Application and Analysis of an Ionic Liquid Gel in a Soft Robot

Due to their light weight, flexibility, and low energy consumption, ionic electroactive polymers have become a hotspot for bionic soft robotics and are ideal materials for the preparation of soft actuators. Because the traditional ionic electroactive polymers, such as ionic polymer-metal composites (IPMCs), contain water ions, a soft actuator does not work properly upon the evaporation of water ions. An ionic liquid polymer gel is a new type of ionic electroactive polymer that does not contain water ions, and ionic liquids are more thermally and electrochemically stable than water. These liquids, with a low melting point and a high ionic conductivity, can be used in ionic electroactive polymer soft actuators. An ionic liquid gel (ILG), a new type of soft actuator material, was obtained by mixing 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4), hydroxyethyl methacrylate (HEMA), diethoxyacetophenone (DEAP) and ZrO2 and then polymerizing this mixture into a gel state under ultraviolet (UV) light irradiation. An ILG soft actuator was designed, the material preparation principle was expounded, and the design method of the soft robot mechanism was discussed. Based on nonlinear finite element theory, the deformation mechanism of the ILG actuator was deeply analyzed and the deformation of the soft robot when grabbing an object was also analyzed. A soft robot was designed with the soft actuator as the basic module. The experimental results show that the ILG soft robot has good driving performance, and the soft robot can grab a 105 mg object at an input voltage of 3.5 V.

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Motion Simulation of Ionic Liquid Gel Soft Actuators Based on CPG Control

Computational Intelligence and Neuroscience ◽

10.1155/2019/8256723 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11 ◽

Cited By ~ 2

Author(s):

Chenghong Zhang ◽

Bin He ◽

An Ding ◽

Shoulin Xu ◽

Zhipeng Wang ◽

...

Keyword(s):

Ionic Liquid ◽

Simulation Analysis ◽

Uv Light ◽

Gold Foil ◽

Cathode Side ◽

Polymer Gel ◽

Anode Side ◽

Soft Actuator ◽

Liquid Polymer ◽

Soft Actuators

The ionic liquid gel (ILG), a new type of soft actuator material, is a mixture of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4), hydroxyethyl methacrylate (HEMA), diethoxyacetophenone (DEAP), and ZrO2 polymerized into a gel state under ultraviolet (UV) light irradiation. The soft actuator structure consists of a layer of ionic liquid polymer gel sandwiched between two layers of activated carbon capped with gold foil. The volume of the cationic BMIM+ in the ionic liquid BMIMBF4 is much larger than that of the anionic BF4−. When voltages are applied to both sides of the actuator, the anions and cations move toward the anode and cathode of the electrode, respectively, under the electric field. The volume of the ILG cathode side therefore expands, and the volume of the ILG anode side shrinks, hence bending the entire actuator toward the anode side. The Ogden model was selected as the hyperelastic constitutive model to study the mechanical properties of the ILG by nonlinear analysis. As the ILG is an ideal material for the preparation of a supercapacitor, the equivalent circuit of the ILG can be modeled by the supercapacitor theory to identify the transfer function of the soft actuator. The central pattern generator (CPG) control is widely used in the area of biology, and CPGs based on bioinspired control methods have attracted great attention from researchers worldwide. After the continuum soft actuator is discretized, the CPG-based bioinspired method can be used to control the soft robot drivers. According to the simulation analysis results, the soft actuator can be smooth enough to reach the specified location.

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A Computing Method to Determine the Performance of an Ionic Liquid Gel Soft Actuator

Applied Bionics and Biomechanics ◽

10.1155/2018/8327867 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 2

Author(s):

Bin He ◽

Chenghong Zhang ◽

Yanmin Zhou ◽

Zhipeng Wang

Keyword(s):

