Geometric analysis of the singularities of a magnetic manipulation system with several mobile coils.

International audienceIt has been demonstrated that magnetic fields are relevant for manipulating an untethered magnet, either using fixed coils or mobile permanent magnets. This paper shows however, that any magnetic manipulation method is prone to singular configurations and that the simple numerical analysis of the rank of the "manipulation matrix" is not enough to detect them. Alternatively, we propose a geometrical analysis to interpret and detect the singularities as well as to decide on the acceptability of a reference trajectory. Then, we present results obtained by simulating a planar manipulation system including a multiple mobile coils and a Helmholtz like set-up

Study on Magnetic Control Systems of Micro-Robots

Magnetic control systems of micro-robots have recently blossomed as one of the most thrilling areas in the field of medical treatment. For the sake of learning how to apply relevant technologies in medical services, we systematically review pioneering works published in the past and divide magnetic control systems into three categories: stationary electromagnet control systems, permanent magnet control systems and mobile electromagnet control systems. Based on this, we ulteriorly analyze and illustrate their respective strengths and weaknesses. Furthermore, aiming at surmounting the instability of magnetic control system, we utilize SolidWorks2020 software to partially modify the SAMM system to make its final overall thickness attain 111 mm, which is capable to control and observe the motion of the micro-robot under the microscope system in an even better fashion. Ultimately, we emphasize the challenges and open problems that urgently need to be settled, and summarize the direction of development in this field, which plays a momentous role in the wide and safe application of magnetic control systems of micro-robots in clinic

Actuation, Sensing And Control For Micro Bio Robots

The continuing trend in miniaturization of technology, advancements in micro and nanofabrication and improvements in high-resolution imaging has enabled micro- and meso-scale robots that have many applications. They can be used for micro-assembly, directed drug delivery, microsurgery and high-resolution measurement. In order to create microrobots, microscopic sensors, actuators and controllers are needed. Unique challenges arise when building microscale robots. For inspiration, we look toward highly capable biological organisms, which excel at these length scales. In this dissertation we develop technologies that combine biological components and synthetic components to create actuation, sensing and assembly onboard microrobots. For actuation, we study the dynamics of synthetic micro structures that have been integrated with single-cell biological organisms to provide un-tethered onboard propulsion to the microrobot. For sensing, we integrate synthetically engineered sensor cells to enable a system capable of detecting a change in the local environment, then storing and reporting the information. Furthermore, we develop a bottom-up fabrication method using a macroscopic magnetic robot to direct the assembly of inorganic engineered micro structures. We showcase the capability of this assembly method by demonstrating highly-specified, predictable assembly of microscale building blocks in a semi-autonomous experiment. These magnetic robots can be used to program the assembly of passive building blocks, with the building blocks themselves having the potential to be arbitrarily complex. We extend the magnetic robot actuation work to consider control algorithms for multiple robots by exploiting spatial gradients of magnetic fields. This thesis makes contributions toward actuation, sensing and control of autonomous micro systems and provides technologies that will lead to the development of swarms of microrobots with a suite of manipulation and sensing capabilities working together to sense and modify the environment

Advances in Robot Kinematics : Proceedings of the 15th international conference on Advances in Robot Kinematics

International audienceThe motion of mechanisms, kinematics, is one of the most fundamental aspect of robot design, analysis and control but is also relevant to other scientific domains such as biome- chanics, molecular biology, . . . . The series of books on Advances in Robot Kinematics (ARK) report the latest achievement in this field. ARK has a long history as the first book was published in 1991 and since then new issues have been published every 2 years. Each book is the follow-up of a single-track symposium in which the participants exchange their results and opinions in a meeting that bring together the best of world’s researchers and scientists together with young students. Since 1992 the ARK symposia have come under the patronage of the International Federation for the Promotion of Machine Science-IFToMM.This book is the 13th in the series and is the result of peer-review process intended to select the newest and most original achievements in this field. For the first time the articles of this symposium will be published in a green open-access archive to favor free dissemination of the results. However the book will also be o↵ered as a on-demand printed book.The papers proposed in this book show that robot kinematics is an exciting domain with an immense number of research challenges that go well beyond the field of robotics.The last symposium related with this book was organized by the French National Re- search Institute in Computer Science and Control Theory (INRIA) in Grasse, France

The ARMM System-Autonomous Steering of Magnetically-Actuated Catheters:Towards Endovascular Applications

