Cristian Napole, O. Barambones, Mohamed Derbeli, Mohammed Yousri Silaa, I. Calvo, J. Velasco
: Piezoelectric Actuators (PEAs) are devices that can support large actuation forces compared to their small size and are widely used in high-precision applications where micro-and nano-positioning are required. Nonetheless, these actuators have undeniable non-linearities, the well-known ones being creep, vibration dynamics, and hysteresis. The latter originate from a combination of mechanical strain and electric field action; as a consequence, these can affect the PEA tracking performance and even reach instability. The scope of this paper is to reduce the hysteresis effect using and comparing different control strategies like feedback with a Feed-Forward (FF) structure, which is often used to compensate the non-linearities and diminish the errors due to uncertainties. In this research, black-box models are analyzed; subsequently, a classic feedback control like Proportional-Integral (PI) control is combined with the FF methods proposed separately and embedded into a dSpace platform to perform real-time experiments. Results are analyzed in-depth in terms of the error, the control signal, and the Integral of the Absolute Error (IAE). It is found that with the proposed methods, the hysteresis effect could be diminished to acceptable ranges for high-precision tracking with a satisfactory control signal.
{"title":"Tracking Control for Piezoelectric Actuators with Advanced Feed-forward Compensation Combined with PI Control.","authors":"Cristian Napole, O. Barambones, Mohamed Derbeli, Mohammed Yousri Silaa, I. Calvo, J. Velasco","doi":"10.3390/iecat2020-08481","DOIUrl":"https://doi.org/10.3390/iecat2020-08481","url":null,"abstract":": Piezoelectric Actuators (PEAs) are devices that can support large actuation forces compared to their small size and are widely used in high-precision applications where micro-and nano-positioning are required. Nonetheless, these actuators have undeniable non-linearities, the well-known ones being creep, vibration dynamics, and hysteresis. The latter originate from a combination of mechanical strain and electric field action; as a consequence, these can affect the PEA tracking performance and even reach instability. The scope of this paper is to reduce the hysteresis effect using and comparing different control strategies like feedback with a Feed-Forward (FF) structure, which is often used to compensate the non-linearities and diminish the errors due to uncertainties. In this research, black-box models are analyzed; subsequently, a classic feedback control like Proportional-Integral (PI) control is combined with the FF methods proposed separately and embedded into a dSpace platform to perform real-time experiments. Results are analyzed in-depth in terms of the error, the control signal, and the Integral of the Absolute Error (IAE). It is found that with the proposed methods, the hysteresis effect could be diminished to acceptable ranges for high-precision tracking with a satisfactory control signal.","PeriodicalId":152837,"journal":{"name":"Proceedings of 1st International Electronic Conference on Actuator Technology: Materials, Devices and Applications","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128247952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Anilkumar, A. Haldar, S. Scheffler, B. Rao, R. Rolfes
: Multistable structures that possess more than one elastically stable equilibrium state are highly attractive for advanced shape-changing (morphing) applications due to the nominal control effort required to maintain the structure in any of its specific stable shapes. The aim of the paper is to develop a bistable cross-shaped structure consisting of symmetric and unsymmetric laminate actuated using Macro Fibre Composite (MFC) actuators. The critical snap-through voltages required to change the shapes are investigated in a commercially available finite element package. The use of MFC actuators to snap the bistable laminate from one equilibrium shape to another and back again (self-resetting) is demonstrated. A new cross-shaped design of active bistable laminate with MFC actuators is proposed where the cross-shape consist of four rectangles on the four legs and a square on the middle portion. All the rectangles are made up of unsymmetric laminates, and the central portion is designed with a symmetric laminate. MFC actuators are bonded on both sides of the four legs to trigger snap-through and snap-back actions. An attempt is made to address the possible design difficulties arising from the additional stiffness contribution by MFC layers on the naturally cured equilibrium shapes of cross-shaped bistable laminates.
