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Liam Paull

45 accepted papers

2026

PerceptTwin: Semantic Scene Reconstruction for Iterative LLM Planning and Verification

ICRA 2026poster

Simulation environments are useful for both robot policy learning and planning verification and validation. Traditionally, the process of creating a simulation was onerous. Creating a bespoke simulation environment for each individual environment that a robot would operate in was simply infeasible. …

2026

SHAPO: Sharpness-Aware Policy Optimization for Safe Exploration

ICLR 2026poster

Safe exploration is a prerequisite for deploying reinforcement learning (RL) agents in safety-critical domains. In this paper, we approach safe exploration through the lens of epistemic uncertainty, where the actor’s sensitivity to parameter perturbations serves as a practical proxy for regions of h…

Cited by 0SourceScholar
2025

OpenLex3D: A Tiered Benchmark for Open-Vocabulary 3D Scene Representations

NeurIPS 2025poster

3D scene understanding has been transformed by open-vocabulary language models that enable interaction via natural language. However, at present the evaluation of these representations is limited to datasets with closed-set semantics that do not capture the richness of language. This work presents O…

Cited by 0SourcecodeScholar
2025

Perpetua: Multi-Hypothesis Persistence Modeling for Semi-Static Environments

IROS 2025

Many robotic systems require extended deployments in complex, dynamic environments. In such deployments, parts of the environment may change between subsequent robot observations. Most robotic mapping or environment modeling algorithms are incapable of representing dynamic features in a way that ena

Cited by 1SourceScholar
2025

Safety Representations for Safer Policy Learning

ICLR 2025poster

Reinforcement learning algorithms typically necessitate extensive exploration of the state space to find optimal policies. However, in safety-critical applications, the risks associated with such exploration can lead to catastrophic consequences. Existing safe exploration methods attempt to mitigate…

Cited by 0SourcePDFScholar
2025

Scenario Dreamer: Vectorized Latent Diffusion for Generating Driving Simulation Environments

CVPR 2025poster

We introduce Scenario Dreamer, a fully data-driven generative simulator for autonomous vehicle planning that generates both the initial traffic scene--comprising a lane graph and agent bounding boxes--and closed-loop agent behaviours. Existing methods for generating driving simulation environments e…

Cited by 3SourcePDFScholar
2025

The Harmonic Exponential Filter for Nonparametric Estimation on Motion Groups

RA-L 2025

Bayesian estimation is a vital tool in robotics as it allows systems to update the robot state belief using incomplete information from noisy sensors. To render the state estimation problem tractable, many systems assume that the motion and measurement noise, as well as the state distribution, are a

Cited by 1SourcecodeScholar
2024

ConceptGraphs: Open-Vocabulary 3D Scene Graphs for Perception and Planning

ICRA 2024poster

For robots to perform a wide variety of tasks, they require a 3D representation of the world that is semantically rich, yet compact and efficient for task-driven perception and planning. Recent approaches have attempted to leverage features from large vision-language models to encode semantics in 3D…

Cited by 202SourceScholar
2024

CtRL-Sim: Reactive and Controllable Driving Agents with Offline Reinforcement Learning

CoRL 2024poster

Evaluating autonomous vehicle stacks (AVs) in simulation typically involves replaying driving logs from real-world recorded traffic. However, agents replayed from offline data are not reactive and hard to intuitively control. Existing approaches address these challenges by proposing methods that rel…

Cited by 6SourceScholar
2024

Ghost on the Shell: An Expressive Representation of General 3D Shapes

ICLR 2024oral

The creation of photorealistic virtual worlds requires the accurate modeling of 3D surface geometry for a wide range of objects. For this, meshes are appealing since they enable 1) fast physics-based rendering with realistic material and lighting, 2) physical simulation, and 3) are memory-efficient…

