158 research outputs found
Special Issue on Wearable Computing and Machine Learning for Applications in Sports, Health, and Medical Engineering
Note: In lieu of an abstract, this is an excerpt from the first page.
Recent advancement in digital technologies is driving a remarkable transformation in sports, health, and medical engineering, aiming to achieve the accurate quantification of performance, well-being, and disease condition, and the optimization of sports, clinical, and therapeutic training and treatment programs. Traditionally, understanding and monitoring of functional performance and capacity has been performed in gait laboratories based on optoelectronic motion capture systems. However, gait laboratories in practical settings are often not readily available because the systems are costly and require trained experts to operate. Most importantly, when assessments are restricted to laboratory settings, they provide a narrow snapshot of function and do not capture functionality in natural free-living settings, thus representing a severely under-sampled view of an individualâs condition. The use of mobile and wearable technologies has been explored in many sports, health, and medical research studies examining individuals in âin-the-wildâ settings. Among the most important drivers of this transformation are (1) wearable sensors and (2) signal processing and machine learning algorithms. Wearable sensors are capable of collecting physical and/or physiological data continuously and seamlessly outside of laboratory settings. Signal processing and machine learning algorithms allow data-driven approaches for analyzing considerable amounts of multidimensional sensory data and for extracting important information relevant to the mentioned application areas (e.g., validating the efficacy of sports training, health benefits, and chronic disease progression). These technologies together would support how sports and clinical professionals understand and interpret individualsâ performance more objectively, and enable proactive, evidence-based, and personalized management systems
Simulating Human Gaze with Neural Visual Attention
Existing models of human visual attention are generally unable to incorporate
direct task guidance and therefore cannot model an intent or goal when
exploring a scene. To integrate guidance of any downstream visual task into
attention modeling, we propose the Neural Visual Attention (NeVA) algorithm. To
this end, we impose to neural networks the biological constraint of foveated
vision and train an attention mechanism to generate visual explorations that
maximize the performance with respect to the downstream task. We observe that
biologically constrained neural networks generate human-like scanpaths without
being trained for this objective. Extensive experiments on three common
benchmark datasets show that our method outperforms state-of-the-art
unsupervised human attention models in generating human-like scanpaths
Estimating 3D kinematics and kinetics from virtual inertial sensor data through musculoskeletal movement simulations
Portable measurement systems using inertial sensors enable motion capture outside the lab, facilitating longitudinal and large-scale studies in natural environments. However, estimating 3D kinematics and kinetics from inertial data for a comprehensive biomechanical movement analysis is still challenging. Machine learning models or stepwise approaches performing Kalman filtering, inverse kinematics, and inverse dynamics can lead to inconsistencies between kinematics and kinetics. We investigated the reconstruction of 3D kinematics and kinetics of arbitrary running motions from inertial sensor data using optimal control simulations of full-body musculoskeletal models. To evaluate the feasibility of the proposed method, we used marker tracking simulations created from optical motion capture data as a reference and for computing virtual inertial data such that the desired solution was known exactly. We generated the inertial tracking simulations by formulating optimal control problems that tracked virtual acceleration and angular velocity while minimizing effort without requiring a task constraint or an initial state. To evaluate the proposed approach, we reconstructed three trials each of straight running, curved running, and a v-cut of 10 participants. We compared the estimated inertial signals and biomechanical variables of the marker and inertial tracking simulations. The inertial data was tracked closely, resulting in low mean root mean squared deviations for pelvis translation (â€20.2 mm), angles (â€1.8âdeg), ground reaction forces (â€1.1âBW%), joint moments (â€0.1âBWBH%), and muscle forces (â€5.4âBW%) and high mean coefficients of multiple correlation for all biomechanical variables (â„0.99). Accordingly, our results showed that optimal control simulations tracking 3D inertial data could reconstruct the kinematics and kinetics of individual trials of all running motions. The simulations led to mutually and dynamically consistent kinematics and kinetics, which allows researching causal chains, for example, to analyze anterior cruciate ligament injury prevention. Our work proved the feasibility of the approach using virtual inertial data. When using the approach in the future with measured data, the sensor location and alignment on the segment must be estimated, and soft-tissue artifacts are potential error sources. Nevertheless, we demonstrated that optimal control simulation tracking inertial data is highly promising for estimating 3D kinematics and kinetics for a comprehensive biomechanical analysis
Online at Will: A Novel Protocol for Mutual Authentication in Peer-to-Peer Networks for Patient-Centered Health Care Information Systems
Patient-centered health care information systems (PHSs) on peer-to-peer (P2P) networks promise decentralization benefits. P2P PHSs, such as decentralized personal health records or interoperable Covid-19 proximity trackers, can enhance data sovereignty and resilience to single points of failure, but the openness of P2P networks introduces new security issues. We propose a novel, simple, and secure mutual authentication protocol that supports offline access, leverages independent and stateless encryption services, and enables patients and medical professionals to establish secure connections when using P2P PHSs. Our protocol includes a virtual smart card (software-based) feature to ease integration of authentication features of emerging national health-IT infrastructures. The security evaluation shows that our protocol resists most online and offline threats while exhibiting performance comparable to traditional, albeit less secure, password-based authentication methods. Our protocol serves as foundation for the design and implementation of P2P PHSs that will make use of P2P PHSs more secure and trustworthy
Velocity-Based Channel Charting with Spatial Distribution Map Matching
Fingerprint-based localization improves the positioning performance in
challenging, non-line-of-sight (NLoS) dominated indoor environments. However,
fingerprinting models require an expensive life-cycle management including
recording and labeling of radio signals for the initial training and regularly
at environmental changes. Alternatively, channel-charting avoids this labeling
effort as it implicitly associates relative coordinates to the recorded radio
signals. Then, with reference real-world coordinates (positions) we can use
such charts for positioning tasks. However, current channel-charting approaches
lag behind fingerprinting in their positioning accuracy and still require
reference samples for localization, regular data recording and labeling to keep
the models up to date. Hence, we propose a novel framework that does not
require reference positions. We only require information from velocity
information, e.g., from pedestrian dead reckoning or odometry to model the
channel charts, and topological map information, e.g., a building floor plan,
to transform the channel charts into real coordinates. We evaluate our approach
on two different real-world datasets using 5G and distributed
single-input/multiple-output system (SIMO) radio systems. Our experiments show
that even with noisy velocity estimates and coarse map information, we achieve
similar position accuraciesComment: This work has been submitted to the IEEE for possible publication.
