带有关节权重的DTW 动作识别算法研究

大多数动作仅包含部分关节的运动,现有方法未对运动剧烈的关节与几乎不参与运 动的关节进行区分,一定程度上降低了动作识别精度。针对这个问题,提出一种自适应关节权重 计算方法。结合动态时间规整(DTW)方法,利用获得的关节权重进行动作识别。首先对分类动作 序列进行分段,每段动作序列中运动较剧烈的关节选择分配更高权重,其余关节平均分配权重; 然后提取特征向量,计算两段动作序列的DTW 距离;最后采用K 近邻方法进行动作识别。实验 结果表明,该算法的总体分类识别准确率较高,且对于较相似的动作也能获得较好的识别结果。     

基于动态时间规整的手势加速度信号识别

为了提高基于加速度传感器的动态手势识别算法的性能,本文采用了动态时间规整(DTW)识别算法。通过该算法计算测试模板和参考模板的相似度,从而得出识别结果。为了验证该方法,建立了一套手势加速度无线采集系统,并采集了41个志愿者的手势信息。实验结果表明,该方法手势平均识别率在97%以上。与HMM识别算法相比,DTW识别算法在识别的准确率上比HMM识别算法更具优势。     

Weighted dynamic time warping for time series classification

Dynamic time warping (DTW), which finds the minimum path by providing non-linear alignments between two time series, has been widely used as a distance measure for time series classification and clustering. However, DTW does not account for the relative importance regarding the phase difference between a reference point and a testing point. This may lead to misclassification especially in applications where the shape similarity between two sequences is a major consideration for an accurate recognition. Therefore, we propose a novel distance measure, called a weighted DTW (WDTW), which is a penalty-based DTW. Our approach penalizes points with higher phase difference between a reference point and a testing point in order to prevent minimum distance distortion caused by outliers. The rationale underlying the proposed distance measure is demonstrated with some illustrative examples. A new weight function, called the modified logistic weight function (MLWF), is also proposed to systematically assign weights as a function of the phase difference between a reference point and a testing point. By applying different weights to adjacent points, the proposed algorithm can enhance the detection of similarity between two time series. We show that some popular distance measures such as DTW and Euclidean distance are special cases of our proposed WDTW measure. We extend the proposed idea to other variants of DTW such as derivative dynamic time warping (DDTW) and propose the weighted version of DDTW. We have compared the performances of our proposed procedures with other popular approaches using public data sets available through the UCR Time Series Data Mining Archive for both time series classification and clustering problems. The experimental results indicate that the proposed approaches can achieve improved accuracy for time series classification and clustering problems.     

融合关节旋转特征和指尖距离特征的手势识别

作为人机交互的重要方式,手势交互和识别由于其具有的高自由度而成为计算机图形学、虚拟现实与人机交互等领域的研究热点.传统直接提取手势轮廓或手部关节点位置信息的手势识别方法,其提取的特征通常难以准确表示手势之间的区别.针对手势识别中不同手势具有的高自由度以及由于手势图像分辨率低、背景杂乱、手被遮挡、手指形状尺寸不同、个体差异性导致手势特征表示不准确等问题,本文提出了一种新的融合关节旋转特征和指尖距离特征的手势特征表示与手势识别方法.首先从手势深度图中利用手部模板并将手部看成链段结构提取手部20个关节点的3D位置信息;然后利用手部关节点位置信息提取四元数关节旋转特征和指尖距离特征,该表示构成了手势特征的内在表示;最后利用一对一支持向量机对手势进行有效识别分类.本文不仅提出了一种新的手势特征表示与提取方法,该表示融合了关节旋转信息和指尖距离特征;而且从理论上证明了该特征表示能唯一地表征手势关节点的位置信息;同时提出了基于一对一SVM多分类策略进行手势分类与识别.对ASTAR静态手势深度图数据集中8类中国数字手势和21类美国字母手势数据集分别进行了实验验证,其分类识别准确率分别为99.71%和85.24%.实验结果表明,本文提出的基于关节旋转特征和指尖距离特征的融合特征能很好地表示不同手势的几何特征,能准确地表征静态手势并进行手势识别.     

