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2 pages, 158 KiB

Open AccessEditorial

Editorial for the Special Issue on Soft Robotics: Design, Fabrication, Modeling, Control and Applications

by Thanh Nho Do

Micromachines 2023, 14(1), 27; https://doi.org/10.3390/mi14010027 - 23 Dec 2022

Viewed by 1037

Abstract

Living environments often require high adaptation from biological organisms, such as altering their shape and mechanical properties [...] Full article

(This article belongs to the Special Issue Soft Robotics: Design, Fabrication, Modeling, Control and Applications)

Research

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12 pages, 3402 KiB

Open AccessArticle

Model Analysis of Robotic Soft Arms including External Force Effects

by Zhi Chen, Zhong Liu and Xingguo Han

Micromachines 2022, 13(3), 350; https://doi.org/10.3390/mi13030350 - 23 Feb 2022

Cited by 5 | Viewed by 1766

Abstract

Because robotic soft arms have a high power-to-weight ratio, low cost, and ease of manufacturability, increasing numbers of researchers have begun to focus on their characteristics in recent years. However, many urgent problems remain to be resolved. For example, soft arms are made [...] Read more.

Because robotic soft arms have a high power-to-weight ratio, low cost, and ease of manufacturability, increasing numbers of researchers have begun to focus on their characteristics in recent years. However, many urgent problems remain to be resolved. For example, soft arms are made of hyperelastic material, making it difficult to obtain accurate model predictions of the soft arm shape. This paper proposes a new modeling method for soft arms, combining the constant curvature model with Euler–Bernoulli beam theory. By combining these two modeling methods, we can quickly solve for the soft arm deformation under the action of an external force. This paper also presents an experimental platform based on a cable-driven soft arm to verify the validity of the proposed model. We carried out model verification experiments to test for different external effects. Experimental results show that the maximum error of our proposed soft arm deformation model is between 2.86% and 8.75%, demonstrating its effectiveness. Full article

(This article belongs to the Special Issue Soft Robotics: Design, Fabrication, Modeling, Control and Applications)

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16 pages, 5261 KiB

Open AccessArticle

Modeling of Soft Pneumatic Actuators with Different Orientation Angles Using Echo State Networks for Irregular Time Series Data

by Samuel M. Youssef, MennaAllah Soliman, Mahmood A. Saleh, Mostafa A. Mousa, Mahmoud Elsamanty and Ahmed G. Radwan

Micromachines 2022, 13(2), 216; https://doi.org/10.3390/mi13020216 - 29 Jan 2022

Cited by 6 | Viewed by 2777

Abstract

Modeling of soft robotics systems proves to be an extremely difficult task, due to the large deformation of the soft materials used to make such robots. Reliable and accurate models are necessary for the control task of these soft robots. In this paper, [...] Read more.

Modeling of soft robotics systems proves to be an extremely difficult task, due to the large deformation of the soft materials used to make such robots. Reliable and accurate models are necessary for the control task of these soft robots. In this paper, a data-driven approach using machine learning is presented to model the kinematics of Soft Pneumatic Actuators (SPAs). An Echo State Network (ESN) architecture is used to predict the SPA’s tip position in 3 axes. Initially, data from actual 3D printed SPAs is obtained to build a training dataset for the network. Irregular-intervals pressure inputs are used to drive the SPA in different actuation sequences. The network is then iteratively trained and optimized. The demonstrated method is shown to successfully model the complex non-linear behavior of the SPA, using only the control input without any feedback sensory data as additional input to the network. In addition, the ability of the network to estimate the kinematics of SPAs with different orientation angles

θ

is achieved. The ESN is compared to a Long Short-Term Memory (LSTM) network that is trained on the interpolated experimental data. Both networks are then tested on Finite Element Analysis (FEA) data for other

θ

angle SPAs not included in the training data. This methodology could offer a general approach to modeling SPAs with varying design parameters. Full article

