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Docking control for probe-drogue refueling: An additive-state-decomposition-based output feedback iterative learning control method

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Chinese Journal of Aeronautics 2020年第3期33卷 1016-1025页

作者： Jinrui REN Quan QUAN cunjia liu Kai-Yuan CAI School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100083China Department of Aeronautical and Automotive Engineering Loughborough UniversityLeicestershire LE113TUUnited Kingdom

Designing a controller for the docking maneuver in Probe-Drogue Refueling(PDR) is an important but challenging task, due to the complex system model and the high precision *** order to overcome the disadvantage of only feedback control, a feedforward control scheme known as Iterative Learning Control(ILC) is adopted in this ***, Additive State Decomposition(ASD) is used to address the tight coupling of input saturation, nonlinearity and the property of Non Minimum Phase(NMP) by separating these features into two subsystems(a primary system and a secondary system).After system decomposition, an adjoint-type ILC is applied to the Linear Time-Invariant(LTI) primary system with NMP to achieve entire output trajectory tracking, whereas state feedback is used to stabilize the secondary system with input *** two controllers designed for the two subsystems can be combined to achieve the original control goal of the PDR ***, to compensate for the receiverindependent uncertainties, a correction action is proposed by using the terminal docking error,which can lead to a smaller docking error at the docking *** tests have been carried out to demonstrate the performance of the proposed control method, which has some advantages over the traditional derivative-type ILC and adjoint-type ILC in the docking control of PDR.

关键词： Additive state decomposition Adjoint operator Docking control Iterative learning control Probe-drogue refueling Stable inversion

Nonlinear composite bilateral control framework for n-DOF teleoperation systems with disturbances

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Science China(Information Sciences) 2018年第7期61卷 182-199页

作者： Zhenhua ZHAO Jun YANG cunjia liu Wen-Hua CHEN School of Automation Southeast University Key Laboratory of Measurement and Control of CSEMinistry of Education Department of Aeronautical and Automotive Engineering Loughborough University

This paper proposes a new nonlinear composite bilateral control framework for n-degree-offreedom(n-DOF) teleoperation systems with external disturbances. Different with the existing methods which usually regard the dynamics of the master and slave robots as linear impedance models, the proposed control framework fully considers the nonlinear dynamics of the n-DOF teleoperation systems. Central to the proposed framework is the utilization of nonlinear disturbance observers for estimating the disturbances in master and slave robot systems. The nonlinear composite bilateral controller is constructed by incorporating the disturbance estimations into the nonlinear feedback linearization controller. The proposed control method guarantees satisfactory position tracking performance and desired remote force haptic simultaneously for the n-DOF teleoperation systems with external disturbances. The effectiveness of the proposed control framework is validated by its applications on 2-DOF teleoperation systems.

关键词： teleoperation system nonlinear bilateral control remote force haptic disturbance rejection nonlinear disturbance observer

Experimental Tests of Autonomous Ground Vehicles with Preview

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International Journal of Automation and computing 2010年第3期7卷 342-348页

作者： cunjia liu Wen-Hua Chen John Andrews Department of Aeronautical and Automotive Engineering Loughborough University Loughborough LE11 3TU UK Nottingham Transportation Engineering Centre Faculty of Engineering University of Nottingham Nottingham NG7 2RD UK

This paper describes the design and experimental tests of a path planning and reference tracking algorithm for autonomous ground vehicles. The ground vehicles under consideration are equipped with forward looking sensors that provide a preview capability over a certain horizon. A two-level control framework is proposed for real-time implementation of the model predictive control （MPC） algorithm, where the high-level performs on-line optimization to generate the best possible local reference respect to various constraints and the low-level commands the vehicle to follow realistic trajectories generated by the high-level controller. The proposed control scheme is implemented on an indoor testbed through networks with satisfactory performance.

关键词： Model predictive control autonomous vehicle online optimization nonholonomic constraint eigenvalue.

Hawk‐eye‐inspired perception algorithm of stereo vision for obtaining orchard 3D point cloud navigation map

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CAAI Transactions on Intelligence Technology 2023年第3期8卷 987-1001页

作者： Zichao Zhang Jian Chen Xinyu Xu cunjia liu Yu Han College of Engineering China Agricultural UniversityBeijingChina Jiangsu Province and Education Ministry Co‐sponsored Synergistic Innovation Center of Modern Agricultural Equipment Jiangsu UniversityZhenjiangChina Key Laboratory of Spatial‐temporal Big Data Analysis and Application of Natural Resources in Megacities MNRShanghaiChina Department of Aeronautical and Automotive Engineering Loughborough UniversityLoughboroughLeicestershireUK College of Water Resources and Civil Engineering China Agricultural UniversityBeijingChina State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijingChina Key Laboratory of Urban Land Resources Monitoring and Simulation Ministry of Natural ResourcesShenzhenChina

