@article{SchorrCarrilloLiKaufholdetal., author = {Schorr, Philipp and Carrillo Li, Enrique Roberto and Kaufhold, Tobias and Rodriguez Hernandez, Jorge Antonio and Zentner, Lena and Zimmermann, Klaus and B{\"o}hm, Valter}, title = {Kinematic analysis of a rolling tensegrity structure with spatially curved members}, series = {Meccanica}, volume = {56}, journal = {Meccanica}, publisher = {Springer}, organization = {Springer}, issn = {0025-6455}, doi = {10.1007/s11012-020-01199-x}, pages = {953 -- 961}, abstract = {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.}, 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{SchorrBoehmStepanetal., author = {Schorr, Philipp and B{\"o}hm, Valter and Stepan, G. and Zentner, Lena and Zimmermann, Klaus and St{\´e}p{\´a}n, G.}, title = {Multi-mode motion system based on a multistable tensegrity structure}, series = {Advances in Mechanism and Machine Science : Proceedings of the 15th IFToMM World Congress on Mechanism and Machine Science}, volume = {73}, booktitle = {Advances in Mechanism and Machine Science : Proceedings of the 15th IFToMM World Congress on Mechanism and Machine Science}, editor = {Uhl, Tadeusz}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-20130-2}, doi = {10.1007/978-3-030-20131-9_296}, pages = {3007 -- 3016}, abstract = {This paper presents a multi-mode motion system based on a compliant tensegrity structure with multiple stable equilibrium configurations. The motion system is in contact to an arbitrarily shaped rigid ground due to gravity. The movement is realized by changing successively between different equilibrium states. Depending on the strategy of changing the equilibrium configuration, different motion types occur. The reachable area of the motion system can be enlarged by adapting the motion type depending on the given environmental characteristics. Furthermore, the efficiency of the motion can be improved by choosing the most suitable motion mode. Theoretical studies regarding the change of the equilibrium states are introduced. Moreover, simulation results for the different motion modes tilting, vibration driven and jumping are illustrated. The resulting motion characteristics emphasize the advantageous adaptability of the motion system regarding to varying environmental conditions.}, language = {en} } @inproceedings{CarrilloLiSchorrKaufholdetal., author = {Carrillo Li, Enrique Roberto and Schorr, Philipp and Kaufhold, Tobias and Rodr{\´i}guez Hern{\´a}ndez, Jorge Antonio and Zentner, Lena and Zimmermann, Klaus and B{\"o}hm, Valter}, title = {Kinematic analysis of the rolling locomotion of mobile robots based on tensegrity structures with spatially curved compressed components}, series = {Applicable Solutions in Non-Linear Dynamical Systems; 15th International Conference "Dynamical Systems - Theory and Applications" (DSTA 2019, 2-5 December, 2019, Lodz, Poland}, booktitle = {Applicable Solutions in Non-Linear Dynamical Systems; 15th International Conference "Dynamical Systems - Theory and Applications" (DSTA 2019, 2-5 December, 2019, Lodz, Poland}, editor = {Awrejcewicz, Jan and Ka{\'{z}}mierczak, Markek and Olejnik, Paweł}, publisher = {Wydawnictwo Politechniki Ł{\´o}dzkiej}, address = {Ł{\´o}d{\'{z}}, Polen}, isbn = {978-83-66287-30-3}, pages = {335 -- 344}, abstract = {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.}, language = {en} } @inproceedings{SchorrBoehmZentneretal., author = {Schorr, Philipp and B{\"o}hm, Valter and Zentner, Lena and Zimmermann, Klaus}, title = {Investigation of a tensegrity structure with multiple equilibrium configurations as jumping motion system}, series = {Theoretical Approaches in Non-Linear Dynamical Systems : Proceedings of the 15th Conference on Dynamical Systems -Theory and Applications}, booktitle = {Theoretical Approaches in Non-Linear Dynamical Systems : Proceedings of the 15th Conference on Dynamical Systems -Theory and Applications}, publisher = {Wydawnictwo Politechniki Ł{\´o}dzkiej}, address = {Ł{\´o}d{\'{z}}, Polen}, isbn = {978-83-66287-29-7}, pages = {465 -- 476}, abstract = {Often, the operating range of mobile robots is limited by environ- mental circumstances like obstacles or gaps. Therefore, an adaptation of the motion principle is required to enable an operating continuation of such robots. A jumping motion is a promising approach. This motion type allows to cross gaps or to overcome obstacles where common motion principles which bases on wheels or legs fail. However, especially