Mathematical models of bio-inspired rotatable sensors with elasticities for object scanning. - In: Proceedings in applied mathematics and mechanics, ISSN 1617-7061, Bd. 18 (2018), 1, e201800264, insges. 2 S.
https://doi.org/10.1002/pamm.201800264
Form- und Parameterfindung von multistabilen Tensegrity-Strukturen mittels Optimierungsalgorithmen und Anwendungen in der Greifertechnik. - Ilmenau : Universitätsbibliothek, 2018. - 1 Online-Ressource (viii, 227 Seiten)
Technische Universität Ilmenau, Dissertation 2018
Der Gegenstand der Arbeit sind Tensegrity-Strukturen mit mehreren stabilen Gleichgewichtskonfigurationen, sogenannte multistabile Tensegrity-Strukturen. Im Vordergrund der Arbeit steht die Entwicklung von Algorithmen, mit denen solche Strukturen entworfen, untersucht und gezielt ausgelegt werden können. Dafür werden Möglichkeiten zur Bestimmung der Gleichgewichtskonfigurationen von multistabilen Tensegrity-Strukturen betrachtet. Des Weiteren wird untersucht, wie Tensegrity-Strukturen so ausgelegt werden können, dass sie vorgegebene Eigenschaften aufweisen. Dazu werden Kenngrößen zur Charakterisierung dieser Eigenschaften definiert. Für beide Aufgabenstellungen werden Optimierungsprobleme hergeleitet. Zur Lösung dieser Optimierungsprobleme werden Algorithmen entworfen, getestet und analysiert. Aufbauend auf diesen theoretischen Untersuchungen liegt ein weiterer Schwerpunkt dieser Arbeit in der Betrachtung der Einsatzmöglichkeiten von multistabilen Tensegrity-Strukturen in der Greifertechnik. Es werden verschiedene Konzepte für die Entwicklung von Greifern aus diesen Strukturen diskutiert. Zu ausgewählten Konzepten erfolgen weiterführende Betrachtungen, unter anderem durch Einbeziehung dynamischer Analysen. Neben theoretischen Untersuchungen dieser Greifer werden die wichtigsten Erkenntnisse experimentell an Funktionsmustern überprüft und potentielle Einsatzgebiete werden aufgezeigt.
https://nbn-resolving.org/urn:nbn:de:gbv:ilm1-2018000245
Portable system for motion induced eddy current testing. - In: Sensors and Measuring Systems, (2018), S. 300-303
https://ieeexplore.ieee.org/document/8436178
Signal tuning of observables at the support of a vibrissa-like tactile sensor in different scanning scenarios. - In: High tech human touch, ISBN 978-1-5386-8183-1, (2018), S. 1138-1143
https://doi.org/10.1109/BIOROB.2018.8487961
Motion characteristics of a vibration driven mobile tensegrity structure with multiple stable equilibrium states. - In: Journal of sound and vibration, ISSN 0022-460X, Bd. 437 (2018), S. 198-208
https://doi.org/10.1016/j.jsv.2018.09.019
Dynamical investigation of crawling motion system based on a multistable tensegrity structure. - In: ICINCO 2018, (2018), S. 122-130
The basic idea of this article is the utilization of the multistable character of a compliant tensegrity structure to control the direction of motion of a crawling motion system. A crawling motion system basing on a two-dimensional tensegrity structure with multiple stable equilibrium states is considered. This system is in contact with a horizontal plane due to gravity. For a selected harmonic actuation of the system small oscillations around the given equilibrium state of the tensegrity structure occur and the corresponding uniaxial motion of the system is evaluated. A change of the equilibrium state of the tensegrity structure yields to novel configuration of the entire system. Moreover, the motion behavior of the novel configuration is totally different although the actuation strategy is not varied. In particular, the direction of motion changes. Therefore, this approach enables a uniaxial bidirectional crawling motion with a controllable direction of motion using only one actuato r with a selected excitation frequency.