Positioning conventional endovascular catheters is not without risk, and there is a multitude of complications that are associated with their use in manual surgical interventions. By utilizing surgical manipulators, the efficacy of remote-controlled catheters can be investigated in vivo. However, technical challenges, such as the duration of catheterizations, accurate positioning at target sites, and consistent imaging of these catheters using non-hazardous modalities, still exist. In this paper, we propose the integration of multiple sub-systems in order to extend the clinical feasibility of an autonomous surgical system designed to address these challenges. The system handles the full synchronization of co-operating manipulators that both actuate a clinical tool. The experiments within this study are conducted within a clinically-relevant workspace and inside a gelatinous phantom that represents a life-size human torso. A catheter is positioned using magnetic actuation and proportional-integral (PI) control in conjunction with real-time ultrasound images. Our results indicate an average error between the tracked catheter tip and target positions of 2:09 0:49 mm. The median procedure time to reach targets is 32:6 s. We expect that our system will provide a step towards collaborative manipulators employing mobile electromagnets, and possibly improve autonomous catheterization procedures within endovascular surgeries

Singular robust room-temperature spin response from topological Dirac fermions

Topological insulators are a class of solids in which the nontrivial inverted bulk band structure gives rise to metallic surface states that are robust against impurity scattering. In three-dimensional (3D) topological insulators, however, the surface Dirac fermions intermix with the conducting bulk, thereby complicating access to the low energy (Dirac point) charge transport or magnetic response. Here we use differential magnetometry to probe spin rotation in the 3D topological material family (Bi$_2$Se$_3$, Bi$_2$Te$_3$, and Sb$_2$Te$_3$). We report a paramagnetic singularity in the magnetic susceptibility at low magnetic fields which persists up to room temperature, and which we demonstrate to arise from the surfaces of the samples. The singularity is universal to the entire family, largely independent of the bulk carrier density, and consistent with the existence of electronic states near the spin-degenerate Dirac point of the 2D helical metal. The exceptional thermal stability of the signal points to an intrinsic surface cooling process, likely of thermoelectric origin, and establishes a sustainable platform for the singular field-tunable Dirac spin response.Comment: 20 pages, 14 figure

Control of Magnetic Continuum Robots for Endoscopy

The present thesis discusses the problem of magnetic actuation and control applied to millimetre-scale robots for endoluminal procedures. Magnetic actuation, given its remote manipulation capabilities, has the potential to overcome several limitations of current endoluminal procedures, such as the relatively large size, high sti�ness and limited dexterity of existing tools. The application of functional forces remotely facilitates the development of softer and more dexterous endoscopes, which can navigate with reduced discomfort for the patient. However, the solutions presented in literature are not always able to guarantee smooth navigation in complex and convoluted anatomical structures. This thesis aims at improving the navigational capabilities of magnetic endoluminal robots, towards achieving full autonomy. This is realized by introducing novel design, sensing and control approaches for magnetically actuated soft endoscopes and catheters. First, the application of accurate closed-loop control to a 1 Internal Permanent Magnet (IPM) endoscope was analysed. The proposed approach can guarantee better navigation capabilities, thanks to the manipulation of every mechanical Degree of Freedom (DOF) - 5 DOFs. Speci�cally, it was demonstrated that gravity can be balanced with su�cient accuracy to guarantee tip levitation. In this way contact is minimized and obstacle avoidance improved. Consequently, the overall navigation capabilities of the endoscope were enhanced for given application. To improve exploration of convoluted anatomical pathways, the design of magnetic endoscopes with multiple magnetic elements along their length was introduced. This approach to endoluminal device design can ideally allow manipulation along the full length; facilitating full shape manipulation, as compared to tip-only control. To facilitate the control of multiple magneto-mechanical DOFs along the catheters' length, a magnetic actuation method was developed based on the collaborative robotic manipulation of 2 External Permanent Magnets (EPMs). This method, compared to the state-of-the-art, facilitates large workspace and applied �eld, while guaranteeing dexterous actuation. Using this approach, it was demonstrated that it is possible to actuate up to 8 independent magnetic DOFs. In the present thesis, two di�erent applications are discussed and evaluated, namely: colonoscopy and navigational bronchoscopy. In the former, a single-IPM endoscopic approach is utilized. In this case, the anatomy is large enough to permit equipping the endoscope with a camera; allowing navigation by direct vision. Navigational bronchoscopy, on-the-other-hand, is performed in very narrow peripheral lumina, and navigation is informed via pre-operative imaging. The presented work demonstrates how the design of the magnetic catheters, informed by a pre-operative Computed Tomography (CT) scan, can mitigate the need for intra-operative imaging and, consequently, reduce radiation exposure for patients and healthcare workers. Speci�cally, an optimization routine to design the catheters is presented, with the aim of achieving follow-the-leader navigation without supervision. In both scenarios, analysis of how magnetic endoluminal devices can improve the current practice and revolutionize the future of medical diagnostics and treatment is presented and discussed

