参数化优化的仿人机器人相似性前向倒地研究

提出了一种基于运动相似性的仿人机器人前向倒地动作设计方法.首先,分析了运动相似性并提出了关键姿势同步转换方法; 其次,为机器人前向倒地运动四级倒立摆建立了相似性变换条件下的动力学约束方程与关联的物理条件约束; 再次,引入参数化优化控制与强化技术,对机器人的触地过程进行了参数化优化.实验结果表明了该方法的有效性.     

基于Kinect的人体实时三维重建及其应用

目前,人体三维重建技术在建模前一般需要采集从多个视角观察人体的数据,并限定人体的姿势,不能很好地用于需要人体模型的交互式应用中.针对这个问题,提出一种基于单个Kinect的渐进式人体重建方法.首先结合特征点检测算法和校错处理,对深度视频帧中人体上的特征点进行定位;其次对身体尺寸进行测算或估算,并在对视频流的处理中渐进式地补充与完善;最后根据以上信息对人体进行分块参数化建模和合成,得到人体模型.实验结果表明,在尺寸不完整的情况下,该方法即可重建包含肢体结构语义的完整人体,易于实现局部模型或姿势的修改,并在虚拟试衣应用中体现出良好的实时性和交互性.     

基于学习的群体动画生成技术研究

为了降低群体动画中生成大量自然而又相似的人体运动的难度和复杂性,研究了一种基于学习的群体动画生成技术。该技术首先通过建立基于高斯过程隐变量模型和隐空间动态模型的运动姿势学习模型,将高维运动姿势映射到低维隐空间中,并在低维隐空间对相邻姿势的动态演化进行建模;然后通过对已有运动数据的学习来获得组成该运动的姿势的概率分布,再通过隐空间中的动态预测和Hybrid Monte Carlo采样来得到符合给定概率分布的隐轨迹;最后通过姿势重构来得到与原运动非常相似但又不同的一系列自然的运动,以产生群体动画,从而避开了传统的基于几何和物理约束的逆运动方法固有的困难和复杂性。     

基于HBC频段动态人体信道传输特性的研究

现有的人体体表通信信道模型仅限于单频或UWB频段的体表传输,且只考虑了静态人体姿势下的场景.利用时域有限差分方法建立35种连续姿势下的人体模型,分析动态人体通信信道(HBC)的传输特性.确立了路径损耗与通信距离的正比关系;将修正后的S-V模型作为动态人体信道模型分析多径效应,并进行了验证;最后,根据二阶信息准则确定了平均功率增益的累计概率密度符合对数正态分布.结果与UWB频段下进行对比,人体运动在HBC频段下对人体通信传输特性的影响更小,更适合动态人体的体表通信.     

基于人体姿势编码的运动数据检索

针对大规模运动捕获数据的检索问题,提出一种基于人体姿势编码的相似运动检索方法.首先将形成人体姿势的9段主要骨骼的运动空间划分成多个子空间,以各骨骼所处的子空间位置作为人体姿势的特征表示;然后根据特征表示对运动数据进行逐帧编码,将编码相同的连续帧划分成等价段;最后建立以等价段为基础的倒排索引来检索候选运动,并通过编码匹配...     

二维碰撞感知的单张图像参数化人体与服装重构

已有的基于图像的人体与服装重构大都不考虑身体与衣物之间的交互,导致独立重构结果互相穿刺.本文提出一个二维碰撞感知的从单张图像重构人体与服装的优化方法,利用SMPL和TailorNet参数化模型来分别表示人体和衣服的三维形状,进而建立约束能量求解人体形状参数,运动参数和服装细节控制参数.我们的方法在初始化阶段对输入图像进行了语义分割以及二维关节点的估计,并采用human mesh recovery初步估计人体的形状与运动参数作为能量优化的初始值.我们的能量优化由两部分构成:其一是形状与姿态约束,利用图像中人体的关节位置和着装人体区域对三维参数化模型的投影的关节位置和投影区域进行约束,保证重建模型与图像在形状与姿态上的一致性;其二是人体与衣服的碰撞约束,引入重构人体与服装模型的二维投影区域间的误差对人体与衣服进行碰撞约束,以避免相互穿刺,考虑到基于投影的约束对视点敏感,我们在三维空间中进行视点采样,从而建立多视角的二维投影约束.考虑到能量中包含了TailorNet,不容易计算梯度,我们利用爬山法交替地对人体形状,姿态和服装尺寸参数进行优化求取最优解.最后,通过一系列实验对本文方法和最近的一...     

