Electrohydraulic Actuator for a Soft Gripper

Park, Tongil; Kim, Kee Hoon; Oh, Sang–Rok; Cha, Youngsu

doi:10.1089/soro.2019.0009

Cited by 74 publications

(41 citation statements)

References 39 publications

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“…For these actuators, the presented scaling analysis may readily be modified to identify the governing timescales to account for differences in geometry ( 12 , 35 ) and modes of electrohydraulic zipping ( 35 , 36 ). Additionally, the conclusions of this work may be applied to other types of electrohydraulic actuators ( 12 , 13 , 37 ), pumps ( 38 – 40 ), and generators ( 41 ) in which elastic deformations play an important role. Elastic strains complicate the theoretical analysis of these transducers, but we also expect them to exhibit an inertial and a viscous regime so that similar strategies can be applied to increase their actuation speed.…”

Section: Discussionmentioning

confidence: 99%

“…Electrohydraulic soft actuators are composed of deformable, liquid-filled shells that deform under electric fields ( 4 , 10 , 11 ). They have drawn attention as high-performance actuators ( 4 , 11 – 14 ), as they achieve large actuation strains (>100%) and stresses (>0.3 MPa), and high specific powers (>600 W/kg) and frequencies (>100 Hz) ( 12 ). We ( 15 , 16 ) and others ( 17 – 19 ) have investigated the quasistatic behavior of electrohydraulic soft actuators, but the fundamental physics that governs their dynamic behavior is unexplored.…”

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confidence: 99%

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Dynamics of electrohydraulic soft actuators

Rothemund

Kirkman

Keplinger

2020

Proc. Natl. Acad. Sci. U.S.A.

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Nature has inspired the design of robots in which soft actuators enable tasks such as handling of fragile objects and adapting to unstructured environments. Those tasks are difficult for traditional robots, which predominantly consist of hard components. Electrohydraulic soft actuators are liquid-filled shells that deform upon the application of electric fields; they excel among soft actuators with muscle-like force outputs and actuation strains, and with actuation frequencies above 100 Hz. However, the fundamental physics that governs the dynamics of electrohydraulic soft actuators is unexplored. Here, we study the dynamics of electrohydraulic soft actuators using the Peano-HASEL (hydraulically amplified self-healing electrostatic) actuator as a model system. Using experiments and a scaling analysis, we discover two dynamic regimes: a regime in which viscous dissipation reduces the actuation speed and a regime governed by inertial effects in which high-speed actuation is possible. For each regime, we derive a timescale that describes the influence of geometry, materials system, and applied external loads on the actuation speed. We also derive a model to study the dynamic behavior of Peano-HASEL actuators in both regimes. Although this analysis focuses on the Peano-HASEL actuator, the presented results may readily be generalized to other electrohydraulic actuators. When designed to operate in the inertial regime, electrohydraulic actuators will enable bio-inspired robots with unprecedented speeds of motion.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Dynamics of electrohydraulic soft actuators

Rothemund

Kirkman

Keplinger

2020

Proc. Natl. Acad. Sci. U.S.A.

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“…We obtain the blocking force of 0.0653 N in the full operation. Within, we compare the blocking force of the actuator with other actuators such as pneumatic actuators with an external pressure pump (Alici et al, 2018), electrohydraulic actuators (Park et al, 2020), and SMA . Therein, the soft pneumatic actuators using an external pump produce a blocking force of up to 1.6767 N with a material with an elastic modulus of 262.4 kPa and up to 0.5543 N with an elastic modulus of 48 kPa.…”

Section: Blocking Forcementioning

confidence: 99%

“…They can perform various tasks in several unpredictable situations (Hughes et al, 2016). In contrast to conventional manipulators with a rigid body (Butterfaß et al, 2001;Wojtara et al, 2005), soft manipulators are actuated by various methods, such as hydraulic (Mitchell et al, 2019;Park et al, 2020) and pneumatic (Deimel and Brock, 2016;Jittungboonya and Maneewarn, 2019), and smart materials, such as ionic polymer metal composite (IPMC) (Carrico and Leang, 2017;Bhattacharya et al, 2019;Roy et al, 2019), shape memory alloy (SMA) (Rodrigue et al, 2017;, and electroactive polymer (Kofod et al, 2007;Taghavi et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Soft Pneumatic Gripper With a Tendon-Driven Soft Origami Pump

Kim

Cha

2020

Front. Bioeng. Biotechnol.

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In this study, we propose a soft pneumatic gripper that uses a tendon-driven soft origami pump. The gripper consists of three pneumatic soft actuators that are controlled by a tendon-driven origami pump. An external air compressor that supplies air to the pneumatic actuator is replaced by an origami pump. The soft actuator is composed of silicone (Ecoflex 00-30) with a chamber-based structure, which is fabricated using a mold, and the origami pump is fabricated by folding a Kresling patterned polypropylene film. In addition, we conduct a series of experiments to evaluate the performance of the pneumatic actuator with a tendon-driven origami pump. Specifically, movement characteristics, frequency response, blocking force, and the relation between bending angle and pressure are analyzed from the results of the experiments. Furthermore, we understand the entire operation mechanism from the deformation of the origami pump to bending through pressure. Finally, we demonstrate the grasping of objects with diverse shapes and materials, and indicate the feasibility of the pneumatic gripper as an independent module without an external compressor.

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“…Completely flexible and safer interactions could be achieved between the actuators and objects. Tongil Park et al [22] proposed an electrohydraulic gripper, which was based on electrostatic and hydraulic forces. The gripper could generate a hydraulic force without an external fluid supply source.…”

Section: Introductionmentioning

confidence: 99%

Simulation and Experiment Study on Deformation Characteristics of the Water Hydraulic Flexible Actuator Used for the Underwater Gripper

Nie

Liu

et al. 2020

IEEE Access

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A water hydraulic flexible gripper with three-fingered structure is developed to deal with the problem of poor adaptability for the existing underwater gripper. This gripper driven by water hydraulics can realize flexible grasping and possess simple structure, high pressure-bearing, strong adaptability and capability of anti-jamming to the water environment and easy to control. In particular, the water hydraulic flexible gripper system is an open system in relation to the underwater environment, with the water source being supplied directly by the underwater environment, eliminating the effects of back pressure generated by the underwater environment in comparison with the closed system of other grippers. It is a good solution to solve the problem of poor adaptability for the existing underwater gripper in underwater environment. The flexible actuator model is established to explore the key parameters influencing the deformation characteristics. The effects of different inlet pressure, knuckle length, wall thickness and material of the inner skeleton and external surface on the deformation characteristics of the flexible actuator are investigated through simulation. It is found that, for the flexible actuator, the wall thickness of the inner skeleton is selected as 1 mm and the inner skeleton length is designed with the first knuckle of 30 mm and the second knuckle of 80 mm. Based on the optimal parameters obtained through simulation, the prototype of flexible actuator and flexible gripper are fabricated. Experiment is performed to test the deformation of the flexible actuator under different inlet pressure. It is found that the experiment results are consistent with the simulation results. Both of the experiment and simulation results exhibit that the total deformation of the flexible actuator is proportional to the inlet pressure. The research will lay foundation for the optimal design of flexible actuator used for the underwater gripper driven by water hydraulics.

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Electrohydraulic Actuator for a Soft Gripper

Cited by 74 publications

References 39 publications

Dynamics of electrohydraulic soft actuators

Dynamics of electrohydraulic soft actuators

Soft Pneumatic Gripper With a Tendon-Driven Soft Origami Pump

Simulation and Experiment Study on Deformation Characteristics of the Water Hydraulic Flexible Actuator Used for the Underwater Gripper

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