Xinyu Cai

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27ranked-venue papers
3as first author
25since 2021 · last 2026
—ORCID · conflict

Domains — the database's venue-derived domains; a paper can count in several

Artificial intelligence and machine learning · 24 · 3 first-author · 22 since 2021Systems, architecture and hardware · 12 · 2 first-author · 11 since 2021Databases, data management, data science and information retrieval · 4 · 4 since 2021Graphics, computer vision, multimedia, augmented reality and games · 3 · 2 since 2021Software engineering, systems software and programming languages · 1 · 1 since 2021
YearPublicationVenuePosition
2026 Lora: Towards Improved Applicability of Reconfigurable Architecture for Versatile Nonlinear Functions
Yuan Dai, Guibin Zou, Yuanda Yang, Jiahang Lou, Yiwen Luo, Xinyu Cai, Wenbo Yin, Wai-Shing Luk, Lingli Wang
ISCA7
2026 FineFT: Efficient and Risk-Aware Ensemble Reinforcement Learning for Futures Trading
abstract
Futures are contracts obligating the exchange of an asset at a predetermined date and price, notable for their high leverage (e.g., 5-fold) and liquidity (e.g., trillions of dollars) and, therefore, thrive in the Crypto market. Reinforcement learning (RL) has been widely applied in various quantitative tasks. However, most methods focus on the spot (e.g., stock) and could not be directly applied to the futures market with high leverage because of 2 key challenges. First, high leverage amplifies reward fluctuations, making RL training highly stochastic and difficult to converge. Second, prior works lacked self-awareness of capability boundaries, exposing them to the risk of significant capital loss when encountering previously unseen market state representations (e.g., during a black swan event like COVID-19). To tackle these challenges, we propose the eFficient and rIsk-aware eNsemble rEinforcement learning for Futures Trading (FineFT), a novel three-stage ensemble RL framework with stable training and proper risk management. In stage I, ensemble Q learners are selectively updated by ensemble temporal difference (TD) errors, i.e., TD errors across different learners, to improve convergence and performance. In stage II, we filter the Q-learners based on their profitabilities under different market dynamics and train variational autoencoders (VAEs) on market representations of each dynamic to identify the capability boundaries of the filtered learners. In stage III, we dynamically choose from the filtered ensemble and a conservative policy, guided by trained VAEs, to maintain profitability and mitigate risk with new market states. Through extensive experiments on crypto futures in a high-frequency trading environment with high fidelity and 5x leverage, we demonstrate that FineFT significantly outperforms 12 state-of-the-art baselines in 6 widely-used financial metrics, reducing risk by more than 40% while achieving superior profitability compared to the runner-up. Visualization of the selective update mechanism shows that different agents specialize in distinct market dynamics, and ablation studies certify routing with VAEs reduces maximum drawdown effectively, and selective update improves convergence and performance.
Molei Qin, Xinyu Cai, Yewen Li, Haochong Xia, Chuqiao Zong, Xinrun Wang, Bo An 0001
KDD (1)2
2026 Fast-DataShapley: Neural Modeling for Training Data Valuation
abstract
The value and copyright of training data are crucial in the artificial intelligence industry. Service platforms should protect data providers' legitimate rights and fairly reward them for their contributions. Shapley value, a potent tool for evaluating contributions, outperforms other methods in theory, but its computational overhead escalates exponentially with the number of data providers. Recent studies on Shapley values have proposed various approximation algorithms to address the computational complexity issues inherent in exact calculations. However, they need to retrain for each test sample, leading to intolerable costs. We propose Fast-DataShapley, a one-pass training framework that leverages the weighted least squares characterization of the Shapley value to train a reusable explainer model with real-time reasoning speed. Given new test samples, no retraining is required to calculate the Shapley values of the training data. Additionally, we propose three methods with theoretical guarantees to reduce training overhead from two aspects: the approximate calculation of the utility function and the reduction of the sample space complexity. We analyze time complexity to show the efficiency of our methods. The experimental evaluations on various image datasets demonstrate superior performance and efficiency compared to baselines. Specifically, the performance is improved to more than 2×, and the explainer's training speed can be increased by two orders of magnitude.
