@article{ChavezZiolkowskiSchorretal., author = {Chavez, Jhohan and Ziolkowski, Marek and Schorr, Philipp and Spiess, Lothar and B{\"o}hm, Valter and Zimmermann, Klaus}, title = {A method to approach constant isotropic permeabilities and demagnetization factors of magneto-rheological elastomers}, series = {Journal of Magnetism and Magnetic Materials}, volume = {527}, journal = {Journal of Magnetism and Magnetic Materials}, publisher = {Elsevier}, doi = {10.1016/j.jmmm.2021.167742}, abstract = {The use of non-conventional materials is nowadays of much interest in scientific community. Magneto-rheological elastomers are hybrid materials, which in presence of magnetic fields state a change in their mechanical properties. They are composed by an elastomeric matrix with embedded magnetic particles. One of the most attractive features of these materials is that as soon as the magnetic field is removed from the material, the original mechanical properties are completely recovered, with negligible differences in comparison to the original state. This paper focuses on the study of magnetic characteristics of these smart materials, such as relative permeability and demagnetizing factors, for samples with different volume concentration of ferromagnetic particles.}, language = {en} } @inproceedings{BoehmSchorrSchaleetal., author = {B{\"o}hm, Valter and Schorr, Philipp and Schale, Florian and Kaufhold, Tobias and Zentner, Lena and Zimmermann, Klaus}, title = {Worm-Like Mobile Robot Based on a Tensegrity Structure}, series = {2021 IEEE 4th International Conference on Soft Robotics (RoboSoft): 2.04.2021 - 16.04.2021, New Haven, CT, USA}, booktitle = {2021 IEEE 4th International Conference on Soft Robotics (RoboSoft): 2.04.2021 - 16.04.2021, New Haven, CT, USA}, publisher = {IEEE}, isbn = {978-1-7281-7713-7}, doi = {10.1109/robosoft51838.2021.9479193}, pages = {358 -- 363}, abstract = {This work presents a novel concept to develop mobile robots enabling crawling locomotion in tubular environment. Chain-like systems are designed by serial cascading a uniform tensegrity module. Inspired by the movement of worms in nature, an undulating shape change of the system is targeted to generate locomotion. The shape changeability of an exemplary tensegrity module due to internal actuation is examined in simulations and experiments. A prototype consisting of these tensegrity modules is manufactured and the locomotion principle is verified in experiments. Comparing to existing prototypes this approach enables an enhanced compliance due to the modular assembly of tensegrity structures.}, language = {en} } @article{ChavezSchorrKaufholdetal., author = {Chavez, Jhohan and Schorr, Philipp and Kaufhold, Tobias and Zentner, Lena and Zimmermann, Klaus and B{\"o}hm, Valter}, title = {Influence of Elastomeric Tensioned Members on the Characteristics of Compliant Tensegrity Structures in Soft Robotic Applications}, series = {Procedia Manufacturing}, volume = {52}, journal = {Procedia Manufacturing}, publisher = {Elsevier}, issn = {2351-9789}, doi = {10.1016/j.promfg.2020.11.048}, pages = {289 -- 294}, abstract = {The use of mechanically prestressed compliant structures in soft robotics is a recently discussed topic. Tensegrity structures, consisting of a set of rigid disconnected compressed members connected to a continuous net of prestressed elastic tensioned members build one specific class of these structures. Robots based on these structures have manifold shape changing abilities and can adapt their mechanical properties reversibly by changing of their prestress state according to specific tasks. In the paper selected aspects on the potential use of elastomer materials in these structures are discussed with the help of theoretical analysis. Therefore, a selected basic tensegrity structure with elastomer members is investigated focusing on the stiffness and shape changing ability in dependence of the nonlinear hyperelastic behavior of the used elastomer materials. The considered structure is compared with a conventional tensegrity structure with linear elastic tensioned members. Finally, selected criterions for the advantageous use of elastomer materials in compliant tensegrity robots are discussed.}, language = {en} } @inproceedings{BoehmSumiSchorretal., author = {B{\"o}hm, Valter and Sumi, Susanne and Schorr, Philipp and Zimmermann, Klaus}, title = {Dynamic Analysis of a Compliant Tensegrity Structure for the Use in a Gripper Application}, series = {Dynamical systems in theoretical perspective (DSTA 2017), Ł{\´o}d{\'{z}}, Poland, December 11-14, 2017}, booktitle = {Dynamical systems in theoretical perspective (DSTA 2017), Ł{\´o}d{\'{z}}, Poland, December 11-14, 2017}, editor = {Awrejcewicz, Jan}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-96598-7}, doi = {10.1007/978-3-319-96598-7_26}, pages = {323 -- 334}, abstract = {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.