基于视觉的动态手势识别及其在仿人机器人交互中的应用

手势识别是人和机器人交互中的重要组成部分，本文针对双目视觉系统SFBinoeye实 现了基于光流PCA(主分量分析)和DTW(动态时间规整)的命令手势识别，用以控制仿人机器人 SFHR的手臂运动．利用块相关算法计算光流，并通过主分量分析得到降维的连续投影系数， 与手掌区域的质心位置组合为混合特征向量．针对DTW定义了新的加权距离测度，并用它对 手势进行匹配识别．针对9个手势训练和识别，识别率达到92.4%，并成功地应用于机器人的 手臂控制中．     

基于光流的动态手势识别

手势识别是人机交互中的重要组成部分，文章针对基于光流PCA（主分量分析）和DTW（动态时间规整）进行命令手势识别。利用块相关算法计算光流，并通过主分量分析得到降维的投影系数，以及手掌区域的质心作为混合特征向量。针对该混合特征向量定义了新的加权距离测度，并用DTW对手势进行匹配。针对9个手势训练和识别，识别率达到92％。     

基于DTW算法的肌电信号手势识别方法

为了提高肌电信号手势识别算法的准确度,增强实时性,提出了一种基于动态时间规整（DTW）算法的手势识别方法,该方法利用肌电信号（EMG）对个体间的手势进行识别。首先,采用滑动平均能量的方法对原始的EMG信号进行数据分割,探测有效动作;其次,对于分割的数据段使用平均绝对值（MAV）来提取信号特征;最后,用DTW算法将8维的EMG信号融合并计算测试样本和模版的相似度,其中采用了DTW算法寻找规整路径的方法进行了模板制作,实现了个体间的手势识别。实验结果表明,使用DTW算法对肌电信号进行手势识别,其动作识别的准确率达到96.09%,该方法计算速度快,实时性强。     

基于Kinect手势识别的应用与研究

为解决当前智能家居系统操作繁琐的问题,同时为获得更简单的控制方式,并增加用户的体验感受,研究了基于Kinect骨骼信息的手势识别技术,并将其融入至智能家居的人机交互系统中。在该系统中,用户可以自定义手势动作或语音实现家居设备的智能控制。使用了一种基于加权动态时间规整的模板匹配手势识别算法。通过Kinect的深度摄像头获取手势深度图像和骨骼图像数据,并采用加权动态时间规整算法进行识别。实验表明使用该算法实现手势识别是可行且有效的,且其最佳识别位置是在Kinect的正前方2～2.5m处,识别准确率达到96%左右。     

一种基于DTW/ISODATA算法的多层分类器手语识别方法

为提高大词汇量手语识别速度,论文提出了一种将动态时间规整(DTW)和隐马尔可夫模型(HMM)相结合的多层次的大词汇量手语识别方法。该方法思想是先进行全局粗略搜索,将要识别的手势词归入某一组范围较小的词表中,然后通过更加精确的HMM局部搜索将词识别出来。各个词汇表用DTW/ISODATA算法来产生。对4942个孤立手语词作了实验,结果表明,相对于仅用HMM单层识别而言,识别速度从原来每个词的2.364秒提高到0.137秒,提高了94.2%,识别准确率也提高了4.66%。     

Rotation invariant hand-drawn symbol recognition based on a dynamic time warping model

One of the major difficulties of handwriting symbol recognition is the high variability among symbols because of the different writer styles. In this paper, we introduce a robust approach for describing and recognizing hand-drawn symbols tolerant to these writer style differences. This method, which is invariant to scale and rotation, is based on the dynamic time warping (DTW) algorithm. The symbols are described by vector sequences, a variation of the DTW distance is used for computing the matching distance, and K-Nearest Neighbor is used to classify them. Our approach has been evaluated in two benchmarking scenarios consisting of hand-drawn symbols. Compared with state-of-the-art methods for symbol recognition, our method shows higher tolerance to the irregular deformations induced by hand-drawn strokes.     