{"title":"Numerical studies on the design of self-resetting active bistable cross-shaped structure for morphing applications","authors":"P. Anilkumar, A. Haldar, S. Scheffler, B. Rao, R. Rolfes","doi":"10.3390/iecat2020-08482","DOIUrl":"https://doi.org/10.3390/iecat2020-08482","url":null,"abstract":": Multistable structures that possess more than one elastically stable equilibrium state are highly attractive for advanced shape-changing (morphing) applications due to the nominal control effort required to maintain the structure in any of its specific stable shapes. The aim of the paper is to develop a bistable cross-shaped structure consisting of symmetric and unsymmetric laminate actuated using Macro Fibre Composite (MFC) actuators. The critical snap-through voltages required to change the shapes are investigated in a commercially available finite element package. The use of MFC actuators to snap the bistable laminate from one equilibrium shape to another and back again (self-resetting) is demonstrated. A new cross-shaped design of active bistable laminate with MFC actuators is proposed where the cross-shape consist of four rectangles on the four legs and a square on the middle portion. All the rectangles are made up of unsymmetric laminates, and the central portion is designed with a symmetric laminate. MFC actuators are bonded on both sides of the four legs to trigger snap-through and snap-back actions. An attempt is made to address the possible design difficulties arising from the additional stiffness contribution by MFC layers on the naturally cured equilibrium shapes of cross-shaped bistable laminates.","PeriodicalId":152837,"journal":{"name":"Proceedings of 1st International Electronic Conference on Actuator Technology: Materials, Devices and Applications","volume":"188 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133337415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a low-cost, small-scale, electrohydrostatic actuator (EHA). This actuator leverages low-cost mass-produced hydraulic components from the radio-controlled model industry, combined with a novel 3D printed valve. The system is capable of relatively high bandwidth operation, with much higher power- and force-density than comparable electrical actuators. This paper presents a dynamic system model, investigating the range of stability and presents simulated and experimental results for systems stabilized by both physical leakage and pressure feedback terms. We also investigate the feasibility of two 3D printed valve options, concentrating on the limits of leakage for low-cost production: one fully 3D printed and another with a metal sleeve that can be machined using only hand tools.
{"title":"A Low-Cost Miniature Electrohydrostatic Actuator","authors":"T. Wiens","doi":"10.3390/IECAT2020-08488","DOIUrl":"https://doi.org/10.3390/IECAT2020-08488","url":null,"abstract":"This paper presents a low-cost, small-scale, electrohydrostatic actuator (EHA). This actuator leverages low-cost mass-produced hydraulic components from the radio-controlled model industry, combined with a novel 3D printed valve. The system is capable of relatively high bandwidth operation, with much higher power- and force-density than comparable electrical actuators. This paper presents a dynamic system model, investigating the range of stability and presents simulated and experimental results for systems stabilized by both physical leakage and pressure feedback terms. We also investigate the feasibility of two 3D printed valve options, concentrating on the limits of leakage for low-cost production: one fully 3D printed and another with a metal sleeve that can be machined using only hand tools.","PeriodicalId":152837,"journal":{"name":"Proceedings of 1st International Electronic Conference on Actuator Technology: Materials, Devices and Applications","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124945878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel self-contained, electro-hydraulic cylinder drive capable of passive load-holding, four-quadrant operations, and energy recovery was presented recently and implemented successfully. This solution improved greatly the energy efficiency and motion control in comparison to state-of-the-art, valve-controlled systems typically used in mobile or offshore applications. The passive load-holding function was realized by two pilot-operated check valves placed on the cylinder ports, where their pilot pressure is selected by a dedicated on/off electro valve. These valves can maintain the actuator position without consuming energy, as demonstrated on a single-boom crane. However, a reduced drop of about 1 mm was observed in the actuator position when the load-holding valves are disengaged to enable the piston motion using closed-loop position control. Such a sudden variation in the piston position that is triggered by switching the load-holding valves can increase up to 4 mm when open-loop position control is chosen. For these reasons, this research paper proposes an improved control strategy for disengaging the passive load-holding functionality smoothly (i.e., by removing this unwanted drop of the piston). A two-step pressure control strategy is used to switch the pilot-operated check valves. The proposed experimental validation of this method eliminates the piston position’s drop highlighted before and improves the motion control, mainly when operating the crane in open-loop. Theses outcomes benefit those systems where the kinematics amplifies the piston motion significantly (e.g., in aerial platforms) increasing, therefore, the operational safety.
