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学者姓名：张立伟
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Abstract ：
Passive vibration isolation techniques with low-frequency characteristics have been a hot topic in the aerospace field. A hydraulic inertial vibration isolator is a highly effective type of isolator for controlling low-frequency vibrations. It typically consists of a main spring, a minor spring, an inertial mass, and a fluid domain. Due to its multi-domain nature, analyzing the isolation mechanism of this type of isolator is challenging. The bond graph method is employed to establish the dynamic model of the isolator. Subsequently, the state equations of the isolator are derived, and the energy equations of both the mechanical and the fluid parts of the isolator are obtained. Based on this, the energy transfer characteristics between the mechanical and fluid domains inside the isolator under external excitation are discussed. The time-domain response of the forces transmitted to the foundation is analyzed. It is shown that the anti-resonance frequency occurs when the forces transmitted to the foundation generated by the main spring and the fluid pressure are equal to that of the minor spring. To verify the proposed method’s correctness, a prototype of the isolator is designed and a carefully designed experiment is conducted. The acceleration transmissibility of the isolator is used to conduct a comparative study. The results show that the theoretical results are in good agreement with the experimental results. To depict the dynamic characteristics of the isolator under large amplitude vibration, the nonlinear dynamic model of the isolator is developed, and the corresponding force transmissibility of the isolator is formulated. The energy flow between the mechanical and the fluid domains under this condition is also analyzed. The results indicate that the energy flow responses exhibit a similar change tendency to the force transmissibility. However, the peak of the energy ratio between the mechanical subsystem and the fluid is the same as the linear condition, suggesting that this value is determined by the amplification ratio of the isolator. This research provides enhanced physical insight to understand the dynamic characteristics of this type of isolator and will help to shorten the design cycle of the isolator. © 2024 by the authors.
Keyword ：
acceleration transmissibility acceleration transmissibility bond graph bond graph energy transfer energy transfer hydraulic inertial isolator hydraulic inertial isolator multi-energy-domain multi-energy-domain
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| GB/T 7714 | Liu, N. , Li, C. , Zhang, L. et al. The Bond Graph Modeling and Experimental Verification of a Hydraulic Inertial Vibration Isolator Including Nonlinear Effects [J]. | Aerospace , 2024 , 11 (8) . |
| MLA | Liu, N. et al. "The Bond Graph Modeling and Experimental Verification of a Hydraulic Inertial Vibration Isolator Including Nonlinear Effects" . | Aerospace 11 . 8 (2024) . |
| APA | Liu, N. , Li, C. , Zhang, L. , Lei, Z. , Yang, J. , Lai, F. . The Bond Graph Modeling and Experimental Verification of a Hydraulic Inertial Vibration Isolator Including Nonlinear Effects . | Aerospace , 2024 , 11 (8) . |
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Abstract ：
Purpose: In order to improve the isolation capability of the longitudinal vibration of the shafting system in the low frequency range, a lever-type isolator with negative stiffness (LTINS) was proposed. Methods: The LTINS arranged in parallel with the thrust bearing to isolate the longitudinal fluctuating force transmitted from the propeller-shaft to its foundation. The Rayleigh–Ritz method is used to establish the longitudinal dynamic model of the propeller-shaft-LTINS system. Results: The force transmissibility of the coupled system is formulated, and computed results are compared with those solutions obtained from the finite element method. A stability analysis is carried out based on the equivalent static and dynamic stiffness of the thrust bearing of the shafting system. A comparison study is conducted to compare the isolation performance of the proposed isolator with the traditional isolator such as the dynamic anti-resonance vibration isolator (DAVI), absorber such as the dynamic vibration absorber (DVA), and dynamic vibration absorber with negative stiffness (DVANS). Parametric optimization is carried out to investigate the impact of the parameters of the LTINS on its isolation performance. Conclusion: The results indicated that the proposed control method can achieve a much wider bandwidth than that of the traditional vibration control scheme with a much smaller mass ratio. © Springer Nature Singapore Pte Ltd. 2024.
