@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{SchuemannMorichKaufholdetal., author = {Sch{\"u}mann, Malte and Morich, J. and Kaufhold, T. and B{\"o}hm, Valter and Zimmermann, Klaus and Odenbach, Stefan}, title = {A mechanical characterisation on multiple timescales of electroconductive magnetorheological elastomers}, series = {Magnetism and Magnetic Materials}, volume = {453}, journal = {Magnetism and Magnetic Materials}, number = {May}, publisher = {Elsevier}, doi = {10.1016/j.jmmm.2018.01.029}, pages = {198 -- 205}, abstract = {Magnetorheological elastomers are a type of smart hybrid material which combines elastic properties of a soft elastomer matrix with magnetic properties of magnetic micro particles. This leads to a material with magnetically controllable mechanical properties of which the magnetorheological effect is the best known. The addition of electroconductive particles to the polymer mix adds electrical properties to the material behaviour. The resulting electrical resistance of the sample can be manipulated by external magnetic fields and mechanical loads. This results in a distinct interplay of mechanical, electrical and magnetic effects with a highly complex time behaviour. In this paper a mechanical characterisation on multiple time scales was conducted to get an insight on the short and long-term electrical and mechanical behaviour of this novel material. The results show a complex resistivity behaviour on several timescales, sensitive to magnetic fields and strain velocity. The observed material exhibits fatigue and relaxation behaviour, whereas the magnetorheological effect appears not to interfere with the piezoresistive properties.}, language = {en} } @article{ZimmermannBoehmBeckerTIetal., author = {Zimmermann, Klaus and B{\"o}hm, Valter and Becker T.I., and Chavez, Jhohan and Kaufhold, T. and Monkman, Gareth J. and Sindersberger, Dirk and Diermeier, Andreas and Prem, Nina}, title = {Mechanical Characterization of the Field-Dependent Properties of Magnetoactive Polymers and Integrated Electrets for their Application in Soft Robotics}, series = {International Scientific Journal "Problems of Mechanics"}, volume = {69}, journal = {International Scientific Journal "Problems of Mechanics"}, number = {4}, issn = {1512-0740}, language = {en} } @misc{ChavezBoehmYinetal., author = {Chavez, Jhohan and B{\"o}hm, Valter and Yin, J. and Becker, Tatiana I. and K{\"o}hring, S. and Monkman, Gareth J. and Odenbach, S. and Zimmermann, Klaus}, title = {Field induced plasticity of magneto-sensitive elastomers for gripping technology applications}, series = {6th Colloquium of SPP 1681, Benediktbeuern, 26. - 28.09.2018 : Book of Abstracts}, journal = {6th Colloquium of SPP 1681, Benediktbeuern, 26. - 28.09.2018 : Book of Abstracts}, pages = {16 -- 17}, language = {en} } @incollection{ChavezBoehmBeckeretal., author = {Chavez, Jhohan and B{\"o}hm, Valter and Becker, Tatiana I. and Gast, Simon and Zeidis, Igor and Zimmermann, Klaus}, title = {Actuators based on a controlled particlematrix interaction in magnetic hybrid materials for applications in locomotion and manipulation systems}, series = {Magnetic Hybrid-Materials: Multi-scale modelling synthesis and applications}, booktitle = {Magnetic Hybrid-Materials: Multi-scale modelling synthesis and applications}, editor = {Odenbach, Stefan}, publisher = {De Gruyter}, address = {Berlin}, isbn = {9783110569636}, doi = {10.1515/9783110569636-027}, pages = {653 -- 680}, abstract = {The paper deals with the investigation of magneto-sensitive elastomers(MSE) and their application in technical actuator systems. MSE consist of an elasticmatrix containing suspended magnetically soft and/or hard particles. Additionally,they can also contain silicone oil, graphite particles, thermoplastic components, etc.,in various concentrations in order to tune specific properties such as viscosity, con-ductivity and thermoelasticity, respectively. The focuses of investigations are thebeneficial properties of MSE in prototypes for locomotion and manipulation purposesthat possess an integrated sensor function. The research follows the principle of amodel-based design, i.e. the working steps are ideation, mathematical modelling,material characterization as well as building first functional models (prototypes). Thedeveloped apedal (without legs) and non-wheeled locomotion systems use the inter-play between material deformations and the mechanical motion in connection with theissues of control and stability. Non-linear friction phenomena lead to a monotonousforward motion of the systems. The aim of this study is the design of such mechanicalstructures, which reduce the control costs. The investigations deal with the movementand control of'intelligent'mechanisms, for which the magnetically field-controlledparticle-matrix interactions provide an appropriate approach. The presented grippersenclose partially gripped objects, which is an advantage for handling sensitive objects.Form-fit grippers with adaptable contour at the contact area enable a uniform pressuredistribution on the surface of gripped objects. Furthermore, with the possibility ofactive shape adaptation, objects with significantly differing geometries can be gripped.To realise the desired active shape adaptation, the effect of field-induced plasticity ofMSE is used. The first developed prototypes mainly confirm the functional principles assuch without direct application. For this, besides the ability of locomotion andmanipulation itself, further technological possibilities have to be added to the systems.