{"title":"A method for smoothly disengaging the load-holding valves of energy-efficient electro-hydraulic systems","authors":"D. Hagen, D. Padovani","doi":"10.3390/IECAT2020-08478","DOIUrl":"https://doi.org/10.3390/IECAT2020-08478","url":null,"abstract":"A novel self-contained, electro-hydraulic cylinder drive capable of passive load-holding, four-quadrant operations, and energy recovery was presented recently and implemented successfully. This solution improved greatly the energy efficiency and motion control in comparison to state-of-the-art, valve-controlled systems typically used in mobile or offshore applications. The passive load-holding function was realized by two pilot-operated check valves placed on the cylinder ports, where their pilot pressure is selected by a dedicated on/off electro valve. These valves can maintain the actuator position without consuming energy, as demonstrated on a single-boom crane. However, a reduced drop of about 1 mm was observed in the actuator position when the load-holding valves are disengaged to enable the piston motion using closed-loop position control. Such a sudden variation in the piston position that is triggered by switching the load-holding valves can increase up to 4 mm when open-loop position control is chosen. For these reasons, this research paper proposes an improved control strategy for disengaging the passive load-holding functionality smoothly (i.e., by removing this unwanted drop of the piston). A two-step pressure control strategy is used to switch the pilot-operated check valves. The proposed experimental validation of this method eliminates the piston position’s drop highlighted before and improves the motion control, mainly when operating the crane in open-loop. Theses outcomes benefit those systems where the kinematics amplifies the piston motion significantly (e.g., in aerial platforms) increasing, therefore, the operational safety.","PeriodicalId":152837,"journal":{"name":"Proceedings of 1st International Electronic Conference on Actuator Technology: Materials, Devices and Applications","volume":"182 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131300766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Michael Olbrich, Arwed Schütz, Koustav Kanjilal, T. Bechtold, U. Wallrabe, C. Ament
A current goal in microsystem research is to overcome small working ranges, typically resulting from mechanical connections and restoring forces such as for cantilevers. In the case of predefined resting positions and unidirectional motion, pseudo-levitation as in magnetic bearings is a promising solution. In order to investigate concepts for energy efficient, cooperative microactuators, which allow free motion of small objects, we present a bistable levitation setup. The system consists of a magnetic proof mass within a glass tube, a piezoelectric staple actuator, two permanent magnets and a solenoid used as an electromagnet. The movable mass is mechanically unconstrained in its upper vertical motion and is intended to switch between two predefined equilibrium positions, namely on the staple actuator and levitating at a defined upper position. The transition is accomplished by an impulse-like kick force by the staple actuator, and subsequent feedback controlled following of a trajectory via electromagnetic actuation. The goal of this work consists of both adapting the system parameters, guaranteeing stable and preferably robust equilibrium positions for the unactuated system, and finding optimal trajectories with a short settling time and minimum input effort for the controlled transition. These design and control objectives are combined within a co-design. In this approach, the system and controller optimizations are not performed consecutively, but within a single optimization, taking into account the coupling between the design and control. Here, we apply flatness-based control combined with feedback linearization, allowing for trajectories to be tracked without error in case of the undisturbed system. Thus, the controller is solely used for disturbance compensation and the problem can be simplified by optimizing only the trajectory without the controller parameters. We show that the combined optimization process is of advantage in comparison to the sequential approach and proficiently exploits the design parameters to improve the generated trajectories.
