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Uhrhan, Katja; Jäger, Max; Witte, Hartmut
Threshold based reduction of EMS stimulation artifacts in the electromyogram when stimulation intensity increases. - In: Engineering for a changing world, (2023), 3.2.144, S. 1-10

To investigate muscular strain, it is possible to record an electromyogram (EMG) during electromyostimulation (EMS). However, stimulation artifacts make it difficult to examine evoked compound muscle action potentials (M-waves). The aim of this work was to algorithmically remove stimulation artifacts from the EMG signal when the stimulation intensity increases. For this purpose, EMG signals were recorded on four subjects who underwent a 30-second EMS of the right M. triceps surae. Afterwards we conducted offline signal processing to reduce stimulation artifacts. We implemented a two-stage threshold algorithm, adapted from O'Keeffe et al. (2001), to remove signal segments passing the thresholds in a defined sequence. Here, the thresholds in the first iteration are two constants, while the algorithm uses linearly or exponentially increasing thresholds in the second iteration. After empirically adjusting the threshold parameters, the stimulation artifacts were successfully reduced. This allows further investigations of the M-waves with respect to muscular fatigue.



https://doi.org/10.22032/dbt.59139
Jäger, Max; Helbig, Thomas; Witte, Hartmut
Control for non-linear compliant actuation of an upper arm exoskeleton. - In: Engineering for a changing world, (2023), 3.2.088, S. 1-15

Musculoskeletal diseases of the back and upper extremities are one of the main causes of sick leave in Europe. Exoskeletons are one possible approach to preventive measures. The Biomechatronics Group at Technische Universität Ilmenau is developing an antagonistically actuated exoskeleton with non-linear compliance to support flexion and extension of the elbow in repetitive tasks like in assembly. Here, we present a control strategy to achieve joint stiffness control while benefitting from the advantages of non-linear compliant actuation. We use a decentralized control approach, combining two PID controllers to control joint position and string force and thus, joint stiffness, in the antagonistically acting drive. We show limitations and benefits of this approach through simulation and measurement.



https://doi.org/10.22032/dbt.58877
Steinz, Josefine; Lutherdt, Stefan; Witte, Hartmut
Concept for the measurement of vital parameters during the use of an infrared cabin to investigate physiological effects and to individualize the sauna session. - In: Engineering for a changing world, (2023), 3.2.050, S. 1-20

Infrared sauna bathing has positive effects on body and mind. Quantifying these effects helps to make sauna use more efficient and safer and to increase the user-observed wellness effects. Currently, there are no practical solutions for a comprehensive and user-friendly monitoring of the physical impact of sauna bathing. This paper focuses on the concept development to investigate which measurement setups are suitable to record and evaluate changes in vital parameters. Based on prioritized vital parameters and requirements a pre-selection of devices in form of wearables is made, which is going to be examined in detail for their suitability. An investigation with ten test persons is planned, in which the wearables’ measurement accuracy and the user acceptance outside and inside the infrared cabin are quantified. The result is a concept for the test procedure and the evaluation of the wearables in order to integrate a suitable device into the overall system.



https://doi.org/10.22032/dbt.58880
Witte, Hartmut; Helbig, Thomas; Hönemann, Claudia; Lutherdt, Stefan; Wenzel, Sabine
Bewältigung der Lehre unter Corona-Bedingungen an einer der kleineren Universitäten. - In: Lessons learned, ISSN 2749-1307, Bd. 2 (2022), 1, 35, insges. 10 S.

Die Technische Universität Ilmenau versucht auch unter „Corona-Zwängen“ durch Kontakteinschränkungen in Kombination mit begrenzten Lehrkapazitäten Seminare, Übungen und Praktika angemessen durchzuführen und die Lehre nicht zu vorlesungslastig werden zu lassen. Die Seminar- und Praktikumsräume gaben jedoch auch unter intensiver zeitlicher Raumbewirtschaftung von 7 Uhr bis 21 Uhr „zentral“ wie durch die Fachgebiete bei Einhaltung der Hygienevorschriften keine ausreichenden Kapazitäten zur Durchführung in Präsenz her. Der Beitrag berichtet daher über von uns getestete Möglichkeiten zur Umsetzung der etablierten Lehrformate in Onlineformate. Zusätzlich werden Lösungen zur sicheren Realisation von Präsenzprüfungen unter Pandemie-Bedingungen dargestellt. Daher war ab April 2020 neben der relativ einfach umzusetzenden Online-Durchführung der Vorlesungen für die Seminare und insbesondere die Praktika viel Eigeninitiative und Einfallsreichtum erforderlich, um den eigenen Qualitätsanforderungen der Lehrenden genüge leisten zu können. Im Vortrag wird über ausgewählte Beispiele der so entstandenen Lösungen berichtet, wie sie in der Fakultät für Maschinenbau der Technischen Universität Ilmenau realisiert wurden. Unsere Fakultät weist ein breites Spektrum von „klassischen“ Fächern bis zu Lichttechnik, Technischer Optik und Biomechatronik auf, so dass schon bei dieser Stichprobe aus nur einem Fachgebiet einer der fünf Fakultäten die dem Wissenschaftler gemeine übergreifende Bewertung kaum zu bieten ist. Selbstverständlich wird nicht nur über Lösungen berichtet, sondern die ungelösten Probleme werden gleichrangig angesprochen.



