Efficient and Interpretable Robot Manipulation with Graph Neural Networks

Manipulation tasks like loading a dishwasher can be seen as a sequence of spatial constraints and relationships between different objects. We aim to discover these rules from demonstrations by posing manipulation as a classification problem over a graph, whose nodes represent task-relevant entities like objects and goals. In our experiments, a single GNN policy trained using imitation learning (IL) on 20 expert demonstrations can solve blockstacking and rearrangement tasks in both simulation and on hardware, generalizing over the number of objects and goal configurations. These experiments show that graphical IL can solve complex long-horizon manipulation problems without requiring detailed task descriptions.