Haifeng Sun 0005, Runze Wu 0001, Xinyu Cai, Changjie Fan, Lan Zhang 0002, Xiang-Yang Li 0001
WSDM4
2026 Toward Efficient Edge AI With Heterogeneous Computing and Multilevel Optimization
abstract
The rapid progress of artificial intelligence (AI) has brought increasing demands on hardware accelerators, particularly as modern models combine dense linear operations with a growing number of irregular, nonlinear, and control-intensive operators. While tensor cores and systolic arrays offer high throughput for regular computations, they often struggle to efficiently support the diverse operations emerging in recent model structures. Coarse-grained reconfigurable arrays (CGRAs), with their spatial parallelism and reconfigurability, may serve as a natural complement to dense accelerators in such heterogeneous workloads. In this work, we propose EUREKA, a heterogeneous acceleration framework that integrates tensor cores with CGRAs through a unified instruction set, cross-architecture data scheduling, tailored hardware support for nonlinear operators, and optimizations at the instruction, task, and operator levels to exploit parallelism. At the software level, we introduce a hierarchical compilation strategy that combines graph-level optimizations with tensor-level scheduling techniques. To address the large design space of hardware–software co-optimization, we further develop a Bayesian optimization-based exploration scheme enhanced with kernel compression methods, which provides an efficient means of identifying promising hardware configurations and scheduling strategies. Experiment results on representative AI benchmarks show that EUREKA improves execution efficiency, achieving an average$12.6\times $normalized performance gain over state-of-the-art frameworks.
Jingyuan Li 0003, Xinyu Cai, Yuan Dai, Wenbo Yin, Lingli Wang
IEEE Trans. Very Large Scale Integr. Syst.2
2025 GeoX: Geometric Problem Solving Through Unified Formalized Vision-Language Pre-training
abstract
Despite their proficiency in general tasks, Multi-modal Large Language Models (MLLMs) struggle with automatic Geometry Problem Solving (GPS), which demands understanding diagrams, interpreting symbols, and performing complex reasoning. This limitation arises from their pre-training on natural images and texts, along with the lack of automated verification in the problem-solving process. Besides, current geometric specialists are limited by their task-specific designs, making them less effective for broader geometric problems. To this end, we present GeoX, a multi-modal large model focusing on geometric understanding and reasoning tasks. Given the significant differences between geometric diagram-symbol and natural image-text, we introduce unimodal pre-training to develop a diagram encoder and symbol decoder, enhancing the understanding of geometric images and corpora. Furthermore, we introduce geometry-language alignment, an effective pre-training paradigm that bridges the modality gap between unimodal geometric experts. We propose a Generator-And-Sampler Transformer (GS-Former) to generate discriminative queries and eliminate uninformative representations from unevenly distributed geometric signals. Finally, GeoX benefits from visual instruction tuning, empowering it to take geometric images and questions as input and generate verifiable solutions. Experiments show that GeoX outperforms both generalists and geometric specialists on publicly recognized benchmarks, such as GeoQA, UniGeo, Geometry3K, and PGPS9k. Our data and code will be released soon to accelerate future research on automatic GPS.
Renqiu Xia, Mingsheng Li, Hancheng Ye, Hongbin Zhou, Jiakang Yuan, Tianshuo Peng, Xinyu Cai, Xiangchao Yan, Bin Wang 0065, Conghui He, Botian Shi, Tao Chen 0003, Junchi Yan, Bo Zhang 0069
ICLR8
2025 OPHR: Mastering Volatility Trading with Multi-Agent Deep Reinforcement Learning
abstract
Options markets represent one of the most sophisticated segments of the financial ecosystem, with prices that directly reflect market uncertainty. In this paper, we introduce the first reinforcement learning (RL) framework specifically designed for volatility trading through options, focusing on profit from the difference between implied volatility and realized volatility. Our multi-agent architecture consists of an Option Position Agent (OP-Agent) responsible for volatility timing by controlling long/short volatility positions, and a Hedger Routing Agent (HR-Agent) that manages risk and maximizes path-dependent profits by selecting optimal hedging strategies with different risk preferences. Evaluating our approach using cryptocurrency options data from 2021-2024, we demonstrate superior performance on BTC and ETH, significantly outperforming traditional strategies and machine learning baselines across all profit and risk-adjusted metrics while exhibiting sophisticated trading behavior. The code framework and sample data of this paper have been released on https://github.com/Edwicn/OPHR-MasteringVolatilityTradingwithMultiAgentDeepReinforcementLearning
Zeting Chen, Xinyu Cai, Molei Qin, Bo An 0001
NeurIPS2
2025 SPOT: Scalable 3D Pre-Training via Occupancy Prediction for Learning Transferable 3D Representations
abstract
Annotating 3D LiDAR point clouds for perception tasks is fundamental for many applications e.g. autonomous driving, yet it still remains notoriously labor-intensive. Pretraining-finetuning approach can alleviate the labeling burden by fine-tuning a pre-trained backbone across various downstream datasets as well as tasks. In this paper, we propose SPOT, namely Scalable Pre-training via Occupancy prediction for learning Transferable 3D representations under such a label-efficient fine-tuning paradigm. SPOT achieves effectiveness on various public datasets with different downstream tasks, showcasing its general representation power, cross-domain robustness and data scalability which are three key factors for real-world application. Specifically, we both theoretically and empirically show, for the first time, that general representations learning can be achieved through the task of occupancy prediction. Then, to address the domain gap caused by different LiDAR sensors and annotation methods, we develop a beam re-sampling technique for point cloud augmentation combined with class-balancing strategy. Furthermore, scalable pre-training is observed, that is, the downstream performance across all the experiments gets better with more pre-training data. Additionally, such pre-training strategy also remains compatible with unlabeled data. The hope is that our findings will facilitate the understanding of LiDAR points and pave the way for future advancements in LiDAR pre-training.
