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Fei Xia

Fei Xia

I'm a Research Scientist at Google Research where I work on the Robotics team. My mission is to build intelligent embodied agents that can interact with complex and unstructured real-world environments, with applications to home robotics. I have been approaching this problem from 3 aspects: 1) Large scale and transferrable simulation for Robotics. 2) Learning algorithms for long-horizon tasks. 3) Combining geometric and semantic representation for environments. Most recently, I have been exploring using foundation models for robot decision making.

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Authored Publications
Google Publications
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    InnerMonologue: Embodied Reasoning through Planning with Language Models
    Wenlong Huang
    Harris Chan
    Jacky Liang
    Pete Florence
    Andy Zeng
    Igor Mordatch
    Yevgen Chebotar
    Noah Brown
    Tomas Jackson
    Linda Luu
    Sergey Levine
    Karol Hausman
    Brian Andrew Ichter
    Conference on Robot Learning (2022) (to appear)
    Preview abstract Recent works have shown the capabilities of large language models to perform tasks requiring reasoning and to be applied to applications beyond natural language processing, such as planning and interaction for embodied robots.These embodied problems require an agent to understand the repertoire of skills available to a robot and the order in which they should be applied. They also require an agent to understand and ground itself within the environment. In this work we investigate to what extent LLMs can reason over sources of feedback provided through natural language. We propose an inner monologue as a way for an LLM to think through this process and plan. We investigate a variety of sources of feedback, such as success detectors and object detectors, as well as human interaction. The proposed method is validated in a simulation domain and on real robotic. We show that Innerlogue can successfully replan around failures, and generate new plans to accommodate human intent. View details
    Preview abstract We propose an end-to-end framework to enablemultipurpose assistive mobile robots to autonomously wipetables and clean spills and crumbs. This problem is chal-lenging, as it requires planning wiping actions with uncertainlatent crumbs and spill dynamics over high-dimensional visualobservations, while simultaneously guaranteeing constraintssatisfaction to enable deployment in unstructured environments.To tackle this problem, we first propose a stochastic differentialequation (SDE) to model crumbs and spill dynamics and ab-sorption with the robot wiper. Then, we formulate a stochasticoptimal control for planning wiping actions over visual obser-vations, which we solve using reinforcement learning (RL). Wethen propose a whole-body trajectory optimization formulationto compute joint trajectories to execute wiping actions whileguaranteeing constraints satisfaction. We extensively validateour table wiping approach in simulation and on hardware. View details
    Do As I Can, Not As I Say: Grounding Language in Robotic Affordances
    Alexander Herzog
    Alexander Toshkov Toshev
    Andy Zeng
    Anthony Brohan
    Brian Andrew Ichter
    Byron David
    Chelsea Finn
    Clayton Tan
    Diego Reyes
    Dmitry Kalashnikov
    Eric Victor Jang
    Jarek Liam Rettinghouse
    Jornell Lacanlale Quiambao
    Julian Ibarz
    Karol Hausman
    Kyle Alan Jeffrey
    Linda Luu
    Mengyuan Yan
    Michael Soogil Ahn
    Nicolas Sievers
    Noah Brown
    Omar Eduardo Escareno Cortes
    Peng Xu
    Peter Pastor Sampedro
    Rosario Jauregui Ruano
    Sally Augusta Jesmonth
    Sergey Levine
    Steve Xu
    Yao Lu
    Yevgen Chebotar
    Yuheng Kuang
    Conference on Robot Learning (CoRL) (2022)
    Preview abstract Large language models can encode a wealth of semantic knowledge about the world. Such knowledge could in principle be extremely useful to robots aiming to act upon high-level, temporally extended instructions expressed in natural language. However, a significant weakness of language models is that they lack contextual grounding, which makes it difficult to leverage them for decision making within a given real-world context. For example, asking a language model to describe how to clean a spill might result in a reasonable narrative, but it may not be applicable to a particular agent, such as a robot, that needs to perform this task in a particular environment. We propose to provide this grounding by means of pretrained behaviors, which are used to condition the model to propose natural language actions that are both feasible and contextually appropriate. The robot can act as the language model’s “hands and eyes,” while the language model supplies high-level semantic knowledge about the task. We show how low-level tasks can be combined with large language models so that the language model provides high-level knowledge about the procedures for performing complex and temporally extended instructions, while value functions associated with these tasks provide the grounding necessary to connect this knowledge to a particular physical environment. We evaluate our method on a number of real-world robotic tasks, where we show that this approach is capable of executing long-horizon, abstract, natural-language tasks on a mobile manipulator. The project's website and the video can be found at \url{say-can.github.io}. View details
    Preview abstract Object-goal navigation (Object-nav) entails searching, recognizing and navigating to a target object. Object-nav has been extensively studied by the Embodied-AI community, but most solutions are often restricted to considering static objects (e.g., television, fridge, etc.). We propose a modular framework for object-nav that is able to efficiently search indoor environments for not just static objects but also movable objects (e.g. fruits, glasses, phones, etc.) that frequently change their positions due to human interaction. Our contextual-bandit agent efficiently explores the environment by showing optimism in the face of uncertainty and learns a model of the likelihood of spotting different objects from each navigable location. The likelihoods are used as rewards in a weighted minimum latency solver to deduce a trajectory for the robot. We evaluate our algorithms in two simulated environments and a real-world setting, to demonstrate high sample efficiency and reliability. View details
    Learning Model Predictive Controllers with Real-Time Attention for Real-World Navigation
    Anthony G. Francis
    Dmitry Kalashnikov
    Edward Lee
    Jake Varley
    Leila Takayama
    Mikael Persson
    Peng Xu
    Stephen Tu
    Xuesu Xiao
    Conference on Robot Learning (2022) (to appear)
    Preview abstract Despite decades of research, existing navigation systems still face real-world challenges when being deployed in the wild, e.g., in cluttered home environments or in human-occupied public spaces. To address this, we present a new class of implicit control policies combining the benefits of imitation learning with the robust handling of system constraints of Model Predictive Control (MPC). Our approach, called Performer-MPC, uses a learned cost function parameterized by vision context embeddings provided by Performers---a low-rank implicit-attention Transformer. We jointly train the cost function and construct the controller relying on it, effectively solving end-to-end the corresponding bi-level optimization problem. We show that the resulting policy improves standard MPC performance by leveraging a few expert demonstrations of the desired navigation behavior in different challenging real-world scenarios. Compared with a standard MPC policy, Performer-MPC achieves 40% better goal reached in cluttered environments and 65% better sociability when navigating around humans. View details
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