Papers by Keyword: Trajectory

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Authors: Wei Xing Zhu, Wei Guang Xu, Guo Lin Hou, Jun You
Abstract: In this paper, a novel model, HDP-HMM-SCFG is proposed for representing and classifying activities based on motion trajectories. In the model, activities are represented by stochastic grammar using trajectory, where trajectory segments are considered as observations emitted by the grammar terminals attached with HMMs. Then, by replacing the Euclidian distance in the kernel function of Gaussian radial radix with EMD-DTW, which is proposed to measure the distance between two trajectories by integrating the pros. of both EMD and DTW, multi-class SVM classifier is constructed. Experiments on ASL dataset are carried on to validate our approach.
Authors: Jiang Guo, Jun Cheng, Yu Guo, Jian Xin Pang
Abstract: In this paper, we present a dynamic gesture recognition system. We focus on the visual sensory information to recognize human activity in form of hand movements from a small, predefined vocabulary. A fast and effective method is presented for hand detection and tracking at first for the trajectory extraction. A novel trajectory correction method is applied for simply but effectively trajectory correction. Gesture recognition is achieved by means of a matching technique by determining the distance between the unknown input direction code sequence and a set of previously defined templates. A dynamic time warping (DTW) algorithm is used to perform the time alignment and normalization by computing a temporal transformation allowing the two signals to be matched. Experiment results show our proposed gesture recognition system achieve well result in real time.
Authors: Zhen Hua Wei, Xue Sen Li, Jie Lin, Le Zhang
Abstract: Safety is of importance for power production. It is known that kinds of abnormal action in power production are concerned with objects. Different from many abnormal action recognitions researches, which ignore the interactive relationship between human and objects, this paper proposes an approach for the specific abnormal action based objects recognition in power production. The major contributions of the paper are to employ an object-based framework for description of hand-trajectory information, reference particle filter for primitive action locating and realize time cost decrease through human silhouette block analysis. Different from simplex trajectory based approach, the presented approach consists of types of trajectory features which belong to specific object and each primitive action is relevant to specific object model. It is verified by experiment that the approach performs on certain abnormal action recognition at an effective level.
Authors: Ji Feng Wei, Xiong Li, Shu Shan Wang, Yu Xin Xu
Abstract: The basic experiment and detailed simulations are carried out to study the aerodynamic characteristics of projectile with deflectable nose. The parameters of computation are revised on the basis of experimental data. Further simulations show that the influence of mach number and deflectable angle on drag, lift, pitching moment and flight trajectory. The drag coefficient increases firstly and then decreases with the change of mach number, while drag coefficient and pitching moment coefficient grows exponentially. It can be seen that the ratio of lift to drag increases consistently, which means the aerodynamic efficiency of projectile would be improved with the increase of deflectable angle and mach number. The range is influenced by the start time of deflection. For the projectile with deflectable angle 10, the maximum range can be obtained if the forehead deflects at 3s.
Authors: Zuo An Wei, Yu Long Chen, Bin Zhu, Hai Ru Liu
Abstract: Rockfall is a frequent engineering disaster confronted in the capital construction engineering. The key for preventing rock fall is the evaluation of the rockfall trajectory. After extensive analysis, an innovative calculation method of rockfall trajectory, called segmented cycling algorithm, has been proposed in the paper. According to the contact relationship between the rolling stones and the slope surface, the movement divided into three sections which include the jumping phase, the rolling (sliding) phase and collision phase, the formulae to calculate the velocity of different phases of motion are proposed respectively by segmented cycling algorithm. A similar model, based on a rock slope in Chongqing-Wanzhou highway, is established to verify the capability and validity of the presented algorithm. Compared with existing algorithm, the new algorithm is simple and clear, easy to use and so on. The algorithm meets the law of the movement of rockfall and can be used to forecast the kinetic feature of rockfall. It is also used as the basis for rockfall disaster prevention.
Authors: Xin Ya Wang, De Yong Shang, Na Liu, Song Yang Li, Xun Fan
Abstract: The reliability of formwork support is directly related to gob-side entry retaining success. In this paper a dual function of supporting and filling formwork support is designed. Use SolidWorks software build 3D modeling and virtual assembly, The establishment of a movement model of the anti-four-bar linkage formwork template using numerical methods and get the motion trajectory of the roof. It has been verify that the anti-four bar linkage design of the hydraulic support is feasible.
Authors: Florina Pop, Valer Dolga, Cristian Pop
Abstract: An experimental test bench is proposed in order to analyze the trajectory shape described by the termination of the Jansen’s type of leg mechanism during a walking sequence. A prototype of a walking robot based upon Jansen walking mechanism is constructed for this purpose. A marker is placed at the end of the leg and a CCD camera recorded the trajectory shape described by the leg driven by a DC motor through a crank. The results are interpreted with the help of a program based on image processing created for determining the length and the height of the step during walking after studying the trajectory.
Authors: Teodora Gîrbacia
Abstract: In this paper is presented a comparative study between using extended Kalman filter and particle filter applied on SLAM algorithm for an autonomous mobile robot. The robot navigates through an unknown indoor environment in which are placed 80 landmarks and it creates the map of the environment. Because the sensors placed on the robots produce measurement errors it is necessary to use Bayesian filters as the Kalman filter or the particle filter. An application was implemented that shows the estimated measurement errors produced while using both filters in order to create the estimated map of the closed environment in which the autonomous mobile robot is navigating.
Authors: Lin Wang, Wen Pu Shi
Abstract: Complex analytical method is employed to study the motion of a kind of mechanism. The angular velocities and the angular accelerations of the connecting rod and the rocker are deduced. The motion trajectory and linear velocity of a key point are also given. The results of the given example show the feasibility and the effectiveness of the method and conclusions here.
Authors: Marin Chirazi, Emil Budescu, Eugen Merticaru
Abstract: The paper deals with the kinematical approach of the trajectory of movement of an academic rowing skiff with a view to determine a given racing speed of the boat. It uses inverse kinematics since this method allows obtaining analytical calculus formulas for the movement of paddles in their two moments of motion: active and passive strokes. Movement of the paddles while following an arc-shaped trajectory outlining a sphere-like quadrilateral requires different values of amplitude of angular displacement of the paddles according both to anthropometrical values of the athlete and to his physical and technical training. The numerical application is made for several values of these angles which define the arcs of the circle for active and passive curves and for the moments between the two strokes (angle of the paddle while slicing in and out the water). These amplitudes of angular displacement are being considered, from the point of view of the horizontal component, equal to the speed of the skiff while imposing the linear speed of the paddle, and they would help determining movement frequencies of the paddle while following the sphere-like quadrilateral trajectory.
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