GelStereo 2.0: An Improved GelStereo Sensor With Multimedium Refractive Stereo Calibration

• Published in: IEEE transactions on industrial electronics (1982) Vol. 71; no. 7; pp. 7452 - 7462
• Main Authors: Zhang, Chaofan, Cui, Shaowei, Wang, Shuo, Hu, Jingyi, Cai, Yinghao, Wang, Rui, Wang, Yu
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 3-D geometry sensing; Calibration; Cameras; Elastomers; Error analysis; Geometry; Light refraction; Ray tracing; refractive calibration; Robot sensing systems; robotic manipulation; Sensors; Solid modeling; tactile sensors
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2023.3312418

Visuotactile sensors have significant advantages in high-resolution contact shape sensing, which is crucial for robots to locate and manipulate objects. However, high precision and robust 3-D geometry sensing is still a challenging problem. In this article, we propose an improved GelStereo sensor, named GelStereo 2.0, with a more stable and compact structure. A refractive stereo ray tracing modeling method is proposed to eliminate 3-D geometry reconstruction errors caused by multimedium light refraction. In addition, we introduce a novel calibration method named multiple contact depths to obtain refractive parameters, which only needs a few pressings using calibration boards. Extensive experimental results show that the measurement error of contact surface depth is less than 0.15 mm. Furthermore, two well-calibrated sensors mounted on the gripper are successfully applied to a fingertip bolt screwing task, which demonstrates the effectiveness of the GelStereo 2.0 sensor and the proposed tactile 3-D geometry sensing method.