The developement of strain wave geared actuator for lightweight lower limb leg exoskeltons

2024 Fiscal Year Final Research Report

• Project/Area Number: 21K14101
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 20010:Mechanics and mechatronics-related
• Research Institution: Ibaraki University
• Principal Investigator: Kitayama Fumiya 茨城大学, 応用理工学野, 講師 (50774197)
• Project Period (FY): 2021-04-01 – 2025-03-31
• Keywords: 磁気式波動歯車 / 伝達トルク / 軽量化 / 脚支援機器

Outline of Final Research Achievements

We have developed a lightweight magnetic strain wave gear for lower-limb exoskeletons, utilizing permanent magnets in place of the mechanical cam. In this gear, the distribution of magnetic forces deforms the flexible outer gear, allowing the gear teeth to engage with the rigid inner gear. The flexible outer gear rotates with deceleration, operating on the principle of differential gears. We analyzed the operation through magnetic and multi-flexible body dynamic analyses, and we measured the transmission torque and deformed shape using a torque sensor and laser displacement sensors. The weight of the primary components ranges from 250 to 400 g. The analyzed and measured maximum transmission torques were 12.5 Nm and 10.0 Nm, respectively. Based on these findings, we anticipate a weight reduction of about 40% in the lower limb exoskeleton (Manipuleg, Ibaraki University).

Free Research Field

アクチュエータ工学

Academic Significance and Societal Importance of the Research Achievements

本研究で開発した磁気式波動歯車は変形と磁場の両方を利用する特異な構造・動作原理を有しており、機械式波動歯車と比べると軽量であり、磁気歯車と比べて高い減速比を実現できる。
磁気式波動歯車を搭載した脚支援機器は軽量となるため、介護者や下肢麻痺者の負担軽減に寄与できる。さらに、人協調ロボットや上肢装着型支援装置などの軽量化を要する幅広い分野での応用も期待される。