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Tim Welschehold

27 accepted papers

2025

DiWA: Diffusion Policy Adaptation with World Models

CoRL 2025poster

Fine-tuning diffusion policies with reinforcement learning (RL) presents significant challenges. The long denoising sequence for each action prediction impedes effective reward propagation. Additionally, standard RL methods require millions of physical interaction steps, making fine-tuning even more…

Cited by 0SourceScholar
2025

MORE: Mobile Manipulation Rearrangement Through Grounded Language Reasoning

IROS 2025

Autonomous long-horizon mobile manipulation encompasses a multitude of challenges, including scene dynamics, unexplored areas, and error recovery. Recent works have leveraged foundation models for scene-level robotic reasoning and planning. However, the performance of these methods degrades when dea

Cited by 8SourceScholar
2025

Whole-Body Teleoperation for Mobile Manipulation at Zero Added Cost

RA-L 2025

Demonstration data plays a key role in learning complex behaviors and training robotic foundation models. While effective control interfaces exist for static manipulators, data collection remains cumbersome and time intensive for mobile manipulators due to their large number of degrees of freedom. W

Cited by 12SourceScholar
2024

Bayesian Optimization for Sample-Efficient Policy Improvement in Robotic Manipulation

IROS 2024poster

Sample efficient learning of manipulation skills poses a major challenge in robotics. While recent approaches demonstrate impressive advances in the type of task that can be addressed and the sensing modalities that can be incorporated, they still require large amounts of training data. Especially w…

Cited by 1SourceScholar
2024

CenterGrasp: Object-Aware Implicit Representation Learning for Simultaneous Shape Reconstruction and 6-DoF Grasp Estimation

RA-L 2024

Reliable object grasping is a crucial capability for autonomous robots. However, many existing grasping approaches focus on general clutter removal without explicitly modeling objects and thus only relying on the visible local geometry. We introduce CenterGrasp, a novel framework that combines objec

Cited by 27SourceScholar
2024

DITTO: Demonstration Imitation by Trajectory Transformation

IROS 2024poster

Teaching robots new skills quickly and conveniently is crucial for the broader adoption of robotic systems. In this work, we address the problem of one-shot imitation from a single human demonstration, given by an RGB-D video recording. We propose a two-stage process. In the first stage we extract t…

Cited by 16SourcecodeScholar
2024

Language-Grounded Dynamic Scene Graphs for Interactive Object Search With Mobile Manipulation

RA-L 2024

To fully leverage the capabilities of mobile manipulation robots, it is imperative that they are able to autonomously execute long-horizon tasks in large unexplored environments. While large language models (LLMs) have shown emergent reasoning skills on arbitrary tasks, existing work primarily conce

Cited by 100SourcecodeScholar
2024

Learning Robotic Manipulation Policies from Point Clouds with Conditional Flow Matching

CoRL 2024poster

Learning from expert demonstrations is a popular approach to train robotic manipulation policies from limited data. However, imitation learning algorithms require a number of design choices ranging from the input modality, training objective, and 6-DoF end-effector pose representation. Diffusion-bas…

Cited by 14SourceScholar
2024

The Art of Imitation: Learning Long-Horizon Manipulation Tasks From Few Demonstrations

RA-L 2024

Task Parametrized Gaussian Mixture Models (TP-GMM) are a sample-efficient method for learning object-centric robot manipulation tasks. However, there are several open challenges to applying TP-GMMs in the wild. In this work, we tackle three crucial challenges synergistically. First, end-effector vel

Cited by 15SourcecodeScholar
2023

Adaptively Calibrated Critic Estimates for Deep Reinforcement Learning

RA-L 2023

Accurate value estimates are important for off-policy reinforcement learning. Algorithms based on temporal difference learning typically are prone to an over- or underestimation bias building up over time. In this letter, we propose a general method called Adaptively Calibrated Critics (ACC) that us

Cited by 14SourcecodeScholar
2023

Catch Me if You Hear Me: Audio-Visual Navigation in Complex Unmapped Environments With Moving Sounds

RA-L 2023

Audio-visual navigation combines sight and hearing to navigate to a sound-emitting source in an unmapped environment. While recent approaches have demonstrated the benefits of audio input to detect and find the goal, they focus on clean and static sound sources and struggle to generalize to unheard

