A Study of Sensor Array Aperture for Damage Localization in a Plate-Like Structure Using Ultrasonic Guided Waves

An array of sensors for source localization has been used in various areas of engineering such as seismology, oceanography and radar operations. However, there are limited studies for applications using guided waves. The aperture function which characterizes the sensors topology is fundamental for the performance of the array. In this work we study the array aperture function in the context of dispersive attenuated multimode Lamb waves. Time-frequency beamforming analysis was used to study the effect of the aperture function characteristics. The methodology was implemented on various symmetric and non-symmetric modes generated on an aluminum thin plate. The results show that it is possible to locate the wave source by optimizing the aperture of the array for the dispersive modes generated

A data-driven adaptive controller for a class of unknown nonlinear discrete-time systems with estimated PPD

An adaptive control scheme based on data-driven controller (DDC) is proposed in this article. Unlike several DDC techniques, the proposed controller is constructed by an adaptive fuzzy rule emulated network (FREN) which is able to include human knowledge based on controlled plant's input–output signals within the format of IF-THEN rules. Regarding to this advantage, an on-line estimation of pseudo partial derivative (PPD) and resetting algorithms, which are commonly used by DDC, can be omitted here. Furthermore, a novel adaptive algorithm is introduced to minimize for both tracking error and control effort with stability analysis for the closed-loop system. The experimental system with brushed DC-motor current control is constructed to validate the performance of the proposed control scheme. Comparative results with conventional DDC and radial basis function (RBF) controllers demonstrate that the proposed controller can provide the less tracking error and minimize the control effort