Analysis of the 'Endoworm' prototype's ability to grip the bowel in in vitro and ex vivo models

[EN] Access to the small bowel by means of an enteroscope is difficult, even using current devices such as single-balloon or double-balloon enteroscopes. Exploration time and patient discomfort are the main drawbacks. The prototype 'Endoworm' analysed in this paper is based on a pneumatic translation system that, gripping the bowel, enables the endoscope to move forward while the bowel slides back over its most proximal part. The grip capacity is related to the pressure inside the balloon, which depends on the insufflate volume of air. Different materials were used as in vitro and ex vivo models: rigid polymethyl methacrylate, flexible silicone, polyester urethane and ex vivo pig small bowel. On measuring the pressure-volume relationship, we found that it depended on the elastic properties of the lumen and that the frictional force depended on the air pressure inside the balloons and the lumen's elastic properties. In the presence of a lubricant, the grip on the simulated intestinal lumens was drastically reduced, as was the influence of the lumen's properties. This paper focuses on the Endoworm's ability to grip the bowel, which is crucial to achieving effective endoscope forward advance and bowel foldingThe author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study was funded by the Spanish Ministry of Economy and Competitiveness through Project (PI18/01365) and by the UPV/IIS LA Fe through the (Endoworm 3.0) Project. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with the assistance of the European Regional Development FundTobella, J.; Pons-Beltrán, V.; Santonja, A.; Sánchez-Diaz, C.; Campillo Fernandez, AJ.; Vidaurre, A. (2020). 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Bio-Inspired Robotics

Modern robotic technologies have enabled robots to operate in a variety of unstructured and dynamically-changing environments, in addition to traditional structured environments. Robots have, thus, become an important element in our everyday lives. One key approach to develop such intelligent and autonomous robots is to draw inspiration from biological systems. Biological structure, mechanisms, and underlying principles have the potential to provide new ideas to support the improvement of conventional robotic designs and control. Such biological principles usually originate from animal or even plant models, for robots, which can sense, think, walk, swim, crawl, jump or even fly. Thus, it is believed that these bio-inspired methods are becoming increasingly important in the face of complex applications. Bio-inspired robotics is leading to the study of innovative structures and computing with sensory–motor coordination and learning to achieve intelligence, flexibility, stability, and adaptation for emergent robotic applications, such as manipulation, learning, and control. This Special Issue invites original papers of innovative ideas and concepts, new discoveries and improvements, and novel applications and business models relevant to the selected topics of ``Bio-Inspired Robotics''. Bio-Inspired Robotics is a broad topic and an ongoing expanding field. This Special Issue collates 30 papers that address some of the important challenges and opportunities in this broad and expanding field

3D-Printing and Machine Learning Control of Soft Ionic Polymer-Metal Composite Actuators

This paper presents a new manufacturing and control paradigm for developing soft ionic polymer-metal composite (IPMC) actuators for soft robotics applications. First, an additive manufacturing method that exploits the fused-filament (3D printing) process is described to overcome challenges with existing methods of creating custom-shaped IPMC actuators. By working with ionomeric precursor material, the 3D-printing process enables the creation of 3D monolithic IPMC devices where ultimately integrated sensors and actuators can be achieved. Second, Bayesian optimization is used as a learning-based control approach to help mitigate complex time-varying dynamic effects in 3D-printed actuators. This approach overcomes the challenges with existing methods where complex models or continuous sensor feedback are needed. The manufacturing and control paradigm is applied to create and control the behavior of example actuators, and subsequently the actuator components are combined to create an example modular reconfigurable IPMC soft crawling robot to demonstrate feasibility. Two hypotheses related to the effectiveness of the machine-learning process are tested. Results show enhancement of actuator performance through machine learning, and the proof-of-concepts can be leveraged for continued advancement of more complex IPMC devices. Emerging challenges are also highlighted

