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 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.     

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.     

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 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.     

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 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.     

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 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.     

A self-stabilizing algorithm to synchronize digital clocks in a distributed system

We have proposed a self-stabilizing algorithm to synchronize multiple digital clocks in a distributed system; whenever any of the clock values gets out of synchronization for any reason, the algorithm is automatically invoked and the system is brought back to a legitimate state in finite time.     

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...     

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°.     

Membrane elements insensitive to distortion using the quadrilateral area coordinate method

Two 4-node quadrilateral membrane elements, denoted as AGQ6-I and AGQ6-II, have been developed in this paper. Instead of the traditional isoparametric coordinate, the quadrilateral area coordinates were used to establish the formulations of the new elements. And several generalized conforming conditions were then introduced to determine all unknown parameters. Numerical examples showed that the presented elements exhibit excellent performances in both regular and distorted mesh divisions. They could even yield exact solutions for pure bending problems under distorted meshes and provide lock-free solutions for the MacNeal’s test problem of trapezoidal locking. Besides, the weak patch test was conducted to guarantee the convergence of both new elements. It has also been demonstrated that the area coordinate method is an efficient tool for developing simple, effective and reliable serendipity plane membrane elements.     

一种改进的数控机床工件坐标找正方法

测头测量存在随机误差,采用二点确定直线的方法进行坐标找正会带来较大误差,本文针对常用的测量垂直坐标系找正方法提出了一种改进算法,通过分别测量一组数据,采用最小二乘法拟合直线,可以较好的减小随机误差影响,得到更精确的坐标结果。     

A generalized coordinate method for the analysis of 3D tall buildings

A generalized coordinate method (GCM) is proposed for the reduction of unknowns in the 3D analysis of tall buildings when the displacement method is employed. The number of variables is reduced by the assumption of in-plane rigid floors and by use of a 2D polynomial approximation for the out-of-plane displacements of floors, and a 1D polynomial approximation of the displacements with the height of building. The overall stiffness equation is obtained in generalized coordinates. The transformations are performed at the member level so that calculations involving large matrices are avoided. The GCM might be considered as a reduction technique based on a combination of the FEM at member level and the Rayleigh-Ritz method at the structure level. The GCM has the advantages that (1) the number of unknowns is significantly reduced and is independent of the number of storeys: (2) the accuracy can be adjusted by selecting the number of terms of the displacement function. The storage needed, the required number of operations and the possibility of choosing hierarchical displacement functions to make the calculation adaptive are discussed. The method presented can easily be extended to nonlinear and dynamic analysis. However, the derivation in this paper is confined only to the linear elastic analysis of frame and frame-shear wall structures. Numerical examples are given to show the efficiency of the proposed method.     

A coordinate descent based method for geometry optimization of trusses

The main objective of the structure optimization is to reduce the manufacturing cost of the structure. However, economical design should not deviate from engineering restrictions and laws. Based on this concept, various methods have been invented to optimize structures. In this research, some variations in one of the very simple and primary methods called “coordinate descent” or “successive coordinate search” is used for geometry optimization of the trusses. In order to increase the optimization speed and decrease the solution time of the problem, fast matrix analysis methods has been employed leading to reduction of the time required for calculating of the objective function. Furthermore, an optimized solution seeking algorithm has been introduced. In this algorithm, some factors have been defined by which the relation between the optimization time and these factors have been calculated, both experimentally and mathematically and the appropriate values of these factors are obtained to reduce the optimization time. Moreover, the effect of increasing the accuracy of the optimum solution on the number of analyses has been studied. Analysis of the presented method shows that regardless of its simplicity, it can be utilized as a fast method for optimizing variety of structures.     

A modified approach to cross entropy method: Elitist stepped distribution algorithm

This paper introduces a new algorithm named Elitist Stepped Distribution Algorithm (ESDA), which is inspired from the existing Cross Entropy Method (CEM) through the modification of elite sample based normal distribution used in CEM. Considering the natural behavior of normal distribution, ESDA is proposed to enhance the drawbacks of CEM through improving the efficiency in both exploration and exploitation processes when applying for complex function optimization problems. In ESDA, the elite sample percent defined in CEM is separated into two parts: (1) elite sample percent to calculate the mean value, and (2) elite sample percent to calculate standard deviation of normal distribution to construct an applicable balance between exploration and exploitation ability of the algorithm at a reasonable convergence speed. The elite sample percent parameter for the mean guides the algorithm to focus more on the better solutions and therefore improves the exploitation ability, whereas the elite sample percent parameter for the standard deviation controls the length of standard deviation to handle the exploration process more effectively. Performance of ESDA is investigated using unconstrained benchmark problems and compared with CEM, Simple Genetic Algorithm and Particle Swarm Optimization. The comparisons on unimodal and multi-modal functions confirm the efficiency of the algorithm in both exploration and exploitation process. In addition, the performance of ESDA is tested using constrained engineering problems commonly used in literature by comparing its performance with the other ones statistically. The results on engineering problems also prove that ESDA is perfectly applicable in real-world applications.     

Experimental study of a momentum-based method for identifying the inertia barycentric parameters of a human body

Physical modeling, simulation and analysis of an individual human body require inertia properties of the body segments of the human. Such subject-specific inertia data can be obtained only by measuring the individual human body as opposed to be derived from statistically generated anthropometric database. This paper presents experimental validation of a momentum-based approach for identifying the barycentric parameters of an individual human body which fully describes the inertia properties of the human. The identification algorithm is derived from the impulse–momentum equations of the human body which is assumed to be a multibody system with tree-type topology. Since the impulse–momentum equations are linear in terms of the unknown barycentric parameters, these parameters can be solved from the equations using a least-squares method. The approach does not require measuring or estimating accelerations and joint forces/torques because they do not appear in the impulse–momentum equations, and thus, the resulting identification procedure is less demanding on measurement data than the methods derived from the equations of motion. In this paper the test results of the identification method are validated by comparing the identified inertia parameters against the statistically established anthropometric data. Additionally, the identification results are also confirmed by comparing the contact forces using inverse dynamics to those obtained by forces plates.