{"title":"Co-Design and Control of a Magnetic Microactuator for Freely Moving Platforms","authors":"Michael Olbrich, Arwed Schütz, Koustav Kanjilal, T. Bechtold, U. Wallrabe, C. Ament","doi":"10.3390/iecat2020-08494","DOIUrl":"https://doi.org/10.3390/iecat2020-08494","url":null,"abstract":"A current goal in microsystem research is to overcome small working ranges, typically resulting from mechanical connections and restoring forces such as for cantilevers. In the case of predefined resting positions and unidirectional motion, pseudo-levitation as in magnetic bearings is a promising solution. \u0000In order to investigate concepts for energy efficient, cooperative microactuators, which allow free motion of small objects, we present a bistable levitation setup. The system consists of a magnetic proof mass within a glass tube, a piezoelectric staple actuator, two permanent magnets and a solenoid used as an electromagnet. The movable mass is mechanically unconstrained in its upper vertical motion and is intended to switch between two predefined equilibrium positions, namely on the staple actuator and levitating at a defined upper position. The transition is accomplished by an impulse-like kick force by the staple actuator, and subsequent feedback controlled following of a trajectory via electromagnetic actuation. \u0000The goal of this work consists of both adapting the system parameters, guaranteeing stable and preferably robust equilibrium positions for the unactuated system, and finding optimal trajectories with a short settling time and minimum input effort for the controlled transition. These design and control objectives are combined within a co-design. In this approach, the system and controller optimizations are not performed consecutively, but within a single optimization, taking into account the coupling between the design and control. Here, we apply flatness-based control combined with feedback linearization, allowing for trajectories to be tracked without error in case of the undisturbed system. Thus, the controller is solely used for disturbance compensation and the problem can be simplified by optimizing only the trajectory without the controller parameters. We show that the combined optimization process is of advantage in comparison to the sequential approach and proficiently exploits the design parameters to improve the generated trajectories.","PeriodicalId":152837,"journal":{"name":"Proceedings of 1st International Electronic Conference on Actuator Technology: Materials, Devices and Applications","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133487192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lena Seigner, O. Bezsmertna, S. Fähler, Georgino Kaleng Tshikwand, F. Wendler, M. Kohl
This paper presents the design, fabrication and performance of origami-based folding microactuators based on NiTi films showing the one-way shape memory effect. Freestanding NiTi films are micromachined by laser cutting or photolithography to achieve double-beam structures allowing for direct Joule heating with an electrical current. The NiTi microactuators are interconnected to rigid sections (tiles) forming an initial planar system that self-folds into a predetermined 3D shape upon heating. A thermo-mechanical treatment is used for shape setting of as-received specimens to approach a maximum folding angle of 180°. The bending moments, bending radii and load-dependent folding angles upon Joule heating are evaluated. The shape setting process is particularly effective for small bending radii, which, however, generates residual plastic strain. After shape setting, unloaded beam structures show recoverable bending deflection between 0° and 140° for a maximum heating power of 900 mW. By introducing additional loads to account for the effect of the tiles, the smooth folding characteristic evolves into a sharp transition, whereby full deflection up to 180° is reached.
{"title":"Origami-Inspired Shape Memory Folding Microactuator","authors":"Lena Seigner, O. Bezsmertna, S. Fähler, Georgino Kaleng Tshikwand, F. Wendler, M. Kohl","doi":"10.3390/iecat2020-08480","DOIUrl":"https://doi.org/10.3390/iecat2020-08480","url":null,"abstract":"This paper presents the design, fabrication and performance of origami-based folding microactuators based on NiTi films showing the one-way shape memory effect. Freestanding NiTi films are micromachined by laser cutting or photolithography to achieve double-beam structures allowing for direct Joule heating with an electrical current. The NiTi microactuators are interconnected to rigid sections (tiles) forming an initial planar system that self-folds into a predetermined 3D shape upon heating. A thermo-mechanical treatment is used for shape setting of as-received specimens to approach a maximum folding angle of 180°. The bending moments, bending radii and load-dependent folding angles