CoinFT: A Coin-Sized, Capacitive 6-Axis Force Torque Sensor for Robotic Applications

We introduce CoinFT, a capacitive 6-axis force/torque (F/T) sensor that is compact, light, low-cost, and robust with an average mean-squared error of 0.11N for force and 0.84mNm for moment when the input ranges from 0~10N and 0~4N in normal and shear directions, respectively. CoinFT is a stack of two rigid PCBs with comb-shaped electrodes connected by an array of silicone rubber pillars. The microcontroller interrogates the electrodes in different subsets in order to enhance sensitivity for measuring 6-axis F/T. The combination of desirable features of CoinFT enables various contact-rich robot interactions at a scale, across different embodiment domains including drones, robot end-effectors, and wearable haptic devices. We demonstrate the utility of CoinFT on drones by performing an attitude-based force control to perform tasks that require careful contact force modulation. The design, fabrication, and firmware of CoinFT are open-sourced atthis https URL.

@article{choi2025_2503.19225,
  title={ CoinFT: A Coin-Sized, Capacitive 6-Axis Force Torque Sensor for Robotic Applications },
  author={ Hojung Choi and Jun En Low and Tae Myung Huh and Gabriela A. Uribe and Seongheon Hong and Kenneth A. W. Hoffman and Julia Di and Tony G. Chen and Andrew A. Stanley and Mark R. Cutkosky },
  journal={arXiv preprint arXiv:2503.19225},
  year={ 2025 }
}