Doctor of Philosophy

dissertationThis dissertation presents results documenting advancements on the control of untethered magnetic devices, such as magnetic \microrobots" and magnetically actuated capsuleendoscopes, motivated by problems in minimally invasive medicine. This dissertationfocuses on applying rotating magnetic elds for magnetic manipulation. The contributions include advancements in the way that helical microswimmers (devices that mimicthe propulsion of bacterial agella) are controlled in the presence of gravitational forces, advancements in ways that groups of untethered magnetic devices can be dierentiated and semi-independently controlled, advancements in the way that untethered magnetic device can be controlled with a single rotating permanent magnet, and an improved understanding in the nature of the magnetic force applied to an untethered device by a rotating magnet

A Novel Propeller Design for Micro-Swimming robot

The applications of a micro-swimming robot such as minimally invasive surgery, liquid pipeline robot etc. are widespread in recent years. The potential application fields are so inspiring, and it is becoming more and more achievable with the development of microbiology and Micro-Electro-Mechanical Systems (MEMS). The aim of this study is to improve the performance of micro-swimming robot through redesign the structure. To achieve the aim, this study reviewed all of the modelling methods of low Reynolds number flow including Resistive-force Theory (RFT), Slender Body Theory (SBT), and Immersed Boundary Method (IBM) etc. The swimming model with these methods has been analysed. Various aspects e.g. hydrodynamic interaction, design, development, optimisation and numerical methods from the previous researches have been studied. Based on the previous design of helix propeller for micro-swimmer, this study has proposed a novel propeller design for a micro-swimming robot which can improve the velocity with simplified propulsion structure. This design has adapted the coaxial symmetric double helix to improve the performance of propulsion and to increase stability. The central lines of two helical tails overlap completely to form a double helix structure, and its tail radial force is balanced with the same direction and can produce a stable axial motion. The verification of this design is conducted using two case studies. The first one is a pipe inspection robot which is in mm scale and swims in high viscosity flow that satisfies the low Reynolds number flow condition. Both simulation and experiment analysis are conducted for this case study. A cross-development method is adopted for the simulation analysis and prototype development. The experiment conditions are set up based on the simulation conditions. The conclusion from the analysis of simulation results gives suggestions to improve design and fabrication for the prototype. Some five revisions of simulation and four revisions of the prototype have been completed. The second case study is the human blood vessel robot. For the limitations of fabrication technology, only simulation is conducted, and the result is compared with previous researches. The results show that the proposed propeller design can improve velocity performance significantly. The main outcomes of this study are the design of a micro-swimming robot with higher velocity performance and the validation from both simulation and experiment

A Platform for Robot-Assisted Intracardiac Catheter Navigation

Steerable catheters are routinely deployed in the treatment of cardiac arrhythmias. During invasive electrophysiology studies, the catheter handle is manipulated by an interventionalist to guide the catheter's distal section toward endocardium for pacing and ablation. Catheter manipulation requires dexterity and experience, and exposes the interventionalist to ionizing radiation. Through the course of this research, a platform was developed to assist and enhance the navigation of the catheter inside the cardiac chambers. This robotic platform replaces the interventionalist's hand in catheter manipulation and provides the option to force the catheter tip in arbitrary directions using a 3D input device or to automatically navigate the catheter to desired positions within a cardiac chamber by commanding the software to do so. To accomplish catheter navigation, the catheter was modeled as a continuum manipulator, and utilizing robot kinematics, catheter tip position control was designed and implemented. An electromagnetic tracking system was utilized to measure the position and orientation of two key points in catheter model, for position feedback to the control system. A software platform was developed to implement the navigation and control strategies and to interface with the robot, the 3D input device and the tracking system. The catheter modeling was validated through in-vitro experiments with a static phantom, and in-vivo experiments on three live swines. The feasibility of automatic navigation was also veri ed by navigating to three landmarks in the beating heart of swine subjects, and comparing their performance with that of an experienced interventionalist using quasi biplane fluoroscopy. The platform realizes automatic, assisted, and motorized navigation under the interventionalist's control, thus reducing the dependence of successful navigation on the dexterity and manipulation skills of the interventionalist, and providing a means to reduce the exposure to X-ray radiation. Upon further development, the platform could be adopted for human deployment