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IEEE Instrumentation and Measurement technology Conference

作者： Siyuan Cheng Meiling Wang Xiang Li Meifeng Xiao Mengyin Fu Xin Zheng Beijing Institute of Technology Key Laboratory of Complex System Intelligent Control and Decision Beijing China Nanjing University of Science and Technology Nanjing China The Third Academic of Aerospace and Technology Group of China Beijing China

ISBN: (纸本)9781467392211

In this paper, a new kind of liquid-circular angular accelerometer is studied. Based on electrokinetic phenomenon, this angular accelerometer is designed with a porous transducer and fluid mass. Due to the existence of electrical double layer between transducer and fluid mass, this angular accelerometer is able to convert angular acceleration input to electrical signal. The whole system is composed of fluidic system and molecular electronic system. Theoretical analysis and several experiments are implemented to obtain transfer function model of fluidic system. The flow in transducer satisfies the Darcy Law in the experiment and angular velocity input is proved to have no effect on the output. A prototype is designed to compare the output of theoretical model and experiments. All of the experiments prove that the fluidic system of this liquid-circular angular accelerometer can be seen as a first-order system, especially when the frequency of input is less than 30Hz and its transfer function is derived.

关键词： Transducers Fluids Prototypes Accelerometers Transfer functions Electron tubes Acceleration

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Real-time terrain estimation based on multi-scale radial basis function for unmanned ground vehicle

Real-time terrain estimation based on multi-scale radial bas...

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International Conference on Information and Automation (ICIA)

作者： Yi Yang Zhili Wang Xinghe Li Mengyin Fu Beijing Institute of Technology Beijing China Nanjing University of Science and Technology Nanjing China School of Automation and State Key Laboratory of Complex System Intelligent Control and Decision Beijing Institute of Technology Beijing China

ISBN: (纸本)9781509041039

Accurate terrain estimation is essential for unmanned ground vehicle (UGV) to achieve autonomous navigation. However, some existing approaches are difficult to reconstruct the 3D surface in real-time because of serious amount of computation. A method of environmental terrain estimation based on multi-scale radial basis function with a 3D lidar mounted on a moving vehicle was proposed in this paper. By combining kernel template with terrain grid map, the approach is applicable to the non-uniform density distribution of laser point cloud with the increasing detection range and improves the efficiency of calculation. What's more, the estimation of culverts and trees will be more accurate if treat the point cloud in separate layers for suspended obstacles problem. All terrain estimation approaches were verified with good performance in an interactive system, which is set up with Virtual Robot Experimentation Platform (VREP) and actual vehicle.

关键词： Three-dimensional displays Estimation Laser radar Kernel Lasers Surface reconstruction Real-time systems

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A comprehensive review of electrochemical hybrid power supply systems and intelligent energy managements for unmanned aerial vehicles in public services

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Energy and AI 2022年第3期9卷 148-171页

作者： Caizhi Zhang Yuqi Qiu Jiawei Chen Yuehua Li Zhitao Liu Yang Liu Jiujun Zhang Chan Siew Hwa College of Mechanical and Vehicle Engineering The State Key Laboratory of Mechanical TransmissionsChongqing Automotive Collaborative Innovation CentreChongqing UniversityChongqing400044China College of Automation Chongqing UniversityKey Laboratory of Complex System Safety and ControlMinistry of EducationChongqing UniversityChongqing400044China School of Mechanical Engineering University of Science and Technology BeijingBeijing100083China State Key Laboratory of Industrial Control Technology Institute of Cyber-Systems and ControlZhejiang UniversityHangzhou310027China Institute for Sustainable Energy/College of Sciences Shanghai UniversityShanghai 200444China School of Mechanical and Aerospace Engineering Nanyang Technological University50 Nanyang Avenue639798Singapore Sichuan Energy Internet Research Institute Tsinghua UniversityChengdu 610213Sichuan ProvinceChina

