysis that was performed using Lyapunov approach to obtain root mean square values of the mirror rotation angle under the effect of a disturbance torque. The disturbance analysis framework was combined with the sensitivity analysis to determine the critical design parameters for improving the system performance. In addition to the disturbance sensitivity analysis, modal sensitivities of the design parameters were also investigated. This analysis was performed by perturbing the design parameters and investigating the change in the modal frequencies.