upon Joule heating are evaluated. The shape setting process is particularly effective for small bending radii, which, however, generates residual plastic strain. After shape setting, unloaded beam structures show recoverable bending deflection between 0° and 140° for a maximum heating power of 900 mW. By introducing additional loads to account for the effect of the tiles, the smooth folding characteristic evolves into a sharp transition, whereby full deflection up to 180° is reached.","PeriodicalId":152837,"journal":{"name":"Proceedings of 1st International Electronic Conference on Actuator Technology: Materials, Devices and Applications","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127950032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electrostatic inchworm motor based on gap-closing variable capacitor provides potential solution for larger force actuation compared to area overlapping one. Unlike the constant electrostatic force in area overlapping variable capacitor, the generated electrostatic force in gap-closing variable capacitor increases as the displacement is increased. However, due to the pull-in phenomena the system stability and controllability is critical design challenges. Various designs of complex electrostatic actuators based on gap-closing variable capacitor were developed as linear inchworm motor [1-2]. However, the force actuation capability is still in mN range. In this paper, a novel monolithic structural design of electrostatic actuator with multiple degree of freedom is presented as an approach for a system that is capable of performing large electrostatic force and scalable stroke. The actuator is a kind of mechanical oscillator can be driven in xy-directions by three voltage electrodes. One voltage electrode is used to apply vertical displacement in order to release or clutch the comb-like structure side with interdigitated shaft, while other voltage electrodes are used to perform displacement in the lateral direction. Multiple actuators can be used to increasethe overall applied electrostatic force on the shaft. In this work, an electromechanical system model based on Simulink software was developed for a proposed design of electrostatic actuator. The dynamic response of the actuator was simulated and the mechanical bouncing response due to effect of realizing extra mechanical stoppers or passivation layer was investigated. Also, the mechanical bouncing as well as steady state response of the actuator was investigated under various mechanical loading values. The switching time increased as the mechanical load was increased. Bouncing amplitude increased as the impact force was increased. Both switching time and bouncing amplitudes are important factors for the oscillation stability of the actuated shaft, knowing that the final system contains multiple actuator units. Literature[1] S.-H. Kim, Il-H. Hwang, K.-W. Jo, E.-S. Yoon, J.-H. Lee; High resolution inchworm linear motor based on electrostatic twisting microactuators, Journal of Micromechanics and Microengineering 2005, 15, pp. 1674-1682; 2005.[2] M. A. Erismis, H. P. Neves, R. Puers, C. V. Hoof; A low voltage large displacement large force inchworm actuator; Journal of Microelectromechanical Systems 2008; 17, 6, pp. 1294-1301; 2008.[3] I. Penskiy, S. Bergbreiter; Optimized electrostatic inchworm motors using a flexible driving arm; Journal of Micromechanics and Microengineering 2013, 23, 015018; 2013.[4] K. Saito, D. S. Contreras, Y. Takeshiro, Y. Okamoto, S. Hirao, Y. Nakata, T. Tanaka, S. Kawamura, M. Kaneko, F. Uchikoba, Y. Mita, K. S. J. Pister; Study on electrostatic inchworm motor device for a heterogeneous integrated microrobot system; Transactions of The Japan Institute of Electronics P
基于间隙闭合可变电容的静电尺蠖电机为实现比面积重叠电机更大的动力驱动提供了潜在的解决方案。与面积重叠可变电容的静电力不变不同，闭隙可变电容产生的静电力随着位移的增大而增大。然而，由于拉入现象，系统的稳定性和可控性是关键的设计挑战。基于间隙闭合可变电容的复杂静电执行器的各种设计，如直线寸蜗杆电机[1-2]。然而，力驱动能力仍在mN范围内。本文提出了一种新颖的多自由度静电执行器整体结构设计方法，为实现大静电力和可扩展行程的系统提供了一种方法。执行器是一种机械振荡器，可以通过三个电压电极在xy方向上驱动。一个电压电极用于垂直位移，以释放或离合器梳状结构侧与交叉轴，而其他电压电极用于横向位移。可以使用多个执行器来增加施加在轴上的整体静电力。针对静电致动器的设计方案，建立了基于Simulink软件的机电系统模型。仿真了作动器的动态响应，研究了由于实现额外的机械挡板或钝化层的影响而产生的机械弹跳响应。同时，研究了不同机械载荷下作动器的机械弹跳和稳态响应。开关时间随机械载荷的增大而增大。随着冲击力的增大，弹跳幅度增大。考虑到最终系统包含多个作动单元，开关时间和弹跳幅值都是影响作动轴振荡稳定性的重要因素。文献[1]工程学系。金,Il-H。黄,K.-W。乔,E.-S。尹,黄永发。李;基于静电扭转微致动器的高分辨率尺蠖直线电机，微力学与微工程学报，2005,15,pp. 1674-1682;2005年。[2]M. A. Erismis, h.p. Neves, R. Puers, C. V. Hoof;一种低压大位移大力寸蜗杆执行机构;微机电系统学报;2008;17, 6, pp. 1294-1301;2008年。[3]彭斯基，伯格布雷特;采用柔性驱动臂优化静电尺蠖电机;微力学与微工程学报，2013,23,015018;2013年。[4]齐藤k、孔特雷拉斯D. S.、竹城Y.、冈本Y.、平尾S.、中田Y.、田中T.、河村S.、金子M.、内叶F.、三田y .、皮斯特K. S.;异质集成微型机器人系统静电尺蠖电机装置的研究日本电子封装学会学报，2019,12;2019.
