个人运动管理系统中的行为识别方法

为使个人运动管理系统更好地感知用户行为,给予科学的运动指导,提出一种基于通用模型迁移的自适应行为识别方法。该方法无需对个体数据进行标定,通过将群体行为的共性知识迁移到个体行为,使通用识别模型可以随着个体行为样本的增多,自适应地调整共性知识,从而形成针对特定个体的个性化行为识别模型。实验结果表明,个性化模型的平均识别精度可以从67.31%提高到83.54%。     

Agent普适机器学习研究

从上世纪90年代Mark Weiser提出普适计算的透明化和不可见性两个特点开始,到2003年国际普适计算会议以后。普适计算开始向机器学习的方向发展。本文通过Agent的移动性和普适计算的随时随地性来实现机器学习的普适功能．从而形成Agent普适机器学习基本内容。借助普适计算的基本性质,结合机器学习的特点。给出Agent普适机器学习设计方法。     

一种Agent普适机器学习分类器在Smart-It中的应用

近年来普适计算得到了快速的发展,在2003年国际普适计算会议后,普适计算开始向机器学习的方向发展即普适机器学习。经过普适机器学习模型设计和普适机器学习分类器设计研究后,本文在实例Smart—It中应用agent普适机器学习分类器,通过分析使用前后的数据。对比其优缺点。     

小样本目标检测研究综述

目标检测是计算机视觉方向的热点领域,其通常需要大量的标注图像用于模型训练,这将花费大量的人力和物力来实现。同时,由于真实世界中的数据存在固有的长尾分布,大部分对象的样本数量都比较稀少,比如众多非常见疾病等,很难获得大量的标注图像。小样本目标检测只需要提供少量的标注信息,就能够检测出感兴趣的对象,对小样本目标检测方法做了详细综述。首先回顾了通用目标检测的发展及其存在的问题,从而引出小样本目标检测的概念,对同小样本目标检测相关的其他任务做了区分阐述。之后介绍了现有小样本目标检测基于迁移学习和基于元学习的两种经典范式。根据不同方法的改进策略,将小样本目标检测分为基于注意力机制、图卷积神经网络、度量学习和数据增强四种类型,对这些方法中使用到的公开数据集和评估指标进行了说明,对比分析了不同方法的优缺点、适用场景以及在不同数据集上的性能表现。最后讨论了小样本目标检测的实际应用领域和未来的研究趋势。     

基于关节点提取的多特征融合人体摔倒检测

意外摔倒是威胁老年人安全的重要因素,能实时高效识别摔倒动作的检测系统可以帮助老年人最大限度地减少摔倒带来的伤害。文章提出一种利用关节点特征结合运动学特征的人体摔倒检测方法。首先使用深度卷积神经网络的人体目标检测算法获取视频中人体的所在位置;然后使用人体姿态估计算法对目标人体进行骨骼关键点提取;最后使用运动学特征人体外接矩形宽高比、质心节点的下降速度、头部关节点与地面之间的距离及人体主躯干、左右腿、左右胳膊和地面之间的夹角与提取的关节点特征进行融合,结果表明摔倒测试在灵敏性、特异性、准确性上分别达到了97.5%、95%、96%的效果。     

一种Agent普适机器学习分类器在Smart-It中的应用

近年来普适计算得到了快速的发展,在2003年国际普适计算会议后,普适计算开始向机器学习的方向发展即普适机器学习。经过普适机器学习模型设计和普适机器学习分类器设计研究后,本文在实例Smart—It中应用agent普适机器学习分类器,通过分析使用前后的数据,对比其优缺点。     

基于双目标定的独居老人摔倒检测算法

独居老人摔倒已成为一个备受关注的问题.为快速有效获取摔倒信息从而使老人得到及时救助,提出一种基于双目标定的独居老人摔倒检测算法.该算法通过色彩不变性分割前景目标（老人）,采用双目视觉标定计算人体在三维坐标中高度作为特征信息,能够有效区分易混淆动作,防止误判,提高检测准确率.实验结果表明：该算法易于实现,具有较好的鲁棒性和实时性.     