Functional Soft Robotic Actuators Based on Dielectric Elastomers

Dielectric elastomer actuators (DEAs) are a promising soft actuator technology for robotics. Adding robotic functionalities--folding, variable stiffness, and adhesion--into their actuator design is a novel method to create functionalized robots with simplified actuator configurations. We first propose a foldable actuator that has a simple antagonistic DEA configuration allowing bidirectional actuation and passive folding. To prove the concept, a foldable elevon actuator with outline size of 70 mm × 130 mm is developed with a performance specification matched to a 400 mm wingspan micro air vehicle (MAV) of mass 130 g. The developed actuator exhibits actuation angles up to ± 26 ° and a torque of 2720 mN·mm in good agreement with a prediction model. During a flight, two of these integrated elevon actuators well controlled the MAV, as proven by a strong correlation of 0.7 between the control signal and the MAV motion. We next propose a variable stiffness actuator consisting of a pre-stretched DEA bonded on a low-melting-point alloy (LMPA) embedded silicone substrate. The phase of the LMPA changes between liquid and solid enabling variable stiffness of the structure, between soft and rigid states, while the DEA generates a bending actuation. A proof-of-concept actuator with dimension 40 mm length × 10mm width × 1mm thickness and a mass of 1 g is fabricated and characterized. Actuation is observed up to 47.5 ° angle and yielding up to 2.4 mN of force in the soft state. The stiffness in the rigid state is ~90 × larger than an actuator without LMPA. We develop a two-finger gripper in which the actuators act as the fingers. The rigid state allows picking up an object mass of 11 g (108 mN), to be picked up even though the actuated grasping force is only 2.4 mN. We finally propose an electroadhesion actuator that has a DEA design simultaneously maximizing electroadhesion and electrostatic actuation, while allowing self-sensing by employing an interdigitated electrode geometry. The concept is validated through development of a two-finger soft gripper, and experimental samples are characterized to address an optimal design. We observe that the proposed DEA design generates 10 × larger electroadhesion force compared to a conventional DEA design, equating to a gripper with a high holding force (3.5 N shear force for 1 cm^2) yet a low grasping force (1 mN). These features make the developed simple gripper to handle a wide range of challenging objects such as highly-deformable water balloons (35.6 g), flat paper (0.8 g), and a raw chicken egg (60.9 g), with its lightweight (1.5 g) and fast movement (100 ms to close fingers). The results in this thesis address the creation of the functionalized robots and expanding the use of DEAs in robotics

Verfahren und Anlagenprototyp zur Herstellung dünnwandiger Hohlzylinder aus Silikonelastomer mit integrierten Fluidkammern und –kanälen

Die minimal-invasive Chirurgie gewinnt innerhalb der invasiven Therapieverfahren weiterhin an Bedeutung, verspricht man sich davon doch eine schnellere Genesung des Patienten, verbunden mit einer Reduktion der finanziellen Aufwände für das Gesundheitssystem. Zu diesem Zweck werden Lokomotionssysteme benötigt, die sich aktiv in den natürlichen Körperhöhlen des Patienten fortbewegen können, um Arbeitskanäle und Operationswerkzeuge des Chirurgen von außen zum gewünschten Operationsfeld zu transportieren. Vollständig nachgiebige, miniaturisierte Systeme mit wurmartiger Fortbewegung sind dabei im Fokus der internationalen Entwicklungen. Eine wesentliche Limitation bei der Entwicklung und weiteren Miniaturisierung solcher Lokomotionssysteme besteht durch die verfügbaren Herstellverfahren. Die vorliegende Arbeit stellt ein neues Verfahren und einen Anlagenprototyp zur Herstellung dünnwandigen Hohlzylinders aus Elastomer vor, in deren Wandung im Rahmen des Verfahrens Fluidkammern und –kanäle integriert werden. Durch Befüllung der Miniaturfluidsysteme mit Fluid und Steuerung des ein- bzw. ausgepumpten Fluidvolumens, kann eine zielgerichtete Verformung der Kammern erzeugt werden. Durch Ausstattung des Hohlzylinder mit einer ganzen Reihe von Kammern und Kanälen soll so im Rahmen weiterer Entwicklungen eine peristaltische Sonde entstehen, die sich wurmartig im Wirbelkanal fortbewegen kann. Das vorgestellte Verfahren besteht aus den folgenden Schritten: 1. Auf einen Metallstab wird durch Tauchen (Dip-Coating) eine lösbare Trennschicht aus Photoresist aufgebracht. 2. Anschließend wird auf der Trennschicht und ebenfalls durch Tauchen eine erste, die innere Schicht aus Silikonelastomer erzeugt. 3. Diese Silikonschicht wird durch Aufsprühen (Spray-Coating) unter Nutzung spezieller Prozeßparameter mit Photoresist beschichtet, welches anschließend mittels Laser-Lithografie belichtet wird. 4. Nach dem Entwickeln, Spülen und Trocknen verbleiben auf der Oberfläche der Silikonschicht Resiststrukturen, die die späteren Fluidkammern und Zuläufe repräsentieren. 5. Diese Resiststrukturen sind Platzhalter für das innere, später mit Fluid gefüllte Volumen, wenn in einem weiteren Schritt erneut durch Tauchen die äußere Silikonelastomerschicht aufgebracht wird. In Anlehnung an die klassische Gießerei- und an die Mikrosystemtechnik können die Resiststrukturen auch als Opferstrukturen bezeichnet werden. 6. Anschließend wird der entstandene Silikonkörper mit entsprechenden Schlauchzuleitungen verbunden und über diese wird Lösungsmittel zugeführt, welches die Resiststrukturen auflöst. 7. Nach dem Spülen der Kammern und Zuläufe können diese mit dem Arbeitsfluid (z.B. sterile, isotonische Kochsalzlösung) befüllt werden