{"title":"Effect of Mechanical Loading and Increased Gap on the Dynamic Response of Multiple Degree of Freedom Electrostatic Actuator","authors":"Hussam A. Kloub","doi":"10.3390/iecat2020-08498","DOIUrl":"https://doi.org/10.3390/iecat2020-08498","url":null,"abstract":"Electrostatic inchworm motor based on gap-closing variable capacitor provides potential solution for larger force actuation compared to area overlapping one. Unlike the constant electrostatic force in area overlapping variable capacitor, the generated electrostatic force in gap-closing variable capacitor increases as the displacement is increased. \u0000However, due to the pull-in phenomena the system stability and controllability is critical design challenges. Various designs of complex electrostatic actuators based on gap-closing variable capacitor were developed as linear inchworm motor [1-2]. However, the force actuation capability is still in mN range. \u0000In this paper, a novel monolithic structural design of electrostatic actuator with multiple degree of freedom is presented as an approach for a system that is capable of performing large electrostatic force and scalable stroke. The actuator is a kind of mechanical oscillator can be driven in xy-directions by three voltage electrodes. One voltage electrode is used to apply vertical displacement in order to release or clutch the comb-like structure side with interdigitated shaft, while other voltage electrodes are used to perform displacement in the lateral direction. Multiple actuators can be used to increasethe overall applied electrostatic force on the shaft. \u0000In this work, an electromechanical system model based on Simulink software was developed for a proposed design of electrostatic actuator. The dynamic response of the actuator was simulated and the mechanical bouncing response due to effect of realizing extra mechanical stoppers or passivation layer was investigated. Also, the mechanical bouncing as well as steady state response of the actuator was investigated under various mechanical loading values. The switching time increased as the mechanical load was increased. Bouncing amplitude increased as the impact force was increased. Both switching time and bouncing amplitudes are important factors for the oscillation stability of the actuated shaft, knowing that the final system contains multiple actuator units. \u0000Literature[1] S.-H. Kim, Il-H. Hwang, K.-W. Jo, E.-S. Yoon, J.-H. Lee; High resolution inchworm linear motor based on electrostatic twisting microactuators, Journal of Micromechanics and Microengineering 2005, 15, pp. 1674-1682; 2005.[2] M. A. Erismis, H. P. Neves, R. Puers, C. V. Hoof; A low voltage large displacement large force inchworm actuator; Journal of Microelectromechanical Systems 2008; 17, 6, pp. 1294-1301; 2008.[3] I. Penskiy, S. Bergbreiter; Optimized electrostatic inchworm motors using a flexible driving arm; Journal of Micromechanics and Microengineering 2013, 23, 015018; 2013.[4] K. Saito, D. S. Contreras, Y. Takeshiro, Y. Okamoto, S. Hirao, Y. Nakata, T. Tanaka, S. Kawamura, M. Kaneko, F. Uchikoba, Y. Mita, K. S. J. Pister; Study on electrostatic inchworm motor device for a heterogeneous integrated microrobot system; Transactions of The Japan Institute of Electronics P","PeriodicalId":152837,"journal":{"name":"Proceedings of 1st International Electronic Conference on Actuator Technology: Materials, Devices and Applications","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123955812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Hubertus, S. Croce, J. Neu, G. Rizzello, S. Seelecke, G. Schultes
: This paper focuses on the electromechanical properties of novel sub-micron compliant metallic thin film electrodes for dielectric elastomer membranes. Electrodes with thicknesses within the range of 10–20 nm and different residual stress states are explored. Both pure nickel films and sandwiches of nickel (Ni) and carbon (C) are deposited by direct current (DC) magnetron sputtering onto pre-stretched silicone elastomer membranes. Both 37.5% biaxial pre-stretch and 57.5% uniaxial pre-stretch under pure shear condition (PSC) are considered in the conducted investigation. After the coating process is completed, the elastomer is allowed to relax. In the contracted configuration, it exhibits a wrinkled surface. After this state is reached, the electromechanical characterization is performed. All types of films reveal a low initial resistance (around 100 Ω /square). Depending on the kind of pre-stretch and the electrode material, a strain of 100% without any major degradation is achieved. It is also shown how the residual stress of the layers can be influenced by suitable sputtering parameters. As a result, low residual film stress significantly improves the electromechanical properties of PSC pre-stretched elastomers, but have only a minor influence on the biaxially pre-stretched ones, regarding the Ni and the Ni + C thin films. This phenomenon is directly connected to the failure mechanisms observed on the two types of pre-stretched membranes. With reversed layer order, i.e., C + Ni electrodes, the residual stress state of Ni does not influence the electromechanical properties for both the biaxially pre-stretched and the PSC pre-stretched coated membranes. The results are of fundamental importance for understanding the role of residual stresses for the creation of electromechanically stable and highly conductive electrode films, to be used in dielectric elastomer (DE) applications.
