引信离心自炸机构待动数学模型的建立及其运动模式分析

建立了引信离心自炸机构待发状态欲动而未动过程的数学模型 ,这是一个各分力在不断变化的静力平衡模型。指出 ,钢珠上、下两处的静摩擦力是在不断地等值变化着且不会同时达到最大 ,因此 ,在临界状态前的待动阶段 ,不能以、更不能同时以 f N的形式代入方程。分析了机构待发状态的三个阶段 ,重点讨论了第三阶段钢珠的力平衡问题。基于钢珠上、下两约束处不会同时滑动 ,得出了两种不同的运动模式及相应条件式 ,它取决于离心自炸机构的结构 (半锥角α)和表面加工质量 (摩擦系数 f、f1 ) ;对条件式进行了讨论 ,结论是 ,该机构很容易实现第一运动模式 ,根据实际需要 ,可以通过表面加工粗糙度的调整来控制引信的性能 。

一种基于位置信息的运动模式分析方法

提出了一种基于网络信号的路径划分方法,并给出了形式化的路径描述模型。结合应用背景,根据划分的路径量化分析得到用户的运动模式。通过实验表明,该方法能够方便地提取用户的运动模式,为评估用户的行动方式提供依据。

Analyzing Motion Patterns in Crowded Scenes via Automatic Tracklets Clustering

Crowded scene analysis is currently a hot and challenging topic in computer vision field. The ability to analyze motion patterns from videos is a difficult, but critical part of this problem. In this paper, we propose a novel approach for the analysis of motion patterns by clustering the tracklets using an unsupervised hierarchical clustering algorithm, where the similarity between tracklets is measured by the Longest Common Subsequences. The tracklets are obtained by tracking dense points under three effective rules, therefore enabling it to capture the motion patterns in crowded scenes. The analysis of motion patterns is implemented in a completely unsupervised way, and the tracklets are clustered automatically through hierarchical clustering algorithm based on a graphic model. To validate the performance of our approach, we conducted experimental evaluations on two datasets. The results reveal the precise distributions of motion patterns in current crowded videos and demonstrate the effectiveness of our approach.

Motion modeling and formation form analysis of spacecraft near collinear libration points

To meet the increasing research demand for deep space exploration,especially for the second libration point (L2) conditional periodic orbit (Halo orbit) in the Sun-Earth system,the methods to get analytical Halo orbit and differential-correction Halo orbit were described firstly,and the corresponding orbits accuracy was analyzed.Then,based on the results of third-order and differential-correction Halo orbits,the formation form was studied.Analysis was carried out to discuss the influence of system amplitude,initial phase,and phase difference on the formation form,as well as that of initial orbit values on form accuracy.Finally,some simulation results demonstrate the validity of the proposed methods.

Development of XY scanner with minimized coupling motions for high-speed atomic force microscope

The design and fabrication processes of a novel scanner with minimized coupling motions for a high-speed atomic force microscope （AFM） were addressed. An appropriate design modification was proposed through the analyses of the dynamic characteristics of existing linear motion stages using a dynamic analysis program, Recurdyn. Because the scanning speed of each direction may differ, the linear motion stage for a high-speed scanner was designed to have different resonance frequencies for the modes, with one dominant displacement in the desired directions. This objective was achieved by using one-direction flexure mechanisms for each direction and mounting one stage for fast motion on the other stage for slow motion. This unsymmetrical configuration separated the frequencies of two vibration modes with one dominant displacement in each desired direction, and hence suppressed the coupling between motions in two directions. A pair of actuators was used for each axis to decrease the crosstalk between the two motions and give a sufficient force to actuate the slow motion stage, which carried the fast motion stage, A lossy material, such as grease, was inserted into the flexure hinge to suppress vibration problems that occurred when using an input triangular waveforrn. With these design modifications and the vibration suppression method, a novel scanner with a scanning speed greater than 20 Hz is achieved.

Eye-Movement While Generating a Trajectory Using the Upper Limb

This paper describes the experimental analysis of eye-movement during the generation of a trajectory by the human upper limb, carried out to elucidate the human mechanism for visual-information recognition. The results showed that the subjects adopted an eye-movement pattern called the subgoal travel method （fixating in the vicinity of the fingertip while drawing/tracing） for the complete circle. Subsequently, when the target trajectory was one of incomplete shapes, some subjects continued following the subgoal travel method by drawing the missing part of the target trajectory, while others followed two other eye-movement patterns. The first is called the center-point fixation method, in which subjects consider the center point as the most important point for generating the target-image trajectory, and therefore, fix their gaze at the center point throughout the experiment. The second is called the point-to-point travel method, in which the subjects＇ gazes shift between the center point of a displayed image and their fingertip. Further, the results confirmed that the eye-movement pattern, movement accuracy, and drawing speed are correlated. Additional experiments clarified the conditions for which different eye-movement patterns are suitable： the subgoal travel method is suitable for high-accuracy drawing; the center-point fixation method is suitable for higher-sneed drawing

An improvement to the reciprocating gait orthosis for aiding paraplegic patients in walking

As the conventional reciprocating gait orthosis(RGO)has been deemed incapable of facilitating the patients’passive movement with significant gait discrepancies and distortion,in addition to characteristics such as poor stability,and negligible knee joint rehabilitation,a power assisted reciprocating gait orthosis(PARGO)was designed.Drive devices were added to the hip and knee joints of the RGO.Through efficient implementation of structural components,the number of the required motors was reduced,therefore decreasing the weight of the orthosis.The PARGO knee joint’s structural principle was analyzed to characterize the effect of the PARGO’s single-axis knee joint design on wear comfort,thereby providing a basis for the wear of the PARGO.By analyzing the sagittal movement patterns of the hip and knee joints during normal human gait,kinematic analysis was carried out to obtain the input patterns of the PARGO hip and knee joint drive motors,enabling the patients to more accurately reproduce the normal gaits of hip and knee joints during the rehabilitation training with the aid of the PARGO,and the control process of the PARGO was studied.Finally,a prototype of the PARGO was developed,and experimentation was carried out to demonstrate the feasibility of the improved orthosis.

COMPLEX CONCEPT LATTICES FOR SIMULATING HUMAN PREDICTION IN SPORT

In order to address the study of complex systems,the detection of patterns in their dynamics could play a key role in understanding their evolution.In particular,global patterns are required to detect emergent concepts and trends,some of them of a qualitative nature.Formal concept analysis(FCA) is a theory whose goal is to discover and extract knowledge from qualitative data(organized in concept lattices).In complex environments,such as sport competitions,the large amount of information currently available turns concept lattices into complex networks.The authors analyze how to apply FCA reasoning in order to increase confidence in sports predictions by means of detecting regularities from data through the management of intuitive and natural attributes extracted from publicly available information.The complexity of concept lattices-considered as networks with complex topological structure- is analyzed.It is applied to building a knowledge based system for confidence-based reasoning,which simulates how humans tend to avoid the complexity of concept networks by means of bounded reasoning skills.