The Third Generation (G3) Dual-Modal and Dual Sensing Mechanisms (DMDSM) Pretouch Sensor for Robotic Grasping

Fingertip-mounted pretouch sensors are very useful for robotic grasping. In this paper, we report a new (G3) dual-modal and dual sensing mechanisms (DMDSM) pretouch sensor for near-distance ranging and material sensing, which is based on pulse-echo ultrasound (US) and optoacoustics (OA). Different from previously reported versions, the G3 sensor utilizes a self-focused US/OA transceiver, thereby eliminating the need of a bulky parabolic reflective mirror for focusing the ultrasound and laser beams. The self-focused laser and ultrasound beams can be easily steered by a (flat) scanning mirror which expands from single-point ranging and detection to areal mapping or imaging. To verify the new design, a prototype G3 DMDSM sensor with a scanning mirror is fabricated. The US and OA ranging performances are tested in experiments. Together with the scanning mirror, thin wire targets made of same or different materials at different positions are scanned and imaged. The ranging and imaging results show that the G3 DMDSM sensor can provide new and better pretouch mapping and imaging capabilities for robotic grasping than its predecessors.