Keyword ：
Axial vibration control Axial vibration control Lever-type isolator with negative stiffness Lever-type isolator with negative stiffness Rayleigh–Ritz method Rayleigh–Ritz method Shafting system Shafting system Thrust bearing Thrust bearing
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| GB/T 7714 | Liu, N. , Lei, X. , Lin, F. et al. Longitudinal Vibration Transmission Suppression for Propeller-Shaft System by a Lever-Type Isolator with Negative Stiffness [J]. | Journal of Vibration Engineering and Technologies , 2024 , 12 (Suppl 1) : 949-965 . |
| MLA | Liu, N. et al. "Longitudinal Vibration Transmission Suppression for Propeller-Shaft System by a Lever-Type Isolator with Negative Stiffness" . | Journal of Vibration Engineering and Technologies 12 . Suppl 1 (2024) : 949-965 . |
| APA | Liu, N. , Lei, X. , Lin, F. , Zhang, L. , Yang, J. . Longitudinal Vibration Transmission Suppression for Propeller-Shaft System by a Lever-Type Isolator with Negative Stiffness . | Journal of Vibration Engineering and Technologies , 2024 , 12 (Suppl 1) , 949-965 . |
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Abstract ：
In recent studies on LiDAR SLAM, the achievement of robust optimized LiDAR odometry is the primary objective. For the mapping part, some studies focus on improving the processing of point cloud, while others aim to the optimization of the result deviation caused by errors. Meanwhile, in the fields of robotics and autonomous driving, multi-sensor fusion solutions based on IMUs are becoming the norm. This paper contributes to the optimization of mapping by leveraging a lightweight LiDAR-inertial state estimator. The proposed method combines information from a 6-axis IMU and a 3D LiDAR to form a tightly-coupled scheme that incorporates iterative error state Kalman filter (IESKF). Due to the continuous error accumulation, trajectory deviations can be significant. To mitigate this, an adaptive distance threshold loop closure detection mechanism is employed. Furthermore, since the algorithm primarily addresses outdoor scenes, ground features collected by sensors account for a significant portion of the computation. Improvements in the ground segmentation method lead to less disturbance during mapping on uneven terrain, enabling the method to effectively ad-dress a wider range of real-world environments. As a result, the proposed method demonstrates excellent stability and accuracy, as verified in experiments conducted on urban dataset and campus environment. © 2024, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Keyword ：
Errors Errors Iterative methods Iterative methods Mapping Mapping Optical radar Optical radar Optimization Optimization Robotics Robotics
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| GB/T 7714 | Wang, Yuhang , Zhang, Liwei . Lidar-Inertial SLAM Method for Accurate and Robust Mapping [C] . 2024 : 33-44 . |
| MLA | Wang, Yuhang et al. "Lidar-Inertial SLAM Method for Accurate and Robust Mapping" . (2024) : 33-44 . |
| APA | Wang, Yuhang , Zhang, Liwei . Lidar-Inertial SLAM Method for Accurate and Robust Mapping . (2024) : 33-44 . |
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Abstract ：
Simultaneous Localization And Mapping (SLAM) is a critical technology for autonomous driving in urban environments. However, in environments with many moving objects, currently available LiDAR-based SLAM methods cannot effectively detect loops as they assume a static environment, resulting in unreliable trajectories. Therefore, in this paper, we propose RB-LIO, a LiDAR SLAM system based on the LIO-SAM framework. The proposed system utilizes a dynamic object segmentation module to mitigate the influence of moving objects with tight-coupled LiDAR inertial odometry. It also corrects the complete 6-DoF loop closure with BoW3D and performs pose graph optimization using GTSAM-ISAM2. We tested RB-LIO on public datasets (KITTI and MulRan) and self-collected datasets and compared it with state-of-the-art SLAM systems such as A-LOAM, LeGO-LOAM, LINS, LIO-SAM, and Fast-LIO2. The experimental results indicate that RB-LIO achieves more than 40% improvement in accuracy and a significant improvement of map quality. © 2024, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Keyword ：
Image segmentation Image segmentation Object detection Object detection Optical radar Optical radar Robotics Robotics
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| GB/T 7714 | Zhang, Yanzhou , Zhang, Liwei . RB-LIO: A SLAM Solution Applied to Large-Scale Dynamic Scenes with Multiple Moving Objects [C] . 2024 : 180-192 . |
