Efficient Optimization of a Permanent Magnet Array for a Stable 2D Trap

Fuente: arXiv
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Autori principali: Müller, Ann-Sophia, Jeong, Moonkwang, Tian, Jiyuan, Zhang, Meng, Qiu, Tian
Natura: Preprint
Pubblicazione: 2025
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author Müller, Ann-Sophia
Jeong, Moonkwang
Tian, Jiyuan
Zhang, Meng
Qiu, Tian
author_facet Müller, Ann-Sophia
Jeong, Moonkwang
Tian, Jiyuan
Zhang, Meng
Qiu, Tian
contents Untethered magnetic manipulation of biomedical millirobots has a high potential for minimally invasive surgical applications. However, it is still challenging to exert high actuation forces on the small robots over a large distance. Permanent magnets offer stronger magnetic torques and forces than electromagnetic coils, however, feedback control is more difficult. As proven by Earnshaw's theorem, it is not possible to achieve a stable magnetic trap in 3D by static permanent magnets. Here, we report a stable 2D magnetic force trap by an array of permanent magnets to control a millirobot. The trap is located in an open space with a tunable distance to the magnet array in the range of 20 - 120mm, which is relevant to human anatomical scales. The design is achieved by a novel GPU-accelerated optimization algorithm that uses mean squared error (MSE) and Adam optimizer to efficiently compute the optimal angles for any number of magnets in the array. The algorithm is verified using numerical simulation and physical experiments with an array of two magnets. A millirobot is successfully trapped and controlled to follow a complex trajectory. The algorithm demonstrates high scalability by optimizing the angles for 100 magnets in under three seconds. Moreover, the optimization workflow can be adapted to optimize a permanent magnet array to achieve the desired force vector fields.
format Preprint
id arxiv_https___arxiv_org_abs_2511_19201
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Efficient Optimization of a Permanent Magnet Array for a Stable 2D Trap
Müller, Ann-Sophia
Jeong, Moonkwang
Tian, Jiyuan
Zhang, Meng
Qiu, Tian
Robotics
Untethered magnetic manipulation of biomedical millirobots has a high potential for minimally invasive surgical applications. However, it is still challenging to exert high actuation forces on the small robots over a large distance. Permanent magnets offer stronger magnetic torques and forces than electromagnetic coils, however, feedback control is more difficult. As proven by Earnshaw's theorem, it is not possible to achieve a stable magnetic trap in 3D by static permanent magnets. Here, we report a stable 2D magnetic force trap by an array of permanent magnets to control a millirobot. The trap is located in an open space with a tunable distance to the magnet array in the range of 20 - 120mm, which is relevant to human anatomical scales. The design is achieved by a novel GPU-accelerated optimization algorithm that uses mean squared error (MSE) and Adam optimizer to efficiently compute the optimal angles for any number of magnets in the array. The algorithm is verified using numerical simulation and physical experiments with an array of two magnets. A millirobot is successfully trapped and controlled to follow a complex trajectory. The algorithm demonstrates high scalability by optimizing the angles for 100 magnets in under three seconds. Moreover, the optimization workflow can be adapted to optimize a permanent magnet array to achieve the desired force vector fields.
title Efficient Optimization of a Permanent Magnet Array for a Stable 2D Trap
topic Robotics
url https://arxiv.org/abs/2511.19201