The binocular stereo vision is the lowest cost sensor for obtaining 3D *** the weakness of long‐distance measurement and stability,the improvement of accuracy and stability of stereo vision is urgently required for application of precision *** address the challenges of stereo vision long‐distance measurement and stable perception without hardware upgrade,inspired by hawk eyes,higher resolution perception and the adaptive HDR(High Dynamic Range)were introduced in this *** the function from physiological structure of‘deep fovea’and‘shallow fovea’of hawk eye,the higher resolution reconstruction method in this paper was aimed at ac-curacy *** by adjustment of pupils,the adaptive HDR method was proposed for high dynamic range optimisation and stable *** various light conditions,compared with default stereo vision,the accuracy of proposed algorithm was improved by 28.0%evaluated by error ratio,and the stability was improved by 26.56%by disparity *** fixed distance measurement,the maximum improvement was 78.6%by standard *** on the hawk‐eye‐inspired perception algorithm,the point cloud of orchard was improved both in quality and *** hawk‐eye‐inspired perception algorithm contributed great advance in binocular 3D point cloud recon-struction in orchard navigation map.

关键词： adaptive high dynamic range binocular stereo vision hawk‐eye‐inspired perception point cloud of orchard super‐resolution generative adversarial network

Fixed Wing UAV Survey Coverage Path Planning in Wind for Improving Existing Ground Control Station Software

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Fixed Wing UAV Survey Coverage Path Planning in Wind for Imp...

直流配网下基于线性方程组系数逆矩阵范数估计的单端测距原理

第37届中国控制会议

作者： Matthew Coombes Wen-Hua Chen cunjia liu Department of Aeronautical and Automotive Engineering Loughborough University

UAV technology is becoming increasingly mature and cheap. This recent cost reduction and performance improvement means that these systems have become reliable and cheap enough to be viable for mass use by farmers and operators for precision agriculture activities;such as disease identification, yield estimation and plant nitrogen monitoring.A critical stage of this is the planning of the flight path which ensures complete image coverage of the region of *** the field is a simple convex shape, then generating an optimal coverage path is hugely simplified by using a back and forth Boustrophedon path. However, most fields have complex polygonal shapes, where planning the coverage path manually is nontrivial, as operators may not have the correct skills and experience. This is why in this paper, we outline an algorithm to improve the performance of survey path generation on complex ROI for mission planning software. The tools implemented in this paper take into account environmental factors and aircraft dynamics. By decomposing these complex survey regions into many smaller arrangements of manageable convex polygon survey regions, Boustrophedon paths can be used to cover them. By using a survey model for calculation of flight time in a wind field, it is used to optimise the decomposition in order to lower flight *** fastest survey path is used to generate waypoints files to be used with a number of popular mission planning software including: DJI PC Ground Control, Mission Planner, QGround Control.

关键词： Aerial Surveying Remote Sensing Polygon Decomposition Coverage Path Planning Boustrophedon paths mission planning and ground control station

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中国电机工程学报 2020年第5期40卷 1443-1453页

作者：薛士敏刘冲刘存甲陆俊弛智能电网教育部重点实验室(天津大学) 天津市南开区300072

随着直流配网的发展与分布式发电的普及,多端供电系统成为直流配网最主要的供电形式,其复杂的拓扑结构与工作模态的多样性,使得几乎所有传统非通信下基于单端量的故障定位原理难以达到满意的效果。找到有效的解决方案,需要从根源上分析... 详细信息

随着直流配网的发展与分布式发电的普及,多端供电系统成为直流配网最主要的供电形式,其复杂的拓扑结构与工作模态的多样性,使得几乎所有传统非通信下基于单端量的故障定位原理难以达到满意的效果。找到有效的解决方案,需要从根源上分析导致这一点的原因。该文从传统R-L法理论着手,通过数学上的建模与分析,对R-L模型建立线性方程组,找到基于单端量的故障定位原理用于多端供电系统时存在方程数不足的缺陷,并引入基于多项式插值的数据预估和线性方程组中系数逆矩阵的1范数来量化估计该缺陷对最终结果的影响。通过对1范数的分析能够找到一些受预估误差干扰很小的测量时刻,利用这些时刻下的数据进行故障定位具有很高的精确度,并通过理论推导证明该方法的合理性。仿真实验结果与理论分析结果相符合,论证了该原理不仅能可靠识别区内外故障,还能反馈高精度的故障距离,有效地弥补基于单端量的故障定位原理在多端供电系统中存在的缺陷。

