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Nathan Ratliff

20 accepted papers

2026

DextrAH-RGB: Visuomotor Policies to Grasp Anything with Dexterous Hands

ICRA 2026poster

One of the most important, yet challenging, skills for a dexterous robot is grasping a diverse range of objects. Much of the prior work has been limited by speed, generality, or reliance on depth maps and object poses. In this paper, we introduce DextrAH-RGB, a system that can perform dexterous arm-…

2023

CuRobo: Parallelized Collision-Free Robot Motion Generation

ICRA 2023poster

This paper explores the problem of collision-free motion generation for manipulators by formulating it as a global motion optimization problem. We develop a parallel optimization technique to solve this problem and demonstrate its effectiveness on massively parallel GPUs. We show that combining simp…

Cited by 74SourceScholar
2021

Towards Coordinated Robot Motions: End-to-End Learning of Motion Policies on Transform Trees

IROS 2021poster

Generating robot motion that fulfills multiple tasks simultaneously is challenging due to the geometric constraints imposed on the robot. In this paper, we propose to solve multi-task problems through learning structured policies from human demonstrations. Our structured policy is inspired by RMPflo…

Cited by 9SourceScholar
2020

Collaborative Interaction Models for Optimized Human-Robot Teamwork

IROS 2020poster

Effective human-robot collaboration requires informed anticipation. The robot must anticipate the human’s actions, but also react quickly and intuitively when its predictions are wrong. The robot must plan its actions to account for the human’s own plan, with the knowledge that the human’s behavior…

Cited by 22SourceScholar
2020

Guided Uncertainty-Aware Policy Optimization: Combining Learning and Model-Based Strategies for Sample-Efficient Policy Learning

ICRA 2020poster

Traditional robotic approaches rely on an accurate model of the environment, a detailed description of how to perform the task, and a robust perception system to keep track of the current state. On the other hand, reinforcement learning approaches can operate directly from raw sensory inputs with on…

Cited by 75SourceScholar
2019

Closing the Sim-to-Real Loop: Adapting Simulation Randomization with Real World Experience

ICRA 2019poster

We consider the problem of transferring policies to the real world by training on a distribution of simulated scenarios. Rather than manually tuning the randomization of simulations, we adapt the simulation parameter distribution using a few real world roll-outs interleaved with policy training. In…

Cited by 666SourceScholar
2019

Joint Inference of Kinematic and Force Trajectories with Visuo-Tactile Sensing

ICRA 2019poster

To perform complex tasks, robots must be able to interact with and manipulate their surroundings. One of the key challenges in accomplishing this is robust state estimation during physical interactions, where the state involves not only the robot and the object being manipulated, but also the state…

Cited by 38SourceScholar
2019

Learning Latent Space Dynamics for Tactile Servoing

ICRA 2019poster

To achieve a dexterous robotic manipulation, we need to endow our robot with tactile feedback capability, i.e. the ability to drive action based on tactile sensing. In this paper, we specifically address the challenge of tactile servoing, i.e. given the current tactile sensing and a target/goal tact…

Cited by 39SourceScholar
2019

Learning Reactive Motion Policies in Multiple Task Spaces from Human Demonstrations

CoRL 2019

Complex manipulation tasks often require non-trivial and coordinated movements of different parts of a robot. In this work, we address the challenges associated with learning and reproducing the skills required to execute such complex tasks. Specifically, we decompose a task into multiple subtasks a

Cited by 0SourcePDFScholar
2019

Representing Robot Task Plans as Robust Logical-Dynamical Systems

IROS 2019poster

It is difficult to create robust, reusable, and reactive behaviors for robots that can be easily extended and combined. Frameworks such as Behavior Trees are flexible but difficult to characterize, especially when designing reactions and recovery behaviors to consistently converge to a desired goal…

Cited by 82SourceScholar
2019

Riemannian Motion Policy Fusion through Learnable Lyapunov Function Reshaping

CoRL 2019

RMPflow is a recently proposed policy-fusion framework based on differential geometry. While RMPflow has demonstrated promising performance, it requires the user to provide sensible subtask policies as Riemannian motion policies (RMPs: a motion policy and an importance matrix function), which can be

Cited by 0SourcePDFScholar
2019

Robust Learning of Tactile Force Estimation through Robot Interaction

ICRA 2019poster

Current methods for estimating force from tactile sensor signals are either inaccurate analytic models or task-specific learned models. In this paper, we explore learning a robust model that maps tactile sensor signals to force. We specifically explore learning a mapping for the SynTouch BioTac sens…

Cited by 71SourceScholar
2016

Warping the workspace geometry with electric potentials for motion optimization of manipulation tasks

IROS 2016poster

In this paper we present motion optimization algorithms for computing manipulation motions in presence of obstacles. Our approach builds a geometric representation of the workspace by constructing Riemannian metrics using electric potentials emanating from the workspace obstacles. Velocity of the ro…

Cited by 20SourceScholar
2015

Direct Loss Minimization Inverse Optimal Control

RSS 2015poster

Inverse Optimal Control (IOC) has strongly impacted the systems engineering process, enabling automated planner tuning through straightforward and intuitive demonstration. The most successful and established applications, though, have been in lower dimensional problems such as navigation planning wh…

Cited by 57SourcePDFScholar