during landing large forces occur as a consequence of the impact with the ground. This issue encourages the use of compliant tensegrity structures which feature a great shock resistance. In this paper a tensegrity structure with multiple equilibrium configurations is considered. The two-dimensional structure is equipped with two actuators to vary the prestress of the system. The tensegrity structure is in contact to a horizontal plane due to gravity. Two actuation strategies are derived. Beside varying the prestress state of the structure, a jump can be realized by changing the equilibrium configuration. Both actuation strategies and the corresponding motion characteristics are evaluated by numeric simulations. The results emphasize the advantageous properties of tensegrity structures for a jumping motion system. In particular, the multistabilty of the structure allows a simple actuation strategy for a reliable jumping motion.}, language = {en} } @article{SchorrZentnerZimmermannetal., author = {Schorr, Philipp and Zentner, Lena and Zimmermann, Klaus and B{\"o}hm, Valter}, title = {Jumping locomotion system based on a multistable tensegrity structure}, series = {Mechanical systems and signal processing}, journal = {Mechanical systems and signal processing}, number = {152}, publisher = {Elsevier}, doi = {10.1016/j.ymssp.2020.107384}, abstract = {All known locomotion principles are limited respective to environmental conditions. Often, the occurrence of obstacles or gaps means the break-off for the operating motion systems. For such circumstances, a controllable jumping locomotion is required to cross these barriers. However, this locomotion demands sophisticated requirements to the actuation. The abrupt actuation is commonly realized by high dynamic actuators or complex mechanisms. In this work, a simple solution utilizing the multistability of a compliant tensegrity structure is described. Therefore, a two-dimensional tensegrity structure featuring four stable equilibria is considered. Based on bifurcation analyses a feasible actuation to control the current equilibrium configuration is derived. Changing between selected equilibrium states enables a great difference in potential energy, which yields a jumping motion of the structure. Based on numerical simulations a suitable actuation strategy is chosen to overcome obstacle and steps by jumping forward or backward, respectively. The theoretical approach is examined experimentally with a prototype of the multistable tensegrity structure. (c) 2020 Elsevier Ltd. All rights reserved. All known locomotion principles are limited respective to environmental conditions. Often, the occurrence of obstacles or gaps means the break-off for the operating motion systems. For such circumstances, a controllable jumping locomotion is required to cross these barriers. However, this locomotion demands sophisticated requirements to the actuation. The abrupt actuation is commonly realized by high dynamic actuators or complex mechanisms. In this work, a simple solution utilizing the multistability of a compliant tensegrity structure is described. Therefore, a two-dimensional tensegrity structure featuring four stable equilibria is considered. Based on bifurcation analyses a feasible actuation to control the current equilibrium configuration is derived. Changing between selected equilibrium states enables a great difference in potential energy, which yields a jumping motion of the structure. Based on numerical simulations a suitable actuation strategy is chosen to overcome obstacle and steps by jumping forward or backward, respectively. The theoretical approach is examined experimentally with a prototype of the multistable tensegrity structure.}, language = {en} } @inproceedings{BoehmSchorrZimmermannetal., author = {B{\"o}hm, Valter and Schorr, Philipp and Zimmermann, Klaus and Zentner, Lena}, title = {An Approach to the Estimation of the Actuation Parameters for Mobile Tensegrity Robots with Tilting Movement Sequences}, series = {2018 International Conference on Reconfigurable Mechanisms and Robots (ReMAR); 20-22 June 2018; Delft, Netherlands}, booktitle = {2018 International Conference on Reconfigurable Mechanisms and Robots (ReMAR); 20-22 June 2018; Delft, Netherlands}, publisher = {IEEE}, doi = {10.1109/REMAR.2018.8449871}, pages = {1 -- 8}, abstract = {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.}, 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} }