人体运动捕捉过程中的人体下肢动作识别

为了实现对虚拟人大范围运动的控制,针对人体下肢运动过程提出一种动作识别方法.首先根据人体下肢运动特点选取人体下肢动作识别运动参数,提出一种基于小波分形和最小二乘拟合的动作特征提取方法;然后基于支持向量机实现了对下肢运动链中各运动参数的动作识别;在获得各运动参数识别结果的基础上,采用证据理论实现了对识别结果的融合.采用运动捕捉数据进行实验的结果表明,该方法需要的训练样本少、实时性好,能够满足不同体型的人体动作识别需求,具有较好的应用前景.     

基于人体传感和Android技术的运动监测系统设计与实现

为了避免运动过程中和比赛中运动姿态不正确以及运动过量对身体造成的伤害,提出了基于人体传感和Android技术的运动监测系统的设计,在运动过程中对人体运动参数和运动姿态实时监测,通过Android平台实现卡路里消耗计算和运动姿态建模评估,以避免出现运动损伤和体能透支现象。监测系统以MSP430单片机为控制核心,采用MPU6050三轴加速度传感器实时测量人体三轴加速度,利用Android平台计算加速度、速度、里程等运动参数、运动中消耗的卡路里能量,以及人体运动轨迹跟踪、定位;并通过人体运动模型识别算法评估人体运动姿态,实现危险动作预判。实验证明系统能够实现实时运动监测、运动跟踪定位,保护运动者的身体健康。     

运动员三维运动图像姿态参数测量的仿真分析

研究运动员运动中的三维图像姿态参数准确测量问题.运动过程中,人体的关节运动程度较为复杂,并且运动速度很快,关节间的细微变化角度很难运用固定的约束算法进行约束.传统的三维运动图像建模运用固定约束模型,很难对上述动态小区域变化进行描述,导致对细微运动姿态的测量效果不好.提出一种运动员三维运动姿态测量方法,通过对人体运动参数进行优化,把运动参数的约束优化问题看成一个非线性求解最小化的问题,运用L-M运动约束参数提供快速收敛的正则化方法,求取非刚体三维运动时的运动参数和结构参数矩阵,完成运动三维参数测量.仿真结果表明,上述方法可以高精度测量运动员的三维运动参数,提高参数测量精度.     

基于有限元方法的电动自行车静动力学仿真

电动自行车具有骑行简便、省时省力的特点,在中国拥有庞大的消费群.然而,随着近年来电动自行车的使用量急剧增加,安全事故频发,电动自行车的质量和设计问题凸显.基于有限元方法,对某型号电动车进行静动力学仿真分析.首先,建立车体的有限元模型,确定电动自行车车身外观尺寸和主受力体的受力特征.然后,对电动车车架、车把手、电池盒和后...     

Course holding by cyclists and moped riders

Course holding by cyclists and moped riders includes both steering alongside a course and stabilising the vehicle. Inability to hold course may lead to conflicts with other road users. To design safe bicycle and moped facilities, and to consider the safety of those existing, knowledge about performance during course holding is necessary. Based on a literature survey, the article discusses how course holding will be influenced by characteristics of the course, the vehicle and the rider. Effects of disturbing factors such as side-wind and road-surface unevenness are also described. In a field study subjects carried out riding tests with various models of bicycles and mopeds on three courses. Speed, riding with one hand on the handlebars, side-wind and road-surface unevenness were included as independent variables.

Results indicate that cyclists and moped riders need a width of at least 1 m on straight roads. At intersections this width should be at least 1.25 m. Performance in the tests also showed differences between vehicle models and modes of riding.     

An immersive virtual peer for studying social influences on child cyclists' road-crossing behavior

The goal of our work is to develop a programmatically controlled peer to bicycle with a human subject for the purpose of studying how social interactions influence road-crossing behavior. The peer is controlled through a combination of reactive controllers that determine the gross motion of the virtual bicycle, action-based controllers that animate the virtual bicyclist and generate verbal behaviors, and a keyboard interface that allows an experimenter to initiate the virtual bicyclist's actions during the course of an experiment. The virtual bicyclist's repertoire of behaviors includes road following, riding alongside the human rider, stopping at intersections, and crossing intersections through specified gaps in traffic. The virtual cyclist engages the human subject through gaze, gesture, and verbal interactions. We describe the structure of the behavior code and report the results of a study examining how 10- and 12-year-old children interact with a peer cyclist that makes either risky or safe choices in selecting gaps in traffic. Results of our study revealed that children who rode with a risky peer were more likely to cross intermediate-sized gaps than children who rode with a safe peer. In addition, children were significantly less likely to stop at the last six intersections after the experience of riding with the risky than the safe peer during the first six intersections. The results of the study and children's reactions to the virtual peer indicate that our virtual peer framework is a promising platform for future behavioral studies of peer influences on children's bicycle riding behavior.     