(This article belongs to the Special Issue Soft Robotics: Design, Fabrication, Modeling, Control and Applications)

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20 pages, 11405 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Dynamic Modeling and Experimental Validation of a Water Hydraulic Soft Manipulator Based on an Improved Newton—Euler Iterative Method

by Yinglong Chen, Qiang Sun, Qiang Guo and Yongjun Gong

Micromachines 2022, 13(1), 130; https://doi.org/10.3390/mi13010130 - 14 Jan 2022

Cited by 11 | Viewed by 4345

Abstract

Compared with rigid robots, soft robots have better adaptability to the environment because of their pliability. However, due to the lower structural stiffness of the soft manipulator, the posture of the manipulator is usually decided by the weight and the external load under [...] Read more.

Compared with rigid robots, soft robots have better adaptability to the environment because of their pliability. However, due to the lower structural stiffness of the soft manipulator, the posture of the manipulator is usually decided by the weight and the external load under operating conditions. Therefore, it is necessary to conduct dynamics modeling and movement analysis of the soft manipulator. In this paper, a fabric reinforced soft manipulator driven by a water hydraulic system is firstly proposed, and the dynamics of both the soft manipulator and hydraulic system are considered. Specifically, a dynamic model of the soft manipulator is established based on an improved Newton–Euler iterative method, which comprehensively considers the influence of inertial force, elastic force, damping force, as well as combined bending and torsion moments. The dynamics of the water hydraulic system consider the effects of cylinder inertia, friction, and water response. Finally, the accuracy of the proposed dynamic model is verified by comparing the simulation results with the experimental data about the steady and dynamic characteristics of the soft manipulator under various conditions. The results show that the maximum sectional error is about 0.0245 m and that the maximum cumulative error is 0.042 m, which validate the effectiveness of the proposed model. Full article

(This article belongs to the Special Issue Soft Robotics: Design, Fabrication, Modeling, Control and Applications)

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18 pages, 2737 KiB

Open AccessArticle

Bio-Inspired Take-Off Maneuver and Control in Vertical Jumping for Quadruped Robot with Manipulator

by Ru Kang, Fei Meng, Lei Wang, Xuechao Chen, Zhangguo Yu, Xuxiao Fan, Ryuki Sato, Aiguo Ming and Qiang Huang

Micromachines 2021, 12(10), 1189; https://doi.org/10.3390/mi12101189 - 30 Sep 2021

Cited by 6 | Viewed by 2296

Abstract

The jumping motion of legged robots is an effective way to overcome obstacles in the rugged microgravity planetary exploration environment. At the same time, a quadruped robot with a manipulator can achieve operational tasks during movement, which is more practical. However, the additional [...] Read more.

The jumping motion of legged robots is an effective way to overcome obstacles in the rugged microgravity planetary exploration environment. At the same time, a quadruped robot with a manipulator can achieve operational tasks during movement, which is more practical. However, the additional manipulator will restrict the jumping ability of the quadruped robot due to the increase in the weight of the system, and more active degrees of freedom will increase the control complexity. To improve the jumping height of a quadruped robot with a manipulator, a bio-inspired take-off maneuver based on the coordination of upper and lower limbs is proposed in this paper. The kinetic energy and potential energy of the system are increased by driving the manipulator-end (ME) to swing upward, and the torso driven by the legs will delay reaching the required peak speed due to the additional load caused by the accelerated ME. When the acceleration of ME is less than zero, it will pull the body upward, which reduces the peak power of the leg joints. Therefore, the jumping ability of the system is improved. To realize continuous and stable jumping, a control framework based on whole-body control was established, in which the quadruped robot with a manipulator was a simplified floating seven-link model, and the hierarchical optimization was used to solve the target joint torques. This method greatly simplifies the dynamic model and is convenient for calculation. Finally, the jumping simulations in different gravity environments and a 15° slope were performed. The jump heights have all been improved after adding the arm swing, which verified the superiority of the bio-inspired take-off maneuver proposed in this paper. Furthermore, the stability of the jumping control method was testified by the continuous and stable jumping. Full article