Mobility, Navigation and Localization Towards Robotic Endoscopy

With significant progress being made towards improving endoscope technology such as capsule endoscopy and robotic endoscopy, the development of advanced strategies for manipulating, controlling and more generally, easing the accessibility of these devices for physicians is an important next step. This work presents the development of several robotic platforms for experimentally testing navigation and localization strategies in robotic endoscopy followed by the development and testing of navigation strategies using these devices. Finally, visual and visual inertial localization and mapping is explored on two of these robotic systems. We first present a detailed description on the state-of-the-art with regard to minimally invasive robotic surgery and then follow this with in-depth description of our design and validation of two important systems, the Robotic Endoscope Platform (REP) and the Modular Endoscopy Simulation Apparatus (MESA), for exploring some of the challenges in robotic endoscopy. Following these descriptions we present a technique for autonomous navigation of the REP within the MESA as well as an attempt at applying Simultaneous Localization and Mapping (SLAM) to allow for the real-time localization of this system. Finally, we transition these techniques to the Endoculus, a complete robotic endoscope suitable for in vivo testing, and demonstrate both autonomous navigation for this device, and the implementation of three different SLAM systems for localization and mapping of the Endoculus system in real-time. Throughout these experiments we demonstrate the potential for advanced methods in computer vision along with other sensory techniques to substantially benefit endoscopy, enabling greater and greater autonomy of these systems and furthering the case for robotic endoscopy as a whole.</p

Nonlinear viscoelastic materials : bioinspired applications and new characterization measures

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Vita.Includes bibliographical references (p. 297-313).Viscoelastic materials, such as biomaterials and non-Newtonian fluids, typically experience mechanical loading which evokes a nonlinear rheological response. Rheologically complex materials can provide novel functionality in biological and engineered systems. However, it is found that standard characterization techniques are insufficient to appropriately describe nonlinear viscoelasticity. The goal of this thesis is to transcend the limitations of current characterization methods as well as demonstrate applications of nonlinear viscoelastic materials, including reversible adhesion and snail-like wall climbing. PART ONE of this thesis introduces a complete language and framework (or ontology) for characterizing nonlinear viscoelasticity using large amplitude oscillatory shear (LAOS) deformation. The LAOS protocol spans the 2D parameter space of deformation amplitude and frequency, known as a Pipkin space. Physically meaningful material measures are proposed, corresponding to clearly defined language such as strain-stiffening/softening and shear-thickening/thinning. The new ontology is general enough to be applied to any viscoelastic material, mapping behaviors from purely elastic to purely viscous, and any complex response in-between. The framework has been packaged into a distributable data analysis program (MITlaos) to widen its use in both academic and industrial settings. PART TWO examines the nonlinear rheological response of various soft materials and constitutive models.(cont.) The new framework is illustrated by examining prototypical nonlinear constitutive models (Giesekus, pseudoplastic Carreau, and elastoplastic Bingham). Various soft materials are tested experimentally, including pedal mucus gel from terrestrial gastropods, a wormlike micelle solution, ultrasoft hagfish slime, and an oilfield drilling fluid. PART THREE describes the use of nonlinear rheological behavior to enable unique functionality, specifically for bioinspired snail-like wall climbing and tunable adhesion using magnetorheological fluids. Yield stress fluids are examined here to enable the bioinspired adhesive locomotion of a self-contained mechanical device (Robosnail, developed by Brian Chan, Ph.D. '09). Field-responsive magnetorheological fluids are analyzed in the context of providing fast-switching reversible adhesion for use with adhesive locomotion devices and shape-changing soft robots. In conclusion, interest in soft materials is increasing across many disciplines. The contributions presented here provide the means to a better understanding of biological and engineered systems which involve complex viscoelastic materials.by Randy H. Ewoldt.Ph.D

Design of a walking robot

Carnegie Mellon University's Autonomous Planetary Exploration Program (APEX) is currently building the Daedalus robot; a system capable of performing extended autonomous planetary exploration missions. Extended autonomy is an important capability because the continued exploration of the Moon, Mars and other solid bodies within the solar system will probably be carried out by autonomous robotic systems. There are a number of reasons for this - the most important of which are the high cost of placing a man in space, the high risk associated with human exploration and communication delays that make teleoperation infeasible. The Daedalus robot represents an evolutionary approach to robot mechanism design and software system architecture. Daedalus incorporates key features from a number of predecessor systems. Using previously proven technologies, the Apex project endeavors to encompass all of the capabilities necessary for robust planetary exploration. The Ambler, a six-legged walking machine was developed by CMU for demonstration of technologies required for planetary exploration. In its five years of life, the Ambler project brought major breakthroughs in various areas of robotic technology. Significant progress was made in: mechanism and control, by introducing a novel gait pattern (circulating gait) and use of orthogonal legs; perception, by developing sophisticated algorithms for map building; and planning, by developing and implementing the Task Control Architecture to coordinate tasks and control complex system functions. The APEX project is the successor of the Ambler project