Xiangchao Yan, Runjian Chen, Bo Zhang 0069, Hancheng Ye, Renqiu Xia, Jiakang Yuan, Hongbin Zhou, Xinyu Cai, Botian Shi, Wenqi Shao, Ping Luo 0002, Yu Qiao 0001, Tao Chen 0003, Junchi Yan
IEEE Trans. Pattern Anal. Mach. Intell.8
2024 ReSimAD: Zero-Shot 3D Domain Transfer for Autonomous Driving with Source Reconstruction and Target Simulation
abstract
Domain shifts such as sensor type changes and geographical situation variations are prevalent in Autonomous Driving (AD), which poses a challenge since AD model relying on the previous domain knowledge can be hardly directly deployed to a new domain without additional costs. In this paper, we provide a new perspective and approach of alleviating the domain shifts, by proposing a Reconstruction-Simulation-Perception (ReSimAD) scheme. Specifically, the implicit reconstruction process is based on the knowledge from the previous old domain, aiming to convert the domain-related knowledge into domain-invariant representations, e.g., 3D scene-level meshes. Besides, the point clouds simulation process of multiple new domains is conditioned on the above reconstructed 3D meshes, where the target-domain-like simulation samples can be obtained, thus reducing the cost of collecting and annotating new-domain data for the subsequent perception process. For experiments, we consider different cross-domain situations such as Waymo-to-KITTI, Waymo-to-nuScenes, etc, to verify the zero-shot target-domain perception using ReSimAD. Results demonstrate that our method is beneficial to boost the domain generalization ability, even promising for 3D pre-training. Code and simulated points are available at: https://github.com/PJLab-ADG/3DTrans
Bo Zhang 0069, Xinyu Cai, Jiakang Yuan, Donglin Yang, Jianfei Guo, Xiangchao Yan, Renqiu Xia, Botian Shi, Min Dou, Tao Chen 0003, Si Liu 0001, Junchi Yan, Yu Qiao 0001
ICLR2
2024 DiLu: A Knowledge-Driven Approach to Autonomous Driving with Large Language Models
abstract
Recent advancements in autonomous driving have relied on data-driven approaches, which are widely adopted but face challenges including dataset bias, overfitting, and uninterpretability. Drawing inspiration from the knowledge-driven nature of human driving, we explore the question of how to instill similar capabilities into autonomous driving systems and summarize a paradigm that integrates an interactive environment, a driver agent, as well as a memory component to address this question. Leveraging large language models (LLMs) with emergent abilities, we propose the DiLu framework, which combines a Reasoning and a Reflection module to enable the system to perform decision-making based on common-sense knowledge and evolve continuously. Extensive experiments prove DiLu's capability to accumulate experience and demonstrate a significant advantage in generalization ability over reinforcement learning-based methods. Moreover, DiLu is able to directly acquire experiences from real-world datasets which highlights its potential to be deployed on practical autonomous driving systems. To the best of our knowledge, we are the first to leverage knowledge-driven capability in decision-making for autonomous vehicles. Through the proposed DiLu framework, LLM is strengthened to apply knowledge and to reason causally in the autonomous driving domain. Project page: https://pjlab-adg.github.io/DiLu/
Licheng Wen, Daocheng Fu, Xin Li 0110, Xinyu Cai, Tao Ma 0002, Pinlong Cai, Min Dou, Botian Shi, Liang He 0001, Yu Qiao 0001
ICLR4
2024 VeloVox: A Low-Cost and Accurate 4D Object Detector with Single-Frame Point Cloud of Livox LiDAR
abstract
Combining motion prediction in LiDAR-based 3D object detection is an effective method for improving overall accuracy, especially the downstream autonomous driving tasks. The recent development of low-cost LiDARs (e.g. Livox LiDAR) enables us to explore such 4D perception systems with a lower budget and higher performance. In this paper, we propose a 4D object detector, VeloVox, to establish accurate object detection and velocity estimation with a single-frame point cloud of Livox LiDAR. Based on the non-repetitive scanning pattern and point-level temporal nature, we propose a two-stage module to enhance the spatial-temporal point feature interaction along the time dimension. The aggregated feature also benefits a more accurate proposal refinement. To demonstrate the performance, comparison of VeloVox with several SOTA detector based baselines is evaluated on our in-house dataset and synthesized dataset built under Carla simulation. Code will be released at https://github.com/PJLab-ADG/VeloVox.