(This article belongs to the Special Issue Soft Robotics: Design, Fabrication, Modeling, Control and Applications)

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25 pages, 4375 KiB

Open AccessArticle

An Approach of Social Navigation Based on Proxemics for Crowded Environments of Humans and Robots

by Marcos Daza, Dennis Barrios-Aranibar, José Diaz-Amado, Yudith Cardinale and João Vilasboas

Micromachines 2021, 12(2), 193; https://doi.org/10.3390/mi12020193 - 13 Feb 2021

Cited by 24 | Viewed by 7150

Abstract

Nowadays, mobile robots are playing an important role in different areas of science, industry, academia and even in everyday life. In this sense, their abilities and behaviours become increasingly complex. In particular, in indoor environments, such as hospitals, schools, banks and museums, where [...] Read more.

Nowadays, mobile robots are playing an important role in different areas of science, industry, academia and even in everyday life. In this sense, their abilities and behaviours become increasingly complex. In particular, in indoor environments, such as hospitals, schools, banks and museums, where the robot coincides with people and other robots, its movement and navigation must be programmed and adapted to robot–robot and human–robot interactions. However, existing approaches are focused either on multi-robot navigation (robot–robot interaction) or social navigation with human presence (human–robot interaction), neglecting the integration of both approaches. Proxemic interaction is recently being used in this domain of research, to improve Human–Robot Interaction (HRI). In this context, we propose an autonomous navigation approach for mobile robots in indoor environments, based on the principles of proxemic theory, integrated with classical navigation algorithms, such as ORCA, Social Momentum, and A*. With this novel approach, the mobile robot adapts its behaviour, by analysing the proximity of people to each other, with respect to it, and with respect to other robots to decide and plan its respective navigation, while showing acceptable social behaviours in presence of humans. We describe our proposed approach and show how proxemics and the classical navigation algorithms are combined to provide an effective navigation, while respecting social human distances. To show the suitability of our approach, we simulate several situations of coexistence of robots and humans, demonstrating an effective social navigation. Full article

(This article belongs to the Special Issue Soft Robotics: Design, Fabrication, Modeling, Control and Applications)

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21 pages, 6715 KiB

Open AccessArticle

Soft Finger Modelling and Co-Simulation Control towards Assistive Exoskeleton Hand Glove

by Mohammed N. El-Agroudy, Mohammed I. Awad and Shady A. Maged

Micromachines 2021, 12(2), 181; https://doi.org/10.3390/mi12020181 - 11 Feb 2021

Cited by 5 | Viewed by 2261

Abstract

The soft pneumatic actuators of an assistive exoskeleton hand glove are here designed. The design of the actuators focuses on allowing the actuator to perform the required bending and to restrict elongation or twisting of the actuator. The actuator is then modeled using [...] Read more.

The soft pneumatic actuators of an assistive exoskeleton hand glove are here designed. The design of the actuators focuses on allowing the actuator to perform the required bending and to restrict elongation or twisting of the actuator. The actuator is then modeled using ABAQUS/CAE, a finite element modeling software, and the open loop response of the model is obtained. The parameters of the actuator are then optimized to reach the optimal parameters corresponding to the best performance. Design of experiment (DOE) techniques are then approached to study the robustness of the system. Software-in-the-loop (SiL) is then approached to control the model variables via a proportional-integral-derivative (PID) control generated by FORTRAN code. The link between the two programs is to be achieved by the user subroutine that is written, where the subroutine receives values from ABAQUS/CAE, performs calculations, and passes values back to the software. The controller’s parameters are tuned and then the closed loop response of the model is obtained by setting the desired bending angle and running the model. Furthermore, a concentrated force at the tip of the actuator is added to observe the actuator’s response to external disturbance. Full article

