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Mengdi Xu

20 accepted papers

2026

MoMaGen: Generating Demonstrations under Soft and Hard Constraints for Multi-Step Bimanual Mobile Manipulation

ICLR 2026poster

Imitation learning from large-scale, diverse human demonstrations has been shown to be effective for training robots, but collecting such data is costly and time-consuming. This challenge intensifies for multi-step bimanual mobile manipulation, where humans must teleoperate both the mobile base and…

Cited by 0SourcecodeScholar
2026

ROSETTA: Constructing Code-Based Reward from Unconstrained Language Preference

ICLR 2026poster

Intelligent embodied agents not only need to accomplish preset tasks, but also learn to align with individual human needs and preferences. Extracting reward signals from human language preferences allows an embodied agent to adapt through reinforcement learning. However, human language preferences a…

Cited by 0SourcecodeScholar
2025

Dynamics as Prompts: In-Context Learning for Sim-to-Real System Identifications

RA-L 2025

Sim-to-real transfer remains a significant challenge in robotics due to the discrepancies between simulated and real-world dynamics. Traditional methods like Domain Randomization often fail to capture fine-grained dynamics, limiting their effectiveness for precise control tasks. In this work, we pro

Cited by 15SourceScholar
2024

Embodied Executable Policy Learning with Language-based Scene Summarization

NAACL 2024long

Large Language models (LLMs) have shown remarkable success in assisting robot learning tasks, i.e., complex household planning.However, the performance of pretrained LLMs heavily relies on domain-specific templated text data, which may be infeasible in real-world robot learning tasks with image-base…

Cited by 7SourcePDFScholar
2023

A trajectory is worth three sentences: multimodal transformer for offline reinforcement learning

UAI 2023poster

Transformers hold tremendous promise in solving offline reinforcement learning (RL) by formulating it as a sequence modeling problem inspired by language modeling (LM). Prior works using transformers model a sample (trajectory) of RL as one sequence analogous to a sequence of words (one sentence) in…

Cited by 11SourcePDFScholar
2023

Adaptive Online Replanning with Diffusion Models

NeurIPS 2023poster

Diffusion models have risen a promising approach to data-driven planning, and have demonstrated impressive robotic control, reinforcement learning, and video planning performance. Given an effective planner, an important question to consider is replanning -- when given plans should be regenerated du…

Cited by 22SourcePDFScholar
2023

Can Brain Signals Reveal Inner Alignment with Human Languages?

EMNLP 2023short findings

Brain Signals, such as Electroencephalography (EEG), and human languages have been widely explored independently for many downstream tasks, however, the connection between them has not been well explored. In this study, we explore the relationship and dependency between EEG and language. To study at…

Cited by 0SourcecodeScholar
2023

Cardiac Disease Diagnosis on Imbalanced Electrocardiography Data Through Optimal Transport Augmentation

ICASSP 2023accepted

In this paper, we focus on a new method of data augmentation to solve the data imbalance problem within imbalanced ECG datasets to improve the robustness and accuracy of heart disease detection. By using Optimal Transport, we augment the ECG disease data from normal ECG beats to balance the data amo…

Cited by 0SourceScholar
2023

Continual Vision-based Reinforcement Learning with Group Symmetries

CoRL 2023oral

Continual reinforcement learning aims to sequentially learn a variety of tasks, retaining the ability to perform previously encountered tasks while simultaneously developing new policies for novel tasks. However, current continual RL approaches overlook the fact that certain tasks are identical unde…

Cited by 10SourceScholar
2023

Group Distributionally Robust Reinforcement Learning with Hierarchical Latent Variables

AISTATS 2023poster

One key challenge for multi-task Reinforcement learning (RL) in practice is the absence of task specifications. Robust RL has been applied to deal with task ambiguity but may result in over-conservative policies. To balance the worst-case (robustness) and average performance, we propose Group Distri…

