Zhang Zhengya, Klingner Anke, Misra Sarthak, Khalil Islam S M
Department of Biomaterials & Biomedical Technology, University of Groningen and University Medical Center Groningen, Groningen, 9713 AV, The Netherlands.
Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Wenzhou, 325035, China.
Sci Rep. 2025 Aug 23;15(1):31041. doi: 10.1038/s41598-025-15247-7.
Tetherless magnetic devices (TMDs) that are driven using external stimuli have potential applications in minimally invasive surgery. The magnetic field produced by electromagnet- and permanent magnet-based robotic systems is a viable option as an external stimulus to enable the motion of a TMD in viscous and viscoelastic media. In order to realize the navigation of TMDs in fluidic environments, we design a permanent magnet-based robotic system with an open configuration using two synchronized rotating magnetic dipoles to generate time-varying rotating magnetic fields. These fields are used to apply torque on a TMD in low-Reynolds-number flow regimes. The configuration of the system is vertically symmetric, allowing permanent magnets to exert relatively uniform magnetic fields within the center of the workspace. We derive the configuration-to-pose kinematics and the pose-to-field mapping of the system. Such derivation is the basis for realizing the motion control of TMDs in three-dimensional space. The kinematic system holds one translational degree of freedom (DOF) and three rotational DOFs, allowing it to control the pose of actuator magnets with four DOFs. The nonlinear inverse kinematic problem is solved using an optimization algorithm. The experimental results of this level of control demonstrate that the mean absolute error and the maximum tracking error of three-dimensional motion control are 1.18 mm and 2.64 mm, respectively. This paper tackles the challenge of generating and controlling synchronized rotating magnetic fields to actuate and navigate TMDs. Commonly, this involves collaboratively manipulating two permanent magnets by attaching each to the end-effector of an industrial robot. This paper proposes a novel approach: robotically manipulating two permanent magnets through a symmetric configuration constrained by a connecting plate. This method simplifies the manipulation of rotating magnetic fields, thereby aiding the simplification of TMD motion control strategies. Future research will improve the design of this robotic system to offer more degrees of freedom, thus achieving greater flexibility in TMD motion control.
利用外部刺激驱动的无系留磁性装置（TMDs）在微创手术中具有潜在应用。基于电磁体和永磁体的机器人系统产生的磁场作为一种外部刺激，能够使TMD在粘性和粘弹性介质中运动，是一种可行的选择。为了实现TMD在流体环境中的导航，我们设计了一种基于永磁体的开放式机器人系统，该系统使用两个同步旋转的磁偶极子来产生随时间变化的旋转磁场。这些磁场用于在低雷诺数流动状态下对TMD施加扭矩。该系统的结构是垂直对称的，使得永磁体能够在工作空间中心内施加相对均匀的磁场。我们推导了该系统的构型到位姿运动学以及位姿到磁场映射。这种推导是实现TMD在三维空间中运动控制的基础。该运动学系统具有一个平移自由度（DOF）和三个旋转自由度，使其能够控制具有四个自由度的致动器磁体的位姿。使用优化算法解决了非线性逆运动学问题。这种控制水平的实验结果表明，三维运动控制的平均绝对误差和最大跟踪误差分别为1.18毫米和2.64毫米。本文解决了产生和控制同步旋转磁场以驱动和导航TMD的挑战。通常，这涉及通过将两个永磁体分别连接到工业机器人的末端执行器上来协同操纵它们。本文提出了一种新颖的方法：通过由连接板约束的对称构型以机器人方式操纵两个永磁体。这种方法简化了旋转磁场的操纵，从而有助于简化TMD运动控制策略。未来的研究将改进该机器人系统的设计以提供更多自由度，从而在TMD运动控制中实现更大的灵活性。