A model-based hand gesture recognition system

This paper introduces a model-based hand gesture recognition system, which consists of three phases: feature extraction, training, and recognition. In the feature extraction phase, a hybrid technique combines the spatial (edge) and the temporal (motion) information of each frame to extract the feature images. Then, in the training phase, we use the principal component analysis (PCA) to characterize spatial shape variations and the hidden Markov models (HMM) to describe the temporal shape variations. A modified Hausdorff distance measurement is also applied to measure the similarity between the feature images and the pre-stored PCA models. The similarity measures are referred to as the possible observations for each frame. Finally, in recognition phase, with the pre-trained PCA models and HMM, we can generate the observation patterns from the input sequences, and then apply the Viterbi algorithm to identify the gesture. In the experiments, we prove that our method can recognize 18 different continuous gestures effectively. Received: 19 May 1999 / Accepted: 4 September 2000     

基于随机投影的加速度手势识别

针对手势交互中手势信号的相似性及不稳定性,设计并实现了一种基于随机投影(RP)的加速度手势识别方法.识别系统包含训练阶段和测试阶段:训练阶段运用动态时间规整(DTW)和近邻传播(AP)算法对训练集中的每一个手势迹创建样本中心;测试阶段先通过计算未知手势迹与样本中心的距离找出候选姿势迹,然后用RP算法将候选手势迹和未知手势迹投影到低维子空间,把识别问题转换成l₁-minimization问题来对未知的手势迹进行识别.在采集的2400个数据样本上进行了基于特定人和非特定人的实验,结果表明所提算法分别取得了98.41%和96.67%的识别率,该方法能够有效识别加速度手势动作.     

基于TLD和DTW的动态手势跟踪识别

针对动态手势跟踪稳定性的不足和识别效率的问题, 提出一种基于TLD和DTW的动态手势跟踪识别框架. 首先利用基于Haar特征的静态手势分类器获得手势区域, 然后使用TLD跟踪算法对获得的手势区域进行跟踪以获取手势轨迹, 最后提取轨迹特征, 使用改进的DTW算法进行识别. 实验表明, 该框架能够长时间稳定地跟踪手势区域, 并能够在保证识别率的基础上显著提高识别效率.     

室内机器人动态手势指令识别系统研究

针对目前室内移动机器人手势指令识别系统存在的问题,对图像传感器与机器人相分离的图像采集方案进行了研究,并利用动态手势指令对机器人进行控制。动态手势指令识别方法是对手的不同运动轨迹进行识别,通过皮肤颜色模型和手势中心点方向向量法追踪得到手势运动轨迹,提取手势运动轨迹的特征向量,通过基于动态时间规整（DTW）实现对轨迹的识别。实验结果表明,该系统可以实现对机器人前进、后退、左转、右转的实时控制。     

航天员虚拟交互操作训练多体感融合驱动方法研究

针对航天员虚拟训练中的人机自然交互问题,基于体态/手势识别和人体运动特性, 提出一种多通道数据融合的虚拟驱动与交互方法。结合Kinect 设备能够完整识别人体姿态特点 及LeapMotion 设备能精确识别手势姿态的优势,提出了基于判断的数据传递方法,在人体关节 识别的基础上对手部关节进行识别与数据处理计算,采用多通道体感识别融合方法将二者结合, 并进行了实验。结果表明,通过采用LeapMotion 和Kinect 对手部识别的判别,当手势在 LeapMotion 识别范围内,能够在实现人体体感识别的基础上增加较为精确的手势识别。此方法 成功实现了人体姿态识别和手势精确识别的结合,可应用于航天员虚拟训练中的人机自然交互 中去。     

Hand gesture recognition using two-level speed normalization,feature selection and classifier fusion

