The recent advances in additive manufacturing techniques (AM), in particular three -dimensional printing (3D) and four -dimensional printing (4D), have made the production of different parts of robots, including sensors and actuators , with high multifunctionality, compliance and flexibility, unlike traditional approaches (Bodaghi and Zolfagharian, 2022). On the basis of pre-programmed architectures which are often inspired by biological structures, 4D printed robots and soft robots are adaptive mechanisms responding to external stimuli, such as temperature, strength, electricity, light and humidity made with polymer -based composites (Duigou and Correa, 2022). Indeed, the autonomous activation offered by 4D printing envisages frugal engineering with wireless robots or engine. They can be applied in a wide range of applications, including medical assisted robots, automotive, aerospace, microfluidal, tissue engineering, drug delivery and portable electronics (Zolfagharian et al., 2022). The design and prediction of the behavior and control of these products are still a complex problem requiring multiphysical formulation where automatic learning and in -depth learning techniques have been promising. This research subject aimed at promoting the dissemination of recent advances in the MA of soft robots, including sensors, actuators, metamaterials, control of morphology and new design strategies. It presented via Five original research articles made jointly by involvement of 22 academics active in the field of Austria, Germany, Switzerland, Japan, Australia, the United Arab Emirates and the United States.
In the opening article, Dämmer et al. From Johannes Kepler Linz University, Austria, in collaboration with Bram Vanderborght, in Advanced Development Control and Robotics, Festo SE and Co. KG, Germany, presented an additively manufactured rotary actuator made in an additional manner via Inkjet printing. They have shown that the complex structural behavior of the structure of the actuator’s elastomers can be predicted by a finite element simulation (FE). The simulations presented in their work contributed to the science of materials of the inkjet printed elastomers by demonstrating the use of a model of hyper viscoelastic material to estimate the deformation behavior of a prototyped robotic component. The results contribute to the long -term objective of light and pneumatically manufacturing robots.
Georgopoulou et al. From EMPA-SWISS FEDEral Laboratories for Materials Science and Technology, Switzerland, and the Scientists in Vrije Universiteit Brussel, Belgium, Have Published Their Work on the Development of An Open-Source Soft Robotic Gripper to Evaluate the Fused Device Modeling (FDM) Printing of Thermoplastic polyurethane structures (TPU) with integrated deformation detection elements in order to provide directives for the selection of materials when an elastomer and a gentle piezoresistive sensor are combined. These sweet pliers, with integrated deformation detection elements, were successfully printed using a multi-material FDM 3D printer. Their results show that the in situ The tension detection elements printed on the soft pliers were able to detect the deformation of the structure when the tentacles of the pliers were open or closed. The sensor signal could make the difference between picking small or large objects and when an obstacle prevented the tentacles from opening. The correlation between the hardness of the TPU coast, which was used for the body of the pliers and the sensitivity of integration in situ The deformation detection elements have revealed that the selection of materials has a significant impact on the sensor signal. This study can be an example to guide the selection of material combinations for soft robotic systems produced with FDM.
Shintake et al. From the University of Electro-Communizations, Japan, demonstrates a method to monolithically manufacture the stacked dielectric actuator (DEAS) without alternately stacking dielectric and electrodes in their article. They studied the feasibility of the method via The manufacture and characterization of simple monolithic disintegers with several electrodes. The manufactured actuators are characterized in terms of acting, output force and frequency response. In actuators, polydimethylsiloxane (PDMS) and gallium-indectic (Egain) are used for the elastomer matrix and electrode material, respectively. The microfluidic channels are made by dissolving a 3D printed part suspended in the elastomer structure. The experimental results show the successful implementation of the proposed method and the right agreement between the measured data and the theoretical preaching, validating the feasibility of the proposed method.
In the fourth article, Tawk et al.In a joint work between the University of Wollongong in Australia and the United Arab Emirates, presented the application of metamaterials in the design of soft robotic pliers. They created a modular modular pliers printed in 3D with soft fingers very conforming in soft pneumatic pressure of positive pressure and a mechanical metamaterial. The fingers of the flexible clip, as well as the mechanical metamaterial, which incorporates a soft focus structure and compliant ribs, were printed in 3D in a single step, without requiring support or post-processing material, using a printer FDM FDM at low cost and open-open and TPU available in the trade. The FE simulations have precisely predicted the behavior and performance of the fingers in terms of deformation and cutting -edge force, thus proving its effectiveness in improving the performance of the pliers.
The research subject ends with the work of Stanislav et al. From the College of Engineering, Embry-Riddle Aeronautical University, United States. They studied on the modeling and manufacturing of Unimorph DEA, a configuration capable of producing a large deformation of flexion and one of the most suitable for the implementation by 3D printing. The proposed model made it possible to illustrate the effect of each Udea layer on the performance of the actuator and to obtain several merit figures for simple design optimization and a selection of materials. In order to facilitate research on all 3D printed printed actuators and robotics, this article demonstrates the DEA manufacturing challenges composed of commercially available silicones using accessible 3D printing equipment. The manufacture, viscosity and hardening of materials are mainly studied to determine their time of manipulation of printing. They validated the modeling and manufacturing methodologies developed using 3D printing by testing a unimorph DEA.
Contributions from authors
All the authors listed made a substantial, direct and intellectual contribution to the work and approved it for publication.
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References
Bodaghi, M. and Zolfagharian, A. (2022). “Intelligent materials in additive manufacturing”, in 4D printing mechanics, advanced engineering modeling and engineering applications (Elsevier), 2. Doi: 10.1080 / 17452759.2018.1518016
Le Duigou, A., and Correa, D. (2022). “4D printing of the composite of natural fibers, in intelligent materials in additive manufacturing”, in 4D printing principles and manufacturing (Elsevier), 1, 297–333. DOI: 10.1016 / C2020-0-01479-9
Zolfagharian, A., Kaynak, A., and Kouzani, A. (2022). “Closed loop control of flexible hydrogels printed in 4D, in intelligent materials in additive manufacturing”, in 4D printing mechanics, advanced engineering modeling and engineering applications (Elsevier), 2, 251–278. DOI: 10.1016 / J. MATDES.2019.108411