A novel real-time DIC-FPGA-based measurement method for dynamic testing of light and flexible structures

Abstract

A high-speed 3D digital image correlation (DIC) setup is developed and coupled with an FPGA-based real-time operating system (RT-FPGA) for dynamic testing of light and flexible structures. An in-house image correlation program is developed using MATLAB. This program is validated using a virtual stereovision system created in AUTODESK 3DS MAX to simulate a translating and rotating plate and generate synthetic images. An experimental setup is designed and fabricated to mount the high-speed cameras at precise relative locations and orientations. The developed 3D-DIC technique is validated by comparing it with a laser displacement sensor while measuring point displacement of a rotating plate mounted on a servo mechanism. The displacement measurements obtained from the DIC setup match those obtained from the laser sensor with less than 2% error. The high-speed cameras are coupled and synchronized with an accelerometer and displacement sensor using the RT-FPGA system. A LabVIEW-FPGA program is developed for the coupling, synchronization and data acquisition tasks. The DIC-FPGA coupling is validated by measuring the oscillatory motion of a rigid block and structural dynamic parameters of an ASTM-standard beam. This technique is successfully applied for structural dynamic testing of a hyperviscoelastic membrane, a polymeric sandwich beam and a biomimetic flapping wing. The present study successfully demonstrates the development, validation and application of a novel real-time high-speed noncontact DIC-FPGA technique. Using the reported validation and application exercises, similar measurement methodology can be developed at any lab and used for dynamic testing of light and flexible structures.

Optimization and assessment of MWCNT dispersion in polypropylene nanocomposite films

“…A correlation algorithm was applied on the images captured and natural frequency of the wings were obtained. 43 Dynamic tests performed exhibit increase in natural frequency of the developed nanocomposite wings with modified solvent casting process. The natural frequency of PP wing and MWCNT-PP nanocomposite wings shown in Table 5, was found to be greater than those obtained previously in the similar weight category.…”

Encapsulation Based Method for Natural Frequency Identification of Deployable Solar Arrays with Multiple Plates

“…However, this method has defects in the application of noise data [10]. Hunady and Hagara used the high-speed camera for modal testing [11], and Kumar et al developed a 3D digital image system based on FPGA [12]. Both of them used the 3D data image to determine the modal parameters of the mechanical system.…”

Time-of-flight ranging method by measuring pulse laser phase based on field-programmable gate array digital mixing

“…It can realize high measurement precision at long distance but a great number of devices are required and the system is extremely complex [12], which causes great limitation on the measurement and calculation speed. In recent years, with the rapid development of programmable digital devices, field-programmable gate arrays (FPGAs) and programmable logic devices have become widely used in image processing, signal processing, system control and communication systems [13][14][15][16][17][18][19][20]. The development cost of FPGA is much lower than that of application-specific integrated circuit (ASICs), and its reaction speed and low cost allow it to be widely used in the field of time measurement [21][22][23][24][25][26].…”