Development of displacement measurement equipment using sampling moiré technique in single board computers | |
| Author | Srikulnath Nilnoree |
| Call Number | AIT Thesis no.ST-20-29 |
| Subject(s) | Moiré method Real-time data processing |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Structural Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ST-20-29 |
| Abstract | Nowadays, non-contact deformation measurement has been significantly applied to investigate structures and infrastructure systems, for instants, bridges, tall buildings, and other engineering structures. This technique can advance the measurement system in structural health monitoring (SHM). The performance of the structures and safety assessment have to be evaluated preventing unexpected failures. In this study, real-time monitoring system based digital image processing was successfully developed by using sampling Moiré method (SM method) for two-dimensional in plane displacement measuring of the structures. The system consists of an SBC (RPi 3 B+ in this research) with RPi HQ camera and commercial lens. The SM method was written as a piece of code using Python 3 and embedded in RPi. The Raspberry pi HQ camera was utilized to obtain digital images of a two dimensional grating which is attached on linear moving stage. The two dimensional grating images were filtered into one-directional gratings, u- and v-direction, separately. The first image was called “the undeformed image” and the other were called “the deformed image”. The phase distribution obtained from one directional grating were sampled and interpolated to construct the moiré pattern and moiré phase distribution. The phase difference between deformed and undeformed images were used to calculate displacements. The experiments were conducted under the lab conditions, e.g., vibration control, lighting control, temperature control during testing time to verify the proposed algorithm accuracy. The experimental results showed that the accuracy of the system can achieve 1/100 of the grating pitch where the grating pitch was greater than 10-pixel and the grating pitch was identical to sampling pitch. Moreover, this system also provided the compensation of misalignment between the camera and grating. |
| Year | 2020 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ST-20-29 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Punchet Thammarak; |
| Examination Committee(s) | Pennung Warnitchai;Anwar, Naveed; |
| Scholarship Donor(s) | Royal Thai Government Fellowship; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2020 |