| MLA | Zhang, Yanzhou et al. "RB-LIO: A SLAM Solution Applied to Large-Scale Dynamic Scenes with Multiple Moving Objects" . (2024) : 180-192 . |
| APA | Zhang, Yanzhou , Zhang, Liwei . RB-LIO: A SLAM Solution Applied to Large-Scale Dynamic Scenes with Multiple Moving Objects . (2024) : 180-192 . |
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Abstract ：
In this paper, we present a lightweight, integrated LiDAR SLAM system designed for high efficiency and robust loop closure detection. Our evaluation focuses on LiDAR-based platforms with limited on-board computation capabilities in long-distance and large-scale scenarios. We identify that front-end only SLAM systems are prone to drift due to accumulated errors in pose estimation. To mitigate this issue, we propose two enhancements: 1) the implementation of an incremental kd tree (ikd-tree) data structure for efficient map management, and 2) the utilization of Normal Distribution Descriptor (NDD) for loop closure detection, combined with GTSAM for global optimization, which effectively corrects the final trajectory of the algorithm. Finally, we validate our proposed method using the KITTI and MulRan datasets and benchmark it against the FLOAM system. The experimental results reveal that our method surpasses FLOAM in terms of computational efficiency by 26.21% and 53.53%, and in terms of accuracy by 36.88% and 84.76% on the KITTI and MulRan datasets, respectively. These findings demonstrate the potential of our lightweight integrated LiDAR SLAM system to significantly improve both efficiency and accuracy in challenging environments, making it a valuable contribution to the field of SLAM research. © 2024, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Keyword ：
Computational efficiency Computational efficiency Global optimization Global optimization Information management Information management Normal distribution Normal distribution Optical radar Optical radar Trees (mathematics) Trees (mathematics)
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| GB/T 7714 | Yin, Guoqiang , Zhang, Liwei . Robust Real-Time Optimized LiDAR Odometry with Loop Closure Detection [C] . 2024 : 322-333 . |
| MLA | Yin, Guoqiang et al. "Robust Real-Time Optimized LiDAR Odometry with Loop Closure Detection" . (2024) : 322-333 . |
| APA | Yin, Guoqiang , Zhang, Liwei . Robust Real-Time Optimized LiDAR Odometry with Loop Closure Detection . (2024) : 322-333 . |
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Abstract ：
Passive vibration isolation techniques with low-frequency characteristics have been a hot topic in the aerospace field. A hydraulic inertial vibration isolator is a highly effective type of isolator for controlling low-frequency vibrations. It typically consists of a main spring, a minor spring, an inertial mass, and a fluid domain. Due to its multi-domain nature, analyzing the isolation mechanism of this type of isolator is challenging. The bond graph method is employed to establish the dynamic model of the isolator. Subsequently, the state equations of the isolator are derived, and the energy equations of both the mechanical and the fluid parts of the isolator are obtained. Based on this, the energy transfer characteristics between the mechanical and fluid domains inside the isolator under external excitation are discussed. The time-domain response of the forces transmitted to the foundation is analyzed. It is shown that the anti-resonance frequency occurs when the forces transmitted to the foundation generated by the main spring and the fluid pressure are equal to that of the minor spring. To verify the proposed method's correctness, a prototype of the isolator is designed and a carefully designed experiment is conducted. The acceleration transmissibility of the isolator is used to conduct a comparative study. The results show that the theoretical results are in good agreement with the experimental results. To depict the dynamic characteristics of the isolator under large amplitude vibration, the nonlinear dynamic model of the isolator is developed, and the corresponding force transmissibility of the isolator is formulated. The energy flow between the mechanical and the fluid domains under this condition is also analyzed. The results indicate that the energy flow responses exhibit a similar change tendency to the force transmissibility. However, the peak of the energy ratio between the mechanical subsystem and the fluid is the same as the linear condition, suggesting that this value is determined by the amplification ratio of the isolator. This research provides enhanced physical insight to understand the dynamic characteristics of this type of isolator and will help to shorten the design cycle of the isolator.