The electric unmanned aerial vehicles (UAVs) are rapidly growing due to their abilities to perform some difficult or dangerous tasks as well as many public services including real-time monitoring, wireless coverage, search and rescue, wildlife surveys, and precision agriculture. However, the electrochemical power supply system of UAV is a critical issue in terms of its energy/power densities and lifetime for service endurance. In this paper, the current power supply systems used in UAVs are comprehensively reviewed and analyzed on the existing power configurations and the energy management systems. It is identified that a single type of electrochemical power source is not enough to support a UAV to achieve a long-haul flight;hence, a hybrid power system architecture is necessary. To make use of the advantages of each type of power source to increase the endurance and achieve good performance of the UAVs, the hybrid systems containing two or three types of power sources (fuel cell,battery, solar cell, and supercapacitor,) have to be developed. In this regard, the selection of an appropriate hybrid power structure with the optimized energy management system is critical for the efficient operation of a UAV. It is found that the data-driven models with artificial intelligence (AI) are promising in intelligent energy management. This paper can provide insights and guidelines for future research and development into the design and fabrication of the advanced UAV power systems.

关键词： Unmanned aerial vehicles(UAVs) Power supply system Fuel cell system Artificial intelligence(AI) Energy management systems

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An Optimal Terrain Following Trajectory Online Regeneration Method

An Optimal Terrain Following Trajectory Online Regeneration ...

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control technology and Applications (CCTA),

作者： Yijun Feng Wanchun Chen Liang Yang Donghui Wei School of Astronautics Beihang University Beijing China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing Electro-Mechanical Engineering Institute Beijing China

In this paper, we present a numerical method for two-dimensional terrain following (TF) optimal trajectory regeneration. This method corrects the planned optimal trajectory to avoid collision with previously unknown obstacles. Firstly, an optimal TF trajectory is acquired using Hp-adaptive Gaussian quadrature collocation method. Then, a neighboring optimum feedback law is presented for trajectory regeneration using a backward sweep method. Numerical simulations are provided to validate the effectiveness and demonstrate the features of the problem.

关键词： Trajectory History Vehicle dynamics Mathematical model Optimal control Aircraft Aerodynamics

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Fast Vision Decoder: A Robust Automatic Target Recognition Model for Sar Images

SSRN

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SSRN 2022年

作者： Ayodeji, Abiodun Wang, Wenhai Su, Jianzhong Yuan, Jianquan Liu, Xinggao State Key Laboratory of Industrial Control Technology Control Department Zhejiang University Hangzhou310027 China Tianjin Jinhang Technical Physics Institute Tianjin300192 China Science and Technology on Complex System Control and Intelligent Agent Cooperative Laboratory Beijing100074 China

The synthetic aperture radar (SAR) is the recent all-weather technology used to monitor areas with low to moderate penetration. However, the scarcity of SAR imagery, and the high-level noise in the images makes it difficult for real-time image interpretation. This work presents a novel fast vision decoder (FViD), a target recognition model with a frozen backbone and stack dilated autoencoder. The autoencoder architecture is introduced to learn the compressed latent representation. Moreover, a robust backbone selection method is introduced to select a task-specific optimal backbone. The proposed FViD is extensively evaluated using the Chinese TerraSAR-X ship images, and the US MSTAR datasets. Evaluation results show that the proposed method has significant improvement over the conventional models. The speed and accuracy of the proposed FViD are further compared with five state of the art models previously used for SAR target recognition tasks, and the comparison result shows that the FViD performs better. Moreover, an ablation study is performed to provide insights into the contribution of FViD architecture. The results of the ablation study as well as the performance improvement of FViD are discussed in this paper. © 2022, The Authors. All rights reserved.

关键词： Computer vision

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An empirical evaluation of attention-based multi-head models for improved turbofan engine remaining useful life prediction

arXiv

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arXiv 2021年

A single unit (head) is the conventional input feature extractor in deep learning architectures trained on multivariate time series signals. The importance of the fixed-dimensional vector representation generated by the single-head network has been demonstrated for industrial machinery condition monitoring and predictive maintenance. However, processing heterogeneous sensor signals with a single-head may result in a model that cannot explicitly account for the diversity in time-varying multivariate inputs. This work extends the conventional single-head deep learning models to a more robust form by developing context-specific heads to independently capture the inherent pattern of each sensor reading in multivariate time series signals. Using the turbofan aircraft engine benchmark dataset (CMAPSS), an extensive experiment is performed to verify the effectiveness and benefits of multi-head fully connected neurons, recurrent networks, convolution network, the transformer-style stand-alone attention network, and their variants for remaining useful life estimation. Moreover, the effect of different attention mechanisms on the multi-head models is also evaluated. In addition, each architecture's relative advantage and computational overhead are analyzed. Results show that utilizing the attention layer is task-sensitive and model dependent, as it does not provide consistent improvement across the models investigated. The result is further compared with five state-of-the-art models, and the comparison shows that a relatively simple multi-head architecture performs better than the state-of-the-art models. The results presented in this study demonstrate the importance of multi-head models and attention mechanisms to improved understanding of the remaining useful life of industrial assets. © 2021, CC BY.

