In the master thesis, we have replaced the RPi camera with an HQ camera and lens, on a Raspberry Pi 4 single board computer. This increased the resolution of the elongation measurement and calibration of the camera. The camera calibration was performed according to Zhang's procedure, thus getting rid of the distortion that appears at the edges of the captured images. The distortion is caused by the refraction of the rays through the lens. We also compared two different algorithms for detecting markings on test tubes and chose the best one for our application. We also made a prototype of the gripper and printed it with a 3D printer. Finally, we performed 25 tests on the printed PETG test tubes and then compared them with the tests we performed on the MultiTest 2.5-dV testbed. The standard deviation of the elongation and tensile stress measurements was also calculated. The maximum tensile stress was found to be in satisfactory agreement with the reference value and the value provided by the filament manufacturer.
|
