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The purpose of this paper is to generate grinding trajectory of unknown model parts simply and efficiently. In this paper, a method of grinding trajectory generation of hybrid robot based on Cartesian space direct teaching technology is proposed.

This method first realizes the direct teaching of hybrid robot based on 3Dconnexion SpaceMouse (3DMouse) sensor, and the full path points of the robot are recorded in the teaching process. To reduce the jitter and make the speed control more freely when dragging the robot, the sensor data is processed by Kalman filter, and a variable admittance control model is established. And the joint constraint processing is given during teaching. After that, the path points are modified and fitted into double B-splines, and the speed planning is performed to generate the final grinding trajectory.

Experiment verifies the feasibility of using direct teaching technology in Cartesian space to generate grinding trajectory of unknown model parts. By fitting all the teaching points into cubic B-spline, the smoothness of the grinding trajectory is improved.

The whole method is verified by the self-developed TriMule-600 hybrid robot, and it can also be applied to other industrial robots.

The main contribution of this paper is to realize the direct teaching and trajectory generation of the hybrid robot in Cartesian space, which provides an effective new method for the robot to generate grinding trajectory of unknown model parts.

When establishing a mathematical model to simulate solid mechanics, considering realistic geometries, special tools are needed to translate measured data, possibly with noise, into idealized geometrical entities. As an engineering application, wheel-rail contact interactions are fundamental in the dynamic modeling of railway vehicles. Many approaches used to solve the contact problem require a continuous parametric description of the geometries involved. However, measured wheel and rail profiles are often available as sets of discrete points. A reconstruction method is needed to transform discrete data into a continuous geometry.

The authors present an approximation method based on optimization to solve the problem of fitting a set of points with an arc spline. It consists of an initial guess based on a curvature function estimated from the data, followed by a least-squares optimization to improve the approximation. The authors also present a segmentation scheme that allows the method to increment the number of segments of the spline, trying to keep it at a minimal value, to satisfy a given error tolerance.

The paper provides a better understanding of arc splines and how they can be deformed. Examples with parametric curves and slightly noisy data from realistic wheel and rail profiles show that the approach is successful.

The developed methods have theoretical value. Furthermore, they have practical value since the approximation approach is better suited to deal with the reconstruction of wheel/rail profiles than interpolation, which most methods use to some degree.

Layered manufacturing with curved layers is a recently proposed rapid prototyping (RP) strategy for the manufacture of curved, thin and shell-type parts and the repair of worn surfaces, etc. The present investigation indicates another possible application area. In case of flat-layered RP of computer-aided design models having randomly located, small-dimensioned but critical surface features, adaptive slicing is resorted to. Large number of thin slices have to be employed to preserve the critical features. In contrast, a considerably lower number of curved thin slices would be required to preserve such surface features in case of RP with curved layers.

The method of preservation of critical features by RP with curved layers is formulated and demonstrated for two clusters of critical features on the surface of a part. A minimum number of such curved layers is identified by application of genetic algorithms (GAs) in case of a simple example. GA evolves the shape of the curved layer passing through the lower cluster so as to make a curved layer pass through the upper cluster of critical features.

In the example part, a 21 per cent reduction in the number of layers is achieved by the application of adaptive curved layers over adaptive straight layers.

The novelty of the concept is the proposed use of curved layered RP with adaptive slicing for the preservation of critical features in final prototyped part. This methodology, applied to part with two distinct clusters, leads to reduced number of layers compared to that obtained in flat-layered RP.

The purpose of this paper is to present a robotic off-line programming method for freeform surface grinding based on visualization toolkit (VTK). Nowadays, manual grinding and traditional robot on-line programming are difficult to ensure the surface grinding accuracy, thus off-line programming is gradually used in grinding, however, several problems are needed to be resolved which include: off-programming environment depends on the third-party CAD software, leads to insufficient self-development flexibility; single support for robot type or workpiece model format contributes to lack of versatility; grinding point data depends on external data calculation and import process, causes human-computer interaction deterioration.

In this method, the visualization pipeline and observer/command mode of VTK are used to display the 3D model of the robot grinding system and pick up the workpiece surfaces to be grinded respectively. Two groups of cutter planes with equidistant spacing are created to form the grinding nodes on the surface, and the extraction method for the position and posture of the nodes is proposed. Furthermore, the position and posture of discretized points along the grinding curve are obtained by B-spline curve interpolation and quaternion spherical linear interpolation respectively. Finally, the motion simulation is realized by robot inverse kinematics.

Through a watch case grinding experiment, the results show that the proposed method based on VTK can achieving high precision grinding effect, which is obviously better than traditional method.

The proposed method is universal which does not depend on the specific forms of surface, and all calculations in simulation are completed within the system, avoiding tedious external data calculation and import process. The grinding trajectory can be generated only by the mouse picking operation without relying on the other third-party CAD software.

In order to mass‐customize clothes, it is essential to create prototype pattern according to individual body shape. The purpose of this paper is to present a new method to generate prototype pattern based on individual three‐dimensional (3D) virtual dummy for further study on apparel customization.

The symmetrized preprocessing and convex hull method are employed to create a dress‐like virtual dummy based on 3D body scanning data. The corresponding structure lines of 2D prototype pattern are defined on the 3D dummy in advance and 3D dummy surface (only half) is cut into ten zones. Based on the characteristics of each surface, further subdivision was made in each zone to create 3D wireframe of garment prototype by calculating the intersection curves between the dummy surface and local planners. Via flattening geometrically 3D wireframe of each zone, final pattern of the prototype is got. Moreover, during the course of flattening of each zone, define constrained lines in advance so as to ensure the position and direction of each cutting pattern beforehand.

