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This paper introduces a method for learning symbolic world models for long-horizon decision-making in robotics by leveraging pretrained vision-language models (VLMs) to propose and evaluate visual predicates from camera images. The proposed approach uses these predicates and demonstrations in an optimization-based model-learning algorithm to obtain a compact symbolic world model. The method demonstrates strong zero-shot generalization capabilities in both simulated and real-world robotic tasks with varying visual conditions, goals, and horizons.
Forget hand-engineered features: this method uses VLMs to automatically discover symbolic predicates for robot planning, enabling zero-shot generalization to unseen environments and goals.
Our aim is to learn to solve long-horizon decision-making problems in complex robotics domains given low-level skills and a handful of demonstrations containing sequences of images. To this end, we focus on learning abstract symbolic world models that facilitate zero-shot generalization to novel goals via planning. A critical component of such models is the set of symbolic predicates that define properties of and relationships between objects. In this work, we leverage pretrained vision-language models (VLMs) to propose a large set of visual predicates potentially relevant for decision-making, and to evaluate those predicates directly from camera images. At training time, we pass the proposed predicates and demonstrations into an optimization-based model-learning algorithm to obtain an abstract symbolic world model that is defined in terms of a compact subset of the proposed predicates. At test time, given a novel goal in a novel setting, we use the VLM to construct a symbolic description of the current world state, and then use a search-based planning algorithm to find a sequence of low-level skills that achieves the goal. We demonstrate empirically across experiments in both simulation and the real world that our method can generalize aggressively, applying its learned world model to solve problems with varying visual backgrounds, types, numbers, and arrangements of objects, as well as novel goals and much longer horizons than those seen at training time.