Cited by 13SourcePDFScholar
2023

Hyper-Decision Transformer for Efficient Online Policy Adaptation

ICLR 2023poster

Decision Transformers (DT) have demonstrated strong performances in offline reinforcement learning settings, but quickly adapting to unseen novel tasks remains challenging. To address this challenge, we propose a new framework, called Hyper-Decision Transformer (HDT), that can generalize to novel ta…

Cited by 44SourcePDFScholar
2023

SCCS: Semantics-Consistent Cross-domain Summarization via Optimal Transport Alignment

ACL 2023findings

Multimedia summarization with multimodal output (MSMO) is a recently explored application in language grounding. It plays an essential role in real-world applications, i.e., automatically generating cover images and titles for news articles or providing introductions to online videos. However, exist…

Cited by 9SourcePDFScholar
2023

What Went Wrong? Closing the Sim-to-Real Gap via Differentiable Causal Discovery

CoRL 2023poster

Training control policies in simulation is more appealing than on real robots directly, as it allows for exploring diverse states in an efficient manner. Yet, robot simulators inevitably exhibit disparities from the real-world \rebut{dynamics}, yielding inaccuracies that manifest as the dynamical si…

Cited by 33SourceScholar
2022

Curriculum Reinforcement Learning using Optimal Transport via Gradual Domain Adaptation

NeurIPS 2022accept

Curriculum Reinforcement Learning (CRL) aims to create a sequence of tasks, starting from easy ones and gradually learning towards difficult tasks. In this work, we focus on the idea of framing CRL as interpolations between a source (auxiliary) and a target task distribution. Although existing studi…

2022

Prompting Decision Transformer for Few-Shot Policy Generalization

ICML 2022spotlight

Human can leverage prior experience and learn novel tasks from a handful of demonstrations. In contrast to offline meta-reinforcement learning, which aims to achieve quick adaptation through better algorithm design, we investigate the effect of architecture inductive bias on the few-shot learning ca…

2022

Robust Reinforcement Learning as a Stackelberg Game via Adaptively-Regularized Adversarial Training

IJCAI 2022poster

Robust Reinforcement Learning (RL) focuses on improving performances under model errors or adversarial attacks, which facilitates the real-life deployment of RL agents. Robust Adversarial Reinforcement Learning (RARL) is one of the most popular frameworks for robust RL. However, most of the existing…

Cited by 41SourcePDFScholar
2022

Scalable Safety-Critical Policy Evaluation with Accelerated Rare Event Sampling

IROS 2022poster

Evaluating rare but high-stakes events is one of the main challenges in obtaining reliable reinforcement learning policies, especially in large or infinite state/action spaces where limited scalability dictates a prohibitively large number of testing iterations. On the other hand, a biased or inaccu…

Cited by 4SourcecodeScholar
2021

Context-Aware Safe Reinforcement Learning for Non-Stationary Environments

ICRA 2021poster

Safety is a critical concern when deploying reinforcement learning agents for realistic tasks. Recently, safe reinforcement learning algorithms have been developed to optimize the agent’s performance while avoiding violations of safety constraints. However, few studies have addressed the nonstationa…

Cited by 45SourceScholar
2020

CMTS: A Conditional Multiple Trajectory Synthesizer for Generating Safety-Critical Driving Scenarios

ICRA 2020poster

Naturalistic driving trajectory generation is crucial for the development of autonomous driving algorithms. However, most of the data is collected in collision-free scenarios leading to the sparsity of the safety-critical cases. When considering safety, testing algorithms in near-miss scenarios that…

Cited by 70SourceScholar
2020

Task-Agnostic Online Reinforcement Learning with an Infinite Mixture of Gaussian Processes

NeurIPS 2020poster

Continuously learning to solve unseen tasks with limited experience has been extensively pursued in meta-learning and continual learning, but with restricted assumptions such as accessible task distributions, independently and identically distributed tasks, and clear task delineations. However, real…