Real-time monitoring of laser based 3D printing process using image processing

• Main Author: Viswanathan Sriram
• Other Authors: Kim Young-Jin
• Format: Theses and Dissertations
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/73319
• Institution: Nanyang Technological University

The Laser Based Additive Manufacturing is an Additive Manufacturing (AM) process in which a part is built or constructed in layers by depositing materials as per the 3D design model. The monitoring of this process is done to ensure whether the part is built as per model dimensions. However, the monitoring process currently experiences problems due to perspective defects, lack of requirement specific calibration and positioning of the Charged Coupled Device (CCD) camera used. Usually, the correction of perspective is done by using devices which require additional setup for their functioning. Deploying additional instruments require space which creates more constraints in the monitoring system. The algorithmic approach for perspective correction requires great understanding of the concept of planes and 3D geometry. The problem of lack of requirement specific calibration is addressed by algorithms and experimental techniques that does not provide a proper physical calibration pattern for measuring the dimensions of the part and to confirm the validity of perspective correction algorithm. This dissertation involves the reduction or possible elimination of the mentioned problems. Image processing tools such as MATLAB and Adobe Photoshop CS4 are used to propose elegant solutions to overcome the errors caused by perspective issues. A grid paper is introduced as a simple and an effective means of measuring the part's dimensions and verifying the correctness of the perspective correction algorithm. The problem of positioning the CCD is solved by means of conducting an experiment which is based on the concepts of concentric circles. Additionally, this paper discusses the repeatability error of the experiment performed to solve the positioning issue of the CCD camera. Solutions are supported with the appropriate results and inferences.