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A pulmonary embolism is a blood clot that develops in a blood vessel (often in the leg) and then travels to a lung artery, where it suddenly blocks blood flow. A miniature magnetic rotating swimmer (MMRS) is a device with internal magnets and propeller fins. It can be steered by an external rotating magnetic field. The shape of the swimmer combined with the rotational movement can generate a propulsive force to move the swimmer to the target location, abrading blood clots using the rotational motion. This chapter presents the MMRS’s design and fabrication, thrombi disruption performance, and 3D path-following capability. Algorithms that enable controlling a swimmer in 3D using a 2D ultrasonography device are presented. A tool that can deliver and retrieve the MMRS for thrombi disruption is demonstrated. 

Miniature Magnetic Rotating Swimmers (MMRSs) are emerging as a promising technology to improve minimally invasive vascular and cardiac surgeries. Currently, these procedures are typically performed using catheters, which are thin flexible tubes inserted into blood vessels. However, catheters rub against artery walls and can dislodge fat deposits, which can lead to complications such as stroke. In contrast, MMRSs are untethered, wirelessly controlled devices actuated by an external magnetic field. Their compact size could allow them to navigate the bloodstream of a patient and reach treatment areas without the risks associated with catheter use. Surgical tasks, such as tissue cutting or ablation, require significant power, but due to their miniature size, MMRSs lack the capacity to store sufficient onboard energy. This paper studies an MMRS that can be heated wirelessly via induction. The method allows transferring enough power to denature proteins. 

This study investigates the efficacy of an untethered magnetic robot (UMR) for wireless mechanical and hybrid blood clot removal in ex vivo tissue environments. By integrating x-ray-guided wireless manipulation with UMRs, we aim to address challenges associated with precise and controlled blood clot intervention. The untethered nature and size of these robots enhance maneuverability and accessibility within complex vascular networks, potentially improving clot removal efficiency. We explore mechanical fragmentation, chemical lysis, and hybrid dissolution techniques that combine mechanical fragmentation with chemical lysis, highlighting their potential for targeted and efficient blood clot removal. Through experimental validation using an ex vivo endovascular thrombosis model within the iliac artery of a sheep, we demonstrate direct revascularization of a 13-mm-long, 1-day-old blood clot positioned inside the left common iliac artery. This was achieved by deploying a UMR into the abdominal aorta within 15 min. Additionally, both mechanical fragmentation and hybrid dissolution achieve a greater volume rate of change compared to no intervention (control) and chemical lysis alone. Mechanical fragmentation exhibits clot removal with a median of 0.87 mm3/min and a range of 2.81 mm3/min, while the hybrid approach demonstrates slower but more consistent clot removal, with a median of 0.45 mm3/min and a range of 0.23 mm3/min. 

Many potential medical applications for magnetically controlled tetherless devices inside the human body have been proposed, including procedures such as biopsies, blood clot removal, and targeted drug delivery. These devices are capable of wirelessly navigating through fluid-filled cavities in the body, such as the vascular system, eyes, urinary tract, and ventricular system, to reach areas difficult to access via conventional methods. Once at their target location, these devices could perform various medical interventions. This paper focuses on a special type of magnetic tetherless device called a magnetic rotating swimmer, which has internal magnets and propeller fins with a helical shape. To facilitate the design process, an automated geometry generation program using OpenSCAD was developed to create the swimmer design, while computational fluid dynamics simulations using OpenFOAM were employed to calculate the propulsive force produced by the swimmer. Furthermore, an experimental approach is proposed and demonstrated to validate the model. The results show good agreement between simulations and experiments, indicating that the model could be used to develop an automatic geometry optimization pipeline for rotating swimmers. 

We present a heuristic method to construct an optimal communication network in an obstacle-dense environment. A set of immobile terminals must be connected by a network of straight-line edges by adding agents to serve as relays. Obstacles are represented by polygons, unaccessible by the agents of the network or by the edges. The problem with obstacles is reduced to a problem without obstacles by choosing the nodes of the optimal network among the obstacles’ vertices that are in mutual line of sight. A second heuristic method is developed to solve the bicriteria optimization problem with number of agents and length of the network as concurrent costs. 

We present a magnetic camera system developed to detect ferrous or ferromagnetic objects. The main motivation is detection and tracking of underwater pipelines. Many industries, such as oil and gas, must perform inspection and maintenance of pipelines and automation is desirable. An electromagnet generates a static magnetic field which is read by an array of Hall-effect sensors. The presence of ferromagnetic materials distorts this field, which can be detected by the sensors and creates a magnetic image. The grid configuration of the camera allows for quick computation of the center of mass and general orientation of detected pipes, facilitating tracking. This camera is carried by an ROV and tested in a pool environment. 

We present strategies for realizing a swarm of mobile relays to provide a bi-directional wireless network that connects fixed terminals. Neither terminals or relays are permitted to transmit into disk-shaped no-transmission zones. We assume a planar environment and that each transmission area is a disk centered at the transmitter. We seek a strongly connected network between all terminals with minimal total cost, where the cost is the sum area of the transmission disks.Results for networks with increasing levels of complexity are provided. The solutions for local networks containing low numbers of relays and terminals are applied to larger networks. For more complex networks, algorithms for a minimum-spanning tree (MST) based procedure are implemented to reduce the solution cost. 

Given starting and ending positions and velocities, L2 bounds on the acceleration and velocity, and the restriction to no more than two constant control inputs, this paper provides routines to compute the minimal-time path. Closed form solutions are provided for reaching a position in minimum time with and without a velocity bound, and for stopping at the goal position. A numeric solver is used to reach a goal position and velocity with no more than two constant control inputs. If a cruising phase at the terminal velocity is needed, this requires solving a non-linear equation with a single parameter. Code is provided on GitHub 1 , extended paper version at [1]. [1] https://github.com/RoboticSwarmControl/MinTimeL2pathsConstraints/ 

Magnetic modular cubes are cube-shaped bodies with embedded permanent magnets. The cubes are uniformly controlled by a global time-varying magnetic field.A 2D physics simulator is used to simulate global control and the resulting continuous movement of magnetic modular cube structures. We develop local plans, closed-loop control algorithms for planning the connection of two structures at desired faces. The global planner generates a building instruction graph for a target structure that we traverse in a depth-first-search approach by repeatedly applying local plans.We analyze how structure size and shape affect planning time. The planner solves 80% of the randomly created instances with up to 12 cubes in an average time of about 200 seconds. 

We present an analytic solution to the 3D Dubins path problem for paths composed of an initial circular arc, a straight component, and a final circular arc. These are commonly called CSC paths. By modeling the start and goal configurations of the path as the base frame and final frame of an RRPRR manipulator, we treat this as an inverse kinematics problem. The kinematic features of the 3D Dubins path are built into the constraints of our manipulator model. Furthermore, we show that the number of solutions is not constant, with up to seven valid CSC path solutions even in non-singular regions. An implementation of solution is available at https: //github.com/aabecker/dubins3D.