Snake Robots for Surgical Applications: A Review

Although substantial advancements have been achieved in robot-assisted surgery, the blueprint to existing snake robotics predominantly focuses on the preliminary structural design, control, and human–robot interfaces, with features which have not been particularly explored in the literature. This paper aims to conduct a review of planning and operation concepts of hyper-redundant serpentine robots for surgical use, as well as any future challenges and solutions for better manipulation. Current researchers in the field of the manufacture and navigation of snake robots have faced issues, such as a low dexterity of the end-effectors around delicate organs, state estimation and the lack of depth perception on two-dimensional screens. A wide range of robots have been analysed, such as the i2Snake robot, inspiring the use of force and position feedback, visual servoing and augmented reality (AR). We present the types of actuation methods, robot kinematics, dynamics, sensing, and prospects of AR integration in snake robots, whilst addressing their shortcomings to facilitate the surgeon’s task. For a smoother gait control, validation and optimization algorithms such as deep learning databases are examined to mitigate redundancy in module linkage backlash and accidental self-collision. In essence, we aim to provide an outlook on robot configurations during motion by enhancing their material compositions within anatomical biocompatibility standards

Using the Fringe Field of MRI Scanner for the Navigation of Microguidewires in the Vascular System

Le traitement du cancer, la prévention des accidents vasculaires cérébraux et le diagnostic ou le traitement des maladies vasculaires périphériques sont tous des cas d'application d'interventions à base de cathéter par le biais d'un traitement invasif minimal. Cependant, la pratique du cathétérisme est généralement pratiquée manuellement et dépend fortement de l'expérience et des compétences de l'interventionniste. La robotisation du cathétérisme a été étudiée pour faciliter la procédure en augmentant les niveaux d’autonomie par rapport à cette pratique clinique. En ce qui concerne ce problème, un des problèmes concerne le placement super sélectif du cathéter dans les artères plus étroites nécessitant une miniaturisation de l'instrument cathéter / fil de guidage attaché. Un microguide qui fonctionne dans des vaisseaux sanguins étroits et tortueux subit différentes forces mécaniques telles que le frottement avec la paroi du vaisseau. Ces forces peuvent empêcher la progression de la pointe du fil de guidage dans les vaisseaux. Une méthode proposée consiste à appliquer une force de traction à la pointe du microguide pour diriger et insérer le dispositif tout en poussant l’instrument attaché à partir de l’autre extrémité n’est plus pratique, et à exploiter le gradient du champ de franges IRM surnommé Fringe Field Navigation (FFN ) est proposée comme solution pour assurer cet actionnement. Le concept de FFN repose sur le positionnement d'un patient sur six DOF dans le champ périphérique du scanner IRM afin de permettre un actionnement directionnel pour la navigation du fil-guide. Ce travail rend compte des développements requis pour la mise en oeuvre de la FFN et l’étude du potentiel et des possibilités qu’elle offre au cathétérisme, en veillant au renforcement de l’autonomie. La cartographie du champ de franges d'un scanner IRM 3T est effectuée et la structure du champ de franges en ce qui concerne son uniformité locale est examinée. Une méthode pour la navigation d'un fil de guidage le long d'un chemin vasculaire souhaité basée sur le positionnement robotique du patient à six DOF est développée. Des expériences de FFN guidées par rayons X in vitro et in vivo sur un modèle porcin sont effectuées pour naviguer dans un fil de guidage dans la multibifurcation et les vaisseaux étroits. Une caractéristique unique de FFN est le haut gradient du champ magnétique. Il est démontré in vitro et in vivo que cette force surmonte le problème de l'insertion d'un fil microguide dans des vaisseaux tortueux et étroits pour permettre de faire avancer le fil-guide avec une distale douce au-delà de la limite d'insertion manuelle. La robustesse de FFN contre les erreurs de positionnement du patient est étudiée en relation avec l'uniformité locale dans le champ périphérique. La force élevée du champ magnétique disponible dans le champ de franges IRM peut amener les matériaux magnétiques doux à son état de saturation. Ici, le concept d'utilisation d'un ressort est présenté comme une alternative vi déformable aux aimants permanents solides pour la pointe du fil-guide. La navigation d'un microguide avec une pointe de ressort en structure vasculaire complexe est également réalisée in vitro. L'autonomie de FFN en ce qui concerne la planification d'une procédure avec autonomie de tâche obtenue dans ce travail augmente le potentiel de FFN en automatisant certaines étapes d'une procédure. En conclusion, FFN pour naviguer dans les microguides dans la structure vasculaire complexe avec autonomie pour effectuer le positionnement du patient et contrôler l'insertion du fil de guidage - avec démonstration in vivo dans un modèle porcin - peut être considéré comme un nouvel outil robotique facilitant le cathétérisme vasculaire. tout en aidant à cibler les vaisseaux lointains dans le système vasculaire.----------ABSTRACT Treatment of cancer, prevention of stroke, and diagnosis or treatment of peripheral vascular diseases are all the cases of application of catheter-based interventions through a minimal-invasive treatment. However, performing catheterization is generally practiced manually, and it highly depends on the experience and the skills of the interventionist. Robotization of catheterization has been investigated to facilitate the procedure by increasing the levels of autonomy to this clinical practice. Regarding it, one issue is the super selective placement of the catheter in the narrower arteries that require miniaturization of the tethered catheter/guidewire instrument. A microguidewire that operates in narrow and tortuous blood vessels experiences different mechanical forces like friction with the vessel wall. These forces can prevent the advancement of the tip of the guidewire in the vessels. A proposed method is applying a pulling force at the tip of the microguidewire to steer and insert the device while pushing the tethered instrument from the other end is no longer practical, and exploiting the gradient of the MRI fringe field dubbed as Fringe Field Navigation (FFN) is proposed as a solution to provide this actuation. The concept of FFN is based on six DOF positioning of a patient in the fringe field of the MRI scanner to enable directional actuation for the navigation of the guidewire. This work reports on the required developments for implementing FFN and investigating the potential and the possibilities that FFN introduces to the catheterization, with attention to enhancing the autonomy. Mapping the fringe field of a 3T MRI scanner is performed, and the structure of the fringe field regarding its local uniformity is investigated. A method for the navigation of a guidewire along a desired vascular path based on six DOF robotic patient positioning is developed. In vitro and in vivo x-ray Guided FFN experiments on a swine model of are performed to navigate a guidewire in the multibifurcation and narrow vessels. A unique feature of FFN is the high gradient of the magnetic field. It is demonstrated in vitro and in vivo that this force overcomes the issue of insertion of a microguidewire in tortuous and narrow vessels to enable advancing the guidewire with a soft distal beyond the limit of manual insertion. Robustness of FFN against the error in the positioning of the patient is investigated in relation to the local uniformity in the fringe field. The high strength of the magnetic field available in MRI fringe field can bring soft magnetic materials to its saturation state. Here, the concept of using a spring is introduced as a deformable alternative to solid permanent magnets for the tip of the guidewire. Navigation of a microguidewire with a viii spring tip in complex vascular structure is also performed in vitro. The autonomy of FFN regarding planning a procedure with Task Autonomy achieved in this work enhances the potential of FFN by automatization of certain steps of a procedure. As a conclusion, FFN to navigate microguidewires in the complex vascular structure with autonomy in performing tasks of patient positioning and controlling the insertion of the guidewire – with in vivo demonstration in swine model – can be considered as a novel robotic tool for facilitating the vascular catheterization while helping to target remote vessels in the vascular system

