Malte Ollenschläger

Mr. Malte Ollenschläger

Friedrich-Alexander-Universität Erlangen-Nürnberg
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orcid

Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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17 April 2018 in ACM Computing Surveys
Verified
Journal Article
Open access
PDF file
RARodolfo S. Antunes
Rodolfo S. Antunes
LSLucas A. Seewald
Lucas A. Seewald
Vinicius Facco RodriguesVinicius Facco Rodrigues
Vinicius Facco Rodrigues
Cristiano da CostaCristiano da Costa
Cristiano da Costa
Luiz JrLuiz Jr
Luiz Jr
GCGelson Campanatti
Gelson Campanatti
Activities of a clinical staff in healthcare environments must regularly be adapted to new treatment methods, medications, and technologies. This constant evolution requires the monitoring of the workflow, or the sequence of actions from actors involved in a procedure, to ensure quality of medical services. In this context, recent advances in sensing technologies, including Real-time Location Systems and Computer Vision, enable high-precision tracking of actors and equipment. The current state-of-the-art about healthcare workflow monitoring typically focuses on a single technology and does not discuss its integration with others. Such an integration can lead to better solutions to evaluate medical workflows. This study aims to fill the gap regarding the analysis of monitoring technologies with a systematic literature review about sensors for capturing the workflow of healthcare environments. Its main scientific contribution is to identify both current technologies used to track activities in a clinical environment and gaps on their combination to achieve better results. It also proposes a taxonomy to classify work regarding sensing technologies and methods. The literature review does not present proposals that combine data obtained from Real-time Location Systems and Computer Vision sensors. Further analysis shows that a multimodal analysis is more flexible and could yield better results.

23 August 2017 in Sensors
Verified
Journal Article
Open access
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JHJulius Hannink
Julius Hannink
Malte OllenschlägerMalte Ollenschläger
Malte Ollenschläger
Felix KlugeFelix Kluge
Felix Kluge
NRNils Roth
Nils Roth
JKJochen Klucken
Jochen Klucken
Bjoern EskofierBjoern Eskofier
Bjoern Eskofier
Mobile gait analysis systems based on inertial sensing on the shoe are applied in a wide range of applications. Especially for medical applications, they can give new insights into motor impairment in, e.g., neurodegenerative disease and help objectify patient assessment. One key component in these systems is the reconstruction of the foot trajectories from inertial data. In literature, various methods for this task have been proposed. However, performance is evaluated on a variety of datasets due to the lack of large, generally accepted benchmark datasets. This hinders a fair comparison of methods. In this work, we implement three orientation estimation and three double integration schemes for use in a foot trajectory estimation pipeline. All methods are drawn from literature and evaluated against a marker-based motion capture reference. We provide a fair comparison on the same dataset consisting of 735 strides from 16 healthy subjects. As a result, the implemented methods are ranked and we identify the most suitable processing pipeline for foot trajectory estimation in the context of mobile gait analysis.

22 January 2024 in IEEE Open Journal of Engineering in Medicine and Biology
Verified
Journal Article
Open access
AKArne Küderle
Arne Küderle
MUMartin Ullrich
Martin Ullrich
NRNils Roth
Nils Roth
Malte OllenschlägerMalte Ollenschläger
Malte Ollenschläger
AIAlzhraa A. Ibrahim
Alzhraa A. Ibrahim
Bjoern EskofierBjoern Eskofier
Bjoern Eskofier
Goal: Gait analysis using inertial measurement units (IMUs) has emerged as a promising method for monitoring movement disorders. However, the lack of public data and easy-to-use open-source algorithms hinders method comparison and clinical application development. To address these challenges, this publication introduces the gaitmap ecosystem, a comprehensive set of open source Python packages for gait analysis using foot-worn IMUs. Methods: This initial release includes over 20 state-of-the-art algorithms, enables easy access to seven datasets, and provides eight benchmark challenges with reference implementations. Together with its extensive documentation and tooling, it enables rapid development and validation of new algorithm and provides a foundation for novel clinical applications. Conclusion: The published software projects represent a pioneering effort to establish an open-source ecosystem for IMU-based gait analysis. We believe that this work can democratize the access to high-quality algorithm and serve as a driver for open and reproducible research in the field of human gait analysis and beyond.