基于多传感器融合的摔倒检测算法的研究

针对传统摔倒检测算法中误报和漏报率高的不足,提出一种基于多传感器融合的摔倒检测算法;该算法分别以人体的加速度和姿态角值为判定依据;首先,采用三轴加速度传感器和电子罗盘对上述两种数据进行采集,并通过无线模块发送至PC机;之后对采集数据进行分析和处理,进而根据阈值进行异常姿态检测;最终,综合加速度和姿态角的分析结果给出准确的检测结论;实验结果表明,该算法检测的准确率达99.2％、与传统检测算法相比具有更强的稳定性与可靠性.     

基于轮廓关键点和LSTM的摔倒检测方法

针对传统人体摔倒检测方法误检率高、无法有效结合时序特征等问题,提出一种新的人体轮廓关键点提取方法,并将该方法和LSTM网络相结合构建一种新的摔倒检测模型。该模型对视频中的人体进行轮廓检测,选取轮廓关键点坐标和质心坐标作为人体特征;使用LSTM对人体特征序列进行时序特征提取;用全连接层实现分类。在公开数据集上进行实验,结果表明该模型具有较高的准确率和良好的泛化性。     

Transfer learning and information retrieval applied to fall detection

Detecting falls in the elderly population is a very important issue that is related with the time of recovery. This study focuses on using wearable smart watches to monitor the movements of the user in order to detect patterns that might be related to fall events. The proposed solution explores Symbolic Aggregate approXimation (SAX) Time Series representation, together with two information retrieval techniques enriched with transfer learning (TL). The solution is user centred; that is, a model is developed for each specific user. Basically, the fall detection approach makes use of a finite-state machine to detect peaks; the time series window embedding these peaks are represented using SAX. Assuming the data from the public fall detection data sets are valid, a dictionary is prepared using the most relevant words. This dictionary is then introduced as previous knowledge to an online learning classifier that is trained with normal activities of daily living. The two classifiers are evaluated and compared with two classical approaches. Before this comparison, two clustering approaches are studied to produce the bag of relevant words. A complete experimentation is included, which makes use of several publicly available data sets and also with a data set developed by the research group. Comparisons are performed for all the data sets, showing how the TL stage empowers the classifier. The results show that this solution produces high detection rates and at the same time performed similarly for all the individuals tested. Furthermore, the positive effects of TL in this context are clearly remarked.     

基于半监督学习的跌倒检测系统设计

针对老人跌倒时的复杂运动情况,进行跌倒标注的较难实现,提出了基于Tri-training半监督算法的跌倒检测系统。本系统使用3D加速度传感器采集运动加速度数据,然后对数据进行特征提取与部分样本标注,使用Tri-training算法训练分类器,最后使用训练好的分类器进行跌倒识别。具体的数据采集传感器设计为可穿戴式设备,服务器端使用Java编写了一个服务器的程序实现对数据的分析与处理。实验结果表明：该方法使用了大量无标签数据的信息,有效提高了跌倒识别的准确率。实验结果表明：本系统能够满足老年人在日常生活中的需求,对于一些意外跌倒能够给予及时的检测与报警。     

Combining domain knowledge and machine learning for robust fall detection

This paper presents a method for combining domain knowledge and machine learning (CDKML) for classifier generation and online adaptation. The method exploits advantages in domain knowledge and machine learning as complementary information sources. Whereas machine learning may discover patterns in interest domains that are too subtle for humans to detect, domain knowledge may contain information on a domain not present in the available domain dataset. CDKML has three steps. First, prior domain knowledge is enriched with relevant patterns obtained by machine learning to create an initial classifier. Second, genetic algorithms refine the classifier. Third, the classifier is adapted online on the basis of user feedback using the Markov decision process. CDKML was applied in fall detection. Tests showed that the classifiers developed by CDKML have better performance than machine‐learning classifiers generated on a training dataset that does not adequately represent all real‐life cases of the learned concept. The accuracy of the initial classifier was 10 percentage points higher than the best machine‐learning classifier and the refinement added 3 percentage points. The online adaptation improved the accuracy of the refined classifier by an additional 15 percentage points.     