Models for reinforcement learning and design of a soft robot inspired by Drosophila larvae

Designs for robots are often inspired by animals, as they are designed mimicking animals’ mechanics, motions, behaviours and learning. The Drosophila, known as the fruit fly, is a well-studied model animal. In this thesis, the Drosophila larva is studied and the results are applied to robots. More specifically: a part of the Drosophila larva’s neural circuit for operant learning is modelled, based on which a synaptic plasticity model and a neural circuit model for operant learning, as well as a dynamic neural network for robot reinforcement learning, are developed; then Drosophila larva’s motor system for locomotion is studied, and based on it a soft robot system is designed. Operant learning is a concept similar to reinforcement learning in computer science, i.e. learning by reward or punishment for behaviour. Experiments have shown that a wide range of animals is capable of operant learning, including animal with only a few neurons, such as Drosophila. The fact implies that operant learning can establish without a large number of neurons. With it as an assumption, the structure and dynamics of synapses are investigated, and a synaptic plasticity model is proposed. The model includes nonlinear dynamics of synapses, especially receptor trafficking which affects synaptic strength. Tests of this model show it can enable operant learning at the neuron level and apply to a broad range of NNs, including feedforward, recurrent and spiking NNs. The mushroom body is a learning centre of the insect brain known and modelled for associative learning, but not yet for operant learning. To investigate whether it participates in operant learning, Drosophila larvae are studied with a transgenic tool by my collaborators. Based on the experiment and the results, a mushroom body model capable of operant learning is modelled. The proposed neural circuit model can reproduce the operant learning of the turning behaviour of Drosophila larvae. Then the synaptic plasticity model is simplified for robot learning. With the simplified model, a recurrent neural network with internal neural dynamics can learn to control a planar bipedal robot in a benchmark reinforcement learning task which is called bipedal walker by OpenAI. Benefiting efficiency in parameter space exploration instead of action space exploration, it is the first known solution to the task with reinforcement learning approaches. Although existing pneumatic soft robots can have multiple muscles embedded in a component, it is far less than the muscles in the Drosophila larva, which are well-organised in a tiny space. A soft robot system is developed based on the muscle pattern of the Drosophila larva, to explore the possibility to embed a high density of muscles in a limited space. Three versions of the body wall with pneumatic muscles mimicking the muscle pattern are designed. A pneumatic control system and embedded control system are also developed for controlling the robot. With a bioinspired body wall will a large number of muscles, the robot performs lifelike motions in experiments

SOFT ROBOTIC APPENDAGES USING PNEUMATIC ARTIFICIAL MUSCLES

This dissertation focuses on advancing the state of the art in soft robotics using pneumatic artificial (PAM) actuators. Pneumatic artificial muscles are currently used in robotic and prosthetic applications due to their high power to weight ratio, controllable compliance, and simple design. Contractile PAMs are typically used in traditional hard robotics in place of heavy electric motors. As the field of soft robotics grows, extensile PAMs are beginning to have increased usage. The bladder of a PAM affects common actuator performance metrics, specifically: blocked force, free contraction, hysteresis, and dead-band pressure. This work investigates the effect that bladder thickness has on static actuation performance of small scale PAMs. Miniature PAMs were fabricated with a range of bladder thicknesses then experimentally characterized in quasi-static conditions, where results showed that increasing bladder wall thickness decreases blocked force and free contraction, while the dead-band pressure increases. A nonlinear model was then applied to determine the structure of the stress-strain relationship that enables accurate modeling and the minimum number of terms. Contractile and extensile PAMs were experimentally fabricated and parametrically compared to demonstrate the advantages and disadvantages of each type of PAM and applications for which they are best suited. An additional PAM model was developed based on finite strain theory to address the lack of predicitive models. The closed-form pneumatic artificial muscle quasi-static actuator force is obtained. The analysis was experimentally validated using actuation force versus contraction ratio test data at a series of discrete inflation pressures for four different pneumatic artificial muscles, two contractile and two extensile. This work investigates adding bio-inspired ossicle structures from brittle stars to pneumatic artificial muscle continuum arm sections. The ossicle structure increases the range of motion and load capability of the continuum arm section while reducing the pneumatic pressure requirements. In this work, a static model of the continuum arm section is developed assuming constant curvature in the section and finding the center of mass of the section and its end plate. This model is validated by comparing the pressure-angle relationship at various loading conditions