Keyword ：
acceleration transmissibility acceleration transmissibility bond graph bond graph energy transfer energy transfer hydraulic inertial isolator hydraulic inertial isolator multi-energy-domain multi-energy-domain
Cite：
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| GB/T 7714 | Liu, Niuniu , Li, Cheng , Zhang, Liwei et al. The Bond Graph Modeling and Experimental Verification of a Hydraulic Inertial Vibration Isolator Including Nonlinear Effects [J]. | AEROSPACE , 2024 , 11 (8) . |
| MLA | Liu, Niuniu et al. "The Bond Graph Modeling and Experimental Verification of a Hydraulic Inertial Vibration Isolator Including Nonlinear Effects" . | AEROSPACE 11 . 8 (2024) . |
| APA | Liu, Niuniu , Li, Cheng , Zhang, Liwei , Lei, Zhiyang , Yang, Jing , Lai, Fuqiang . The Bond Graph Modeling and Experimental Verification of a Hydraulic Inertial Vibration Isolator Including Nonlinear Effects . | AEROSPACE , 2024 , 11 (8) . |
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Abstract ：
PurposeIn order to improve the isolation capability of the longitudinal vibration of the shafting system in the low frequency range, a lever-type isolator with negative stiffness (LTINS) was proposed.MethodsThe LTINS arranged in parallel with the thrust bearing to isolate the longitudinal fluctuating force transmitted from the propeller-shaft to its foundation. The Rayleigh-Ritz method is used to establish the longitudinal dynamic model of the propeller-shaft-LTINS system.ResultsThe force transmissibility of the coupled system is formulated, and computed results are compared with those solutions obtained from the finite element method. A stability analysis is carried out based on the equivalent static and dynamic stiffness of the thrust bearing of the shafting system. A comparison study is conducted to compare the isolation performance of the proposed isolator with the traditional isolator such as the dynamic anti-resonance vibration isolator (DAVI), absorber such as the dynamic vibration absorber (DVA), and dynamic vibration absorber with negative stiffness (DVANS). Parametric optimization is carried out to investigate the impact of the parameters of the LTINS on its isolation performance.ConclusionThe results indicated that the proposed control method can achieve a much wider bandwidth than that of the traditional vibration control scheme with a much smaller mass ratio.
Keyword ：
Axial vibration control Axial vibration control Lever-type isolator with negative stiffness Lever-type isolator with negative stiffness Rayleigh-Ritz method Rayleigh-Ritz method Shafting system Shafting system Thrust bearing Thrust bearing
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| GB/T 7714 | Liu, Niuniu , Lei, Xianliang , Lin, Fuming et al. Longitudinal Vibration Transmission Suppression for Propeller-Shaft System by a Lever-Type Isolator with Negative Stiffness [J]. | JOURNAL OF VIBRATION ENGINEERING & TECHNOLOGIES , 2024 , 12 (SUPPL 1) : 949-965 . |
| MLA | Liu, Niuniu et al. "Longitudinal Vibration Transmission Suppression for Propeller-Shaft System by a Lever-Type Isolator with Negative Stiffness" . | JOURNAL OF VIBRATION ENGINEERING & TECHNOLOGIES 12 . SUPPL 1 (2024) : 949-965 . |
| APA | Liu, Niuniu , Lei, Xianliang , Lin, Fuming , Zhang, Liwei , Yang, Jing . Longitudinal Vibration Transmission Suppression for Propeller-Shaft System by a Lever-Type Isolator with Negative Stiffness . | JOURNAL OF VIBRATION ENGINEERING & TECHNOLOGIES , 2024 , 12 (SUPPL 1) , 949-965 . |
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Abstract ：
A lever-enhanced negative stiffness isolator (LENSI) is proposed to attenuate the longitudinal vibration of a shaft-plate coupled system in the low-frequency range. The isolator comprises a rigid lever, an isolator mass and a negative stiffness element, installed in parallel with the thrust bearing. The dynamic model of the shaft-plate coupled system is formulated using the Rayleigh-Ritz method. Longitudinal acceleration frequency response of the bearing pedestal and mean square velocity of the plate are used to evaluate the isolation performance of the proposed isolator. By comparing the isolation performance of LENSI with traditional isolator such as dynamic anti-resonance isolator (DAVI) or absorber such as dynamic vibration absorber with negative stiffness (DVANS), the superiority of the LENSI is demonstrated. A parametric study is presented to clarify the influence of the isolator parameters on its isolation performance. It is shown that the LENSI is capable of isolate the longitudinal vibration of the shaft-plate coupled system with a much lower mass ratio in the low-frequency range.
