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A Fractional-Order Ultra-Local Model-Based Adaptive Neural Network Sliding Mode control of n-DOF Upper-Limb Exoskeleton With Input Deadzone

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 760-781页

作者： Dingxin He HaoPing Wang Yang Tian Yida Guo the School of Automation Nanjing University of Science and TechnologyNanjing 210094China IEEE Norinco Group Institute of Navigation and Control Technology Beijing 100089China

This paper proposes an adaptive neural network sliding mode control based on fractional-order ultra-local model for n-DOF upper-limb exoskeleton in presence of uncertainties,external disturbances and input *** the model complexity and input deadzone,a fractional-order ultra-local model is proposed to formulate the original dynamic system for simple controller ***,the control gain of ultra-local model is considered as a *** fractional-order sliding mode technique is designed to stabilize the closed-loop system,while fractional-order time-delay estimation is combined with neural network to estimate the lumped ***,a fractional-order ultra-local model-based neural network sliding mode controller(FO-NNSMC) is ***,to avoid disadvantageous effect of improper gain selection on the control performance,the control gain of ultra-local model is considered as an unknown ***,the Nussbaum technique is introduced into the FO-NNSMC to deal with the stability problem with unknown ***,a fractional-order ultra-local model-based adaptive neural network sliding mode controller(FO-ANNSMC) is ***,the stability analysis of the closed-loop system with the proposed method is presented by using the Lyapunov ***,with the co-simulations on virtual prototype of 7-DOF iReHave upper-limb exoskeleton and experiments on 2-DOF upper-limb exoskeleton,the obtained compared results illustrate the effectiveness and superiority of the proposed method.

关键词： Adaptive control input deadzone model-free control n-DOF upper-limb exoskeleton neural network

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Temperature-Dependent Noise Analysis of Angular Accelerometer Using Cross-Correlation Method

Temperature-Dependent Noise Analysis of Angular Acceleromete...

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2024 China Automation Congress, CAC 2024

作者： Zhai, Kexuan Yue, Yufeng Wang, Simai Wang, Meiling Institute of Navigation Guidance and Control Technology Beijing Institute of Technology Department of Automation Beijing100081 China

ISBN: (纸本)9798350368604

Noise characteristics significantly affect the accuracy of the angular accelerometers and limit their application in various fields. According to the working principle, noises are affected by both internal mechanisms and external environments, especially temperature. Therefore, in this paper, we propose a method to identify the temperature-dependent noise model of the angular accelerometers. First, the output signals of the angular accelerometers are collected at different temperatures using the temperature chamber. Then, a cross-correlation method is applied to reduce the noise caused by the vibration of the temperature chamber and obtain the self-noise of the angular accelerometers. Moreover, the obtained noise data is analyzed by the Allan variance method to construct the noise model. Experiments are carried out on two angular accelerometers under ten different temperatures within their operation range. The results show that the proposed method can effectively identify the noise model, and the temperature characteristics of these angular accelerometers’ noise are investigated. © 2024 IEEE.

关键词： Accelerometers

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Research on the dynamic characteristics of HPFOG based on closed-loop control loop 10

Research on the dynamic characteristics of HPFOG based on cl...

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10th Symposium on Novel Optoelectronic Detection technology and Applications

作者： Yan, Jun Zang, Jingwen Zuo, Wenlong Tianjin Navigation Instruments Research Institute Tianjin300131 China Laboratory of Science and Technology on Marine Navigation and Control Tianjin300131 China

ISBN: (数字)9781510688155

ISBN: (纸本)9781510688148

The control loop of high-precision fiber optic gyroscope (HPFOG) has inherent delay. If the loop-gain is constrained to suppress the loop overshoot and vibration bias effect, the bandwidth of HPFOG will be limited to a certain extent, which leads to a large angular rate tracking error when the gyroscope is applied in high dynamic conditions and affects the dynamic performance of the system. A loop correction technique is proposed to reduce large dynamic angular rate tracking error and transient angular error. The loop stability margin and frequency characteristics after correction are analyzed, and the characteristic angular rate tracking error and transient angular error are simulated. The simulation results show that for a certain type of HPFOG, by using the proposed loop correction technique and design parameters, the angular rate tracking error and the maximum transient angular error grad respectively. The bandwidth is increased and the correction loop does not affect the stability performance of the closed-loop HPFOG, which can meet the requirements of angular motion measurement accuracy under the condition of specific vehicle impact vibration. © 2025 SPIE.