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David Robles-Cuenca, V. Ruiz-Díez, J. Sánchez-Rojas, J. Hernando-García
Despite the breakthroughs in the locomotion of robots at the macroscale, there is not a counterpart at the miniature scale. A recent review [1] pointed out the limitations of sub-gram systems. Locomotion based on legs is already well established for robotic platforms. Assuming a back and forth motion of the legs, a net displacement can be attained when the forward slip is not equal to the backward slip. The use of inclined legs is a common approach to achieve such an asymmetric slip. Reference [2] provides an excellent review of this approach. Here we propose a sub-gram system based on flexible materials. The body of the robot was a 3 cm long thin film of piezoelectric polyvinylidene fluoride (PVDF) polymer. The actuation mechanism was an in-plane extensional vibration mode of the PVDF film. Two U-shaped 3D printed nylon legs were fabricated, each attached to the edges of the PVDF support. The total mass of the PVDF/legs combination was below 20 mg for all the cases under study. Unidirectional locomotion was achieved, with a maximum speed of 47 mm/s, equivalent to 1.5 body lengths/s, at a voltage of 15 V, with 2 mm long legs at an angle of 60o to the PVDF film. [1] Ryan St. Pierre, Sarah Bergbreiter, “Toward Autonomy in Sub-Gram Terrestrial Robots”. Annual Review of Control, Robotics, and Autonomous Systems 2, 16.1-16.22, 2019. [2] Walter Driesen, “Concept, Modeling and experimental characterization of the modulated friction inertial drive (MFID) locomotion principle: Application to mobile microrobots”. PhD thesis, Ecole polytecnique federale de Lausanne, 2008.
{"title":"Sub-gram in-plane vibration-driven robot with inclined legs","authors":"David Robles-Cuenca, V. Ruiz-Díez, J. Sánchez-Rojas, J. Hernando-García","doi":"10.3390/iecat2020-08487","DOIUrl":"https://doi.org/10.3390/iecat2020-08487","url":null,"abstract":"Despite the breakthroughs in the locomotion of robots at the macroscale, there is not a counterpart at the miniature scale. A recent review [1] pointed out the limitations of sub-gram systems. Locomotion based on legs is already well established for robotic platforms. Assuming a back and forth motion of the legs, a net displacement can be attained when the forward slip is not equal to the backward slip. The use of inclined legs is a common approach to achieve such an asymmetric slip. Reference [2] provides an excellent review of this approach. \u0000 \u0000Here we propose a sub-gram system based on flexible materials. The body of the robot was a 3 cm long thin film of piezoelectric polyvinylidene fluoride (PVDF) polymer. The actuation mechanism was an in-plane extensional vibration mode of the PVDF film. Two U-shaped 3D printed nylon legs were fabricated, each attached to the edges of the PVDF support. The total mass of the PVDF/legs combination was below 20 mg for all the cases under study. Unidirectional locomotion was achieved, with a maximum speed of 47 mm/s, equivalent to 1.5 body lengths/s, at a voltage of 15 V, with 2 mm long legs at an angle of 60o to the PVDF film. \u0000 \u0000[1] Ryan St. Pierre, Sarah Bergbreiter, “Toward Autonomy in Sub-Gram Terrestrial Robots”. Annual Review of Control, Robotics, and Autonomous Systems 2, 16.1-16.22, 2019. \u0000[2] Walter Driesen, “Concept, Modeling and experimental characterization of the modulated friction inertial drive (MFID) locomotion principle: Application to mobile microrobots”. PhD thesis, Ecole polytecnique federale de Lausanne, 2008.","PeriodicalId":152837,"journal":{"name":"Proceedings of 1st International Electronic Conference on Actuator Technology: Materials, Devices and Applications","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124921486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Ruiz-Díez, J. Hernando-García, J. Sánchez-Rojas
: This paper reports the design, fabrication and performance of MEMS-based piezoelectric bidirectional conveyors featuring 3D printed legs in bridge resonators. The structures consisted of aluminium-nitride (AlN) piezoelectric film on top of millimetre-sized rectangular thin silicon bridges and two electrode patches. The position and size of the patches were analytically optimised for the wave generation, while the addition of 3D-printed legs, for a controlled contact, allowed for a further step into the manufacturing of efficient linear motors. Such hybrid devices have recently demonstrated the conveyance of sliders – surpassing several times the motor weight – with speeds of 1.7 mm/s, while operated at 6 V and 19.3kHz. However, by the optimisation of various aspects of the device such as the vibrational modes and excitation signals speeds above 25 mm/s were demonstrated.
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