The work addresses the problem of clothing perception and manipulation by a two armed industrial robot aiming at a real-time automated folding of a piece of garment spread out on a flat surface. A complete solution combining vision sensing, garment segmentation and understanding, planning of the manipulation and its real execution on a robot is proposed. A new polygonal model of a garment is introduced. Fitting the model into a segmented garment contour is used to detect garment landmark points. It is shown how folded variants of the unfolded model can be derived automatically. Universality and usefulness of the model is demonstrated by its favorable performance within the whole folding procedure which is applicable to a variety of garments categories (towel, pants, shirt, etc.) and evaluated experimentally using the two armed robot. The principal novelty with respect to the state of the art is in the new garment polygonal model and its manipulation planning algorithm which leads to the speed up by two orders of magnitude.
The aim of this prospective study was to compare the outcome of orthodontic therapy using two different therapeutic strategies: the labial straightwire (SW) technique and the lingual two-dimensional (2D) technique on the lower dental arch. The sample included 50 subjects (39 females and 11 males) with a complete dentition and an Angle Class I malocclusion with crowding who were treated non-extraction. The subjects were divided into two groups: group A, consisted of 25 patients (19 females and 6 males), who were treated with the lingual 2D technique, and group B, 25 patients (20 females and 5 males) treated using the labial SW appliance (Roth system). Changes in the position of the lower incisors to the A-Po and mandibular lines were measured on cephalograms and those in the transverse and sagittal planes on individual sectors of the dental arch from 2D images of model casts obtained before and after the active phase of orthodontic treatment. Standard statistical methods were used for evaluation. Both methods (when used with appropriate indications) showed comparable results. The lingual 2D technique also represents an aesthetically favourable solution for adult patients.
Planning accurate manipulation for deformable objects requires prediction of their state. The prediction is often complicated by a loss of stability that may result in collapse of the deformable object. In this work, stability of a fabric strip folding performed by a robot is studied. We show that there is a static instability in the folding process. This instability is detected in a physics-based simulation and the position of the instability is verified experimentally by real robotic manipulation. Three state-of-the-art methods for folding are assessed in the presence of static instability. It is shown that one of the existing folding paths is suitable for folding of materials with internal friction such as fabrics. Another folding path that utilizes dynamic motion exists for ideal elastic materials without internal friction. Our results show that instability needs to be considered in planning to obtain accurate manipulation of deformable objects.
Computer image monitoring was used for evaluation of dental arch changes. A new special device captured geometrically calibrated images permitting comparison of several different dental casts. In the first part of this study 792 sets of study casts were screened. Measurements of dental arch width between reference points of canines, first premolars and first molars were made: upper jaw: men: canines: 35.1 ± 0.13 mm; first premolars: 37.5 ± 0.13 mm; first molars: 48.1 ± 0.19 mm; women: canines: 33.4 ± 0.13 mm; first premolars: 35.6 ± 0.15 mm; first molars: 46.7 ± 0.19 mm. In the second part of the study, changes between initial, post-treatment and post-retention alignment (5-years after orthodontic therapy) of upper and lower dental arch of 36 subjects were analyzed. Upper and lower arch compression in first premolars and molars area was visible before treatment. We conclude that computer image monitoring can be used for evaluation of dental arch changes during the different steps of treatment.
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