关键词：直流配网继电保护故障测距单端电气量

Bayesian Calibration of Aqua Crop Model

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Bayesian Calibration of Aqua Crop Model

Wheat Drought Assessment by Remote Sensing Imagery Using Unmanned Aerial Vehicle

第37届中国控制会议

作者： Tianxiang Zhang Jinya Su cunjia liu Wen-Hua Chen Department of Aeronautical and Automotive Engineering Loughborough University

The Aqua Crop simulation model, modelling the dynamic change of crop growth status, is an important crop management tool for quantifying crop yield response to water. To effectively simulate the soil water balance and the crop growth process, a number of system parameters and canopy state variables are inevitably adopted. As a result, certain key parameters need to be calibrated so that the Aqua Crop model can achieve a better performance of prediction for various scales of *** paper aims to apply Bayesian technique to calibrate the Aqua Crop model. In this approach, the prior information regarding the system parameters is expressed in the form of a uniform probability distribution. Then with the advent of output variable measurement（e.g. biomass） by remote sensing techniques, the parameter distributions are iteratively updated by using Bayesian Markov Chain Monte Carlo（MCMC） method. The calibrated system parameters are expressed by the posterior distributions and gained by distribution mean value. Finally, the Bayesian calibration is compared with the conventional optimisation based calibration in terms of biomass and canopy cover, where simulated annealing is chosen as the optimisation approach, indicating a better calibration performance can be achieved by using Bayesian methods. Consequently, it is recommended that Bayesian calibration is one promising approach to the problem of crop model calibration.

关键词： Bayesian method Aqua Crop model parameterisation data assimilation

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Wheat Drought Assessment by Remote Sensing Imagery Using Unm...

第37届中国控制会议

作者： Jinya Su Matthew Coombes cunjia liu Lei Guo Wen-Hua Chen Department of Aeronautical and Automotive Engineering Loughborough University Key Laboratory of Measurement and Control of Complex Systems of Engineering (Southeast University) Ministry of Education School of Electrical Engineering and Automation Beihang University

This work aims at evaluating the usability of remote sensing RGB imagery by an Unmanned Aerial Vehicle（UAV） in assessing wheat drought status. A UAV survey is conducted to collect high-resolution RGB imageries by using DJI S1000 for the experimental wheat fields of Gucheng town, Heibei Province, China. The soil moisture for different plots of the experimental filed is kept at an approximately constant level for the whole growing season in a well controlled environment, where field measurements are performed just after the UAV survey to obtain the soil water content for each plot. A machine learning based wheat drought assessment framework is proposed in this work. In the proposed framework, wheat pixels are first segmented from the soil background using the classical normalized excess green index（NEx G）. Rather than using pixel-wise classification,a pixel square of appropriate dimension is defined as the samples, based on which various features are extracted for the wheat pixels including statistical features and spectral index features. Different classification algorithms are experimented to identify a suitable one in terms of classification accuracy and computation time. It is discovered that Support Vector Machine with Gaussian kernel can obtain an accuracy over 90%, which demonstrates the usefulness of RGB imagery in wheat drought assessment.

关键词： Classification Remote sensing UAV imagery Wheat drought

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基于控保协同的环形直流微网测距式保护

高电压技术 2019年第10期45卷 3059-3067页

作者：薛士敏刘存甲李蒸陆俊弛天津大学智能电网教育部重点实验室

针对传统单端量测距式保护中对端电流量无法测量的问题,以四端环形直流微网系统为研究对象,提出了一种基于控保协同的单端测距式保护。该方法以传统的R-L线路模型为基础,仅利用单端电气量即可实现精准测距。首先,系统故障发生之后,基于... 详细信息

针对传统单端量测距式保护中对端电流量无法测量的问题,以四端环形直流微网系统为研究对象,提出了一种基于控保协同的单端测距式保护。该方法以传统的R-L线路模型为基础,仅利用单端电气量即可实现精准测距。首先,系统故障发生之后,基于控保协同思想,先对可控器件进行控制,然后实施保护,通过对环形直流微网进行拓扑变换,使其变为单电源系统。其次,通过保护装置采集到的本端电气量即可实现对端电流的精确求解,进而实现单端精准故障定位。最后在PSCAD/EMTDC仿真平台上搭建四端环形直流微网模型,验证了所提测距式保护的有效性。仿真结果表明,该原理在仿真实验中具有很高的测距精度,测距误差≤3%,且具有一定的抗过渡电阻能力。

关键词：直流微网继电保护控保协同测距式保护单端电气量