SPARC: A Soft, Proprioceptive, Agile Robot for 3D Climbing and Exploration with Precise Trajectory Following.

Abstract

Soft robots, like their natural counterparts, are well-suited for exploring 3D terrains due to their large deformation, impact resistance, and adaptive adhesion, derived from their inherent compliance. However, developing soft robots that can navigate both horizontal and vertical surfaces with seamless transitions and precise trajectory tracking remains a challenge. SPARC, a Soft, Proprioceptive, Agile Robot is presented for 3D climbing and exploration with accurate trajectory following. SPARC integrates three parallel 3D-printed Kresling origami actuators with suction cups for 3D actuation and adhesion across diverse surfaces. Leveraging the contraction-twisting coupling of Kresling structures, SPARC enables real-time proprioception through inverse kinematics modeling. A dual closed-loop control strategy combined with efficient online path planning allows precise pose control using onboard angle sensors and global position tracking. Experiments demonstrate SPARC's ability to follow curved and sharply angled trajectories with high precision'achieving 0.5% accuracy on horizontal and 3% on vertical surfaces'while carrying payloads exceeding twice its weight (500 g) on vertical climbs. Moreover, connecting two SPARC modules enables smooth ground-to-wall transitions. The seamless integration of large-magnitude 3D actuation, proprioceptive state sensing, and efficient online path planning makes SPARC a unique soft robot capable of precise trajectory following and navigation in 3D terrains.