Tao Ma 0002, Zhiwei Zheng, Hongbin Zhou, Xinyu Cai, Xuemeng Yang, Yikang Li 0002, Botian Shi, Hongsheng Li 0001
ICRA4
2024 Zero-training LiDAR-Camera Extrinsic Calibration Method Using Segment Anything Model
abstract
Extrinsic calibration for LiDAR and camera is an essential prerequisite for sensor fusion. Recently, automatic and target-less extrinsic calibration has become the mainstream of academic research. However, geometric feature-based methods still have requirements on the scene. Deep learning methods, while achieving high accuracy and good adaptability, rely on large annotated dataset and need additional training. We propose a novel LiDAR-camera calibration method by using the Segment Anything Model(SAM) without additional training. With the automatically generated masks, we optimize the extrinsic parameters by maximizing the consistency score of the point attributes that fall on each mask. The point cloud attributes include intensity, normal vector and segmentation class. Experiments on different real-world dataset demonstrate the accuracy and robustness of our proposed method. The code is available at https://github.com/OpenCalib/CalibAnything.
Zhaotong Luo, Guohang Yan, Xinyu Cai, Botian Shi
ICRA3
2024 An Extrinsic Calibration Method between LiDAR and GNSS/INS for Autonomous Driving
abstract
Accurate and reliable sensor calibration is critical for fusing LiDAR and inertial measurements in autonomous driving. This paper proposes a novel three-stage extrinsic calibration method between LiDAR and GNSS/INS for autonomous driving. The first stage can quickly calibrate the extrinsic parameters between the sensors through point cloud surface features so that the extrinsic can be narrowed from a large initial error to a small error range in little time. The second stage can further calibrate the extrinsic parameters based on LiDAR-mapping space occupancy while removing motion distortion. In the final stage, the z-axis (the vertical direction relative to the ground plane) errors caused by the plane motion of the autonomous vehicle are corrected, and an accurate extrinsic parameter is finally obtained. Specifically, This method utilizes the planar features in the environment, making it possible to quickly carry out calibration. Experimental results on real-world datasets demonstrate the reliability and accuracy of our method. The codes are open-sourced on the Github website. The code link is https://github.com/OpenCalib/LiDAR2INS.
Jiahao Pi, Guohang Yan, Chengjie Wang 0009, Xinyu Cai, Botian Shi
ICRA4
2024 Realistic Rainy Weather Simulation for LiDARs in CARLA Simulator
abstract
Data augmentation methods to enhance perception performance in adverse weather have recently attracted considerable attention. Most of the LiDAR data augmentation methods post-process the existing dataset by physics-based models or machine-learning methods. However, due to the limited environmental annotations and the fixed vehicle trajectories in existing datasets, it is challenging to edit the scene and expand the diversity of traffic flow and scenario. To this end, we propose a simulator-based physical modeling approach to augment LiDAR data in rainy weather, enhancing the performance of the perception model. We complete the modeling task of the rainy weather effect in the CARLA simulator and establish a data collection pipeline for LiDAR. Furthermore, we pay special attention to the spray generated by vehicles in rainy weather and simulate this phenomenon through the Spray Emitter method we developed. In addition, considering the influence of different weather conditions on point cloud intensity, we develop a prediction network to forecast the intensity of the LiDAR echo. This enables us to complete the rainy weather simulation of 4D point cloud data. In the experiment, we observe that the model augmented by our synthetic dataset improves the performance for 3D object detection in rainy weather. Both code and dataset are available at https://github.com/PJLab-ADG/PCSim#rainypcsim.