}, 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} } @article{ChavezBoehmBeckeretal., author = {Chavez, Jhohan and B{\"o}hm, Valter and Becker, Tatiana I. and Gast, Simon and Zeidis, Igor and Zimmermann, Klaus}, title = {Actuators based on a controlled particle-matrix interaction in magnetic hybrid materials for applications in locomotion and manipulation systems}, series = {Physical Sciences Reviews}, volume = {7}, journal = {Physical Sciences Reviews}, number = {11}, publisher = {de Gruyter}, doi = {10.1515/psr-2019-0087}, pages = {1263 -- 1290}, abstract = {The paper deals with the investigation of magneto-sensitive elastomers (MSE) and their application in technical actuator systems. MSE consist of an elastic matrix containing suspended magnetically soft and/or hard particles. Additionally, they can also contain silicone oil, graphite particles, thermoplastic components, etc., in various concentrations in order to tune specific properties such as viscosity, conductivity and thermoelasticity, respectively. The focuses of investigations are the beneficial properties of MSE in prototypes for locomotion and manipulation purposes that possess an integrated sensor function. The research follows the principle of a model-based design, i.e. the working steps are ideation, mathematical modelling, material characterization as well as building first functional models (prototypes). The developed apedal (without legs) and non-wheeled locomotion systems use the interplay between material deformations and the mechanical motion in connection with the issues of control and stability. Non-linear friction phenomena lead to a monotonous forward motion of the systems. The aim of this study is the design of such mechanical structures, which reduce the control costs. The investigations deal with the movement and control of 'intelligent' mechanisms, for which the magnetically field-controlled particle-matrix interactions provide an appropriate approach. The presented grippers enclose partially gripped objects, which is an advantage for handling sensitive objects. Form-fit grippers with adaptable contour at the contact area enable a uniform pressure distribution on the surface of gripped objects. Furthermore, with the possibility of active shape adaptation, objects with significantly differing geometries can be gripped. To realise the desired active shape adaptation, the effect of field-induced plasticity of MSE is used. The first developed prototypes mainly confirm the functional principles as such without direct application. For this, besides the ability of locomotion and manipulation itself, further technological possibilities have to be added to the systems. The first steps are therefore being taken towards integrated MSE based adaptive sensor systems.}, language = {en} } @article{BeckerRaikherStolbovetal., author = {Becker, Tatiana I. and Raikher, Yuriy L. and Stolbov, Oleg V. and B{\"o}hm, Valter and Zimmermann, Klaus}, title = {Magnetoactive elastomers for magnetically tunable vibrating sensor systems}, series = {Physical Sciences Reviews}, volume = {7}, journal = {Physical Sciences Reviews}, number = {10}, publisher = {de Gruyter}, issn = {2365-659X}, doi = {10.1515/psr-2019-0125}, pages = {1 -- 28}, abstract = {Magnetoactive elastomers (MAEs) are a special type of smart materials consisting of an elastic matrix with embedded microsized particles that are made of ferromagnetic materials with high or low coercivity. Due to their composition, such elastomers possess unique magnetic field-dependent material properties. The present paper compiles the results of investigations on MAEs towards an approach of their potential application as vibrating sensor elements with adaptable sensitivity. Starting with the model-based and experimental studies of the free vibrational behavior displayed by cantilevers made of MAEs, it is shown that the first bending eigenfrequency of the cantilevers depends strongly on the strength of an applied uniform magnetic field. The investigations of the forced vibration response of MAE beams subjected to in-plane kinematic excitation confirm the possibility of active magnetic control of the amplitude-frequency characteristics. With change of the uniform field strength, the MAE beam reveals different steady-state responses for the same excitation, and the resonance may occur at various ranges of the excitation frequency. Nonlinear dependencies of the amplification ratio on the excitation frequency are obtained for different magnitudes of the applied field. Furthermore, it is shown that the steady-state vibrations of MAE beams can be detected based on the magnetic field distortion. The field difference, which is measured simultaneously on the sides of a vibrating MAE beam, provides a signal with the same frequency as the excitation and an amplitude proportional to the amplitude of resulting vibrations. The presented prototype of the MAE-based vibrating unit with the field-controlled "configuration" can be implemented for realization of acceleration sensor systems with adaptable sensitivity. The ongoing research on MAEs is oriented to the use of other geometrical forms along with beams, e.g. two-dimensional structures such as membranes.}, language = {de} } @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} }