}, language = {en} } @inproceedings{SchorrBoehmZentneretal., author = {Schorr, Philipp and B{\"o}hm, Valter and Zentner, Lena and Zimmermann, Klaus}, title = {Dynamical Investigation of Crawling Motion System based on a Multistable Tensegrity Structure}, series = {Proceedings of the 15th International Conference on Informatics in Control, Automation and Robotics : Porto, Portugal, 29.07.2018 - 31.07.2018}, booktitle = {Proceedings of the 15th International Conference on Informatics in Control, Automation and Robotics : Porto, Portugal, 29.07.2018 - 31.07.2018}, publisher = {SCITEPRESS}, isbn = {978-989-758-321-6}, doi = {10.5220/0006852701220130}, pages = {122 -- 130}, abstract = {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 actuat or with a selected excitation frequency.}, language = {en} } @inproceedings{ChavezSchorrScharffetal., author = {Chavez, Jhohan and Schorr, Philipp and Scharff, Moritz and Schale, Florian and B{\"o}hm, Valter and Zimmermann, Klaus}, title = {Towards Magneto-Sensitive Elastomers Based End-Effectors for Gripping Application Technologies}, series = {2019 IEEE International Conference on Mechatronics (ICM), 18-20 March 2019, Ilmenau, Germany}, volume = {1}, booktitle = {2019 IEEE International Conference on Mechatronics (ICM), 18-20 March 2019, Ilmenau, Germany}, publisher = {IEEE}, doi = {10.1109/ICMECH.2019.8722922}, pages = {217 -- 222}, abstract = {Nowadays, the demands in engineering systems become more challenging and the use of conventional materials for certain applications is not suitable. This issue encourages the investigation of novel and innovative materials in soft robotics field. A promising approach is the consideration of magneto-sensitive elastomers (MSE). These materials enable a useful adaptability responding to their mechanical properties. By applying a static magnetic field, the static and dynamic characteristics can be tuned. However, currently the knowledge about the correlations are not satisfying and the resulting material properties can only be predicted approximately with the use of time-expensive simulations regarding to the nano scale. Therefore, feasible material simulations of the description of the mechanical behavior are necessary. In this paper experimental studies of the influence of a static magnetic field on the mechanical properties and shape adaptability of MSE are presented. Furthermore, based on these results a simulation for the material behavior is executed. These results can be implemented into further simulations for various MSE exemplars.}, language = {en} } @article{SchorrBoehmZentneretal., author = {Schorr, Philipp and B{\"o}hm, Valter and Zentner, Lena and Zimmermann, Klaus}, title = {Motion characteristics of a vibration driven mobile tensegrity structure with multiple stable equilibrium states}, series = {Journal of Sound and Vibration}, volume = {437}, journal = {Journal of Sound and Vibration}, number = {December}, publisher = {Elsevier}, doi = {10.1016/j.jsv.2018.09.019}, pages = {198 -- 208}, abstract = {A novel type of a vibration driven motion system based on a compliant tensegrity structure with multiple stable equilibrium states is considered. These equilibrium configurations correspond to different prestress states with different dynamical properties. Therefore, the motion characteristics can be varied by changing the equilibrium state. For the application in the fields of mobile robotics, these discrete adjustable dynamics are advantageous. The vibration modes of the structure as well as the corresponding motion characteristics of the system can be adapted to the given environmental conditions in order to ensure a reliable motion. In this paper, dynamical investigations of an exemplary two-dimensional multistable tensegrity structure are considered. For the chosen parameter values the structure features two relevant equilibrium configurations. The resulting motion system is in contact to a horizontal plane due to gravity and the actuation is realized by the harmonic variation of the length of a single tensioned member. The motion of the system is simulated for various actuation frequencies with the different equilibrium states as an initial configuration. A uniaxial or a planar movement occurs depending on the selection of the actuated member within the tensegrity structure. The steady state motion is evaluated regarding motion characteristics like the steady state velocity. Moreover, the influences on the motion behavior caused by the different equilibrium states as an initial condition are emphasized. (C) 2018 Elsevier Ltd. All rights reserved.}, language = {en} } @inproceedings{SchorrSchaleOtterbachetal., author = {Schorr, Philipp and Schale, Florian and Otterbach, Jean Marc and Zentner, Lena and Zimmermann, Klaus and B{\"o}hm, Valter}, title = {Investigation of a Multistable Tensegrity Robot applied as Tilting Locomotion System}, series = {Proceedings of the 2020 IEEE International Conference on Robotics and Automation (ICRA): 31 May-31 August 2020, Paris}, booktitle = {Proceedings of the 2020 IEEE International Conference on Robotics and Automation (ICRA): 31 May-31 August 2020, Paris}, doi = {10.1109/ICRA40945.2020.9196706}, pages = {2932 -- 2938}, abstract = {This paper describes the development of a tilting locomotion system based on a compliant tensegrity structure with multiple stable equilibrium configurations. A tensegrity structure featuring 4 stable equilibrium states is