Rui Liu 0040

dblp:42/469-40 · DBLP profile ↗
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5ranked-venue papers
4as first author
5since 2021 · last 2025
—ORCID · conflict

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Artificial intelligence and machine learning · 5 · 4 first-author · 5 since 2021Systems, architecture and hardware · 4 · 3 first-author · 4 since 2021
YearPublicationVenuePosition
2025 IMRL: Integrating Visual, Physical, Temporal, and Geometric Representations for Enhanced Food Acquisition
abstract
Robotic assistive feeding holds significant promise for improving the quality of life for individuals with eating disabilities. However, acquiring diverse food items under varying conditions and generalizing to unseen food presents unique challenges. Existing methods that rely on surface-level geometric information (e.g., bounding box and pose) derived from visual cues (e.g., color, shape, and texture) often lacks adaptability and robustness, especially when foods share similar physical properties but differ in visual appearance. We employ imitation learning (IL) to learn a policy for food acquisition. Existing methods employ IL or Reinforcement Learning (RL) to learn a policy based on off-the-shelf image encoders such as ResNet-50. However, such representations are not robust and struggle to generalize across diverse acquisition scenarios. To address these limitations, we propose a novel approach, IMRL (Integrated Multi-Dimensional Representation Learning), which integrates visual, physical, temporal, and geometric representations to enhance the robustness and generalizability of IL for food acquisition. Our approach captures food types and physical properties (e.g., solid, semi-solid, granular, liquid, and mixture), models temporal dynamics of acquisition actions, and introduces geometric information to determine optimal scooping points and assess bowl fullness. IMRL enables IL to adaptively adjust scooping strategies based on context, improving the robot's capability to handle diverse food acquisition scenarios. Experiments on a real robot demonstrate our approach's robustness and adaptability across various foods and bowl configurations, including zero-shot generalization to unseen settings. Our approach achieves an improvement up to 35 % in success rate compared with the best-performing baseline. More details can be found on our website https://ruiiu.github.io/imrl.
Rui Liu 0040, Zahiruddin Mahammad, Amisha Bhaskar, Pratap Tokekar
ICRA1
2025 MMCD: Multi-Modal Collaborative Decision-Making for Connected Autonomy with Knowledge Distillation
abstract
Autonomous systems have advanced significantly, but challenges persist in accident-prone environments where robust decision-making is crucial. A single vehicle’s limited sensor range and obstructed views increase the likelihood of accidents. Multi-vehicle connected systems and multi-modal approaches, leveraging RGB images and LiDAR point clouds, have emerged as promising solutions. However, existing methods often assume the availability of all data modalities and connected vehicles during both training and testing, which is impractical due to potential sensor failures or missing connected vehicles. To address these challenges, we introduce a novel framework MMCD (Multi-Modal Collaborative Decision-making) for connected autonomy. Our framework fuses multi-modal observations from ego and collaborative vehicles to enhance decision-making under challenging conditions. To ensure robust performance when certain data modalities are unavailable during testing, we propose an approach based on cross-modal knowledge distillation with a teacher-student model structure. The teacher model is trained with multiple data modalities, while the student model is designed to operate effectively with reduced modalities. In experiments on connected autonomous driving with ground vehicles and aerial-ground vehicles collaboration, our method improves driving safety by up to 20.7%, surpassing the best-existing baseline in detecting potential accidents and making safe driving decisions. More information can be found on our website https://ruiiu.github.io/mmcd.
Rui Liu 0040, Zikang Wang, Peng Gao 0007, Pratap Tokekar, Ming C. Lin
IROS1
2025 CAML: Collaborative Auxiliary Modality Learning for Multi-Agent Systems
abstract
Multi-modal learning has emerged as a key technique for improving performance across domains such as autonomous driving, robotics, and reasoning. However, in certain scenarios, particularly in resource-constrained environments, some modalities available during training may be absent during inference. While existing frameworks effectively utilize multiple data sources during training and enable inference with reduced modalities, they are primarily designed for single-agent settings. This poses a critical limitation in dynamic environments such as connected autonomous vehicles (CAV), where incomplete data coverage can lead to decision-making blind spots. Conversely, some works explore multi-agent collaboration but without addressing missing modality at test time. To overcome these limitations, we propose Collaborative Auxiliary Modality Learning (CAML), a novel multi-modal multi-agent framework that enables agents to collaborate and share multi-modal data during training, while allowing inference with reduced modalities during testing. Experimental results in collaborative decision-making for CAV in accident-prone scenarios demonstrate that CAML achieves up to a 58.1% improvement in accident detection. Additionally, we validate CAML on real-world aerial-ground robot data for collaborative semantic segmentation, achieving up to a 10.6% improvement in mIoU.
Rui Liu 0040, Peng Gao 0007, Pratap Tokekar, Ming C. Lin
NeurIPS1
2024 LAVA: Long-horizon Visual Action based Food Acquisition
abstract
Robotic Assisted Feeding (RAF) addresses the fundamental need for individuals with mobility impairments to regain autonomy in feeding themselves. The goal of RAF is to use a robot arm to acquire and transfer food to individuals from the table. Existing RAF methods primarily focus on solid foods, leaving a gap in manipulation strategies for semisolid and deformable foods. We present Long-horizon Visual Action-based (LAVA) food acquisition of liquid, semisolid, and deformable foods. Long-horizon refers to the goal of "clearing the bowl" by sequentially acquiring the food from the bowl. LAVA is hierarchical: (1) At the highest level, we determine primitives using ScoopNet. (2) At the mid-level, LAVA finds parameters for the low-level primitives. (3) At the lowest level, LAVA carries out action execution using behavior cloning. We validate LAVA on real-world acquisition trials involving granular, liquid, semisolid, and deformable foods along with fruit chunks and soup. Across 46 bowls, LAVA acquires much more efficiently than baselines with a success rate of 89±4%, and generalizes across realistic plate variations such as varying positions, varieties, and amount of food in the bowl. Datasets and supplementary materials can be found on our website.
Amisha Bhaskar, Rui Liu 0040, Vishnu Dutt Sharma, Guangyao Shi, Pratap Tokekar
IROS2
2023 Data-Driven Distributionally Robust Optimal Control with State-Dependent Noise
abstract
Distributionally Robust Optimal Control (DROC) is a technique that enables robust control in a stochastic setting when the true distribution is not known. Traditional DROC approaches require given ambiguity sets or a KL divergence bound to represent the distributional uncertainty. These may not be known a priori and may require hand-crafting. In this paper, we lift this assumption by introducing a data-driven technique for estimating the uncertainty and a bound for the KL divergence. We call this technique D3ROC. To evaluate the effectiveness of our approach, we consider a navigation problem for a car-like robot with unknown noise distributions. The results demonstrate that D3ROC provides robust and efficient control policies that outperform the iterative Linear Quadratic Gaussian (iLQG) control. The results also show the effectiveness of our proposed approach in handling different noise distributions.
Rui Liu 0040, Guangyao Shi, Pratap Tokekar
IROS1