Learning Sequences of Manipulation Primitives for Robotic Assembly

This paper explores the idea that skillful assembly is best represented as dynamic sequences of Manipulation Primitives, and that such sequences can be automatically discovered by Reinforcement Learning. Manipulation Primitives, such as ``Move down until contact'', ``Slide along x while maintaining contact with the surface'', have enough complexity to keep the search tree shallow, yet are generic enough to generalize across a wide range of assembly tasks. Policies are learned in simulation, and then transferred onto the physical platform. Direct sim2real transfer (without retraining in real) achieves excellent success rates on challenging assembly tasks, such as round peg insertion with 100 micron clearance or square peg insertion with large hole position/orientation estimation errors.