Experimental Data ◽

Ionic Liquid ◽

Tensile Stress ◽

Uv Light ◽

Uniaxial Tensile ◽

Optimized Design ◽

Soft Actuator ◽

Uniaxial Tensile Testing ◽

New Type ◽

Uniaxial Tensile Stress

A new type of soft actuator material—an ionic liquid gel (ILG) that consists of BMIMBF4, HEMA, DEAP, and ZrO2—is polymerized into a gel state under ultraviolet (UV) light irradiation. In this paper, we first propose that the ILG conforms to the assumptions of hyperelastic theory and that the Mooney-Rivlin model can be used to study the properties of the ILG. Under the five-parameter and nine-parameter Mooney-Rivlin models, the formulas for the calculation of the uniaxial tensile stress, plane uniform tensile stress, and 3D directional stress are deduced. The five-parameter and nine-parameter Mooney-Rivlin models of the ILG with a ZrO2 content of 3 wt% were obtained by uniaxial tensile testing, and the parameters are denoted as c10, c01, c20, c11, and c02 and c10, c01, c20, c11, c02, c30, c21, c12, and c03, respectively. Through the analysis and comparison of the uniaxial tensile stress between the calculated and experimental data, the error between the stress data calculated from the five-parameter Mooney-Rivlin model and the experimental data is less than 0.51%, and the error between the stress data calculated from the nine-parameter Mooney-Rivlin model and the experimental data is no more than 8.87%. Hence, our work presents a feasible and credible formula for the calculation of the stress of the ILG. This work opens a new path to assess the performance of a soft actuator composed of an ILG and will contribute to the optimized design of soft robots.

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Design and optimization of actuator for multi-joint soft rehabilitation glove

Industrial Robot the international journal of robotics research and application ◽

10.1108/ir-02-2021-0036 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Xinjie Wang ◽

Yan Cheng ◽

Huadong Zheng ◽

Yihao Li ◽

Caidong Wang

Keyword(s):

Constitutive Model ◽

Element Model ◽

Longitudinal Section ◽

Bending Test ◽

Hand Rehabilitation ◽

Content Type ◽

Design And Optimization ◽

Soft Actuator ◽

New Type ◽

Soft Actuators

Purpose Currently, rehabilitation medical care is expensive, requires a large number of rehabilitation therapist and which can only limit in the fixed location. In addition, there is a lack of research on the structure optimization and theoretical analysis of soft actuators for hand rehabilitation. In view of the problems above, this paper aims to propose a cheap, portable, wearable soft multiple joints rehabilitation glove. Design/methodology/approach First, this paper determined the hyperelastic constitutive model by material tensile test. Second, the soft actuator’s internal longitudinal section shape was optimized through the comparison of three diverse chamber structures. Meanwhile, the motion model of the soft actuator is established by the finite element model analysis method. Then, this paper established the constitutive model of the soft actuator according to the torque equilibrium equation and analyzed the relationship between the soft actuator’s bending angle and the input air pressure. This paper has verified that the theoretical model is correct through the soft actuator bending test. Finally, rehabilitation gloves were manufactured according to the model and the rehabilitation performance and grasping ability of gloves were verified through experiments. Findings The optimization results show that the internal semicircular cavity has better performance. Then, the actuator performance is better after adding the external arc structure and optimizing the physical dimension. The experimental results show that the trajectory of the actuator conforms to the mathematical model and rehabilitation gloves can meet the needs of rehabilitation treatment. Practical implications Rehabilitation gloves made of actuators can help patients with hand dysfunction in daily rehabilitation training. Then, it can also assist patients with some fine and complicated hand movements. Originality/value This paper proposes a new type of soft rehabilitation glove, which is composed of new soft actuators and adapting pieces. The new actuator is small enough to be fitted to the knuckle of the glove to move each joint of the finger.

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Design and application of integrated parabolic soft actuator

Industrial Robot the international journal of robotics research and application ◽

10.1108/ir-03-2019-0062 ◽

2019 ◽

Vol 46 (6) ◽

pp. 792-799

Author(s):

Dong Liu ◽

Minghao Wang ◽

Ming Cong

Keyword(s):