The paper finds that 2D cutting patterns of the prototype have been constructed from the computerized 3D dummy. The length of major structure lines for both 3D model and 2D cutting pattern remain the same. The seven out of ten of cutting patterns have area error within ±1 cm² compared to 3D surface. Only two cutting have relatively larger error but controlled within 3 cm².

The most outstanding property of the method developed is the possibility of geometrical transformation of 3D surface to 2D pattern through constructing 3D wireframe of the prototype garment, with no need to define physical‐mechanical properties of fabric used. The newly created 2D cutting patterns have the coincident construction and shape with conventional prototype and are of outstanding quality and preciseness.

This preliminary research revolute the conventional clothing design process by true designs from three‐dimensional (3D) rather than two‐dimensional. The aim of the research is to develop a handy 3D clothing design software tool for general garment designers. Work carried out in this paper is the preliminary result of the 3D software infrastructure. In addition, 3D collar design based on a mathematical formula is accomplished as a template for other garment portions. Object‐oriented technology is invoked as a tool for software developing. The system is divided into two major modulus, the user interface and the kernel. The user interface is used to collect messages from the users, and then send it to the kernel for further computations. Moreover, it exhibits real‐time pictures received from the kernel. The major work of the kernel is to handle the operations that are called by the user interface. In this paper two basal collars, convertible collar and shirt collar, are illustrated as diversified figurations.

The purpose of this paper is to describe a multisource system for nondestructive inspection of welded elements exploited in aircraft industry developed in West Pomeranian University of Technology, Szczecin in the frame of CASELOT project. The system task is to support the operator in flaws identification of welded aircraft elements using data obtained from X-ray inspection and 3D triangulation laser scanners.

For proper defects detection a set of special processing algorithms were developed. For easier system exploitation and integration of all components a user friendly interface in LabVIEW environment was designed.

It is possible to create the fully independent, intelligent system for welds’ flaws detection. This kind of technology might be crucial in further development of aircraft industry.

In this paper a number of innovative solutions (new algorithms, algorithms’ combinations) for defects’ detection in welds are presented. All of these solutions are the basis of presented complete system. One of the main original solution is a combination of the systems based on 3D triangulation laser scanner and X-ray testing.

This paper aims to solve the problem of free-form tubes’ machining errors which are caused by their complex geometries and material properties.

In this paper, the authors propose a multi-view vision-based method for measuring free-form tubes. The authors apply photogrammetry theory to construct the initial model and then optimize the model using an energy function. The energy function is based on the features of the image of the tube. Solving the energy function allows to use the gray features of the images to reconstruct centerline point clouds and thus obtain the pertinent geometric parameters.

According to the experiments, the measurement process takes less than 2 min and the precision of the proposed system is 0.2 mm. The authors used simple operations to carry out the measurements, and the process is fully automatic.

This paper proposes a method for measuring free-form tubes based on multi-view vision, which has not been attempted to the best of authors’ knowledge. This method differs from traditional multi-view vision measurement methods, because it does not rely on the data of the design model of the tube. The application of the energy function also avoids the problem of matching corresponding points and thus simplifying the calculation and improving its stability.

This paper aims to present error compensation based on surface reconstruction to improve the positioning accuracy of industrial robots.

In previous research, it has been proved that the positioning error of industrial robots is continuous on the two-dimensional manifold of six-joint space. The point cloud generated by positioning error data can be used to fit the continuous surfaces, which makes it possible to apply surface reconstruction on error compensation. The moving least-squares interpolation and the B-spline method are used for the error surface reconstruction.

The results of experiments and simulations validate the effectiveness of error compensation by the moving least-squares interpolation and the B-spline method.

The proposed methods can control the average of compensated positioning error within 0.2 mm, which meets the requirement of a tolerance (±0.5 mm) for fastener hole drilling in aircraft assembly.

The error surface reconstruction based on the B-spline method has great superiority because fewer sample points are needed to use this method than others while keeping the compensation accuracy at the same level. The control points of the B-spline error surface can be adjusted with measured data, which can be applied for the error prediction in any temperature field.

To explore three‐dimensional scanning technology in capturing the shape of inflated parachutes for accurate estimation of surface area and volume.

The volume and surface area of an inflated round parachute are important parameters for the design and analysis of its performance. However, it is difficult to acquire the three‐dimensional (3D) surface shape of a parachute due to its flexible fabric and dynamic movement. This paper presents how we collect 3D data with a laser scanner and calculate volume and surface area of parachutes from their scans. The necessary data clean and approximation steps with non‐uniform B‐spline function are introduced and implemented. Numerical integration methods are employed to estimate surface area and volume. The approximation of the parachute based on an ellipsoid is compared with the numerical integration approach in their volumes and surface areas.

It is found that 3D scanning technology, with help of mathematic program developed, provides a feasible mean to estimate the surface area and volume of inflated parachutes. The numerical integration method derived in this paper is reliable and robust for the computation.

It is the first time that the 3D shape of an inflated parachute has been scanned with a laser scanner. The mathematical methods developed for processing of scan data are useful for others who use 3D scanning technology. The computational approach and results of surface area and volume of inflated parachutes are valuable to parachute performance modeling and design community.