Cooperating with free riders in unstructured P2P networks

Free riding is a common phenomenon in peer-to-peer (P2P) file sharing networks. Although several mechanisms have been proposed to handle free riding—mostly to exclude free riders, few of them have been adopted in a practical system. This may be attributed to the fact that the mechanisms are often nontrivial, and that completely eliminating free riders could jeopardize the sheer power of the network arising from the huge volume of its participants. Rather than excluding free riders, we incorporate and utilize them to provide global index service to the files shared in the network, as well as to relay messages in the search process. The simulation results indicate that our mechanism not only can shift the query processing load from non-free riders to free riders, but can also significantly boost the search efficiency of a plain Gnutella. Moreover, the mechanism is quite resilient to high free riding ratio.     

Rider motion identification during normal bicycling by means of principal component analysis

Recent observations of a bicyclist riding through town and on a treadmill show that the rider uses the upper body very little when performing normal maneuvers and that the bicyclist may, in fact, primarily use steering input for control. The observations also revealed that other motions such as lateral movement of the knees were used in low speed stabilization. In order to validate the hypothesis that there is little upper body motion during casual cycling, an in-depth motion capture analysis was performed on the bicycle and rider system.     

基于虚拟人设计与实现机器人舞蹈动作的一种方法

基于三维虚拟人的骨骼模型仿真实现了机器人的舞蹈动作。分析了机器人舞蹈动作运动的基本规律和实现动作的基本方法,基于此建立了三维虚拟人实现机器人舞蹈动作的关键帧数据库,在此基础上利用中间帧的过渡函数实现了虚拟人骨骼模型仿真机器人舞蹈动作的方法。实验中利用NOBODY机器人舞蹈视频实现了三维虚拟人骨骼模型的仿机器人的舞蹈动画,结果证明了方法的正确性和可行性,对于机器人的三维虚拟化和仿真研究具有重要意义。     

Discourage free riding in Peer-to-Peer file sharing systems with file migration and workload balancing approach

Free riding is a great challenge to the development and maintenance of Peer-to-Peer (P2P) networks. A file migration and workload balancing based approach (FMWBBA) to discourage free riding is proposed in this paper. The heart of our mechanism is to migrate some shared files from the overloaded peers to the neighboring free riders automatically and transparently, which enforces free riders to offer services when altruistic peers are heavily overloaded. File migration is a key issue in our approach, and some related strategies are discussed. A simulation is designed to verify this approach, and the results show that it can not only alleviate free riding, but also improve the Quality of Service (QoS) and robustness of P2P networks efficiently.     

Counteracting free riding in Peer-to-Peer networks

The existence of a high degree of free riding is a serious threat to Peer-to-Peer (P2P) networks. In this paper, we propose a distributed framework to reduce the adverse effects of free riding on P2P networks. Our solution primarily focuses on locating free riders and taking actions against them. We propose a framework in which each peer monitors its neighbors, decides if they are free riders, and takes appropriate actions. Unlike other proposals against free riding, our framework does not require any permanent identification of peers or security infrastructures for maintaining a global reputation system. Our simulation results show that the framework can reduce the effects of free riding and can therefore increase the performance of a P2P network.     

基于C3D数据的人体模型逆向动力学仿真分析方法

基于AnyBody人体建模仿真分析软件,采用试验得到的动作捕捉格式数据C3D文件,研究人体逆向动力学仿真分析方法,给出C3D驱动AnyBody人体运动仿真分析时的操作步骤、报错分析及其解决方案。仿真结果表明:人体模型基本参数设置、C3D参数设置、关键点的拟合和足底压力板参数调节是实现人体模型动态分析的关键,其能有效提高人体模型逆向动力学仿真精度。     

自行车车架结构尺寸的计算机辅助设计

本文探讨了自行车车架结构尺寸的计算机辅助设计方法．以创建人体尺寸数据库、自行车国家标准数据库及自行车车架设计经验数据库为基础，给出了结合人机学原理进行车架各管长度及夹角的计算机辅助设计步骤．与手工设计相比，该方法除可较大幅度地提高设计效率外，还可综合考虑设计结果对整车安全性能、适用性能及运动性能的影响，从而提高设计质量．     

人机合作机器人重力平衡设计

为提高人—机器人合作的质量，研究了机器人机构的重力平衡方法，以减小其带给操作者的重力感受．对于关节式机器人结构，采用拉弹簧的方式对机器人重力进行较大范围的平衡；通过对弹簧刚度和预变形的设计，使得随着机构的运动，弹簧系统可以适当调节弹簧力以实现机构在各种位形下重力的自主平衡．在机器人运动范围内的若干点对设计方案进行了验证，各关节的残余重力矩是原始重力矩的1~10%．结果说明，该设计可以基本实现重力平衡．