基于刚体运动学的坐标系配准理论及算法

为避免公共点的误差及不一致性对坐标系转换精度的影响,研究了一种基于刚体运动理论的坐标系配准方法.将公共点组合成刚体,根据刚体上的点相互之间位置关系在两个坐标系下不变的特征,采用最小二乘法求解出最优变换矩阵.指出公共点空间布局方法对转换精度的影响,研究并实现了剔除超差公共点的算法.实验结果证明了该方法的正确性,为高精度测量的坐标系转换提供了理论依据.     

First Sight: A human body outline labeling system

First Sight, a vision system in labeling the outline of a moving human body, is proposed in this paper. The emphasis of First Sight is on the analysis of motion information gathered solely from the outline of a moving human object. Two main processes are implemented in First Sight. The first process uses a novel technique to extract the outline of a moving human body from an image sequence. The second process, which employs a new human body model, interprets the outline and produces a labeled two-dimensional human body stick figure for each frame of the image sequence. Extensive knowledge of the structure, shape, and posture of the human body is used in the model. The experimental results of applying the technique on unedited image sequences with self-occlusions and missing boundary lines are encouraging     

Local search: A new hidden line elimination algorithm to display spherical coordinate equations

Local Search, a new hidden line elimination algorithm, is presented. Local Search is a variant of the Scan-Line algorithm. Its performance is compared to that of two other Scan-Line algorithms for elimination of hidden lines from displays defined by spherical coordinate equations. In this paper, metrics are developed to evaluate the theoretical worst-case performance of each algorithm as a function of the display's complexity. Our performance evaluation is restricted to algorithms which can be implemented on personal computers. Data on the run-time performance of each algorithm were then collected to validate the worst case metrics. These data substantiate the hypothesis that, for complex displays, the Local Search algorithm performs hidden line elimination more efficiently than other Scan-Line algorithms.     

A new calibration method for a dynamic coordinate system in a robotic blade grinding and polishing system based on the six-point limit principle

Automatic robotic grinding and polishing systems have become a developing trend in aerospace parts manufacturing. In a robotic blade grinding and polishing system (RBGPS), the automatic and precise calibration of the dynamic workpiece coordinate frame is the most important process. In this research, a new method that introduces the concept of six-point positioning into the dynamic workpiece coordinate frame calibration process is proposed using a point laser displacement sensor (PLDS). The static coordinate frame calibration process is conducted based on a robot flange and force sensor. The results indicate that the new method can achieve a higher precision calibration result and has improved operational efficiency and cost. Finally, its practicality is verified in the BRGPS, and the results indicate that the polished blade surface after using the new method has good consistency.     

A coordinate system associated with points scattered on a surface

Coordinate systems associated to a finite set of sample points have been extensively studied, especially in the context of interpolation of multivariate scattered data. Notably, Sibson proposed the so-called natural neighbor coordinates that are defined from the Voronoi diagram of the sample points. A drawback of those coordinate systems is that their definition domain is restricted to the convex hull of the sample points. This makes them difficult to use when the sample points belong to a surface. To overcome this diffculty, we propose a new system of coordinates. Given a closed surface S, i.e. a (d−1)-manifold of the coordinate system is defined everywhere on the surface, is continuous, and is local even if the sampling density is finite. Moreover, it is inherently (d−1)-dimensional while the previous systems are d-dimensional. No assumption is made about the ordering, the connectivity or topology of the sample points nor of the surface. We illustrate our results with an application to interpolation over a surface.     

基于非线性优化的机器人坐标系标定方法

利用激光跟踪仪检测或校准工业机器人,须先对机器人坐标系进行标定。研究一种基于非线性优化的机器人坐标系标定方法。即在机器人末端固定一靶点,机器人运动多个位姿,激光跟踪仪对靶点进行测量,建立多位姿约束方程,并采用非线性优化算法同步标定机座坐标系及靶点坐标。该方法无须特殊机械工装,可适用于空载或末端带有各类执行器的工业机器人系统。经实验验证:相较于经典封闭解法,该方法采用非线性优化,具有良好的鲁棒性,可有效减小因机器人运动模型不准确引起的转换误差。     

A two-stage approach to align two surfaces of deformable objects

This paper introduces a new approach for non-rigid registration which is able to align two surfaces under large deformation. At the first stage, the two surfaces are remeshed to create two sub-meshes. Then, correspondences between the two sub-meshes are obtained by employing a robust probabilistic method. Reliable correspondences are used to find a global rigid transformation to bring the two surfaces closer. Using these correspondences and taking one sub-mesh as a deformation graph, the second stage applies a deformation model to align the two surfaces together. This stage solves for more correct correspondences as well as for a local transformation at each node simultaneously. With these two stages, the method deals robustly with large motion and preserves small details during the alignment process of the two surfaces. The efficiency of the method is demonstrated by comparing the alignment results it achieves with the results obtained by state-of-the-art methods.     