Keyword ：
Lever-enhanced negative stiffness isolator (LENSI) Lever-enhanced negative stiffness isolator (LENSI) Longitudinal vibration transmission control Longitudinal vibration transmission control Rayleigh-Ritz method Rayleigh-Ritz method Shaft-plate coupled system Shaft-plate coupled system
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| GB/T 7714 | Liu, Niuniu , Lin, Fuming , Lei, Xianliang et al. Longitudinal Vibration Control of A Shaft-plate Coupled System with A Lever-enhanced Negative Stiffness Isolator [J]. | PROCEEDINGS OF THE 2024 3RD INTERNATIONAL SYMPOSIUM ON INTELLIGENT UNMANNED SYSTEMS AND ARTIFICIAL INTELLIGENCE, SIUSAI 2024 , 2024 : 193-198 . |
| MLA | Liu, Niuniu et al. "Longitudinal Vibration Control of A Shaft-plate Coupled System with A Lever-enhanced Negative Stiffness Isolator" . | PROCEEDINGS OF THE 2024 3RD INTERNATIONAL SYMPOSIUM ON INTELLIGENT UNMANNED SYSTEMS AND ARTIFICIAL INTELLIGENCE, SIUSAI 2024 (2024) : 193-198 . |
| APA | Liu, Niuniu , Lin, Fuming , Lei, Xianliang , Zhang, Liwei , Yang, Jing . Longitudinal Vibration Control of A Shaft-plate Coupled System with A Lever-enhanced Negative Stiffness Isolator . | PROCEEDINGS OF THE 2024 3RD INTERNATIONAL SYMPOSIUM ON INTELLIGENT UNMANNED SYSTEMS AND ARTIFICIAL INTELLIGENCE, SIUSAI 2024 , 2024 , 193-198 . |
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The processing of 3D point clouds from laser scanning is still challenging in self-driving perception and positioning community. Ground segmentation is the key topic, splitting out the ground point cloud effectively reduces the amount of data and increases the speed of subsequent point cloud clustering and feature point extraction. The ground points segmented in SLAM can be used as constraints for back-end optimisation, improving the accuracy of map building and localisation. After the ground segmentation is completed, it can be used as a passable area for vehicle path planning. Existing approaches are based on the assumption that the ground is plane, but unfortunately the ground is not a plane, with a large number of slopes, roadsides, and parts of the ground even rugged and full of obstacles. In order to solve the ground segmentation problem, this paper proposes a ground segmentation method based on polar grid. The main contributions of this paper include: (1) We divide a frame of point cloud space into several regions, each of which is divided into several grids, based on the scanning characteristics of the LIDAR. (2) The plane was fitted based on the improved RANSAC algorithm for each of the previously divided grids. Experiments with KITTI and campus real environment datasets show that the sensitivity of our proposed method can reach more than 98% and the specificity is below 10%. The proposed algorithm can effectively and correctly separate the ground from the point cloud, even on slopes and the ground with many obstacles. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Keyword ：
Motion planning Motion planning Optical radar Optical radar
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| GB/T 7714 | Zhou, Jiyang , Zhang, Liwei . Polar Grid Based Point Cloud Ground Segmentation [C] . 2023 : 632-643 . |
| MLA | Zhou, Jiyang et al. "Polar Grid Based Point Cloud Ground Segmentation" . (2023) : 632-643 . |
| APA | Zhou, Jiyang , Zhang, Liwei . Polar Grid Based Point Cloud Ground Segmentation . (2023) : 632-643 . |
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Abstract ：
At present, most of the traditional algorithms for mobile robot autonomous exploration in unknown environments use frontier as a guide and adopt greedy strategies for determining the next exploration target. They generate new frontier as new regions of the map, and thus the cycle repeats itself to finally complete the exploration of unknown environments. In this paper, we propose a region clustering-based approach for autonomous exploration of mobile robots in complex environments. Our approach incorporates the concept of region clustering at its global level based on the current advanced hierarchical exploration framework. The robot is more inclined to finish exploring a certain region of the map first, thereby minimizing the robot’s repetitive exploration of explored regions. Mobile robot autonomous exploration experiments were implemented in our college campus. The experimental results show that the average exploration trajectory length was reduced by 14.03%, and the average exploration time was reduced by 16.15%, respectively. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Keyword ：
Mobile robots Mobile robots
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| GB/T 7714 | Zheng, Haoping , Zhang, Liwei , Chen, Meng . Region Clustering for Mobile Robot Autonomous Exploration in Unknown Environment [C] . 2023 : 371-388 . |
| MLA | Zheng, Haoping et al. "Region Clustering for Mobile Robot Autonomous Exploration in Unknown Environment" . (2023) : 371-388 . |
| APA | Zheng, Haoping , Zhang, Liwei , Chen, Meng . Region Clustering for Mobile Robot Autonomous Exploration in Unknown Environment . (2023) : 371-388 . |
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