Donglin Yang, Xinyu Cai, Zhenfeng Liu, Bo Zhang 0069, Guohang Yan, Xing Gao 0005, Si Liu 0001, Botian Shi
IROS2
2024 A Multimodal Foundation Agent for Financial Trading: Tool-Augmented, Diversified, and Generalist
abstract
Financial trading is a crucial component of the markets, informed by a multimodal information landscape encompassing news, prices, and Kline charts, and encompasses diverse tasks such as quantitative trading and high-frequency trading with various assets. While advanced AI techniques like deep learning and reinforcement learning are extensively utilized in finance, their application in financial trading tasks often faces challenges due to inadequate handling of multimodal data and limited generalizability across various tasks. To address these challenges, we present FinAgent, a multimodal foundational agent with tool augmentation for financial trading. FinAgent's market intelligence module processes a diverse range of data-numerical, textual, and visual-to accurately analyze the financial market. Its unique dual-level reflection module not only enables rapid adaptation to market dynamics but also incorporates a diversified memory retrieval system, enhancing the agent's ability to learn from historical data and improve decision-making processes. The agent's emphasis on reasoning for actions fosters trust in its financial decisions. Moreover, FinAgent integrates established trading strategies and expert insights, ensuring that its trading approaches are both data-driven and rooted in sound financial principles. With comprehensive experiments on 6 financial datasets, including stocks and Crypto, FinAgent significantly outperforms 12 state-of-the-art baselines in terms of 6 financial metrics with over 36% average improvement on profit. Specifically, a 92.27% return (a 84.39% relative improvement) is achieved on one dataset. Notably, FinAgent is the first advanced multimodal foundation agent designed for financial trading tasks.
Wentao Zhang 0007, Lingxuan Zhao, Haochong Xia, Jiaze Sun, Molei Qin, Yilei Zhao 0001, Xinyu Cai, Longtao Zheng, Xinrun Wang, Bo An 0001
KDD10
2024 Continuously Learning, Adapting, and Improving: A Dual-Process Approach to Autonomous Driving
abstract
Autonomous driving has advanced significantly due to sensors, machine learning, and artificial intelligence improvements. However, prevailing methods struggle with intricate scenarios and causal relationships, hindering adaptability and interpretability in varied environments. To address the above problems, we introduce LeapAD, a novel paradigm for autonomous driving inspired by the human cognitive process. Specifically, LeapAD emulates human attention by selecting critical objects relevant to driving decisions, simplifying environmental interpretation, and mitigating decision-making complexities. Additionally, LeapAD incorporates an innovative dual-process decision-making module, which consists of an Analytic Process (System-II) for thorough analysis and reasoning, along with a Heuristic Process (System-I) for swift and empirical processing. The Analytic Process leverages its logical reasoning to accumulate linguistic driving experience, which is then transferred to the Heuristic Process by supervised fine-tuning. Through reflection mechanisms and a growing memory bank, LeapAD continuously improves itself from past mistakes in a closed-loop environment. Closed-loop testing in CARLA shows that LeapAD outperforms all methods relying solely on camera input, requiring 1-2 orders of magnitude less labeled data. Experiments also demonstrate that as the memory bank expands, the Heuristic Process with only 1.8B parameters can inherit the knowledge from a GPT-4 powered Analytic Process and achieve continuous performance improvement. Project page: https://pjlab-adg.github.io/LeapAD
Jianbiao Mei, Yukai Ma, Xuemeng Yang, Licheng Wen, Xinyu Cai, Xin Li 0110, Daocheng Fu, Bo Zhang 0069, Pinlong Cai, Min Dou, Botian Shi, Liang He 0001, Yong Liu 0007, Yu Qiao 0001
NeurIPS5
2023 Av-Sepformer: Cross-Attention Sepformer for Audio-Visual Target Speaker Extraction
abstract
Visual information can serve as an effective cue for target speaker extraction (TSE) and is vital to improving extraction performance. In this paper, we propose AV-SepFormer, a SepFormer-based attention dual-scale model that utilizes cross- and self-attention to fuse and model features from audio and visual. AV-SepFormer splits the audio feature into a number of chunks, equivalent to the length of the visual feature. Then self- and cross-attention are employed to model the multi-modal features. Furthermore, we use a novel 2D positional encoding, that introduces the positional information between and within chunks and provides significant gains over the traditional positional encoding. Our model has two key advantages: the time granularity of audio chunked feature is synchronized to the visual feature, which alleviates the harm caused by the inconsistency of audio and video sampling rate; by combining self- and cross-attention, feature fusion and speech extraction processes are unified within an attention paradigm. The experimental results show that AV-SepFormer significantly outperforms other existing methods.
