Soft Robot Arm Shape Sensing: A Solution Based on Millimeter Wave Ranging Nodes

Flexible robots exhibit a high degree of agility, offering significant advantages over rigid robots in the manipulation of objects and the emulation of biomimetic motions. However, the absence of key rotational joints presents challenges in posture estimation through traditional Inertial Measurement Units (IMUs) or rotation metrics of motors, leading to difficulties in self-shape perception. This study introduces a novel conformation measurement methodology and device for flexible robotic arms using millimeter wave ranging technology. The method includes the arrangement of multiple primary positioning tags along the flexible arm, supplemented by auxiliary tags at fixed intervals; acquisition of relative distances between primary tags; determination of relative positions of these tags; absolute positioning of the primary tags in three-dimensional space with auxiliary ones; and curve fitting of the absolute positions to generate a conforming profile of the flexible arm. This approach effectively addresses the shape perception challenge in flexible robots, significantly contributing to efficient operation and precise control in complex environments.