Gait transitions in artificial non-standard snake-like locomotion systems using adaptive control. - In: Dynamical Systems in Applications, (2018), S. 1-12
This chapter contributes to the modeling, analysis and control of terrestrial artificial locomotion systems. Inspired by previous models, we set up an unconventional model for a snake-like locomotion systems in form of a chain of visco-elastically interconnected mass points in a plane with passive joints, but - in contrast to literature - active links (time-varying link-length) and rotatable skids to change the movement direction and to avoid obstacles. We investigate this model in a dynamical way and focus on controlling these link lengths to achieve a global movement, steered by the skids. From dynamics, the actuator forces have to adjust the prescribed link length for the locomotion. Since it is impossible to determine the necessary actuator forces a-priori, we apply an adaptive lambda-tracking controller to enable the system to adjust these force outputs on-line on its own. Prescribed motion patterns, i.e. specific gaits, are required to guarantee a controlled movement that differ in the number of resting mass points, the load of actuators and spikes, and the lateral forces of the skids. In contrast to literature, the investigated system of n = 10 mass points exhibit a large variety of possible gaits. To determine the most advantageous gaits, numerical investigations are performed and a weighting function offers a decision of best possible gaits. Using these gaits, a gait transition algorithm, which autonomously changes velocity and number of resting mass points depending on the spike, actuator and lateral skid force load, is presented and tested in numerical simulations.
https://doi.org/10.1007/978-3-319-96601-4_1
Dynamic analysis of a compliant tensegrity structure for the use in a gripper application. - In: Dynamical systems in theoretical perspective, (2018), S. 323-334
The use of compliant tensegrity structures in robotic applications offers several advantageous properties. In this work the dynamic behaviour of a planar tensegrity structure with multiple static equilibrium configurations is analysed, with respect to its further use in a two-finger-gripper application. In this application, two equilibrium configurations of the structure correspond to the opened and closed states of the gripper. The transition between these equilibrium configurations, caused by a proper selected actuation method, is essentially dependent on the actuation parameters and on the system parameters. To study the behaviour of the dynamic system and possible actuation methods, the nonlinear equations of motion are derived and transient dynamic analyses are performed. The movement behaviour is analysed in relation to the prestress of the structure and actuation parameters.
https://doi.org/10.1007/978-3-319-96598-7_26
Theoretical investigations on the behavior of artificial sensors for surface texture detection. - In: Dynamical systems in theoretical perspective, (2018), S. 311-321
Animal vibrissae are used as natural inspiration for artificial tactile sensors, e.g., the mystacial vibrissae enable rodents to perform several tasks in using these tactile hairs: object shape determination and surface texture discrimination. Referring to the literature, the Kinetic Signature Hypothesis states that the surface texture detection is a highly dynamic process. It is assumed that the animals gather information about the surface texture out of a spatial, temporal pattern of kinetic events. This process has to be analyzed in detail to develop an artificial tactile sensor with similar functionalities. Hence, we set up a mechanical model for theoretical investigations of the process. This model is analyzed in two different directions using numerical simulations: at first a quasi-static and then a fully dynamic description.
https://doi.org/10.1007/978-3-319-96598-7_25
Properties of polydimethylsiloxane and magnetoactive polymers with electroconductive particles. - In: Macromolecular chemistry and physics, ISSN 1521-3935, Bd. 219 (2018), 18, S. 1800222, insges. 8 S.
Magnetoactive polymers are intelligent materials whose mechanical and electrical characteristics are reversibly influenced by external magnetic stimuli. They consist of a highly elastic polymer matrix in which magnetically soft and/or hard particles are distributed by means of special fabrication processes. In addition to ferromagnetic particles such as carbonyl iron powder, electrically conductive particles may also be embedded into the polymer matrix. After characterizing a range of compounds, this work focuses on a comparison of the electrical properties and the suitability of various materials for applications, with particular emphasis on integration into 3D and 6D printing processes. 6D printing is based on the selective positioning of particles in a 3D polymer matrix with a further three degrees of freedom for a graduated dispersion of the particles at certain points and in desired directions. The aim is therefore to ensure that the polymers containing electroconductive tracks have the best possible electrical properties, that is, low resistivity but are still capable of being printed. A comparison between the traditionally used compounds containing graphite and carbon black is made for the first time. This latter is found to be greatly superior both in terms of electrical conductivity and applicability to 3D printing and 6D printing.
https://doi.org/10.1002/macp.201800222