Shape-Space Graphs: Fast and Collision-Free Path Planning for Soft Robots
Veil C, Flaschel M, Kuhl E (2026)
Publication Type: Journal article
Publication year: 2026
Journal
Book Volume: 11
Pages Range: 5582-5589
Issue: 5
Abstract
Soft robots, inspired by elephant trunks or octopus arms, offer extraordinary flexibility to bend, twist, and elongate in ways that rigid robots cannot. However, their motion planning remains a challenge, especially in cluttered environments with obstacles, due to their highly nonlinear and infinite-dimensional kinematics. Here, we present a graph-based path planning tool for an elephant-trunk-inspired soft robot designed with three artificial muscle fibers that allow for continuous deformation through contraction. Using a biomechanical model that integrates morphoelastic and active filament theories, we precompute a shape library and construct a k-nearest neighbor graph in shape space, ensuring that each node corresponds to a valid robot shape. For the graph, we use signed distance functions to prune nodes and edges colliding with obstacles, and define multi-objective edge costs based on geometric distance and actuation effort, enabling energy-aware planning with collision avoidance. We demonstrate that our algorithm reliably avoids obstacles and generates feasible paths within milliseconds from precomputed graphs using Dijkstra's algorithm. We show that including energy costs can drastically reduce the actuation effort compared to geometry-only planning, at the expense of longer tip trajectories. Our results highlight the potential of shape-space graph search for fast and reliable path planning in the field of soft robotics, paving the way for real-time applications in surgical, industrial, and assistive settings.
Authors with CRIS profile
Moritz Flaschel
Lehrstuhl für Technische Mechanik (LTM)
Ellen Kuhl
Lehrstuhl für Technische Mechanik (LTM)
Involved external institutions
United States (USA) (US)How to cite
APA:
Veil, C., Flaschel, M., & Kuhl, E. (2026). Shape-Space Graphs: Fast and Collision-Free Path Planning for Soft Robots. IEEE Robotics and Automation Letters, 11, 5582-5589. https://doi.org/10.1109/LRA.2026.3674004
MLA:
Veil, Carina, Moritz Flaschel, and Ellen Kuhl. "Shape-Space Graphs: Fast and Collision-Free Path Planning for Soft Robots." IEEE Robotics and Automation Letters 11 (2026): 5582-5589.
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