Unidirectional Fabric Drape Testing System Design

As an important drape property, fabric drape refers to the 3-dimensional (3D) deformation of fabrics arising from their own weight. Almost all the traditional fabric drape testing methods are based on umbrella projection method, which makes the sample draped on a circular plate and captures its projection size and contour to evaluate drape. However in most cases, fabrics (such as curtains, skirts, suit pants and so on) are draped under their own gravity parallel to fabric plane while the gravity is perpendicular to fabric plane in traditional drape testing method. As a result, it does not conform to actual mechanical conditions and the test data is not convincing enough. Finding new drape testing methods and improving drape meters have become an urgent issue to be solved.This paper presents another drape testing method, the unidirectional drape testing method, which imitates the actual mechanical conditions of draped fabrics such as curtains. The fabric sample is clamped in a manner at one end and hangs free at the other. The unidirectional drape parameters are extracted from 3D fabric model which is captured by a 3D scanner.This paper designed a testing system including hardware structure and system softwarefor the unidirectional drape testing method. Hardware structure contains a 3D scanner, motion control structure of 3D scanning, clamping manner and device framework. We chose a low-cost Microsoft Kinect device that the scanning precision can reach millimeter level as our 3D scanner. We adopted GTS four axes motion controller of Googol product in the motion control structure. This motion controller can complete high performance and complex movement patterns. Hardware structure is designed based on the scanning features and requirements of Kinect device and the principle of unidirectional drape testing method, which is mainly used for completing 3D scanning. The system software consists of four parts:motion control programs,3D model scanning software,3D model processing software and data processing software. The reconstruction of 3D sample is completed by the KinectFusion point cloud splicing technology and the model is saved as STL format file. The 3D model is displayed through C++ language with OpenGL programing and then we can obtain the 3D drape projection through denoising, cutting and correcting the 3D model. Intercepting the 3D projection horizontally and drawing the intersections of a horizontal plane and the sample outline, lining the latter intersection’s head to the former intersection’s end to form a line segment, thus the two-dimensional drape projection curve is obtained after filtering. Through a certain algorithm to recognize the peaks and the troughs, the parameters (unidirectional drape coefficient) characterizing draping degree and artistic parameters (peak numbers, bending index, peak height, and peak symmetry coefficient, et al) can be extracted and the unidirectional fabric drape evaluation system is then established.We found that the relative error of scanning precision of our testing device is about 1% through error testing. We selected 15 different samples and tested their drape performance through traditional method (XDP-1 drape meter) and our testing system to verify the feasibility and stability of our drape testing system.The result showed that these two methods were highly correlated linearly. We chosed three samples and tested their drape performance for 10 times each and it was revealed that the variation of this testing system ranged from 2% to 5%. Thus indicated that this testing system is stable and the reproducibility of testing result is good enough.Unidirectional fabric testing method has some obvious advantages compared with traditional umbrella projection method. First, this method consists with actual mechanical conditions of draped fabric, so the result is more reliable. Second, this is a non-contact 3D measurement and it can reflect drape performance more completely. This paper provides a new drape testing method and stable testing device.