The textile specimen we consider have a size of 1m x 1m. Simultaneously, the spatial accuracy of detected stitch positions needs to be in the order of 50µm to account for very thin threads. In a real world scenario, both requirements can only be combined by using a commercially available camera sequentially scanning individual parts of the specimen. Afterwards, all of the acquired tiles are composed to obtain a unified, large RGB image, C(x, y) = (R(x, y), G(x, y), B(x, y))T , where (x, y) denotes the pixel position. Figure 2 shows the real world system for image acquisition and quality inspection. A camera is mounted on a gantry robot, allowing to automatically translate the camera in 3D space. The specimen to inspect is placed on the floor below. The camera has a sensor size of 2332 x 1752 pixels. Considering the employed lens, this translates to a resolution of 8 pix mm . However, the pixel resolution can be dynamically changed by decreasing or increasing the camera height over the conveyor plate using the gantry robot. Once the measurement has been started, the specimen is scanned in equidistant intervals resulting in a set of tile images which need to be composed. Sewing Machine in Chennai The image composition is performed using standard image registration techniques [8].
Given arbitrary complex thread patterns, the system automatically detects the real world thread pattern and compares it with the pattern intended by the manufacturer. A deformation vector can be calculated for every individual stitch with an accuracy of up to 50µm. The system may serve as a stand-alone for quality assurance. However, it also lays the foundation for the automated correction of stitch positions in textiles distorted by the elasticity of the material. Based on the computed deformation vector field, an automated correction of the CNC program to create the desired pattern is possible. An obvious limitation of the proposed system is the requirement for the thread to appear visually different than the background tissue. However, this is not the case for a variety of products, for which the thread color is wanted to be identical to the background color. A typical example is a black car seat sewed using a black thread. https://vssewingmachine.in/ We are currently working on exchanging the RGB-camera for a multi-spectral image acquisition in order to distinguish originally metamer, i.e. identical appearing, objects.
A camera based inspection system was introduced to automate the quality inspection process within the area of CNC sewing. Created thread patterns are automatically detected and compared against the intended pattern model. A deformation vector is computed for every individual stitch position. For both the thread detection as well as the model-based registration and adaptation, dedicated image processing pipelines were proposed.