Cited by 15SourcePDFScholar
2023

ConceptFusion: Open-set multimodal 3D mapping

RSS 2023poster

Building 3D maps of the environment is central to robot navigation, planning, and interaction with objects in a scene. Most existing approaches that integrate semantic concepts with 3D maps largely remain confined to the closed-set setting: they can only reason about a finite set of concepts, pre-de…

2023

Estimating Regression Predictive Distributions with Sample Networks

AAAI 2023technical

Estimating the uncertainty in deep neural network predictions is crucial for many real-world applications. A common approach to model uncertainty is to choose a parametric distribution and fit the data to it using maximum likelihood estimation. The chosen parametric form can be a poor fit to the dat…

Cited by 4SourcePDFScholar
2023

MeshDiffusion: Score-based Generative 3D Mesh Modeling

ICLR 2023top-25%

We consider the task of generating realistic 3D shapes, which is useful for a variety of applications such as automatic scene generation and physical simulation. Compared to other 3D representations like voxels and point clouds, meshes are more desirable in practice, because (1) they enable easy and…

2023

Robust and Controllable Object-Centric Learning through Energy-based Models

ICLR 2023poster

Humans are remarkably good at understanding and reasoning about complex visual scenes. The capability of decomposing low-level observations into discrete objects allows us to build a grounded abstract representation and identify the compositional structure of the world. Thus it is a crucial step for…

Cited by 12SourcePDFScholar
2023

Self-Supervised Image-to-Point Distillation via Semantically Tolerant Contrastive Loss

CVPR 2023poster

An effective framework for learning 3D representations for perception tasks is distilling rich self-supervised image features via contrastive learning. However, image-to-point representation learning for autonomous driving datasets faces two main challenges: 1) the abundance of self-similarity, whic…

2022

Sample Efficient Deep Reinforcement Learning via Uncertainty Estimation

ICLR 2022spotlight

In model-free deep reinforcement learning (RL) algorithms, using noisy value estimates to supervise policy evaluation and optimization is detrimental to the sample efficiency. As this noise is heteroscedastic, its effects can be mitigated using uncertainty-based weights in the optimization process.…

2022

f-Cal: Aleatoric uncertainty quantification for robot perception via calibrated neural regression

ICRA 2022poster

While modern deep neural networks are performant perception modules, performance (accuracy) alone is insufficient, particularly for safety-critical robotic applications such as self-driving vehicles. Robot autonomy stacks also require these otherwise blackbox models to produce reliable and calibrate…

Cited by 2SourceScholar
2021

Iterative Teaching by Label Synthesis

NeurIPS 2021spotlight

In this paper, we consider the problem of iterative machine teaching, where a teacher provides examples sequentially based on the current iterative learner. In contrast to previous methods that have to scan over the entire pool and select teaching examples from it in each iteration, we propose a lab…

Cited by 15SourcePDFScholar
2021

On Assessing the Usefulness of Proxy Domains for Developing and Evaluating Embodied Agents

IROS 2021poster

In many situations it is either impossible or impractical to develop and evaluate agents entirely on the target domain on which they will be deployed. This is particularly true in robotics, where doing experiments on hardware is much more arduous than in simulation. This has become arguably more so…

Cited by 2SourcecodeScholar
2021

Taskography: Evaluating robot task planning over large 3D scene graphs

CoRL 2021poster

3D scene graphs (3DSGs) are an emerging description; unifying symbolic, topological, and metric scene representations. However, typical 3DSGs contain hundreds of objects and symbols even for small environments; rendering task planning on the \emph{full} graph impractical. We construct \textbf{Taskog…

Cited by 84SourcecodeScholar
2021

gradSim: Differentiable simulation for system identification and visuomotor control

ICLR 2021poster

In this paper, we tackle the problem of estimating object physical properties such as mass, friction, and elasticity directly from video sequences. Such a system identification problem is fundamentally ill-posed due to the loss of information during image formation. Current best solutions to the pro…

Cited by 40SourcePDFScholar
2020

Integrated Benchmarking and Design for Reproducible and Accessible Evaluation of Robotic Agents