Copyright may be transferred without notice, after which this version may no
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How to Learn from Risk: Explicit Risk-Utility Reinforcement Learning for Efficient and Safe Driving Strategies
Autonomous driving has the potential to revolutionize mobility and is hence
an active area of research. In practice, the behavior of autonomous vehicles
must be acceptable, i.e., efficient, safe, and interpretable. While vanilla
reinforcement learning (RL) finds performant behavioral strategies, they are
often unsafe and uninterpretable. Safety is introduced through Safe RL
approaches, but they still mostly remain uninterpretable as the learned
behaviour is jointly optimized for safety and performance without modeling them
separately. Interpretable machine learning is rarely applied to RL. This paper
proposes SafeDQN, which allows to make the behavior of autonomous vehicles safe
and interpretable while still being efficient. SafeDQN offers an
understandable, semantic trade-off between the expected risk and the utility of
actions while being algorithmically transparent. We show that SafeDQN finds
interpretable and safe driving policies for a variety of scenarios and
demonstrate how state-of-the-art saliency techniques can help to assess both
risk and utility.Comment: 8 pages, 5 figure
Restoration of Gait using Personalized Brain/Neural-Controlled Exoskeletons
The development of brain/neural-controlled exoskeletons allow for restoration of movements in paralysis. By translating brain activity associated with the intention to move, such systems enabled, e.g., quadriplegic patients with complete finger paralysis to eat and drink in an outside restaurant. However, noninvasive means to record brain activity often lack sufficient signal quality for reliable and safe operation, particularly in noisy, uncontrolled environments or presence of muscle artifacts due to whole body movements. Thus, hybrid control paradigms were developed that merge different biosignals to increase reliability of exoskeleton control. Here, we introduce such control paradigm for restoration of gait using a personalized exoskeleton based on electroencephalographic and electrooculographic (EEG/EOG) signals. While exoskeleton movements were initiated by event-related desynchronization (ERD) of sensorimotor rhythms (SMR) associated with the intention to walk, the exoskeleton was stopped by a specific EOG signal. Using such paradigm does not only provide intuitive control, but may also trigger neural recovery when used repeatedly over a longer period of time. Further validation of this approach in a larger clinical study on gait assistance and rehabilitation will be needed
Security Engineering of Patient-Centered Health Care Information Systems in Peer-to-Peer Environments: Systematic Review
Background: Patient-centered health care information systems (PHSs) enable patients to take control and become knowledgeable about their own health, preferably in a secure environment. Current and emerging PHSs use either a centralized database, peer-to-peer (P2P) technology, or distributed ledger technology for PHS deployment. The evolving COVID-19 decentralized Bluetooth-based tracing systems are examples of disease-centric P2P PHSs. Although using P2P technology for the provision of PHSs can be flexible, scalable, resilient to a single point of failure, and inexpensive for patients, the use of health information on P2P networks poses major security issues as users must manage information security largely by themselves. Objective: This study aims to identify the inherent security issues for PHS deployment in P2P networks and how they can be overcome. In addition, this study reviews different P2P architectures and proposes a suitable architecture for P2P PHS deployment. Methods: A systematic literature review was conducted following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) reporting guidelines. Thematic analysis was used for data analysis. We searched the following databases: IEEE Digital Library, PubMed, Science Direct, ACM Digital Library, Scopus, and Semantic Scholar. The search was conducted on articles published between 2008 and 2020. The Common Vulnerability Scoring System was used as a guide for rating security issues. Results: Our findings are consolidated into 8 key security issues associated with PHS implementation and deployment on P2P networks and 7 factors promoting them. Moreover, we propose a suitable architecture for P2P PHSs and guidelines for the provision of PHSs while maintaining information security. Conclusions: Despite the clear advantages of P2P PHSs, the absence of centralized controls and inconsistent views of the network on some P2P systems have profound adverse impacts in terms of security. The security issues identified in this study need to be addressed to increase patients\u27 intention to use PHSs on P2P networks by making them safe to use
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