Hand gesture recognition provides an alternative way to many devices for human computer interaction. In this work, we have developed a classifier fusion based dynamic free-air hand gesture recognition system to identify the isolated gestures. Different users gesticulate at different speed for the same gesture. Hence, when comparing different samples of the same gesture, variations due to difference in gesturing speed should not contribute to the dissimilarity score. Thus, we have introduced a two-level speed normalization procedure using DTW and Euclidean distance-based techniques. Three features such as ‘orientation between consecutive points’, ‘speed’ and ‘orientation between first and every trajectory points’ were used for the speed normalization. Moreover, in feature extraction stage, 44 features were selected from the existing literatures. Use of total feature set could lead to overfitting, information redundancy and may increase the computational complexity due to higher dimension. Thus, we have tried to overcome this difficulty by selecting optimal set of features using analysis of variance and incremental feature selection techniques. The performance of the system was evaluated using this optimal set of features for different individual classifiers such as ANN, SVM, k-NN and Naïve Bayes. Finally, the decisions of the individual classifiers were combined using classifier fusion model. Based on the experimental results it may be concluded that classifier fusion provides satisfactory results compared to other individual classifiers. An accuracy of 94.78 % was achieved using the classifier fusion technique as compared to baseline CRF (85.07 %) and HCRF (89.91 %) models.     

Sequential data classification by dynamic state warping

The ubiquity of sequences in many domains enhances significant recent interest in sequence learning, for which a basic problem is how to measure the distance between sequences. Dynamic time warping (DTW) aligns two sequences by nonlinear local warping and returns a distance value. DTW shows superior ability in many applications, e.g. video, image, etc. However, in DTW, two points are paired essentially based on point-to-point comparisons without considering the autocorrelation of sequences. Thus, points with different semantic meanings, e.g. peaks and valleys, may be matched providing their coordinate values are similar. As a result, DTW may be sensitive to noise and poorly interpretable. This paper proposes an improved alignment method, dynamic state warping (DSW). DSW integrates the dynamic information of sequences into DTW by converting each time point into a latent state. Alignment is performed by using the state sequences. Thus, DSW is able to yield alignment that is semantically more interpretable than that of DTW. Using one nearest neighbour classifier, DSW shows significant improvement on classification accuracy in comparison with Euclidean distance (68/85 wins), DTW (70/85 wins) and its variants. We also empirically demonstrate that DSW is more robust and scales better to long sequences than Euclidean distance and DTW.     

Compression and recognition of dance gestures using a deformable model

In this paper, we aim for the recognition of a set of dance gestures from contemporary ballet. Our input data are motion trajectories followed by the joints of a dancing body provided by a motion-capture system. It is obvious that direct use of the original signals is unreliable and expensive. Therefore, we propose a suitable tool for non-uniform sub-sampling of spatiotemporal signals. The key to our approach is the use of a deformable model to provide a compact and efficient representation of motion trajectories. Our dance gesture recognition method involves a set of hidden Markov models (HMMs), each of them being related to a motion trajectory followed by the joints. The recognition of such movements is then achieved by matching the resulting gesture models with the input data via HMMs. We have validated our recognition system on 12 fundamental movements from contemporary ballet performed by four dancers. This revised version was published online in November 2004 with corrections to the section numbers. Ballet Atlantique Régine Chopinot.     

A Hilbert warping method for handwriting gesture recognition

We propose a novel sequence alignment algorithm for recognizing handwriting gestures by a camera. In the proposed method, an input image sequence is aligned to the reference sequences by phase-synchronization of analytic signals which are transformed from original feature values. A cumulative distance is calculated simultaneously with the alignment process, and then used for the classification. A major benefit of this method is that over-fitting to sequences of incorrect categories is restricted. The proposed method exhibited higher recognition accuracy in handwriting gesture recognition, compared with the conventional dynamic time warping method which explores optimal alignment results for all categories.     

基于DTW的交警指挥手势识别方法

对于日益成熟的无人驾驶技术,如何快速准确地识别交警的手势成为无人驾驶领域中一个重要的研究内容。本文提出一种基于DTW算法的交警指挥手势识别方法。首先,使用Kinect传感器获取人体关节点数据并根据交警手势特点进行预处理,建立训练模板库;接着深入分析了该模板库的两个特征：类内高内聚性和类间低耦合性,由此给出交警指挥手势识别的实现步骤。实验结果表明,该方法能自动识别各种交警指挥手势,具有识别准确度较高、实时性较强、稳定性好的特点。