Flexible sensor measures three-axis forces for robot touch safety
VecTile: A Low-Cost Flexible Tactile Array for 3-DoF Force Sensing
Robotics
Summary
Robots need a sense of touch that can feel forces not just pressing straight down but also sliding sideways. The authors created VecTile, a thin, flexible, and inexpensive sensor that detects these three directions of force. It uses a special material and bumps that turn pressure into easy-to-read signals. VecTile can be made without fancy machines and helps robots avoid damage, like stopping a sharp blade from poking a balloon. It also helps robots perform precise tasks like plugging in power cords.
What this means in practice
- •For roboticists: Add low-cost, flexible sensors that detect normal and shear forces to improve robot manipulation and grasp stability.
- •For industrial automation engineers: Use a flexible tactile array to enhance precision and safety in robot-assisted assembly tasks, such as power-plug insertion.
Authors
Jian Hou, Xin Zhou, Adam J. Spiers
Abstract
Tactile sensing provides robots with contact information difficult to obtain from vision alone. Shear force is particularly important for understanding tangential contact, guiding corrective motions, and maintaining grasp stability, yet flexible and low-cost tactile arrays often measure only normal force. We introduce VecTile, a low-cost, 6 mm thin, flexible tactile array capable of three-axis force sensing. VecTile combines a piezoresistive layer with passive silicone nubs that convert normal and shear forces into distinguishable pressure patterns. The sensor can be fabricated in-house without specialized equipment. The complete system costs less than 35 USD for a 4x4 array. We validate the sensing mechanism through finite element analysis and hardware experiments. In controlled single-taxel tests over 1-5 N normal force and up to 1.5 N shear force, VecTile achieves root-mean-square errors of 0.39 N and 0.16 N for normal and shear forces. A VecTile calibrated while flat retains accuracy when curved, while a five-minute manual calibration is sufficient for practical use. Two applications demonstrate its utility. First, shear readings are sensitive enough to stop a sharp scalpel from puncturing a balloon after contact. Second, the sensor substantially improves Diffusion Policy-guided power-plug insertion. All designs and code will be released upon paper acceptance. Project website: https://jiannnh.github.io/VecTile/.