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Matthew Walter

13 accepted papers

2026

Do You Know Where Your Camera Is? View-Invariant Policy Learning with Camera Conditioning

ICRA 2026poster

We study view-invariant imitation learning by explicitly conditioning policies on camera extrinsics. Using Plücker embeddings of per-pixel rays, we show that conditioning on extrinsics significantly improves generalization across viewpoints for standard behavior cloning policies, including ACT, Diff…

2026

HapCompass: A Rotational Haptic Device for Contact-Rich Robotic Teleoperation

ICRA 2026poster

The contact-rich nature of manipulation makes it a significant challenge for robotic teleoperation. While haptic feedback is critical for contact-rich tasks, providing intuitive directional cues within wearable teleoperation interfaces remains a bottleneck. Existing solutions, such as non-directiona…

2025

PAC Learning with Improvements

ICML 2025poster

One of the most basic lower bounds in machine learning is that in nearly any nontrivial setting, it takes at least $1/\epsilon$ samples to learn to error $\epsilon$ (and more, if the classifier being learned is complex). However, suppose that data points are agents who have the ability to improve b…

Cited by 0SourcePDFScholar
2024

Blending Imitation and Reinforcement Learning for Robust Policy Improvement

ICLR 2024spotlight

While reinforcement learning (RL) has shown promising performance, its sample complexity continues to be a substantial hurdle, restricting its broader application across a variety of domains. Imitation learning (IL) utilizes oracles to improve sample efficiency, yet it is often constrained by the qu…

Cited by 12SourcePDFScholar
2024

READ: Retrieval-Enhanced Asymmetric Diffusion for Motion Planning

CVPR 2024poster

This paper proposes Retrieval-Enhanced Asymmetric Diffusion (READ) for image-based robot motion planning. Given an image of the scene READ retrieves an initial motion from a database of image-motion pairs and uses a diffusion model to refine the motion for the given scene. Unlike prior retrieval-bas…

2024

Subwords as Skills: Tokenization for Sparse-Reward Reinforcement Learning

NeurIPS 2024poster

Exploration in sparse-reward reinforcement learning (RL) is difficult due to the need for long, coordinated sequences of actions in order to achieve any reward. Skill learning, from demonstrations or interaction, is a promising approach to address this, but skill extraction and inference are expensi…

2023

Active Policy Improvement from Multiple Black-box Oracles

ICML 2023poster

Reinforcement learning (RL) has made significant strides in various complex domains. However, identifying an effective policy via RL often necessitates extensive exploration. Imitation learning aims to mitigate this issue by using expert demonstrations to guide exploration. In real-world scenarios,…

2023

Cold Diffusion on the Replay Buffer: Learning to Plan from Known Good States

CoRL 2023poster

Learning from demonstrations (LfD) has successfully trained robots to exhibit remarkable generalization capabilities. However, many powerful imitation techniques do not prioritize the feasibility of the robot behaviors they generate. In this work, we explore the feasibility of plans produced by LfD.…

Cited by 6SourceScholar
2023

Eliciting User Preferences for Personalized Multi-Objective Decision Making through Comparative Feedback

NeurIPS 2023poster

In this work, we propose a multi-objective decision making framework that accommodates different user preferences over objectives, where preferences are learned via policy comparisons. Our model consists of a known Markov decision process with a vector-valued reward function, with each user having a…

Cited by 7SourcePDFScholar
2019

Maximum Expected Hitting Cost of a Markov Decision Process and Informativeness of Rewards

NeurIPS 2019poster

We propose a new complexity measure for Markov decision processes (MDPs), the maximum expected hitting cost (MEHC). This measure tightens the closely related notion of diameter [JOA10] by accounting for the reward structure. We show that this parameter replaces diameter in the upper bound on the opt…

Cited by 7SourcePDFScholar