CAREER: Design, Optimization, and Feedback Control of Noncontact Magnetic Manipulators

当医生需要进入患者的内部器官时，许多医疗程序本质上是侵入性的。由于这些程序通常是不方便的，痛苦的，昂贵的，显着的研究工作正在进行的非侵入性医疗工具和技术的发展。在这方面的任何努力都必须回答一个基本问题：如何在不实际接触的情况下操作医疗工具。这个问题的一个可行的答案是使用磁铁：磁化工具可以在患者体内安全地使用位于体外的足够强的磁铁。例如，人们可以想象一种无痛、无麻醉的胃肠道内窥镜检查程序，该程序利用由磁化的微小胶囊携带的小型化相机，并且胶囊通过一组外部磁体在胃肠道内导航。这套磁铁，连同控制他们的机械，一般被称为非接触式magnetic manipulator.本项目的目的是建立一个技术基础的设计，实施和评估的非接触式磁操纵器适用于广泛的外科手术，医学成像和诊断应用。这项研究的结果将支持许多研究人员，工程师，医生和私营公司目前致力于设计和开发非侵入性医疗设备的努力，因此，将有助于更广泛地开发新的医疗技术，提高护理质量，患者安全，并获得负担得起的医疗保健。此外，本项目还将推进小型化非接触式磁操纵器的开发，这对于生物医学和纳米技术应用中广泛使用的微和纳米尺度系统的致动和控制至关重要。非接触式磁操纵器利用多个磁体的阵列来产生和精确控制磁场，其在其影响区域内与磁性物体或流体相互作用，以便在没有直接机械接触的情况下从远处操纵它们。由于磁场通过磁屏障传播不变，非接触式磁操纵器提供了一种独特的能力，以控制在这些物理屏障后面的区域中的磁性物体，否则这些物体是不可接近的。该项目的重点将是永磁机械手，其中磁场由永磁体的机械运动控制，而不是传统的方法依赖于电磁体和容易控制其端子电压。这种传统的方法一直是磁操纵器的现有文献的焦点。然而，永磁体产生的磁场比相同尺寸，重量和成本的电磁体强得多。这一关键优势主张将技术范式转向永磁体，作为开发紧凑，有效和廉价的磁性机械手的必要步骤，用于医疗应用，这些应用通常需要更大的磁力，距离更远。现有的文献永磁机械手仍处于早期阶段，不足以支持广泛的新应用的尖端技术的发展。建议的研究旨在填补这一空白，建立一个框架的设计，分析，优化和反馈控制的永磁机械手。该框架由实验支持的数学建模工具，实时优化方法和反馈控制技术组成，适用于几种具有实际意义的场景。这些场景包括单个或多个磁性粒子的路径跟踪、磁性刚体的多自由度运动控制以及磁性流体的输送。这套连贯的分析和数值工具将促进精确、可靠、紧凑和具有成本效益的磁操纵器的设计和制造的进步，这些磁操纵器适合集成到新一代医疗设备中，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Many medical procedures are invasive in nature when the physicians need to access internal organs of a patient. Since these procedures are usually inconvenient, painful, and costly, significant research efforts are being conducted on development of noninvasive medical tools and techniques. Any effort in this direction has to answer a fundamental question: how to operate a medical tool without actually touching it. A viable answer to this question is the use of magnets: magnetized tools can be safely operated inside a patient's body using sufficiently strong magnets located outside the body. For example, one can imagine a painless, anesthesia-free gastrointestinal endoscopy procedure that utilizes a miniaturized camera carried by a magnetized tiny capsule, and the capsule is navigated inside the gastrointestinal tract by a set of external magnets. This set of magnets, together with the machinery controlling them, is generically called noncontact magnetic manipulator.The purpose of this project is to establish a technical foundation for design, implementation, and evaluation of noncontact magnetic manipulators suited for a wide range of surgical, medical imaging, and diagnostic applications. The results of this research will support the efforts of many researchers, engineers, physicians, and private companies currently working on design and development of noninvasive medical devices, and therefore, will contribute to a broader effort in development of novel medical techniques which improve the quality of care, patient safety, and access to affordable health care. Furthermore, this project will advance the development of miniaturized noncontact magnetic manipulators, which are essential for actuation and control of micro- and nano-scale systems widely used in biomedical and nanotechnology applications.Noncontact magnetic manipulators utilize arrays of multiple magnets to generate and precisely control magnetic fields, which interact with magnetic objects or fluids in their region of influence in order to manipulate them from a distance without direct mechanical contact. Since magnetic fields propagate unchanged through nonmagnetic barriers, noncontact magnetic manipulators provide a unique capability to control magnetic objects in the regions behind such physical barriers, which are otherwise inaccessible. The focus of this project will be on permanent magnet manipulators in which magnetic fields are controlled by mechanical movement of permanent magnets, rather than the conventional approach relying on electromagnets and easy control of their terminal voltages. This conventional approach has been the focus of much of the existing literature on magnetic manipulators. However, permanent magnets produce much stronger magnetic fields than electromagnets of the same size, weight, and cost. This key advantage advocates a technological paradigm shift toward permanent magnets as a necessary step in development of compact, effective, and inexpensive magnetic manipulators for medical applications which often require larger magnetic forces at further distances. The existing literature on permanent magnet manipulators is still at an early stage and inadequate to support the development of cutting-edge technologies for a broad range of novel applications. The proposed research is aimed at filling this void by establishing a framework for design, analysis, optimization, and feedback control of permanent magnet manipulators. This framework consists of mathematical modeling tools supported by experiment, real-time optimization methods, and feedback control techniques for several scenarios of practical importance. These scenarios include path tracking of single or multiple magnetic particles, multi-degree-of-freedom motion control of magnetic rigid bodies, and transport of magnetic fluids. This coherent set of analytical and numerical tools will promote advancements in design and manufacturing of precise, reliable, compact, and cost-effective magnetic manipulators suitable for integration into new generations of medical devices, as well as micro- and nano-scale systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.