基于智能手机的实时跌倒检测系统研究

为减少跌倒对老年人造成的伤害,并对跌倒进行实时检测,提出了一种基于Android智能手机的人体跌倒检测系统,手机安置于腰上采集手机加速度传感器数据,利用了姿态识别和跌倒检测相结合的算法,区分出跌倒行为和人体日正常常活动。当检测到异常跌倒时,报警信息以及从手机中GPS获取的位置被发送。仿真及实验表明：系统能够有效地识别出跌倒和日常行为,算法具有较高实时性、具有较高灵敏度和特异度。     

基于AdaBoost的类不平衡学习算法

处理类不平衡数据时,少数类的边界实例非常容易被错分。为了降低类不平衡对分类器性能的影响,提出了自适应边界采样算法(AB-SMOTE)。AB-SMOTE算法对少数类的边界样本进行自适应采样,提高了数据集的平衡度和有效性。同时将AB-SMOTE算法与数据清理技术融合,形成基于AdaBoost的集成算法ABTAdaBoost。ABTAdaBoost算法主要包括三个阶段：第一个阶段对训练数据集采用AB-SMOTE算法,降低数据集的类不平衡度;第二个阶段使用Tomek links数据清理技术,清除数据集中的噪声和抽样方法产生的重叠样例,有效提高数据的可用性;第三个阶段使用AdaBoost集成算法生成一个基于N个弱分类器的集成分类器。实验分别以J48决策树和朴素贝叶斯作为基分类器,在12个UCI数据集上的实验结果表明：ABTAdaBoost算法的预测性能优于其它几种算法。     

A multi-objective optimisation approach for class imbalance learning

Class imbalance limits the performance of most learning algorithms since they cannot cope with large differences between the number of samples in each class, resulting in a low predictive accuracy over the minority class. In this respect, several papers proposed algorithms aiming at achieving more balanced performance. However, balancing the recognition accuracies for each class very often harms the global accuracy. Indeed, in these cases the accuracy over the minority class increases while the accuracy over the majority one decreases. This paper proposes an approach to overcome this limitation: for each classification act, it chooses between the output of a classifier trained on the original skewed distribution and the output of a classifier trained according to a learning method addressing the course of imbalanced data. This choice is driven by a parameter whose value maximizes, on a validation set, two objective functions, i.e. the global accuracy and the accuracies for each class. A series of experiments on ten public datasets with different proportions between the majority and minority classes show that the proposed approach provides more balanced recognition accuracies than classifiers trained according to traditional learning methods for imbalanced data as well as larger global accuracy than classifiers trained on the original skewed distribution.     

基于目标均衡度量的核增量学习跌倒检测方法

针对增量学习模型在更新阶段的识别效果不稳定的问题,提出一种基于目标均衡度量的核增量学习方法。通过设置经验风险均值最小化的优化目标项,设计了均衡度量训练数据个数的优化目标函数,以及在增量学习训练条件下的最优求解方案;再结合基于重要性分析的新增数据有效选择策略,最终构建出了一种轻量型的增量学习分类模型。在跌倒检测公开数据集上的实验结果显示：当已有代表性方法的识别精度下滑至60%以下时,所提方法仍能保持95%以上的精度,同时模型更新的计算消耗仅为3 ms。实验结果表明,所提算法在显著提高增量学习模型更新阶段识别能力稳定性的同时,大大降低了时间消耗,可有效实现云服务平台中关于可穿戴设备终端的智能应用。     

A multi-modal approach for activity classification and fall detection

The society is changing towards a new paradigm in which an increasing number of old adults live alone. In parallel, the incidence of conditions that affect mobility and independence is also rising as a consequence of a longer life expectancy. In this paper, the specific problem of falls of old adults is addressed by devising a technological solution for monitoring these users. Video cameras, accelerometers and GPS sensors are combined in a multi-modal approach to monitor humans inside and outside the domestic environment. Machine learning techniques are used to detect falls and classify activities from accelerometer data. Video feeds and GPS are used to provide location inside and outside the domestic environment. It results in a monitoring solution that does not imply the confinement of the users to a closed environment.     

基于加速度传感器的人体跌倒检测方法

针对人体跌倒检测阈值算法在由于阈值设定不当而引起的检测精度下降问题,采用支持向量机方法决定跌倒检测的阈值大小。从加速度传感器中获取人体运动信号,提取合加速度以及倾角作为分类特征,根据人体在跌倒时经过的失重、撞击地面和平稳三个阶段,建立基于阈值的跌倒检测模型。采用所建立的跌倒检测模型,分别用支持向量机方法以及人工方法设定阈值,仿真结果显示采用支持向量机设定阈值的检测效果优于对比算法,结果表明本文方法能有效识别跌倒。