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Results: 289
Created on: Tue, 28 Nov 2023 23:17:14 +0100 in 0.0645 sec

Andrada, Emanuel; Hildebrandt, Gregor; Witte, Hartmut; Fischer, Martin S.
Positioning of pivot points in quadrupedal locomotion: limbs global dynamics in four different dog breeds. - In: Frontiers in Bioengineering and Biotechnology, ISSN 2296-4185, Bd. 11 (2023), 1193177, S. 1-16

Dogs (Canis familiaris) prefer the walk at lower speeds and the more economical trot at speeds ranging from 0.5 Fr up to 3 Fr. Important works have helped to understand these gaits at the levels of the center of mass, joint mechanics, and muscular control. However, less is known about the global dynamics for limbs and if these are gait or breed-specific. For walk and trot, we analyzed dogs’ global dynamics, based on motion capture and single leg kinetic data, recorded from treadmill locomotion of French Bulldog (N = 4), Whippet (N = 5), Malinois (N = 4), and Beagle (N = 5). Dogs’ pelvic and thoracic axial leg functions combined compliance with leg lengthening. Thoracic limbs were stiffer than the pelvic limbs and absorbed energy in the scapulothoracic joint. Dogs’ ground reaction forces (GRF) formed two virtual pivot points (VPP) during walk and trot each. One emerged for the thoracic (fore) limbs (VPPTL) and is roughly located above and caudally to the scapulothoracic joint. The second is located roughly above and cranially to the hip joint (VPPPL). The positions of VPPs and the patterns of the limbs’ axial and tangential projections of the GRF were gaits but not always breeds-related. When they existed, breed-related changes were mainly exposed by the French Bulldog. During trot, positions of the VPPs tended to be closer to the hip joint or the scapulothoracic joint, and variability between and within breeds lessened compared to walk. In some dogs, VPPPL was located below the pelvis during trot. Further analyses revealed that leg length and not breed may better explain differences in the vertical position of VPPTL or the horizontal position of VPPPL. The vertical position of VPPPL was only influenced by gait, while the horizontal position of VPPTL was not breed or gait-related. Accordingly, torque profiles in the scapulothoracic joint were likely between breeds while hip torque profiles were size-related. In dogs, gait and leg length are likely the main VPPs positions’ predictors. Thus, variations of VPP positions may follow a reduction of limb work. Stability issues need to be addressed in further studies.
Jäger, Max; Helbig, Thomas; Goos, Moritz; Köhring, Sebastian; Witte, Hartmut
Characterization of an antagonistic actuation system with nonlinear compliance for an upper-arm exoskeleton. - In: Actuators, ISSN 2076-0825, Bd. 12 (2023), 5, 196, S. 1-24

The parallel connection of technical and biological systems with a comparable mechanical behavior offers the possibility of reducing the interaction forces between those systems. Especially in the context of human-robot interaction (e.g., exoskeletons), it can improve user safety and acceptance at the same time. With this aim, we used antagonistic actuators with nonlinear compliance for a modular upper-extremity exoskeleton following biological paragons, mirroring the “blueprint” of its human user. In a test-bed setup, we compared antagonistic compliant actuation with antagonistic stiff, unilateral stiff and unilateral compliant actuation in the artificial “elbow joint” of the exoskeleton test bed. We show that this type of actuation allows the variation of the joint stiffness during motion, independent of the position. With the approach we propose, compliance leads to reduced force peaks and angular jerk, without sacrifices in terms of time constants and overshoot of amplitudes. We conclude that the presented actuation principle has considerable benefits in comparison to other types of exoskeleton actuation, even when using only commercially available and 3D printed components. Based on our work, further investigations into the control of compliant antagonistically actuated exoskeletons become realizable.
David, Jonas Paul; Helbig, Thomas; Witte, Hartmut
SenGlove - a modular wearable device to measure kinematic parameters of the human hand. - In: Bioengineering, ISSN 2306-5354, Bd. 10 (2023), 3, 324, S. 1-29

For technical or medical applications, the knowledge of the exact kinematics of the human hand is key to utilizing its capability of handling and manipulating objects and communicating with other humans or machines. The optimal relationship between the number of measurement parameters, measurement accuracy, as well as complexity, usability and cost of the measuring systems is hard to find. Biomechanic assumptions, the concepts of a biomechatronic system and the mechatronic design process, as well as commercially available components, are used to develop a sensorized glove. The proposed wearable introduced in this paper can measure 14 of 15 angular values of a simplified hand model. Additionally, five contact pressure values at the fingertips and inertial data of the whole hand with six degrees of freedom are gathered. Due to the modular design and a hand size examination based on anthropometric parameters, the concept of the wearable is applicable to a large variety of hand sizes and adaptable to different use cases. Validations show a combined root-mean-square error of 0.99° to 2.38° for the measurement of all joint angles on one finger, surpassing the human perception threshold and the current state-of-the-art in science and technology for comparable systems.
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.
Witte, Hartmut;
The interplay of biomimetics and biomechatronics. - In: Biomimetics, ISSN 2313-7673, Bd. 7 (2022), 3, 96, S. 1-9

Biomechatronics is an engineering subject in which biomimetics as a method is one of its two supporting pillars: biology for engineering, or Bio4Eng. This is contrasted with biocompatible design, or Eng4Bio, examples of which are human-serving systems, such as exoskeletons, and biomedical engineering. The paper aims to illustrate that the research fields of biomimetics, biomechatronics, and biomedical engineering are not in competition but mutually supportive. The current attempts to place biomechatronics under the umbrella of biomimetics or biomedical engineering are therefore not expedient; they deprive the subject of its strength of combining Bio4Eng and Eng4Bio at any time in a task-related manner. In addition to research and development, however, the training of the specialists supporting the subjects must not be disregarded and is therefore described based on a proven design.
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
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
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.
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