A system for the representation of human body movement from dance scores

An image processing and computer graphics system for generating graphical representation of human body movement from Labanotation dance score is described.     

A measurement fusion method for nonlinear system identification using a cooperative learning algorithm

Identification of a general nonlinear noisy system viewed as an estimation of a predictor function is studied in this article. A measurement fusion method for the predictor function estimate is proposed. In the proposed scheme, observed data are first fused by using an optimal fusion technique, and then the optimal fused data are incorporated in a nonlinear function estimator based on a robust least squares support vector machine (LS-SVM). A cooperative learning algorithm is proposed to implement the proposed measurement fusion method. Compared with related identification methods, the proposed method can minimize both the approximation error and the noise error. The performance analysis shows that the proposed optimal measurement fusion function estimate has a smaller mean square error than the LS-SVM function estimate. Moreover, the proposed cooperative learning algorithm can converge globally to the optimal measurement fusion function estimate. Finally, the proposed measurement fusion method is applied to ARMA signal and spatial temporal signal modeling. Experimental results show that the proposed measurement fusion method can provide a more accurate model.     

A coordinate method applied to partitioned energy-saving control for grouped hydraulic presses

As applications of forming equipment become increasingly widespread, the demand for low cost and significant energy-saving schemes gets stronger and stronger. A partitioned energy-saving control for drive system was first proposed to match the installed power of hydraulic system with the demanded power of grouped hydraulic presses, in which the drive system is partitioned into several drive zones according to the load profiles of different operations. The configuration and strategy of the control for grouped hydraulic presses are constructed. Based on the control, a coordinate method is then proposed to coordinate this multi-press system and ensure the forming processes of each hydraulic press successive, in which the operations relating to the forming parameters are controlled by position of the slider, and the other operations are controlled by time. Meanwhile, the forming operation in a hydraulic press begins with the end of the forming operation in the former one. Coordinate time error between two successive presses is modified to improve the accuracy of each operation. The method is applied to a multi-actuator system, and result shows orderly coordinate performance even with interference.     

A neuro-fuzzy method applied to the motors of a stereovision system

In this paper, a new approach for steering a binocular head is presented. This approach is based on extracting the expert's knowledge in order to improve the behaviour of the classical control strategies. This is carried out without inserting new elements in the system. Neuro-fuzzy techniques have been chosen in order to reach this target. As a result, a more friendly robotic system is achieved.     

A sketch-based approach to human body modelling

In this paper, we present a new approach and a novel interface, Virtual Human Sketcher (VHS), which enables those who can draw, to sketch-out various human body models. Our approach supports freehand drawing input and a “Stick Figure→Fleshing-out→Skin Mapping” modelling pipeline. Following this pipeline, a stick figure is drawn first to illustrate a figure pose, which is automatically reconstructed into 3D through a “Multi-layered Back-Front Ambiguity Clarifier”. It is then fleshed-out with freehand body contours. A “Creative Model-based Method” is developed for interpreting the body size, shape, and fat distribution of the sketched figure and transferring it into a 3D human body through graphical comparisons and generic model morphing. The generic model is encapsulated with three distinct layers: skeleton, fat tissue, and skin. It can be transformed sequentially through rigid morphing, fatness morphing, and surface matching to match the 2D figure sketch. The initial resulting 3D body model can be incrementally modified through sketching directly on the 3D model. In addition, this body surface can be mapped onto a series of posed stick figures to be interpolated as a 3D character animation. VHS has been tested by various users on Tablet PC. After minimal training, even a beginner can create plausible human bodies and animate them within minutes.     

Swallow swarm optimization algorithm: a new method to optimization

This paper presents an exposition of a new method of swarm intelligence–based algorithm for optimization. Modeling swallow swarm movement and their other behavior, this optimization method represents a new optimization method. There are three kinds of particles in this method: explorer particles, aimless particles, and leader particles. Each particle has a personal feature but all of them have a central colony of flying. Each particle exhibits an intelligent behavior and, perpetually, explores its surroundings with an adaptive radius. The situations of neighbor particles, local leader, and public leader are considered, and a move is made then. Swallow swarm optimization algorithm has proved high efficiency, such as fast move in flat areas (areas that there is no hope to find food and, derivation is equal to zero), not getting stuck in local extremum points, high convergence speed, and intelligent participation in the different groups of particles. SSO algorithm has been tested by 19 benchmark functions. It achieved good results in multimodal, rotated and shifted functions. Results of this method have been compared to standard PSO, FSO algorithm, and ten different kinds of PSO.     

A mobilized automatic human body measure system using neural network

Multimedia Tools and Applications - Mobilized automatic human body measurement systems possess high mobility, easy operation, and reasonable accuracy. However, existing systems focus on accuracy...     