Design considerations for light weight mechanical parts

Context and Background - Lightweight design is important for many engineering fields due to the increased energy efficiency and process performance that it can result in. Functionally graded materials (FGMs) give a key contribution to lightweight design when low mass along with a gradual change in a second primary constraint is required such as alleviation of a large temperature gradient. With the evolution of additive manufacturing (AM), FGM use for light weighting is rising in practicality. Therefore, research into combining FGMs with AM is required, and should include topics relevant to these, including form, material choice and structural design. The work is tested on robotic arm links due to the ever-increasing adoption of automation, and the practical accessibility of them for the researcher. Aim of Research - The aim of the research is to investigate the mass reduction of robotic arm links by merging second moment of area calculations, structured cells, topology optimisation, functionally graded materials and additive manufacture in various combinations. Key Work - The main output of this work is a set of design guidelines that have been written to assist engineers with combining FGMs, topology optimisation, structured cells and high-level AM restrictions. Within the field of lightweight design, the guidelines are use-case agnostic. The design guidelines have been trialled using test cases, each aimed at individual elements of the guidelines. The objective of the first test case is to discover if FGMs will reduce stresses in parts constructed of dissimilar materials when used in conjunction with high-level AM constraints. The second test case trails the various computational testing sections required in the guidelines, including part sectioning rules and material distribution techniques. The third test case incorporates heat ow simulation during AM deposition of the FGMs, including the three heat transfer mechanisms and interaction with the print bed of AM hardware. The final test case assesses the entirety of the design guidelines, re-examining the aspects tested in the second and third test cases, together with a technique to decide whether structured cells or topology optimisation should be used based on the use case of the part, and a first pass at inspecting the residual stresses in the additively manufactured part once it has cooled. Conclusions - Overall, the use of FGMs along with lightweight structural design techniques and high-level AM restrictions are computationally successful at reducing the mass in robotic arm links. While the design guidelines are use case agnostic, they make most sense used in fields of engineering that have a substantial requirement for light weight design, such as aerospace and space. Ideally, physical testing would have been used to increase validity of the design guidelines. Unfortunately, funds were not available, and thus physical testing is deemed the next step for this work in the future.Context and Background - Lightweight design is important for many engineering fields due to the increased energy efficiency and process performance that it can result in. Functionally graded materials (FGMs) give a key contribution to lightweight design when low mass along with a gradual change in a second primary constraint is required such as alleviation of a large temperature gradient. With the evolution of additive manufacturing (AM), FGM use for light weighting is rising in practicality. Therefore, research into combining FGMs with AM is required, and should include topics relevant to these, including form, material choice and structural design. The work is tested on robotic arm links due to the ever-increasing adoption of automation, and the practical accessibility of them for the researcher. Aim of Research - The aim of the research is to investigate the mass reduction of robotic arm links by merging second moment of area calculations, structured cells, topology optimisation, functionally graded materials and additive manufacture in various combinations. Key Work - The main output of this work is a set of design guidelines that have been written to assist engineers with combining FGMs, topology optimisation, structured cells and high-level AM restrictions. Within the field of lightweight design, the guidelines are use-case agnostic. The design guidelines have been trialled using test cases, each aimed at individual elements of the guidelines. The objective of the first test case is to discover if FGMs will reduce stresses in parts constructed of dissimilar materials when used in conjunction with high-level AM constraints. The second test case trails the various computational testing sections required in the guidelines, including part sectioning rules and material distribution techniques. The third test case incorporates heat ow simulation during AM deposition of the FGMs, including the three heat transfer mechanisms and interaction with the print bed of AM hardware. The final test case assesses the entirety of the design guidelines, re-examining the aspects tested in the second and third test cases, together with a technique to decide whether structured cells or topology optimisation should be used based on the use case of the part, and a first pass at inspecting the residual stresses in the additively manufactured part once it has cooled. Conclusions - Overall, the use of FGMs along with lightweight structural design techniques and high-level AM restrictions are computationally successful at reducing the mass in robotic arm links. While the design guidelines are use case agnostic, they make most sense used in fields of engineering that have a substantial requirement for light weight design, such as aerospace and space. Ideally, physical testing would have been used to increase validity of the design guidelines. Unfortunately, funds were not available, and thus physical testing is deemed the next step for this work in the future

