A robot's instantaneous sensory observations do not always reveal task-relevant state information. Under such partial observability, optimal behavior typically involves explicitly acting to gain the missing information. Today's standard robot learning techniques struggle to produce such active perception behaviors. We propose a simple real-world robot learning recipe to efficiently train active perception policies. Our approach, asymmetric advantage weighted regression (AAWR), exploits access to "privileged" extra sensors at training time. The privileged sensors enable training high-quality privileged value functions that aid in estimating the advantage of the target policy. Bootstrapping from a small number of potentially suboptimal demonstrations and an easy-to-obtain coarse policy initialization, AAWR quickly acquires active perception behaviors and boosts task performance. In evaluations on 8 manipulation tasks on 3 robots spanning varying degrees of partial observability, AAWR synthesizes reliable active perception behaviors that outperform all prior approaches. When initialized with a "generalist" robot policy that struggles with active perception tasks, AAWR efficiently generates information-gathering behaviors that allow it to operate under severe partial observability for manipulation tasks. Website: https://penn-pal-lab.github.io/aawr/

In this work, we use Vision-Language Models (VLMs) as a binary success detector given a robot observation and task description, formulated as a Visual Question Answering (VQA) problem. We fine-tune the open-source MiniGPT-4 VLM to detect success on robot trajectories from the Berkeley Bridge and Berkeley AUTOLab UR5 datasets. We find that while a handful of test distribution trajectories can train an accurate detector, transferring learning between different environments is challenging due to distribution shift. In addition, while our VLM is robust to language variations, it is less robust to visual variations. In the future, more powerful VLMs such as Gemini and GPT-4 have the potential to be more accurate and robust success detectors, and success detectors can provide a sparse binary reward to improve existing policies.