There has been an increasing interest in learning dynamics simulators for model-based control. Compared with off-the-shelf physics engines, a learnable simulator can quickly adapt to unseen objects, scenes, and tasks. However, existing models like interaction networks only work for fully observable systems; they also only consider pairwise interactions within a single time step, both restricting their use in practical systems. We introduce Propagation Networks (PropNet), a differentiable, learnable dynamics model that handles partially observable scenarios and enables instantaneous propagation of signals beyond pairwise interactions. Experiments show that our propagation networks not only outperform current learnable physics engines in forward simulation, but also achieve superior performance on various control tasks. Compared with existing model-free deep reinforcement learning algorithms, model-based control with propagation networks is more accurate, efficient, and generalizable to new, partially observable scenes and tasks. k∈Ni e k,t ), i = 1 . . . |O|,where o i,t = x i,t , a o i , p i,t denotes object i at time t, u k and v k are the receiver and sender of relation r k , and N i denotes the relations where object i is the receiver.
B. Propagation NetworksIN defines a flexible and efficient model for explicit reasoning of objects and their relations in a complex system. It can handle a variable number of objects and relations and has performed well in domains like n-body systems, bouncing