Jiuxin Lin, Xinyu Cai, Heinrich Dinkel, Jun Chen 0024, Zhiyong Yan, Zhiyong Wu 0001, Helen M. Meng
ICASSP2
2023 Optimizing the Placement of Roadside LiDARs for Autonomous Driving
abstract
Multi-agent cooperative perception is an increasingly popular topic in the field of autonomous driving, where roadside LiDARs play an essential role. However, how to optimize the placement of roadside LiDARs is a crucial but often overlooked problem. This paper proposes an approach to optimize the placement of roadside LiDARs by selecting optimized positions within the scene for better perception performance. To efficiently obtain the best combination of locations, a greedy algorithm based on perceptual gain is proposed, which selects the location that can maximize the perceptual gain sequentially. We define perceptual gain as the increased perceptual capability when a new LiDAR is placed. To obtain the perception capability, we propose a perception predictor that learns to evaluate LiDAR placement using only a single point cloud frame. A dataset named Roadside-Opt is created using the CARLA simulator to facilitate research on the roadside LiDAR placement problem. Extensive experiments are conducted to demonstrate the effectiveness of our proposed method.
Hao Xiang 0001, Xinyu Cai, Runsheng Xu, Jiaqi Ma 0003, Gim Hee Lee, Si Liu 0001
ICCV3
2023 Analyzing Infrastructure LiDAR Placement with Realistic LiDAR Simulation Library
abstract
Recently, Vehicle-to-Everything (V2X) cooperative perception has attracted increasing attention. Infrastructure sensors play a critical role in this research field; however, how to find the optimal placement of infrastructure sensors is rarely studied. In this paper, we investigate the problem of infrastructure sensor placement and propose a pipeline that can efficiently and effectively find optimal installation positions for infrastructure sensors in a realistic simulated environment. To better simulate and evaluate LiDAR place-ment, we establish a Realistic LiDAR Simulation library that can simulate the unique characteristics of different popular LiDARs and produce high-fidelity LiDAR point clouds in the CARLA simulator. Through simulating point cloud data in different LiDAR placements, we can evaluate the perception accuracy of these placements using multiple detection models. Then, we analyze the correlation between the point cloud distribution and perception accuracy by calculating the density and uniformity of regions of interest. Experiments show that when using the same number and type of LiDAR, the placement scheme optimized by our proposed method improves the average precision by 15%, compared with the conventional placement scheme in the standard lane scene. We also analyze the correlation between perception performance in the region of interest and LiDAR point cloud distribution and validate that density and uniformity can be indicators of performance. Both the RLS Library and related code will be released at https://github.com/PJLab-ADG/LiDARSimLib-and-Placement-Evaluation.
Xinyu Cai, Runsheng Xu, Wenquan Zhao, Jiaqi Ma 0003, Si Liu 0001
ICRA1
2023 Direct Angular Rate Estimation Without Event Motion-Compensation At High Angular Rates
abstract
Feature-based methods are a popular method for camera state estimation using event cameras. Due to the spatiotemporal nature of events, all event images exhibit smearing of events analogous to motion blur for a camera under motion. As such, events must be motion compensated to derive a sharp event image. However, this presents a causality dilemma where motion prior is required to unsmear the events, but a sharp event image is required to estimate motion. While it is possible to use the IMU to develop motion prior, it has been shown that the limited dynamic range of$\pm \mathbf{2000}^{\circ}/\mathrm{s}$is insufficient for high angular rate rotorcrafts. Furthermore, smoothing of motion-compensated images due to actual event detection time latency in event cameras severely limits the performance of feature-based methods at high angular rates. This paper proposes a Fourier-based angular rate estimator capable of estimating angular rates directly on non-motion compensated event images. This method circumvents the need for external motion priors in camera state estimation and sidesteps problematic smoothing of features in the spatial domain due to motion blur. Lastly, using an NVIDIA Jetson Xavier NX, the algorithm is demonstrated to be real-time performant up to 3960°/s.