Engineering derivatives from biological systems for advanced aerospace applications

The present study consisted of a literature survey, a survey of researchers, and a workshop on bionics. These tasks produced an extensive annotated bibliography of bionics research (282 citations), a directory of bionics researchers, and a workshop report on specific bionics research topics applicable to space technology. These deliverables are included as Appendix A, Appendix B, and Section 5.0, respectively. To provide organization to this highly interdisciplinary field and to serve as a guide for interested researchers, we have also prepared a taxonomy or classification of the various subelements of natural engineering systems. Finally, we have synthesized the results of the various components of this study into a discussion of the most promising opportunities for accelerated research, seeking solutions which apply engineering principles from natural systems to advanced aerospace problems. A discussion of opportunities within the areas of materials, structures, sensors, information processing, robotics, autonomous systems, life support systems, and aeronautics is given. Following the conclusions are six discipline summaries that highlight the potential benefits of research in these areas for NASA's space technology programs

Accelerated Design Of Architected Materials With Geometric Heterogeneity For Enhanced Failure Characteristics

Nature provides countless examples of the use of material heterogeneity to enhance the failure properties of materials. Many biological materials, such as bone, marine shells, and fish scales, are extremely resilient to fracture and failure. These often consist of regions that are highly mineralized and stiff and regions of biopolymers that are extremely soft. In practice, combining such disparate materials in synthetic systems is fraught with difficulties, such as poor interfacial adhesion. However, we will show, geometric heterogeneity can lead to similar enhancements to failure characteristics, including distribution of voids (inspired by bamboo) and spatial variations in fiber orientation (inspired by many materials, such as aorta). With the nearly arbitrary arrangements of materials that is enabled by 3D printing, it is possible to produce systems with bioinspired, spatially-varying microstructures that results in large improvements to failure properties. In this dissertation, I will discuss two types of geometric heterogeneities that can be easily introduced to architected materials enhancing their failure characteristics. First, inspired by the microstructure of the dactyl club of the Mantis shrimp, we show how geometric defects that are intrinsic to extrusion-based additive processes (voids and weak interfaces) can be spatially arranged in a helical (Bouligand) pattern to produce complex crack patterns and enhanced energy absorption. Next, we show how spatial variations in fiber orientation (inspired by aorta) can be produced using direct ink writing (DIW), leading to soft composites with high toughness and fatigue threshold. Such geometric heterogeneities in architected materials, and the 3D printing processes used to create them, introduce a large number of parameters into the material design process, such as infill layer angle, fiber orientation, void placement, etc. Bio-inspiration provides a starting point and some basic intuition about how to design heterogeneous materials for improved failure properties, but it cannot guarantee optimal failure properties. I will therefore conclude the talk with a discussion of the use of Bayesian optimization for the acceleration of the design of architected heterogeneous materials with optimal failure properties. We will introduce a multi-fidelity Bayesian optimization approach to accelerate the design of heterogeneous triangular lattices with maximal energy absorption during compressive loading