5 August 2022 in Sensors
Verified
Journal Article
Open access
PDF file
Malte OllenschlägerMalte Ollenschläger
Malte Ollenschläger
AKArne Küderle
Arne Küderle
WMWolfgang Mehringer
Wolfgang Mehringer
ASAnn-Kristin Seifer
Ann-Kristin Seifer
JWJürgen Winkler
Jürgen Winkler
Bjoern EskofierBjoern Eskofier
Bjoern Eskofier
Developing machine learning algorithms for time-series data often requires manual annotation of the data. To do so, graphical user interfaces (GUIs) are an important component. Existing Python packages for annotation and analysis of time-series data have been developed without addressing adaptability, usability, and user experience. Therefore, we developed a generic open-source Python package focusing on adaptability, usability, and user experience. The developed package, Machine Learning and Data Analytics (MaD) GUI, enables developers to rapidly create a GUI for their specific use case. Furthermore, MaD GUI enables domain experts without programming knowledge to annotate time-series data and apply algorithms to it. We conducted a small-scale study with participants from three international universities to test the adaptability of MaD GUI by developers and to test the user interface by clinicians as representatives of domain experts. MaD GUI saves up to 75% of time in contrast to using a state-of-the-art package. In line with this, subjective ratings regarding usability and user experience show that MaD GUI is preferred over a state-of-the-art package by developers and clinicians. MaD GUI reduces the effort of developers in creating GUIs for time-series analysis and offers similar usability and user experience for clinicians as a state-of-the-art package.

1 January 2019 in Computer Vision and Image Understanding
Verified
Journal Article
Closed access
LSLucas Adams Seewald
Lucas Adams Seewald
Vinicius Facco RodriguesVinicius Facco Rodrigues
Vinicius Facco Rodrigues
Malte OllenschlägerMalte Ollenschläger
Malte Ollenschläger
RARodolfo Stoffel Antunes
Rodolfo Stoffel Antunes
Cristiano da CostaCristiano da Costa
Cristiano da Costa
RFRebecca Fahrig
Rebecca Fahrig

29 August 2023 in Orphanet Journal of Rare Diseases
Verified
Journal Article
Open access
PDF file
Malte OllenschlägerMalte Ollenschläger
Malte Ollenschläger
PHPatrick Höfner
Patrick Höfner
MUMartin Ullrich
Martin Ullrich
FKFelix Kluge
Felix Kluge
TGTeresa Greinwalder
Teresa Greinwalder
Heiko GassnerHeiko Gassner
Heiko Gassner
Background: Hereditary spastic paraplegias (HSPs) cause characteristic gait impairment leading to an increased risk of stumbling or even falling. Biomechanically, gait deficits are characterized by reduced ranges of motion in lower body joints, limiting foot clearance and ankle range of motion. To date, there is no standardized approach to continuously and objectively track the degree of dysfunction in foot elevation since established clinical rating scales require an experienced investigator and are considered to be rather subjective. Therefore, digital disease-specific biomarkers for foot elevation are needed. Methods: This study investigated the performance of machine learning classifiers for the automated detection and classification of reduced foot dorsiflexion and clearance using wearable sensors. Wearable inertial sensors were used to record gait patterns of 50 patients during standardized 4 $$\times$$ × 10 m walking tests at the hospital. Three movement disorder specialists independently annotated symptom severity. The majority vote of these annotations and the wearable sensor data were used to train and evaluate machine learning classifiers in a nested cross-validation scheme. Results: The results showed that automated detection of reduced range of motion and foot clearance was possible with an accuracy of 87%. This accuracy is in the range of individual annotators, reaching an average accuracy of 88% compared to the ground truth majority vote. For classifying symptom severity, the algorithm reached an accuracy of 74%. Conclusion: Here, we show that the present wearable gait analysis system is able to objectively assess foot elevation patterns in HSP. Future studies will aim to improve the granularity for continuous tracking of disease severity and monitoring therapy response of HSP patients in a real-world environment.