Ranulfo Bezerra
研究

02

共有セマンティック・ワールドモデル

共有表現は集合的思考の基盤である。そこには幾何情報だけでなく、不確実性と来歴が刻まれていなければならない。

エージェントは生のセンサストリームの上で共に推論することはできない。何が存在し、どう関係し、いつ、誰によって観測され、どれほど確からしいのか——構造化された世界の共通記述が必要である。この柱では、動的・マルチモーダルで、不確実性を明示的に持つセマンティックシーングラフと物理知識グラフを構築する。

未解決の問い

  1. 01

    複数のエージェントが同時に書き込むワールドモデルの適切な粒度とは何か。

  2. 02

    二つのエージェントの見解が食い違うことを、共有モデルはどう表現すべきか。

  3. 03

    世界が変化したとき、セマンティック記憶はどのように減衰すべきか。

01/手法とトピック

02/研究資金

03/関連プロジェクト

04/代表的な業績

9

2021

Knowledge Acquisition from Pedestrian Flow Analysis using Sparse Mobile Probe Data

Ranulfo Bezerra, Kazunori Ohno, Thomas Westfechtel, Shotaro Kojima, Kento Yamada, Satoshi Tadokoro

J. Intell. Robot. Syst.·論文誌

概要 +

Autonomous vehicles require high-level semantic maps, which contain the activities of pedestrians and cars, to ensure safe navigation. High-level semantics can be obtained from mobile probe sensor data. Analyzing pedestrian trajectories obtained from mobile probe data is an effective approach to avoid collisions between autonomous vehicles and pedestrians. Such analyses of pedestrian trajectories can generate new information such as pedestrian behaviors in violation of traffic regulations. However, pedestrian trajectories obtained from mobile probe data significantly sparse and noisy, making it challenging to analyze pedestrian activity. To address this issue, we propose multiple daily data and graph-based approaches to treat sparse and noisy data for estimating the flow of pedestrians based on mobile probe data. To improve the sparseness of the data, multiple daily data are fused. After that, a pedestrian graph is created to enhance the region’s coverage by connecting the sparse data indicating the flow of pedestrians. This proposed approach successfully obtained pedestrian trajectory data from the sparse and noisy data. Moreover, it was possible to identify the potential locations where pedestrians tend to cross the street by analyzing the pedestrian flow. The results indicate that 83% of well-known regions where pedestrians tend to cross the street corresponded with those extracted using the proposed approach. Furthermore, a high-level semantic map of the regions where pedestrians tend to cross the street along a 1-km road is presented. The trajectory information obtained using the proposed approach is expected to be essential for understanding different scenarios of the interactions between individuals and autonomous vehicles.

DOI

2021

Semantic Mapping of Construction Site From Multiple Daily Airborne LiDAR Data

Thomas Westfechtel, Kazunori Ohno, Tetsu Akegawa, Kento Yamada, Ranulfo Bezerra, Shotaro Kojima, Taro Suzuki, Tomohiro Komatsu, Yukinori Shibata, Kimitaka Asano, Keji Nagatani, Naoto Miyamoto, Takahiro Suzuki, Tatsuya Harada, Satoshi Tadokoro

IEEE RA-L·論文誌

概要 +

Semantic maps are an important tool to provide robots with high-level knowledge about the environment, enabling them to better react to and interact with their surroundings. However, as a single measurement of the environment is solely a snapshot of a specific time, it does not necessarily reflect the underlying semantics. In this work, we propose a method to create a semantic map of a construction site by fusing multiple daily data. The construction site is measured by an unmanned aerial vehicle (UAV) equipped with a LiDAR. We extract clusters above ground level from the measurements and classify them using either a random forest or a deep learning based classifier. Furthermore, we combine the classification results of several measurements to generalize the classification of the single measurements and create a general semantic map of the working site. We measured two construction fields for our evaluation. The classification models can achieve an average intersection over union (IoU) score of 69.2 during classification on the Sanbongi field, which is used for training, validation and testing and an IoU score of 49.16 on a hold-out testing field. In a final step, we show how the semantic map can be employed to suggest a parking spot for a dump truck, and in addition, show that the semantic map can be utilized to improve path planning inside the construction site.

DOI

2019

Large Scale Semantic Mapping Through Multi-modal Sensor Fusion

Thomas Westfechtel, Kazunori Ohno, Ranulfo Bezerra, Shotaro Kojima, Satoshi Tadokoro

RSJ 2019·国内会議

2025

Hierarchical Semantic 3D Scene Graphs Generation for Industrial Simulation Environments by Using LVLMs

Nathan Walus, Ranulfo Bezerra, Kazunori Ohno

ROBOMECH 2025·国内会議