Stress Concentration ◽

Fem Analysis ◽

Distribution Model ◽

Content Type ◽

Soft Actuator ◽

Distributed Structure ◽

Air Chamber ◽

New Type ◽

Circular Ladder ◽

Soft Actuators

Purpose The purpose of this paper is to solve the common problems of outer phenomenon and stress concentration among pneumatic networks soft actuators. Design/methodology/approach On the basis of imitating the caterpillar structure, the new soft actuator adopts the integral circular ladder structure instead of the traditional independent distributed structure as the air chamber. Through the comparison of several different structures, the parabolic in-wall curve is found to be fit for designing the optimal integrated chamber structure of the soft actuator. The curve function of each ladder chamber is computed based on the torque distribution model, aiming to decrease the terminal deformation. Meanwhile, the FEM analysis method is applied to establish the motion model of the integrated parabolic ladder soft actuator. The model’s accuracy, as well as structure’s deformation and stress, are verified. Findings Compared with the FEM data, the experimental data indicate that the new soft actuator has no obvious outer phenomenon, the maximum stress decreases and the stiffness increases. The new actuator is applied for designing a flexible gripper to grasp objects of different shapes and sizes. The gripper can grasp objects of 52.6 times its own mass. Practical implications The designed gripper is available for flexible production in various fields, such as capturing fruits of different sizes, soft foods or parts with complex shapes. Originality/value This paper proposes a new type soft actuator, which provides a solution for exploring the field of the soft robot. The problems of outer phenomenon and stress concentration are suppressed with pneumatic networks soft actuators.

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Trunk-like Soft Actuator: Design, Modeling, and Experiments

Robotica ◽

10.1017/s0263574719001012 ◽

2019 ◽

Vol 38 (4) ◽

pp. 732-746

Author(s):

Guanjun Bao ◽

Lingfeng Chen ◽

Yaqi Zhang ◽

Shibo Cai ◽

Fang Xu ◽

...

Keyword(s):

Self Regulation ◽

Salient Feature ◽

Theoretical Models ◽

Soft Robotics ◽

Soft Robot ◽

Soft Actuator ◽

New Type ◽

Modeling And Experiments ◽

Actuator Design ◽

Stiffness Adjustment

SUMMARYIn recent years, soft robotics is widely considered as the most promising field for both research and application. First of all, the actuator is fundamental for designing, modeling, and controlling of soft robots. This paper presents a new type of pneumatic trunk-like soft actuator, which contains a chamber for stiffness adjustment in addition to three chambers for driving. Thus, the salient feature of the proposed actuator is the ability of stiffness self-regulation. The structure of the proposed actuator is described in detail. Then the theoretical models for elongation and bending motion of the actuator are established. The elongation as well as single-chamber and multi-chamber driving bending of the actuator were tested to verify the mathematical models. Finally, a dual-segment soft robot based on the proposed trunk-like soft actuator was developed and tested by experiments, which implies its potential application in practice.

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An Origami Flexiball-Inspired Metamaterial Actuator and Its In-Pipe Robot Prototype

Actuators ◽

10.3390/act10040067 ◽

2021 ◽

Vol 10 (4) ◽

pp. 67

Author(s):

Fuwen Hu ◽

Tian Li

Keyword(s):

Degrees Of Freedom ◽

Three Dimensional ◽

Multiple Degrees Of Freedom ◽

Soft Actuator ◽

Structure Building ◽

Magnetically Actuated ◽

Mechanical Metamaterials ◽

New Type ◽

Soft Actuators ◽

Magnetoactive Elastomer

Usually, polyhedra are viewed as the underlying constructive cells of packing or tilling in many disciplines, including crystallography, protein folding, viruses structure, building architecture, etc. Here, inspired by the flexible origami polyhedra (commonly called origami flexiballs), we initially probe into their intrinsic metamaterial properties and robotized methods from fabrication to actuation. Firstly, the topology, geometries and elastic energies of shape shifting are analyzed for the three kinds of origami flexiballs with extruded outward rhombic faces. Provably, they meet the definitions of reconfigurable and transformable metamaterials with switchable stiffness and multiple degrees of freedom. Secondly, a new type of soft actuator with rhombic deformations is successfully put forward, different from soft bionic deformations like elongating, contracting, bending, twisting, spiraling, etc. Further, we redesign and fabricate the three-dimensional (3D) printable structures of origami flexiballs considering their 3D printability and foldability, and magnetically actuated them through the attachment of magnetoactive elastomer. Lastly, a fully soft in-pipe robot prototype is presented using the origami flexiball as an applicable attempt. Experimental work clearly suggests that the presented origami flexiball robot has good adaptability to various pipe sizes, and also can be easily expanded to different scales, or reconfigured into more complex metastructures by assembly. In conclusion, this research provides a newly interesting and illuminating member for the emerging families of mechanical metamaterials, soft actuators and soft robots.

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