Cited by 54SourcecodeScholar
2023

Dynamic Update-to-Data Ratio: Minimizing World Model Overfitting

ICLR 2023poster

Early stopping based on the validation set performance is a popular approach to find the right balance between under- and overfitting in the context of supervised learning. However, in reinforcement learning, even for supervised sub-problems such as world model learning, early stopping is not applic…

2023

Improving Deep Dynamics Models for Autonomous Vehicles with Multimodal Latent Mapping of Surfaces

IROS 2023poster

The safe deployment of autonomous vehicles relies on their ability to effectively react to environmental changes. This can require maneuvering on varying surfaces which is still a difficult problem, especially for slippery terrains. To address this issue we propose a new approach that learns a surfa…

Cited by 3SourceScholar
2023

Learning Hierarchical Interactive Multi-Object Search for Mobile Manipulation

RA-L 2023

Existing object-search approaches enable robots to search through free pathways, however, robots operating in unstructured human-centered environments frequently also have to manipulate the environment to their needs. In this work, we introduce a novel interactive multi-object search task in which a

Cited by 33SourceScholar
2023

The Treachery of Images: Bayesian Scene Keypoints for Deep Policy Learning in Robotic Manipulation

RA-L 2023

In policy learning for robotic manipulation, sample efficiency is of paramount importance. Thus, learning and extracting more compact representations from camera observations is a promising avenue. However, current methods often assume full observability of the scene and struggle with scale invarian

Cited by 15SourcecodeScholar
2022

Correct Me If I am Wrong: Interactive Learning for Robotic Manipulation

RA-L 2022

Learning to solve complex manipulation tasks from visual observations is a dominant challenge for real-world robot learning. Although deep reinforcement learning algorithms have recently demonstrated impressive results in this context, they still require an impractical amount of time-consuming trial

Cited by 48SourceScholar
2022

Courteous Behavior of Automated Vehicles at Unsignalized Intersections Via Reinforcement Learning

RA-L 2022

The transition from today's mostly human-driven traffic to a purely automated one will be a gradual evolution, with the effect that we will likely experience mixed traffic in the near future. Connected and automated vehicles can benefit human-driven ones and the whole traffic system in different way

Cited by 24SourceScholar
2022

Robot Skill Adaptation via Soft Actor-Critic Gaussian Mixture Models

ICRA 2022poster

AA core challenge for an autonomous agent acting in the real world is to adapt its repertoire of skills to cope with its noisy perception and dynamics. To scale learning of skills to long-horizon tasks, robots should be able to learn and later refine their skills in a structured manner through traje…

Cited by 23SourceScholar
2021

Learning Kinematic Feasibility for Mobile Manipulation Through Deep Reinforcement Learning

RA-L 2021

Mobile manipulation tasks remain one of the critical challenges for the widespread adoption of autonomous robots in both service and industrial scenarios. While planning approaches are good at generating feasible whole-body robot trajectories, they struggle with dynamic environments as well as the i

Cited by 59SourcecodeScholar
2019

Augmenting Action Model Learning by Non-Geometric Features

ICRA 2019poster

Learning from demonstration is a powerful tool for teaching manipulation actions to a robot. It is, however, an unsolved problem how to consider knowledge about the world and action-induced reactions such as forces imposed onto the gripper or measured liquid levels during pouring without explicit an…

Cited by 6SourceScholar
2019

Combined Task and Action Learning from Human Demonstrations for Mobile Manipulation Applications

IROS 2019poster

Learning from demonstrations is a promising paradigm for transferring knowledge to robots. However, learning mobile manipulation tasks directly from a human teacher is a complex problem as it requires learning models of both the overall task goal and of the underlying actions. Additionally, learning…

Cited by 17SourceScholar
2018

3D Human Pose Estimation in RGBD Images for Robotic Task Learning

ICRA 2018poster

We propose an approach to estimate 3D human pose in real world units from a single RGBD image and show that it exceeds performance of monocular 3D pose estimation approaches from color as well as pose estimation exclusively from depth. Our approach builds on robust human keypoint detectors for color…

Cited by 212SourcecodeScholar
2018

Coupling Mobile Base and End-Effector Motion in Task Space

IROS 2018poster

Dynamic systems are a practical alternative to motion planning in executing robot actions. They are of particular interest in Learning from Demonstration, as here we aim to carry out actions in a certain fashion, without a model or in-depth knowledge about the world, which might be difficult to achi…

Cited by 17SourceScholar