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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2509.23561 |
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| _version_ | 1866909946635878400 |
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| author | Wang, Jianren Xie, Quanting Han, Jie Zhang, Yang Atkeson, Christopher G. Gupta, Abhinav Pathak, Deepak Bisk, Yonatan |
| author_facet | Wang, Jianren Xie, Quanting Han, Jie Zhang, Yang Atkeson, Christopher G. Gupta, Abhinav Pathak, Deepak Bisk, Yonatan |
| contents | Quasi-direct-drive (QDD) actuation is transforming legged and manipulator robots by eliminating high-ratio gearboxes, yet it demands motors that deliver very high torque at low speed within a thin, disc-shaped joint envelope. Axial-flux permanent-magnet (AFPM) machines meet these geometric and torque requirements, but scaling them below a 20mm outer diameter is hampered by poor copper fill in conventional wound stators, inflating resistance and throttling continuous torque. This paper introduces a micro-scale AFPM motor that overcomes these limitations through printed-circuit-board (PCB) windings fabricated with advanced IC-substrate high-density interconnect (HDI) technology. The resulting 48-layer stator-formed by stacking four 12-layer HDI modules-achieves a record 45\% copper fill in a package only 5mm thick and 19mm in diameter. We perform comprehensive electromagnetic and thermal analyses to inform the motor design, then fabricate a prototype whose performance characteristics are experimentally verified. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_23561 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | High Torque Density PCB Axial Flux Permanent Magnet Motor for Micro Robots Wang, Jianren Xie, Quanting Han, Jie Zhang, Yang Atkeson, Christopher G. Gupta, Abhinav Pathak, Deepak Bisk, Yonatan Robotics Quasi-direct-drive (QDD) actuation is transforming legged and manipulator robots by eliminating high-ratio gearboxes, yet it demands motors that deliver very high torque at low speed within a thin, disc-shaped joint envelope. Axial-flux permanent-magnet (AFPM) machines meet these geometric and torque requirements, but scaling them below a 20mm outer diameter is hampered by poor copper fill in conventional wound stators, inflating resistance and throttling continuous torque. This paper introduces a micro-scale AFPM motor that overcomes these limitations through printed-circuit-board (PCB) windings fabricated with advanced IC-substrate high-density interconnect (HDI) technology. The resulting 48-layer stator-formed by stacking four 12-layer HDI modules-achieves a record 45\% copper fill in a package only 5mm thick and 19mm in diameter. We perform comprehensive electromagnetic and thermal analyses to inform the motor design, then fabricate a prototype whose performance characteristics are experimentally verified. |
| title | High Torque Density PCB Axial Flux Permanent Magnet Motor for Micro Robots |
| topic | Robotics |
| url | https://arxiv.org/abs/2509.23561 |