considered. The mechanical model of the structure is presented and the according equations of motion are derived. The variation of the length of selected structural members allows to influence the prestress state and the corresponding shape of the tensegrity structure. Based on bifurcation analyses a reliable actuation strategy to control the current equilibrium state is designed. In this work, the tensegrity structure is assumed to be in contact with a horizontal plane due to gravity. The derived actuation strategy is utilized to generate tilting locomotion by successively changing the equilibrium state. Numerical simulations are evaluated considering the locomotion characteristics. In order to validate this theoretical approach a prototype is developed. Experiments regarding to the equilibrium configurations, the actuation strategy and the locomotion characteristics are evaluated using image processing tools and motion capturing. The results verify the theoretical data and confirm the working principle of the investigated tilting locomotion system. This approach represents a feasible actuation strategy to realize a reliable tilting locomotion utilizing the multistability of compliant tensegrity structures.}, language = {en} } @inproceedings{SchorrBoehmZentneretal., author = {Schorr, Philipp and B{\"o}hm, Valter and Zentner, Lena and Zimmermann, Klaus}, title = {Design of a Vibration Driven Motion System Based on a Multistable Tensegrity Structure}, series = {ICINCO 2018: proceedings of the 15th International Conference on Informatics in Control, Automation and Robotics, Porto, Portugal, July 29-31, 2018}, volume = {613}, booktitle = {ICINCO 2018: proceedings of the 15th International Conference on Informatics in Control, Automation and Robotics, Porto, Portugal, July 29-31, 2018}, editor = {Gusikhin, Oleg and Madani, Kurosh}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-31992-2}, doi = {10.1007/978-3-030-31993-9_14}, pages = {302 -- 317}, abstract = {In this paper a novel approach to realize a uniaxial bidirectional vibration driven motion system with controllable direction of motion is investigated. The considered motion system bases on a tensegrity structure with multiple stable equilibrium configurations. The structure is in contact with a horizontal plane due to gravity and the actuation is realized by the harmonic change of the length of a selected member. Beside varying the actuation parameters, the direction of motion can be controlled by changing the equilibrium configuration of the tensegrity structure. In this paper the topology of the tensegrity structure and the parameter values are chosen appropriately to provide two symmetric equilibrium configurations. A change of the equilibrium state yields a novel configuration of the entire motion system which is symmetric to the original state. Utilizing the symmetry of the system the same actuation yields an opposite motion. This approach represents a reliable opportunity to control the direction of motion by changing the equilibrium state for constant actuation parameters. This paper focuses on the parameter selection and the design of the actuation of the vibration driven motion system. The working principle of the vibration driven motion system is verified by numerical simulations. This contribution represents the theoretical investigation for the further development of a prototype.}, language = {en} } @inproceedings{SchorrChavezZentneretal., author = {Schorr, Philipp and Chavez, Jhohan and Zentner, Lena and B{\"o}hm, Valter}, title = {Reconfigurable Planar Quadrilateral Linkages Based on the Tensegrity Principle}, series = {Microactuators, Microsensors and Micromechanisms, MAMM, 2020}, booktitle = {Microactuators, Microsensors and Micromechanisms, MAMM, 2020}, editor = {Zentner, Lena and Strehle, Steffen}, publisher = {Springer International Publishing}, address = {Cham}, isbn = {978-3-030-61651-9}, doi = {10.1007/978-3-030-61652-6_5}, pages = {48 -- 57}, abstract = {A feasible possibility to develop planar reconfigurable mechanisms is introduced in this work. Applying the tensegrity principle to common four-bar linkages allows a controllable change between two configurations of the mechanism. These two states correspond to different working spaces which vary regarding to the kinematic and mechanical properties. Therefore, the reconfiguration of the mechanism enables two different operation modes. Hence, this kind of mechanism enables the advantageous properties of conventional linkages with an additional enhanced adaptability of the kinematic and mechanic behavior. Beside the conceptual design of such tensegrity-based mechanisms, a reconfigurable four-bar parallel linkage is considered exemplarily. Numerical simulations are evaluated focusing on the kinematic behavior and the structural mechanics of this mechanism. Especially the reconfiguration of the mechanism by changing between two different working spaces is considered. The simulation results clarify the benefit of utilizing the tensegrity principle in mechanism theory. Adding only a few members to the original linkage enables a reconfigurable mechanism with comparable complexity.}, language = {en} }