关键词： Gyroscopes

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Fault diagnosis method of link control system for gravitational wave detection

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Journal of Systems Engineering and Electronics 2024年第4期35卷 922-931页

作者： GAO Ai XU Shengnan ZHAO Zichen SHANG Haibin XU Rui School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Autonomous Navigation and Control for Deep Space Exploration Ministry of Industry and Information TechnologyBeijing 100081China Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of EducationBeijing 100081China

To maintain the stability of the inter-satellite link for gravitational wave detection,an intelligent learning monitoring and fast warning method of the inter-satellite link control system failure is *** from the traditional fault diagnosis optimization algorithms,the fault intelligent learning method pro-posed in this paper is able to quickly identify the faults of inter-satellite link control system despite the existence of strong cou-pling *** constructing a two-layer learning network,the method enables efficient joint diagnosis of fault areas and fault *** simulation results show that the average identification time of the system fault area and fault parameters is 0.27 s,and the fault diagnosis efficiency is improved by 99.8%compared with the traditional algorithm.

关键词： large scale multi-satellite formation gravitational wave detection laser link monitoring fault diagnosis deep learning

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Style Transfer Based on Discrete Space Modeling 4

Style Transfer Based on Discrete Space Modeling

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4th IEEE International Conference on Information technology, Big Data and Artificial Intelligence, ICIBA 2024

作者： Huang, Zhiguo Chen, Wei Huang, Ziyu Han, Xu Yan, Jie Tianjin Navigation Instruments Research Institute China China State Shipbuilding Corporation Laboratory of Science and Technology on Marine Navigation and Control Tianjin China

ISBN: (纸本)9798350363586

This paper is dedicated to exploring headline style transfer techniques, with the core objective of enhancing the appeal of headlines while preserving their semantics. A significant challenge is the lack of parallel training datasets. To address this issue, we propose an unsupervised headline style transfer model called the Discrete Headline Generation (DHG) model. This model decomposes the process of generating text with specific styles into two key steps: content feature extraction and style modeling. Two text encoders separately extract the content information and style information from the input text, while a text decoder integrates the knowledge from both encoders to generate content with a specific *** that style signals are more abstract compared to textual content, we propose constructing the style representation space as a discrete space, where each discrete point corresponds to a specific style category. Experimental results demonstrate that the DHG model exhibits state-of-the-art performance in comprehensive evaluations. © 2024 IEEE.

关键词： Semantics

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A Review of Orbital Mechanics for Space-Based Gravitational Wave Observatories

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Space(Science & technology) 2023年第1期3卷 112-132页

作者： Dong Qiao Feida Jia Xiangyu Li Xingyu Zhou School of Aerospace Engineering Beijing Institute of TechnologyBeijingChina Key Laboratory of Autonomous Navigation and Control for Deep Space Exploration Beijing Institute of TechnologyBeijingChina

The confirmation of gravitational waves in recent years has set off a new upsurge of exploring the extreme interactions critical to the origin and evolution of stars,galaxies,and the *** detection of gravitational waves in space is expected to cover the largest number and the greatest variety of gravitational wave sources,which is more compelling and valuable than the initial detection on the *** dynamics and control are the keys to realizing the detection of gravitational waves in *** paper reviews the orbital mechanics for space-based gravitational wave *** principle and typical gravitational wave observation mission concepts are first introduced and classified ***,the orbital mechanics of the space-based gravitational wave observatories in different spatial locations are *** the basis of the characteristics of different observatories,2 groups of methods related to the observatory configuration design and optimization are summarized:the constellation configuration design and optimization method similar to the geocentric configuration and libration point configuration,the formation design and optimization method similar to heliocentric *** prospects of space-based gravitational wave observatories are finally put forward,which shall provide a reference for future research on space-based gravitational wave observatories.

关键词： gravitational galaxies stars

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Optimal crater landmark selection based on optical navigation performance factors for planetary landing

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Chinese Journal of Aeronautics 2023年第3期36卷 254-270页

作者： Yi XIU Shengying ZHU Rui XU Maodeng LI School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Autonomous Navigation and Control for Deep Space Exploration Ministry of Industry and Information TechnologyBeijing 100081China Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of EducationBeijing 100081China Science and Technology on Space Intelligent Control Laboratory Beijing Institute of Control EngineeringBeijing 100091China

Planetary craters are natural navigation landmarks that widely exist and are easily *** navigation based on crater landmarks has become an important autonomous navigation method for planetary *** to the increase in observed crater landmarks and the limitation of onboard computation,the selection of good crater landmarks has gradually become a research hotspot in the field of landmark-based optical *** paper designs a fast crater landmark selection method,which not only considers the configuration observability of crater subsets but also focuses on the influence on navigation performance arising from the measurement uncertainty and the matching confidence of craters,which is different from other landmark selection *** factor of measurement uncertainty,which is anisotropic,correlated and nonidentically distributed,is quantified and integrated into selection based on crater pairing detection and localization error *** addition,the concept of the crater matching confidence factor is introduced,which reflects the possibility of 2D projection measurements corresponding to 3D *** with the configuration observability factor,the crater landmark selection indicator is ***,the effectiveness of the proposed method is verified by Monte Carlo simulations.

