GelRoller: A Rolling Vision-based Tactile Sensor for Large Surface Reconstruction Using Self-Supervised Photometric Stereo Method

Accurate perception of the surrounding environ- ment stands as a primary objective for robots. Through tactile interaction, vision-based tactile sensors provide the capability to capture high-resolution and multi-modal surface informa- tion of objects, thereby facilitating robots in achieving more dexterous manipulations. However, the prevailing GelSight sen- sors entail intricate calibration procedures, posing challenges in their application on curved surfaces and requiring the maintenance of stable lighting conditions throughout experi- mentation. Additionally, constrained by shape and structure, current vision-based tactile sensors are predominantly applied to measurements within a limited area. In this study, we design a novel cylindrical vision-based tactile sensor that enables continuous and swift perception of large-scale object surfaces through rolling. To tackle the challenges posed by laborious calibration processes, we propose a self-supervised photometric stereo method based on deep learning, which eliminates pre- calibration requirements and enables the derivation of surface normals from a single image without relying on stable lighting conditions. Finally, we perform surface reconstruction from normal and point cloud registration on the multiple frames of images obtained by rolling the cylindrical sensor, resulting in large surface reconstruction. We compare our method with the representative lookup table method in the GelSight sensors. The results show that the proposed method enhances both reconstruction accuracy and robustness, thereby demonstrating the potential of the proposed sensor in large-scale surface reconstruction. Codes and mechanical structures are available at: https://github.com/ZhangZhiyuanZhang/GelRoller