IROS 2020poster

As robotics matures and increases in complexity, it is more necessary than ever that robot autonomy research be reproducible. Compared to other sciences, there are specific challenges to benchmarking autonomy, such as the complexity of the software stacks, the variability of the hardware and the rel…

Cited by 17SourceScholar
2020

MapLite: Autonomous Intersection Navigation Without a Detailed Prior Map

RA-L 2020

In this work, we present MapLite: a one-click autonomous navigation system capable of piloting a vehicle to an arbitrary desired destination point given only a sparse publicly available topometric map (from OpenStreetMap). The onboard sensors are used to segment the road region and register the topo

Cited by 28SourceScholar
2020

Your GAN is Secretly an Energy-based Model and You Should Use Discriminator Driven Latent Sampling

NeurIPS 2020poster

We show that the sum of the implicit generator log-density $\log p_g$ of a GAN with the logit score of the discriminator defines an energy function which yields the true data density when the generator is imperfect but the discriminator is optimal, thus making it possible to improve on the typical g…

Cited by 147SourcePDFScholar
2019

A Data-Efficient Framework for Training and Sim-to-Real Transfer of Navigation Policies

ICRA 2019poster

Learning effective visuomotor policies for robots purely from data is challenging, but also appealing since a learning-based system should not require manual tuning or calibration. In the case of a robot operating in a real environment the training process can be costly, time-consuming, and even dan…

Cited by 47SourceScholar
2018

Learning Steering Bounds for Parallel Autonomous Systems

ICRA 2018poster

Deep learning has been successfully applied to “end-to-end” learning of the autonomous driving task, where a deep neural network learns to predict steering control commands from camera data input. However, the learned representations do not support higher-level decision making required for autonomou…

Cited by 30SourceScholar
2018

Local Positioning System Using UWB Range Measurements for an Unmanned Blimp

RA-L 2018

Unmanned blimps are a safe and reliable alternative to conventional drones when flying above people. On-board real-time tracking of their pose and velocities is a necessary step toward autonomous navigation. There is a need for an easily deployable technology that is able to accurately and robustly

Cited by 24SourceScholar
2017

Duckietown: An open, inexpensive and flexible platform for autonomy education and research

ICRA 2017poster

Duckietown is an open, inexpensive and flexible platform for autonomy education and research. The platform comprises small autonomous vehicles (“Duckiebots”) built from off-the-shelf components, and cities (“Duckietowns”) complete with roads, signage, traffic lights, obstacles, and citizens (duckies…

Cited by 281SourceScholar
2016

Decoupled, consistent node removal and edge sparsification for graph-based SLAM

IROS 2016poster

Graph-based SLAM approaches have had success recently despite suffering from ever-increasing computational costs due to the need of optimizing over the entire robot trajectory. To address this issue, in this paper, we advocate the decoupling of marginalization (node removal) and sparsification (edge…

Cited by 49SourceScholar
2016

SLAM with objects using a nonparametric pose graph

IROS 2016poster

Mapping and self-localization in unknown environments are fundamental capabilities in many robotic applications. These tasks typically involve the identification of objects as unique features or landmarks, which requires the objects both to be detected and then assigned a unique identifier that can…

Cited by 107SourcecodeScholar
2015

Bridging text spotting and SLAM with junction features

IROS 2015poster

Navigating in a previously unknown environment and recognizing naturally occurring text in a scene are two important autonomous capabilities that are typically treated as distinct. However, these two tasks are potentially complementary, (i) scene and pose priors can benefit text spotting, and (ii) t…

Cited by 32SourceScholar
2015

Two-Stage Focused Inference for Resource-Constrained Collision-Free Navigation

RSS 2015poster

Long-term operations of resource-constrained robots typically require hard decisions be made about which data to process and/or retain. The question then arises of how to choose which data is most useful to keep to achieve the task at hand. As spacial scale grows, the size of the map will grow witho…

Cited by 34SourcePDFScholar