(This article belongs to the Special Issue Soft Robotics: Design, Fabrication, Modeling, Control and Applications)

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23 pages, 7732 KiB

Open AccessArticle

Multiphysics Simulator for the IPMC Actuator: Mathematical Model, Finite Difference Scheme, Fast Numerical Algorithm, and Verification

by Anton P. Broyko, Ivan K. Khmelnitskiy, Eugeny A. Ryndin, Andrey V. Korlyakov, Nikolay I. Alekseyev and Vagarshak M. Aivazyan

Micromachines 2020, 11(12), 1119; https://doi.org/10.3390/mi11121119 - 17 Dec 2020

Cited by 5 | Viewed by 2525

Abstract

The article is devoted to the development and creation of a multiphysics simulator that can, on the one hand, simulate the most significant physical processes in the IPMC actuator, and on the other hand, unlike commercial products such as COMSOL, can use computing [...] Read more.

The article is devoted to the development and creation of a multiphysics simulator that can, on the one hand, simulate the most significant physical processes in the IPMC actuator, and on the other hand, unlike commercial products such as COMSOL, can use computing resources economically. The developed mathematical model is an adjoint differential equation describing the transport of charged particles and water molecules in the ion-exchange membrane, the electrostatic field inside, and the mechanical deformation of the actuator. The distribution of the electrostatic potential in the interelectrode space is located by means of the solution of the Poisson equation with the Dirichlet boundary conditions, where the charge density is a function of the concentration of cations inside the membrane. The cation distribution was obtained by means of the solution of the equation system, in which the fluxes of ions and water molecules are described by the modified Nernst-Planck equations with boundary conditions of the third kind (the Robin problem). The cantilever beam forced oscillation equation in the presence of resistance (allowing for dissipative processes) with assumptions of elasticity theory was used to describe the actuator motion. A combination of the following computational methods was used as a numerical algorithm for the solution: the Poisson equation was solved by a direct method, the modified Nernst-Planck equations were solved by the Newton-Raphson method, and the mechanical oscillation equation was solved using an explicit scheme. For this model, a difference scheme has been created and an algorithm has been described, which can be implemented in any programming language and allows for fast computational experiments. On the basis of the created algorithm and with the help of the obtained experimental data, a program has been created and the verification of the difference scheme and the algorithm has been performed. Model parameters have been determined, and recommendations on the ranges of applicability of the algorithm and the program have been given. Full article

(This article belongs to the Special Issue Soft Robotics: Design, Fabrication, Modeling, Control and Applications)

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Review

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16 pages, 1016 KiB

Open AccessReview

Underwater Soft Robotics: A Review of Bioinspiration in Design, Actuation, Modeling, and Control

by Samuel M. Youssef, MennaAllah Soliman, Mahmood A. Saleh, Mostafa A. Mousa, Mahmoud Elsamanty and Ahmed G. Radwan

Micromachines 2022, 13(1), 110; https://doi.org/10.3390/mi13010110 - 10 Jan 2022

Cited by 44 | Viewed by 7429

Abstract

Nature and biological creatures are some of the main sources of inspiration for humans. Engineers have aspired to emulate these natural systems. As rigid systems become increasingly limited in their capabilities to perform complex tasks and adapt to their environment like living creatures, [...] Read more.

Nature and biological creatures are some of the main sources of inspiration for humans. Engineers have aspired to emulate these natural systems. As rigid systems become increasingly limited in their capabilities to perform complex tasks and adapt to their environment like living creatures, the need for soft systems has become more prominent due to the similar complex, compliant, and flexible characteristics they share with intelligent natural systems. This review provides an overview of the recent developments in the soft robotics field, with a focus on the underwater application frontier. Full article

(This article belongs to the Special Issue Soft Robotics: Design, Fabrication, Modeling, Control and Applications)

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