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Collaborating Authors

 Yu, Hongzhan


Safe Human Robot Navigation in Warehouse Scenario

arXiv.org Artificial Intelligence

Safe Human Robot Navigation in Warehouse Scenario Seth Farrell* 1, Chenghao Li* 1, Hongzhan Y u 1, Ryo Y oshimitsu 2, Sicun Gao 1 and Henrik I. Christensen 1 Abstract -- The integration of autonomous mobile robots (AMRs) in industrial environments, particularly warehouses, has revolutionized logistics and operational efficiency. However, ensuring the safety of human workers in dynamic, shared spaces remains a critical challenge. This work proposes a novel methodology that leverages control barrier functions (CBFs) to enhance safety in warehouse navigation. By integrating learning-based CBFs with the Open Robotics Middleware Framework (OpenRMF), the system achieves adaptive and safety-enhanced controls in multi-robot, multi-agent scenarios. Experiments conducted using various robot platforms demonstrate the efficacy of the proposed approach in avoiding static and dynamic obstacles, including human pedestrians. Our experiments evaluate different scenarios in which the number of robots, robot platforms, speed, and number of obstacles are varied, from which we achieve promising performance. I. INTRODUCTION In recent decades, the industrial sector, particularly warehouse operations, has experienced a substantial rise in robotic implementation, driven by technological advances, lower costs, and growing consumer demand. This rapid growth has compelled regulatory bodies, including the Occupational Safety and Health Administration (OSHA), to explore measures for securing safe robot operations as automation progresses [1]. A key safety challenge lies in enabling autonomous mobile robots (AMRs) to respond effectively to irregular situations, such as dropped packages or mechanical breakdowns due to prolonged use.


Estimating Control Barriers from Offline Data

arXiv.org Artificial Intelligence

Estimating Control Barriers from Offline Data Hongzhan Y u 1, Seth Farrell 1, Ryo Y oshimitsu 2, Zhizhen Qin 1, Henrik I. Christensen 1 and Sicun Gao 1 Abstract -- Learning-based methods for constructing control barrier functions (CBFs) are gaining popularity for ensuring safe robot control. A major limitation of existing methods is their reliance on extensive sampling over the state space or online system interaction in simulation. In this work we propose a novel framework for learning neural CBFs through a fixed, sparsely-labeled dataset collected prior to training. Our approach introduces new annotation techniques based on out-of-distribution analysis, enabling efficient knowledge propagation from the limited labeled data to the unlabeled data. We also eliminate the dependency on a high-performance expert controller, and allow multiple sub-optimal policies or even manual control during data collection. We evaluate the proposed method on real-world platforms. With limited amount of offline data, it achieves state-of-the-art performance for dynamic obstacle avoidance, demonstrating statistically safer and less conservative maneuvers compared to existing methods. I NTRODUCTION Control Barrier Functions (CBFs) provide an effective framework for safe robot control [1], [2].The recent development of learning-based CBF methods exploit the expressiveness of neural networks and data-driven approaches to handle systems with complex dynamics and high uncertainty, with promising results [3], [4], [5], [6], [7], [8], [9]. However, the scalability of learning-based methods has been a major bottleneck. The typical approach for learning neural CBFs requires sampling over the entire state space to enforce constraints from the standard CBF conditions [10].


ROS-LLM: A ROS framework for embodied AI with task feedback and structured reasoning

arXiv.org Artificial Intelligence

We present a framework for intuitive robot programming by non-experts, leveraging natural language prompts and contextual information from the Robot Operating System (ROS). Our system integrates large language models (LLMs), enabling non-experts to articulate task requirements to the system through a chat interface. Key features of the framework include: integration of ROS with an AI agent connected to a plethora of open-source and commercial LLMs, automatic extraction of a behavior from the LLM output and execution of ROS actions/services, support for three behavior modes (sequence, behavior tree, state machine), imitation learning for adding new robot actions to the library of possible actions, and LLM reflection via human and environment feedback. Extensive experiments validate the framework, showcasing robustness, scalability, and versatility in diverse scenarios, including long-horizon tasks, tabletop rearrangements, and remote supervisory control. To facilitate the adoption of our framework and support the reproduction of our results, we have made our code open-source. You can access it at: https://github.com/huawei-noah/HEBO/tree/master/ROSLLM.


Activation-Descent Regularization for Input Optimization of ReLU Networks

arXiv.org Artificial Intelligence

We present a new approach for input optimization of ReLU networks that explicitly takes into account the effect of changes in activation patterns. We analyze local optimization steps in both the input space and the space of activation patterns to propose methods with superior local descent properties. To accomplish this, we convert the discrete space of activation patterns into differentiable representations and propose regularization terms that improve each descent step. Our experiments demonstrate the effectiveness of the proposed input-optimization methods for improving the state-of-the-art in various areas, such as adversarial learning, generative modeling, and reinforcement learning.


Sequential Neural Barriers for Scalable Dynamic Obstacle Avoidance

arXiv.org Artificial Intelligence

There are two major challenges for scaling up robot navigation around dynamic obstacles: the complex interaction dynamics of the obstacles can be hard to model analytically, and the complexity of planning and control grows exponentially in the number of obstacles. Data-driven and learning-based methods are thus particularly valuable in this context. However, data-driven methods are sensitive to distribution drift, making it hard to train and generalize learned models across different obstacle densities. We propose a novel method for compositional learning of Sequential Neural Control Barrier models (SNCBFs) to achieve scalability. Our approach exploits an important observation: the spatial interaction patterns of multiple dynamic obstacles can be decomposed and predicted through temporal sequences of states for each obstacle. Through decomposition, we can generalize control policies trained only with a small number of obstacles, to environments where the obstacle density can be 100x higher. We demonstrate the benefits of the proposed methods in improving dynamic collision avoidance in comparison with existing methods including potential fields, end-to-end reinforcement learning, and model-predictive control. We also perform hardware experiments and show the practical effectiveness of the approach in the supplementary video.