Seesaw-type force sensor with variable spring constant utilizing magnetic restoring force and external laser displacement measurement
Soft actuators have garnered significant attention for applications in medical and wearable devices owing to their lightweight properties and inherent safety. Nevertheless, standardized performance charts for such actuators remain scarce, complicating the selection of suitable actuators for specific...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
The Japan Society of Mechanical Engineers
2025-06-01
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| Series: | Mechanical Engineering Journal |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/mej/12/4/12_25-00104/_pdf/-char/en |
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| Summary: | Soft actuators have garnered significant attention for applications in medical and wearable devices owing to their lightweight properties and inherent safety. Nevertheless, standardized performance charts for such actuators remain scarce, complicating the selection of suitable actuators for specific applications. One of the fundamental characteristics of soft actuators is that the force–displacement relationship is influenced by the stiffness of the object with which they interact. To evaluate the sensor characteristics, conventional methods employ rigid load cells, which hinders the simultaneous measurement of force and displacement under varying stiffness conditions. Here, we propose a force sensor consisting of a seesaw-type beam embedded with an internal magnet and a laser displacement meter. External magnets are installed above and below the internal magnet, enabling modulation of the beam’s effective spring constant by varying the distance to the external magnets and their magnetic polarity. This configuration enables both repulsive and attractive magnetic forces, facilitating continuous and wide-range stiffness adjustment. The sensor structure was fabricated using a 3D printer. Experimental validation confirmed that the spring constant was tunable within the range of 5.9 to 20 N/m. Furthermore, the sensitivity of the laser displacement meter remained consistent, with a standard deviation corresponding to an error of approximately 2.2% across varying stiffness conditions. These results suggest that the proposed sensor can measure force while adjusting its stiffness, making it useful for evaluating the performance of soft actuators under different mechanical stiffness conditions. |
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| ISSN: | 2187-9745 |