A Full-Optical Pretouch Dual-Modal and Dual-Mechanism (PDM²) Sensor for Robotic Grasping

Abstract

We report a new full-optical pretouch dual-modal and dual-mechanism (PDM2) sensor based on an air-coupled fiber-tip surface micromachined optical ultrasound transducer (SMOUT). Compared to ring-shaped piezoelectric acoustic receivers in previous PDM<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> sensors, the acoustic signal received by the new fiber-tip SMOUT is readout optically, which is naturally resistant to surrounding electromagnetic interference (EMI) and makes the complex grounding and shielding unnecessary. In addition, the new fiber-tip SMOUT receiver has a much smaller size, which makes it possible to further miniaturize the sensor package into a more compact structure. For verification, a prototype of the full-optical PDM<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> sensor has been designed, fabricated, and characterized. The experimental results show that even with the much smaller acoustic receiver, the new sensor can still achieve ranging and material/structure sensing performances comparable with the previous ones. Therefore, the new full optical PDM<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> sensor design is promising in providing a practical and miniaturized solution for ranging and material/structure sensing to assist robotic grasping of unknown objects.