Design of Compliant Mechanosensory Composite (CMC) and its Application Toward the Sensible Mesoscale Robotics

Abstract

Sensed information greatly helps a robot to adjust its motion or modulate the locomotory behavior. While many sensing components have been developed for macroscale robots, such off-the-shelf sensors are hardly integrated with a mesoscale (i.e., 0.1 mm to 10 mm) robot due to the size limitation. In this work, we propose a Compliant Mechanosensory Composite (CMC) to fabricate a small compliant mechanism with embedded sensing ability. As the first demonstration of CMC, we directly print a conductive polymer PEDOT:PSS onto the flexible joint of a compliant mechanism to sense the motion of the flexible joint itself. Owing to the variation of electric contact resistance (ECR) upon bending, the CMC could estimate its bending angle. The performance of the CMC was verified by analyzing the cyclic bending, transient and stationary response. Overall, a sparsely printed serpentine pattern with thicker line exhibited consistent response without a noticeable hysteresis. To demonstrate the applicability of the CMC process, a small gripper actuated by a SMA (shape memory alloy) coil was fabricated, and its motion was successfully measured using the embedded sensors. We expect the proposed CMC will enable a small robot to become sensible at its self motion, external load, and physical contacts in future.