TY - CHAP A1 - Böhm, Valter A1 - Schorr, Philipp A1 - Schale, Florian A1 - Kaufhold, Tobias A1 - Zentner, Lena A1 - Zimmermann, Klaus T1 - Worm-Like Mobile Robot Based on a Tensegrity Structure T2 - 2021 IEEE 4th International Conference on Soft Robotics (RoboSoft): 2.04.2021 - 16.04.2021, New Haven, CT, USA N2 - 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. KW - Mobile robots KW - motion control Y1 - 2021 SN - 978-1-7281-7713-7 U6 - https://doi.org/10.1109/robosoft51838.2021.9479193 SP - 358 EP - 363 PB - IEEE ER - TY - JOUR A1 - Chavez, Jhohan A1 - Schorr, Philipp A1 - Kaufhold, Tobias A1 - Zentner, Lena A1 - Zimmermann, Klaus A1 - Böhm, Valter T1 - Influence of Elastomeric Tensioned Members on the Characteristics of Compliant Tensegrity Structures in Soft Robotic Applications JF - Procedia Manufacturing N2 - 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. KW - compliant tensegrity structures KW - soft robotics KW - elastomers Y1 - 2020 U6 - https://doi.org/10.1016/j.promfg.2020.11.048 SN - 2351-9789 VL - 52 SP - 289 EP - 294 PB - Elsevier ER - TY - CHAP A1 - Schorr, Philipp A1 - Böhm, Valter A1 - Zentner, Lena A1 - Zimmermann, Klaus T1 - Dynamical Investigation of Crawling Motion System based on a Multistable Tensegrity Structure T2 - Proceedings of the 15th International Conference on Informatics in Control, Automation and Robotics : Porto, Portugal, 29.07.2018 - 31.07.2018 N2 - 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. Y1 - 2018 SN - 978-989-758-321-6 U6 - https://doi.org/10.5220/0006852701220130 SP - 122 EP - 130 PB - SCITEPRESS ER - TY - GEN A1 - Chavez, Jhohan A1 - Henning, S. A1 - Zentner, Lena A1 - Böhm, Valter T1 - Soft tensegrity structures with variable stiffness and shape changing ability T2 - Annual Meeting of the DFG Priority Programme Soft Material Robotic Systems, SPP2100, 02-04. März 2020, Schneverdingen Y1 - 2020 ER - TY - JOUR A1 - Schorr, Philipp A1 - Böhm, Valter A1 - Zentner, Lena A1 - Zimmermann, Klaus T1 - Motion characteristics of a vibration driven mobile tensegrity structure with multiple stable equilibrium states JF - Journal of Sound and Vibration N2 - 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. KW - Compliant tensegrity structure KW - LOCOMOTION KW - Multistability KW - Vibration driven motion Y1 - 2018 U6 - https://doi.org/10.1016/j.jsv.2018.09.019 VL - 437 IS - December SP - 198 EP - 208 PB - Elsevier ER - TY - CHAP A1 - Schorr, Philipp A1 - Schale, Florian A1 - Otterbach, Jean Marc A1 - Zentner, Lena A1 - Zimmermann, Klaus A1 - Böhm, Valter T1 - Investigation of a Multistable Tensegrity Robot applied as Tilting Locomotion System T2 - Proceedings of the 2020 IEEE International Conference on Robotics and Automation (ICRA): 31 May-31 August 2020, Paris N2 - 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. KW - actuators KW - bifurcation KW - mechanical stability KW - mobile robots KW - motion control KW - numerical analysis KW - robot dynamics KW - robot kinematics KW - vibration control Y1 - 2020 U6 - https://doi.org/10.1109/ICRA40945.2020.9196706 SP - 2932 EP - 2938 ER - TY - CHAP A1 - Schorr, Philipp A1 - Böhm, Valter A1 - Zentner, Lena A1 - Zimmermann, Klaus ED - Gusikhin, Oleg ED - Madani, Kurosh T1 - Design of a Vibration Driven Motion System Based on a Multistable Tensegrity Structure T2 - ICINCO 2018: proceedings of the 15th International Conference on Informatics in Control, Automation and Robotics, Porto, Portugal, July 29-31, 2018 N2 - 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. KW - Compliant tensegrity structure KW - Vibration driven motion multistability Y1 - 2020 SN - 978-3-030-31992-2 U6 - https://doi.org/10.1007/978-3-030-31993-9_14 VL - 613 SP - 302 EP - 317 PB - Springer CY - Cham ER - TY - CHAP A1 - Schorr, Philipp A1 - Chavez, Jhohan A1 - Zentner, Lena A1 - Böhm, Valter ED - Zentner, Lena ED - Strehle, Steffen T1 - Reconfigurable Planar Quadrilateral Linkages Based on the Tensegrity Principle T2 - Microactuators, Microsensors and Micromechanisms, MAMM, 2020 N2 - 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. KW - Planar four-bar linkage KW - Reconfigurable mechanisms KW - tensegrity Y1 - 2021 SN - 978-3-030-61651-9 U6 - https://doi.org/10.1007/978-3-030-61652-6_5 SP - 48 EP - 57 PB - Springer International Publishing CY - Cham ER - TY - CHAP A1 - Böhm, Valter A1 - Schorr, Philipp A1 - Zimmermann, Klaus A1 - Zentner, Lena T1 - An Approach to the Estimation of the Actuation Parameters for Mobile Tensegrity Robots with Tilting Movement Sequences T2 - 2018 International Conference on Reconfigurable Mechanisms and Robots (ReMAR); 20-22 June 2018; Delft, Netherlands N2 - This paper deals with the locomotion by tilting sequences of shape-variable compliant tensegrity structures. The shape of these structures is controlled by manipulating their prestress state. The tensegrity structure is tilting as consequence of a suitable variation of its shape. By multiple repetition of such tilting sequences a motion is generated. Quasi-static considerations for the considered structures are presented in order to estimate the actuation parameters. For a proper number of actuators this quasi-static approach enables an analytical calculation of the actuation parameters of the structure in order to control the geometrical configuration as required. As an example a two-dimensional tensegrity structure which is in contact with a horizontal plane due to gravity is considered. By successive tilting sequences a uniaxial motion results. The excitation of the structure is calculated for a given change of shape with the quasi-static analysis. The according results are compared with transient dynamic simulations. Qualitative conclusions about the motion behavior and the usability of the quasi-static approach are given. KW - mobile robots KW - motion control KW - robot dynamics KW - structural engineering Y1 - 2018 U6 - https://doi.org/10.1109/REMAR.2018.8449871 SP - 1 EP - 8 PB - IEEE ER - TY - CHAP A1 - Carrillo Li, Enrique Roberto A1 - Schorr, Philipp A1 - Kaufhold, Tobias A1 - Rodríguez Hernández, Jorge Antonio A1 - Zentner, Lena A1 - Zimmermann, Klaus A1 - Böhm, Valter ED - Awrejcewicz, Jan ED - Kaźmierczak, Markek ED - Olejnik, Paweł T1 - Kinematic analysis of the rolling locomotion of mobile robots based on tensegrity structures with spatially curved compressed components T2 - Applicable Solutions in Non-Linear Dynamical Systems; 15th International Conference "Dynamical Systems - Theory and Applications" (DSTA 2019, 2-5 December, 2019, Lodz, Poland N2 - In this work, a tensegrity structure with spatially curved members is applied as rolling locomotion system. The actuation of the structure allows a variation of the originally cylindrical shape to a conical shape. Moreover, the structure is equipped with internal movable masses to control the position of the center of mass of the structure. To control the locomotion system a reliable actuation strategy is required. Therefore, the kinematics of the system considering the nonholonomic constraints are derived in this paper. Based on the resulting insight in the locomotion behavior a feasible actuation strategy is designed to control the trajectory of the system. To verify this approach kinematic analyses are evaluated numerically. The simulation data confirm the path following due to an appropriate shape change of the tensegrity structure. Thus, this system enables a two-dimensional rolling locomotion. The use of mechanically compliant tensegrity structures in mobile robots is an attractive research topic, due to the possibility to adjust their mechanical properties reversibly during locomotion. In this paper rolling locomotion of mobile robots based on simple tensegrity structures, consisting of three compressed spatially curved members connected to a continuous net of prestressed tensional members, is discussed. Planar locomotion of these robots is induced by the movement of internal masses. The movement direction can be changed by changing the robot's shape between a cylinder and a truncated cone. The paper focuses on the description of the kinematics of these systems with respect to the shape change. KW - Inverse kinematics KW - Nonholonomic mechanics KW - Tensegrity structure Y1 - 2019 UR - http://212.191.87.54:1616/k16/awrejcewicz/publikacje/T2.pdf SN - 978-83-66287-30-3 SP - 335 EP - 344 PB - Wydawnictwo Politechniki Łódzkiej CY - Łódź, Polen ER -