关键词： Crater-based optical navigation Crater landmark selection Crater matching Measurement uncertainty Planetary landing

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Research on high-precision time synchronisation technology for sea mobile platforms

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International Journal of Information and Communication technology 2024年第6期24卷 57-70页

作者： Dong, Dao Peng Wu, Hong Shuo Guo, Qing Feng Yang, Jin Wei Li, Xi Cheng Du Spaceon Electronics Co. Ltd. Cheng Du610036 China Laboratory of Science and Technology on Marine Navigation and Control China State Shipbuilding Corporation 300131 China Tianjin Institute of Navigation Instruments 300131 China

Under static conditions, at present, mature technologies for long-distance and high-precision time synchronisation include satellite common view (CV) and two-way satellite time and frequency transfer (TWSTFT) and so on. However, under dynamic conditions, research on high-precision time synchronisation technology is relatively lacking such as mobile platforms on the sea. Considering the dynamic conditions of mobile platforms on the sea, a method of position's smooth filtering with velocity is proposed to improve the accuracy of position measurement, reducing the time measurement error introduced by position error. The proposed method ultimately improves the CV comparison accuracy between sea surface mobile platforms. The simulation and actual test results show that by using the method of position's smooth filtering with velocity, the CV comparison accuracy between mobile platforms on the sea can reach 10 ns. Copyright © The Author(s) 2024. Published by Inderscience Publishers Ltd. This is an Open Access Article distributed under the CC BY-NC-ND license. (http://***/licenses/by-nc-nd/4.0/)

关键词： Surface waters

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CpdsConv: Continuous Pruning for Depthwise Separable Convolution 10

CpdsConv: Continuous Pruning for Depthwise Separable Convolu...

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10th Symposium on Novel Optoelectronic Detection technology and Applications

作者： Ding, Yan Xiao, Jianbang Li, Haitan Zhang, Bozhi Song, Ping Cen, Yetao Fan, Yixiao School of Aerospace Engineering Beijing Institute of Technology Beijing China North Navigation Control Technology Company Limited Beijing China

ISBN: (数字)9781510688155

ISBN: (纸本)9781510688148

Current structured pruning methods typically employ fixed thresholds and rank channels based on evaluation metrics for pruning, leading to significant drops in network accuracy post-pruning. This paper proposes a novel continuous pruning method for depthwise separable convolution, named CpdsConv, to address this issue. CpdsConv uses a two-stage training approach combining depthwise separable convolutions (TSConv) and learnable threshold sparse convolutions (LTSConv) to prune the network, aiming to enhance accuracy while compressing the model. To validate the effectiveness of the proposed method, we conducted experiments on the VGG-16, MobileNet, GoogLeNet, and ResNet-56 models. The results demonstrated that, while maintaining the original accuracy, the proposed method significantly reduced the number of parameters and computational burden in these models, showing a better balance overall. Notably, in the ResNet-56 experiment, the parameters were reduced by 37.9%, with a simultaneous accuracy improvement of 0.81%. This indicates that our method not only effectively reduces computational complexity but also significantly enhances model performance. © 2025 SPIE.

关键词： Convolutional neural networks

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Equivalence analysis of acoustic excitation and random vibration exerted on spacecraft units 2

Equivalence analysis of acoustic excitation and random vibra...

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2023 2nd International Conference on Aerospace, Aerodynamics and Mechatronics Engineering, AAME 2023

作者： Zhang, Jie Wang, Yakun Wu, Pengfei Institute of Telecommunication and Navigation Satellites China Academy of Space Technology Beijing100094 China Institute of Navigation and Control NORINCO Group Beijing100089 China

At the unit level test, the small area-to-mass ratio unit of spacecraft generally adopts the random vibration test to simulate the acoustic environment during the launch event. Acoustic excitation and random vibration exerted on spacecraft units reflect different dynamic characteristics. Thus, the equivalence analysis between them deserves to be conducted. In this work, a thruster outside the spacecraft was taken as an example, for it directly experiences acoustic load compared with the electronic equipment inside. The vibroacoustic and random vibration models of the thruster were established, and response behavior was explored. Results show that there are differences in the response distribution rules of acoustic load and random vibration on the thruster. The farther to the thruster root is, the harder acoustic vibration responses can be covered by the random response, so an appropriate safety margin shall be reserved when formulating random vibration conditions of units. © Published under licence by IOP Publishing Ltd.

关键词： Spacecraft

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