关键词： Recurrent neural networks

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Monocular visual based obstacle distance estimation method for ultra-low altitude flight

Monocular visual based obstacle distance estimation method f...

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IEEE International Conference on Unmanned systems (ICUS)

作者： Jin Cheng Donghui Wei Wanchun Chen Wang Gao Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing Electro-Mechanical Engineering Institute Beijing China School of Astronautics Beihang University Beijing China

ISBN: (纸本)9781728137933

This paper focuses on the problem of ultra-low-altitude flight obstacle distance estimation for monocular vision-assisted aircraft. First, the basic error model of distance estimation using sequence images is derived and the phenomenon of "epipole dead zone" is revealed. Then the distance estimation algorithm based on pairs of coplanar points is proposed as well as its error model. This algorithm is proved to be a solution of the "epipole dead zone" problem theoretically. Finally, numerical simulations show that the proposed distance estimation algorithm can effectively improve the accuracy of distance estimation in the "epipole dead zone".

关键词： Ultra-low altitude flight Monocular vision Distance estimation Monocular Vision error model flight altitude flight Death Dead

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A Stable and Symmetric FDTD Subgridding Method with Arbitrary Grid Ratio

A Stable and Symmetric FDTD Subgridding Method with Arbitrar...

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Antennas and Propagation Society International Symposium

作者： Langran Deng Ningbo Gong Guijie Diao Shunchuan Yang Research Institute for Frontier Science Beihang University Beijing China Beijing Electro-mechanical Engineering Institute Beijing China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory China

A stable and symmetric finite-difference time-domain (FDTD) subgridding method is proposed to effectively and accurately solve the three-dimensional electromagnetic prob-lems. The linear interpolation coefficient (LIC) and the length cutoff coefficient (LCC) are carefully designed to guarantee the stability of the proposed method. In addition, the proposed method is applicable to arbitrary grid ratios and nested meshes. A practical multiscale example is used to validate its accuracy and efficiency.

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A Provably Stable SBP-SAT FDTD Subgridding Method without Modifying Yee's Grids

A Provably Stable SBP-SAT FDTD Subgridding Method without Mo...

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Antennas and Propagation Society International Symposium

作者： Yuhui Wang Guijie Diao Hong Ni Shunchuan Yang Research Institute for Frontier Science Beihang University Beijing China Beijing Electro-mechanical Engineering Institute Beijing China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory China

A stable finite-difference time-domain (FDTD) sub-grid ding method using the summation-by-parts simultaneous approximation term (SBP-SAT) technique is proposed. To meet the SBP properties and keep Yee's grids unchanged, the projection operators are carefully designed to extrapolate fields on the boundaries. Then, the SATs are used to weakly enforce the boundary conditions between multiple mesh blocks with different mesh sizes. Therefore, its long-term stability is theoretically guaranteed. An iris filter is simulated to validate the effectiveness of the proposed method. Results show that the proposed SBP-SAT FDTD subgridding method is stable, accurate and efficient.

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Optimal Terrain Following Trajectory Regeneration Using Linear Gauss Pseudo-Spectral Method

Optimal Terrain Following Trajectory Regeneration Using Line...

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IEEE International Conference on Unmanned systems (ICUS)

ISBN: (纸本)9781728137933

A numerical method for two-dimensional terrain following optimal trajectory regeneration is proposed in this paper, which corrects the planned optimal trajectory to avoid collision with previously unknown obstacles. The neighboring extremal problem is established near the optimal terrain following trajectory, which can be regarded as a two-point boundary-value problem (TPBVP) and solved using Linear Gauss Pseudo-Spectral (LGP) method. Compared with the classical backward sweep method for solving TPBVPs, LGP method is much faster in obtaining approximate results. Numerical simulations are provided to validate the effectiveness and demonstrate the features of the problem.

关键词： Terrain following Optimal control Neighboring extremal Linear gauss pseudo-Spectral terrain following Optimal control Numerical methods trajectory Gauss

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