基于六加速度计的陀螺仪漂移补偿算法的研究

为满足机动无人机姿态测量的需求,尝试了一种新的陀螺仪漂移补偿方案：对6只加速度计按回转轴对称布局,从而解算出角速度;并利用Kalman滤波对该解算角速度与陀螺仪的输出进行融合,通过反馈校正来实现对陀螺仪漂移的补偿。仿真结果证明：该方案能有效补偿陀螺仪漂移,具有一定工程应用价值。     

A control for spatial motions of a robot in a rectangular Cartesian coordinate system

Two mathematical models of a robot with elastic or rigid links working in a rectangular Cartesian coordinate system are proposed. The problems of dynamic and kinematic controls for such a robot are posed within the framework of the specified models. The difficulties of mathematical simulation of real robots of such a type with sliding joints are discussed in connection with the presence of elastic flexibility in the actuators. The technique for estimating the accuracy of positioning of the load carried by the robot based on joint use of the specified mathematical models is presented. As an example, solution of the problems of kinematic control of flexible and rigid robots with equivalent geometric and physical parameters functioning in a rectangular Cartesian coordinate system is considered.     

The back-buffer algorithm: An extension of the radiosity method to dynamic environments

An efficient algorithm is introduced for the production of realistic image sequences of dynamic environments. The practicality of the radiosity method, which computes the interreflection of light within complex diffuse environments independent of viewpoint, is extended to dynamic environments where the paths of moving objects have been predefined. The algorithm takes advantage of the object coherence between static portions of an environment. A preprocessing stage executes once for a given image sequence and precalculates constant geometrical relationships in the environment. When the environment geometry changes, an update stage determines the global illumination using information provided by the preprocessor and the current positions of all moving objects. Test environments show speedups of at least twenty-five times over previous radiosity methods.     

A scheduling algorithm based on the singular value decomposition heuristic method in a distributed manufacturing system

Because distributed manufacturing technology is the foundation of modernized production and traditional heuristic methods exhibit problems of high complexity and low efficiency, this paper designs a scheduling algorithm based on the singular value decomposition heuristic (SVDH) method. The algorithm uses the device distribution and the transportation relationship between devices in a distributed manufacturing system. The algorithm takes the sequence relationship between tasks and the distance between devices as the implicit relationship between the task and the device. The algorithm makes use of the implicit relationship to amend the processing time matrix of the task and corrects the processing time matrix that contains the transportation relationship. Singular value decomposition principal component analysis is performed on the corrected processing time to find the most suitable processing device for each process, and an initial solution matrix is established. The heuristic solution is used to optimize the initial solution to find the optimal scheduling result based on the initial solution matrix. The establishment of the initial solution can effectively reduce the computational complexity of the heuristic solution, realize a parallelizing solution, and improve the efficiency of the heuristic solutions. In addition, the SVDH scheduling result has a lower transfer time between devices due to the consideration of the topology of tasks and devices, that is, the transit time. In this paper, the experiments are conducted on the heuristic performance, scheduling results, and transportation time. The experimental results show the advantages of SVDH over general heuristic algorithms in terms of efficiency and transit time.     

A storage assignment heuristic method based on genetic algorithm for a pick-and-pass warehousing system

An order storage assignment problem (SAP) is to find an effective way to locate products in a warehouse in order to improve the operational efficiency of order picking. Since SAP is an NP-hard problem, many heuristic algorithms have been proposed. Most of previous researches focused on picker-to-parts warehousing systems or automated storage and retrieval systems. However, pick-and-pass systems play an important role for the faster delivery of small and frequent orders of inventory with the rise of e-commerce and e-business in the global supply chain. Two factors lead to idle time of pickers in a pick-and-pass system: picking line imbalance and shortage replenishment of products. This paper develops a genetic based heuristic method to solve SAP for a pick-and-pass system with multiple pickers to determine the appropriate storage space for each product and balance the workload of each picking zone so that the performance of the system can be improved. A simulation model based on FlexSim is used to implement the proposed heuristic algorithm and compare the throughput for different storage assignment methods as well. The results indicate that the proposed heuristic policy outperforms existing assignment methods in a pick-and-pass system.     

On the tangent stiffness matrix in a convected coordinate system

For automotive structures under crash loading, the implicit time integration scheme in the finite element method has its merit. Especially, it can be used for static crush analysis of structural components by setting the mass matrix zero. To formulate this scheme, a tangent stiffness matrix for each element should be established. This paper explains that the element tangent stiffness matrix is difficult, if not impossible, to be established referring to the convected coordinate system. It can easily be established if the updated Lagrangian coordinate system is used. Based upon this concept, the general purpose nonlinear computer program known as WRECKER-II, which referred to the convected coordinate system, has been modified to WRECKER-F. The modified program has the capability to analyze structures with arbitrarily large rotation. Test examples show excellent agreement with the analytic solutions for rotations larger than 90°.