https://doi.org/10.25369/ll.v2i1.35
Zárate, José; Lutherdt, Stefan; Witte, Hartmut
Design of a robot gripping system: theoretical considerations and a new solution. - Osaka : Osaka University Library. - 1 Online-Ressource (2 Seiten)Publikation entstand im Rahmen der Veranstaltung: The 9.5th International Symposium on Adaptive Motion of Animals and Machines, Ottawa, Canada (Virtual Platform), 2021-06-22/25

https://doi.org/10.18910/84879
Helbig, Thomas; Kreipe, Stefan; Goos, Moritz; Wenzel, Sabine; Schumann, Nikolaus; Witte, Hartmut
Prediction of movement for adaptive control of an upper limb exoskeleton. - Osaka : Osaka University Library. - 1 Online-Ressource (2 Seiten)Publikation entstand im Rahmen der Veranstaltung: The 9.5th International Symposium on Adaptive Motion of Animals and Machines, Ottawa, Canada (Virtual Platform), 2021-06-22/25

https://doi.org/10.18910/84880
Eckert, Peter; Schmerbauch, Anja E. M.; Horvat, Tomislav; Söhnel, Katja; Fischer, Martin S.; Witte, Hartmut; Ijspeert, Auke Jan
Towards rich motion skills with the lightweight quadruped robot Serval. - In: Adaptive behavior, ISSN 1741-2633, Bd. 28 (2020), 3, S. 129-150

Bio-inspired robotic designs introducing and benefiting from morphological aspects present in animals allowed the generation of fast, robust, and energy-efficient locomotion. We used engineering tools and interdisciplinary knowledge transferred from biology to build low-cost robots, able to achieve a certain level of versatility. Serval, a compliant quadruped robot with actuated spine and high range of motion in all joints, was developed to address the question of what mechatronic complexity is needed to achieve rich motion skills. In our experiments, the robot presented a high level of versatility (number of skills) at medium speed, with a minimal control effort and, in this article, no usage of its spine. Implementing a basic kinematics-duplication from dogs, we found strengths to emphasize, weaknesses to correct, and made Serval ready for future attempts to achieve more agile locomotion. In particular, we investigated the following skills: walk, trot, gallop, bound (crouched), sidestep, turn with a radius, ascend slopes including flat ground transition, perform single and double step-downs, fall, trot over bumpy terrain, lie/sit down, and stand up.



https://doi.org/10.1177/1059712319853227
Helbig, Thomas; Sturm, Stefan; Frey, Domenic; Hofmeister, Sven; Witte, Hartmut
Einfluss von Gestalt und Pose des Trommelfells auf die Lärmbelastung am Trommelfell. - In: Prävention von arbeitsbedingten Gesundheitsgefahren und Erkrankungen, (2020), S. 261-270

Kreipe, Stefan; Helbig, Thomas; Graßme, Roland; Mey, Elke; Witte, Hartmut; Schumann, Nikolaus
Richtungsabhängige und zeitliche Koordinationsmuster der Schulter- und Armmuskulatur bei Lasthandhabung. - In: Prävention von arbeitsbedingten Gesundheitsgefahren und Erkrankungen, (2020), S. 227-238

Helbig, Thomas; Wenzel, Sabine; Lutherdt, Stefan; Kreipe, Stefan; Schumann, Nikolaus; Witte, Hartmut
Prävention Muskulosekelettaler Erkrankungen mittels aktiver Exoskellett Systeme. - In: Prävention von arbeitsbedingten Gesundheitsgefahren und Erkrankungen, (2020), S. 213-226