Planning for Robotic Dry Stacking with Irregular Stones

Dry stacking with found, minimally processed rocks is a useful capability when it comes to autonomous construction. However, it is a difficult planning problem since both the state and action space are continuous, and structural stability is strongly affected by complex friction and contact constraints. We propose an algorithmic approach for autonomous construction from a collection of irregularly shaped objects. The structure planning is calculated in simulation by first considering geometric and physical constraints to find a small set of feasible actions and then refined by using a hierarchical filter based on heuristics. These plans are then executed open-loop with a robotic arm equipped with a wrist RGB-D camera. Experimental results show that the proposed planning algorithm can significantly improve the state of the art robotics dry-stacking techniques.