A Miniature High-Resolution Tension Sensor Based on a Photo-Reflector for Robotic Hands and Grippers

Fuente: arXiv
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Autores principales: Kim, Hyun-Bin, Kim, Kyung-Soo
Formato: Preprint
Publicado: 2025
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author Kim, Hyun-Bin
Kim, Kyung-Soo
author_facet Kim, Hyun-Bin
Kim, Kyung-Soo
contents This paper presents a miniature tension sensor using a photo-reflector, designed for compact tendon-driven grippers and robotic hands. The proposed sensor has a small form factor of 13~mm x 7~mm x 6.5~mm and is capable of measuring tensile forces up to 200~N. A symmetric elastomer structure incorporating fillets and flexure hinges is designed based on Timoshenko beam theory and verified via FEM analysis, enabling improved sensitivity and mechanical durability while minimizing torsional deformation. The sensor utilizes a compact photo-reflector (VCNT2020) to measure displacement in the near-field region, eliminating the need for light-absorbing materials or geometric modifications required in photo-interrupter-based designs. A 16-bit analog-to-digital converter (ADC) and CAN-FD (Flexible Data-rate) communication enable efficient signal acquisition with up to 5~kHz sampling rate. Calibration experiments demonstrate a resolution of 9.9~mN (corresponding to over 14-bit accuracy) and a root mean square error (RMSE) of 0.455~N. Force control experiments using a twisted string actuator and PI control yield RMSEs as low as 0.073~N. Compared to previous research using photo-interrupter, the proposed method achieves more than tenfold improvement in resolution while also reducing nonlinearity and hysteresis. The design is mechanically simple, lightweight, easy to assemble, and suitable for integration into robotic and prosthetic systems requiring high-resolution force feedback.
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id arxiv_https___arxiv_org_abs_2507_00464
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Miniature High-Resolution Tension Sensor Based on a Photo-Reflector for Robotic Hands and Grippers
Kim, Hyun-Bin
Kim, Kyung-Soo
Robotics
This paper presents a miniature tension sensor using a photo-reflector, designed for compact tendon-driven grippers and robotic hands. The proposed sensor has a small form factor of 13~mm x 7~mm x 6.5~mm and is capable of measuring tensile forces up to 200~N. A symmetric elastomer structure incorporating fillets and flexure hinges is designed based on Timoshenko beam theory and verified via FEM analysis, enabling improved sensitivity and mechanical durability while minimizing torsional deformation. The sensor utilizes a compact photo-reflector (VCNT2020) to measure displacement in the near-field region, eliminating the need for light-absorbing materials or geometric modifications required in photo-interrupter-based designs. A 16-bit analog-to-digital converter (ADC) and CAN-FD (Flexible Data-rate) communication enable efficient signal acquisition with up to 5~kHz sampling rate. Calibration experiments demonstrate a resolution of 9.9~mN (corresponding to over 14-bit accuracy) and a root mean square error (RMSE) of 0.455~N. Force control experiments using a twisted string actuator and PI control yield RMSEs as low as 0.073~N. Compared to previous research using photo-interrupter, the proposed method achieves more than tenfold improvement in resolution while also reducing nonlinearity and hysteresis. The design is mechanically simple, lightweight, easy to assemble, and suitable for integration into robotic and prosthetic systems requiring high-resolution force feedback.
title A Miniature High-Resolution Tension Sensor Based on a Photo-Reflector for Robotic Hands and Grippers
topic Robotics
url https://arxiv.org/abs/2507.00464