Matthew Ng, Xinyu Cai, Shaohui Foong
ICRA2
2023 Joint Camera Intrinsic and LiDAR-Camera Extrinsic Calibration
abstract
Sensor-based environmental perception is a crucial step for autonomous driving systems, for which an accurate calibration between multiple sensors plays a critical role. For the calibration of LiDAR and camera, the existing method is generally to calibrate the intrinsic of the camera first and then calibrate the extrinsic of the LiDAR and camera. If the camera's intrinsic is not calibrated correctly in the first stage, it is not easy to calibrate the LiDAR-camera extrinsic accurately. Due to the complex internal structure of the camera and the lack of an effective quantitative evaluation method for the camera's intrinsic calibration, in the actual calibration, the accuracy of extrinsic parameter calibration is often reduced due to the tiny error of the camera's intrinsic parameters. To this end, we propose a novel target-based joint calibration method of the camera intrinsic and LiDAR-camera extrinsic parameters. Firstly, we design a novel calibration board pattern, adding four circular holes around the checkerboard for locating the LiDAR pose. Subsequently, a cost function defined under the reprojection constraints of the checkerboard and circular holes features is designed to solve the camera's intrinsic parameters, distortion factor, and LiDAR-camera extrinsic parameter. In the end, quantitative and qualitative experiments are conducted in actual and simulated environments, and the result shows the proposed method can achieve accuracy and robust performance. The open-source code is available at https://github.com/OpenCalib/JointCalib.
Guohang Yan, Feiyu He, Chunlei Shi 0001, Pengjin Wei, Xinyu Cai, Yikang Li 0002
ICRA5
2023 Specify Robust Causal Representation from Mixed Observations
abstract
Learning representations purely from observations concerns the problem of learning a low-dimensional, compact representation which is beneficial to prediction models. Under the hypothesis that the intrinsic latent factors follow some casual generative models, we argue that by learning a causal representation, which is the minimal sufficient causes of the whole system, we can improve the robustness and generalization performance of machine learning models. In this paper, we develop a learning method to learn such representation from observational data by regularizing the learning procedure with mutual information measures, according to the hypothetical factored causal graph. We theoretically and empirically show that the models trained with the learned causal representations are more robust under adversarial attacks and distribution shifts compared with baselines.
Mengyue Yang, Xinyu Cai, Furui Liu, Weinan Zhang 0001, Jun Wang 0012
KDD2
2023 Offline RL with Discrete Proxy Representations for Generalizability in POMDPs
abstract
Offline Reinforcement Learning (RL) has demonstrated promising results in various applications by learning policies from previously collected datasets, reducing the need for online exploration and interactions. However, real-world scenarios usually involve partial observability, which brings crucial challenges of the deployment of offline RL methods: i) the policy trained on data with full observability is not robust against the masked observations during execution, and ii) the information of which parts of observations are masked is usually unknown during training. In order to address these challenges, we present Offline RL with DiscrEte pRoxy representations (ORDER), a probabilistic framework which leverages novel state representations to improve the robustness against diverse masked observabilities. Specifically, we propose a discrete representation of the states and use a proxy representation to recover the states from masked partial observable trajectories. The training of ORDER can be compactly described as the following three steps. i) Learning the discrete state representations on data with full observations, ii) Training the decision module based on the discrete representations, and iii) Training the proxy discrete representations on the data with various partial observations, aligning with the discrete representations. We conduct extensive experiments to evaluate ORDER, showcasing its effectiveness in offline RL for diverse partially observable scenarios and highlighting the significance of discrete proxy representations in generalization performance. ORDER is a flexible framework to employ any offline RL algorithms and we hope that ORDER can pave the way for the deployment of RL policy against various partial observabilities in the real world.
Pengjie Gu, Xinyu Cai, Dong Xing, Xinrun Wang, Mengchen Zhao, Bo An 0001
NeurIPS2
2023 Broad learning algorithm of cascaded enhancement nodes based on phase space reconstruction
Xinyu Cai, Xiang Feng 0002, Huiqun Yu
Appl. Intell.1
2022 Cooperative Modular Single Actuator Monocopters Capable of Controlled Passive Separation
abstract
In this paper, we introduce a Modular Single Actuator Monocopter (M-SAM), which is capable of flying in both singular configuration and cooperative configuration. From singular mode, M-SAMs can be manually assembled into cooperative mode, using magnetic connectors built into the body of each M-SAM unit. The design of the connectors allow for passive separation of the units without the need for a dedicated separating actuator, by harnessing the variable centrifugal force from controlled adjustment of the rotating speed of the craft. To achieve control in both configurations, we firstly studied and analyzed their full dynamic models by introducing equilibrium state and relaxed hovering condition. Next, we derived a reduced model to approximate the dynamical behavior of both singular and cooperative configuration in flight to design a generalized cyclic-based cascaded flight controller. Finally, we validated the proposed controller and separation mechanism by conducting several flight experiments for two M-SAMs in singular mode, cooperative mode as well as mid-air separating under motion capture system.
Xinyu Cai, Shane Kyi Hla Win, Luke Soe Thura Win, Danial Sufiyan Bin Shaiful, Shaohui Foong
ICRA1
2022 CROON: Automatic Multi-LiDAR Calibration and Refinement Method in Road Scene
abstract
Sensor-based environmental perception is a crucial part of the autonomous driving system. In order to get an excellent perception of the surrounding environment, an intelligent system would configure multiple LiDARs (3D Light Detection and Ranging) to cover the distant and near space of the car. The precision of perception relies on the quality of sensor calibration. This research aims at developing an accurate, automatic, and robust calibration strategy for multiple LiDAR systems in the general road scene. We thus propose CROON (automatic multi-LiDAR Calibration and Refinement methOd in rOad sceNe), a two-stage method including rough and refinement calibration. The first stage can calibrate the sensor from an arbitrary initial pose, and the second stage is able to precisely calibrate the sensor iteratively. Specifically, CROON utilize the nature characteristics of road scene so that it is independent and easy to apply in large-scale conditions. Experimental results on real-world and simulated data sets demonstrate the reliability and accuracy of our method. All the related data sets and codes are open-sourced on the Github website https://github.com/OpenCalib/LiDAR2LiDAR.
Pengjin Wei, Guohang Yan, Yikang Li 0002, Kun Fang 0004, Xinyu Cai, Jie Yang 0002, Wei Liu 0044
IROS5
2020 Deep Space Probing for Point Cloud Analysis
abstract
3D points distribute in a continuous 3D space irregularly, thus directly adapting 2D image convolution to 3D points is not an easy job. Previous works often artificially divide the space into regular grids, yet it could be suboptimal to learn geometry. In this paper, we propose SPCNN, namely, Space Probing Convolutional Neural Network, which naturally generalizes image CNN to deal with point clouds. The key idea of SPCNN is learning to probe the 3D space in an adaptive manner. Specifically, we define a pool of learnable convolutional weights, and let each point in the local region learn to choose a suitable convolutional weight from the pool. This is achieved by constructing a geometry guided index-mapping function that implicitly establishes a correspondence between convolutional weights and some local regions in the neighborhood (Fig. 1). In this way, the index-mapping function learns to adaptively partition nearby space for local geometry pattern recognition. With this convolution as a basic operator, SPCNN, a hierarchical architecture can be developed for effective point cloud analysis. Extensive experiments on challenging benchmarks across three tasks demonstrate that SPCNN achieves the state-of-the-art or has competitive performance.
Yirong Yang, Bin Fan 0001, Yongcheng Liu, Jiyong Zhang 0001, Xin Liu 0027, Xinyu Cai, Shiming Xiang, Chunhong Pan
ICPR7
2020 Towards Cooperative Transport of a Suspended Payload via Two Aerial Robots with Inertial Sensing
abstract
This paper addresses the problem of cooperative transport of a point mass hoisted by two aerial robots. Treating the robots as a leader and a follower, the follower stabilizes the system with respect to the leader using only feedback from its Inertial Measurement Units (IMU). This is accomplished by neglecting the acceleration of the leader, analyzing the system through the generalized coordinates or the cables’ angles, and employing an observation model based on the IMU measurements. A lightweight estimator based on an Extended Kalman Filter (EKF) and a controller are derived to stabilize the robot-payload-robot system. The proposed methods are verified with extensive flight experiments, first with a single robot and then with two robots. The results show that the follower is capable of realizing the desired quasi-static trajectory using only its IMU measurements. The outcomes demonstrate promising progress towards the goal of autonomous cooperative transport of a suspended payload via small flying robots with minimal sensing and computational requirements.
Xinyu Cai, Pakpong Chirarattananon
IROS2