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Comparing Non-Visual and Visual guidance Methods for Narrow Field of View Augmented Reality Displays

IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2020年第12期26卷 3389-3401页

作者： Marquardt, Alexander Trepkowski, Christina Eibich, Tom David Maiero, Jens Kruijff, Ernst Schoening, Johannes Bonn Rhein Sieg Univ Appl Sci St Augustin Germany Simon Fraser Univ Burnaby BC Canada Univ Bremen Bremen Germany

Current augmented reality displays still have a very limited field of view compared to the human vision. In order to localize out-of-view objects, researchers have predominantly explored visual guidance approaches to visualize information in the limited (in-view) screen space. Unfortunately, visual conflicts like cluttering or occlusion of information often arise, which can lead to search performance issues and a decreased awareness about the physical environment. In this paper, we compare an innovative non-visual guidance approach based on audio-tactile cues with the state-of-the-art visual guidance technique EyeSee360 for localizing out-of-view objects in augmented reality displays with limited field of view. In our user study, we evaluate both guidance methods in terms of search performance and situation awareness. We show that although audio-tactile guidance is generally slower than the well-performing EyeSee360 in terms of search times, it is on a par regarding the hit rate. Even more so, the audio-tactile method provides a significant improvement in situation awareness compared to the visual approach.

关键词： Augmented Reality view-management guidance audio -tactile cues performance situation awareness

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Integrated Extremal Control and Explicit guidance for Quadcopters

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JOURNAL OF INTELLIGENT & ROBOTIC SYSTEMS 2020年第3-4期100卷 1583-1613页

作者： Kawamura, Evan Azimov, Dilmurat Univ Hawaii Manoa Mech Engn Holmes Hall2540 Dole St Honolulu HI 96822 USA

The research study aims to create a framework for autonomous control technology for unmanned aerial vehicles with real-time target-relative guidance capabilities, which leverages onboard decision-making to provide targeting and re-targeting solutions. Thus, this paper aims to develop extremal control and guidance functions in the context of the optimal control problem and their integration for applications. Solving the optimal control problem leads to a constant motor thrust case and trivial and nontrivial cases for the variable motor thrust case. As illustrative examples, two quadcopter maneuvers use integrated extremal control and explicit guidance. The first maneuver is the quadcopter taking off to the desired altitude using maximum and then intermediate thrust. The second maneuver has the quadcopter traveling to a waypoint over an agricultural field. The DJI Onboard Software Development Kit provides a method to implement the proposed integration of extremal control and explicit guidance onboard a Raspberry Pi connected to the DJI M100 quadcopter. Simulated and experimental flight tests demonstrate that the integration of extremal control and explicit guidance allows the DJI M100 to reach the desired locations and velocities for both maneuvers.

关键词： guidance Optimal control Trajectory Unmanned aerial vehicle

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A guidance framework for synthesis of multi-core reconfigurable real-time systems

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INFORMATION SCIENCES 2020年 539卷 327-346页

作者： Lakhdhar, Wafa Mzid, Rania Khalgui, Mohamed Frey, Georg Li, Zhiwu Zhou, MengChu Jinan Univ Sch Elect & Informat Engn Zhuhai 519070 Peoples R China Univ Carthage Tunisia Polytech Sch Tunis 1080 Tunisia Univ Carthage Natl Inst Appl Sci & Technol Tunis 1080 Tunisia Saarland Univ Chair Automat & Energy Syst D-66123 Saarbrucken Germany Univ Tunis El Manar Higher Inst Comp Sci Tunis 1068 Tunisia Univ Sfax Natl Sch Engineers Sfax BPW 3038 Sfax Tunisia Macau Univ Sci & Technol Inst Syst Engn Macau 999078 Peoples R China Xidian Univ Sch Electromech Engn Xian 710071 Peoples R China New Jersey Inst Technol Dept Elect & Comp Engn Newark NJ 07102 USA

Nowadays, multi-core architectures are being more and more used in the design of realtime systems. Those systems react usually to their environment that requires to amend their behaviors by applying reconfiguration scenarios. This paper deals with multi-core reconfigurable real-time systems that should be adapted to their environment under real-time constraints. Meanwhile, their synthesis induces a heavy system code and time overhead due to a huge number of threads. The setting up of those systems involves many stages: i) definition of system functionalities, ii) generating of tasks, iii) placement and scheduling of tasks, and iv) generating system code. Correct transition among these steps has an impact on the final system implementation. Thus the need of a designer's experience is definitely required. However, many problems related to design decisions can be caused due to the complexity of real-time analysis, scheduling, and placement. Those problems may conduct to infeasible implementations. The proposed approach presents a guidance framework to avoid these problems from specification to code generation. This framework is performed by mixed-integer linear programming. It aims to resolve a task partitioning/scheduling problem while optimizing some metrics. The viability of the proposed framework is illustrated by a case study and performance evaluation. (C) 2020 Published by Elsevier Inc.

关键词： Real-time Reconfiguration Multi-core guidance Optimization

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Terminal adaptive guidance via reinforcement meta-learning: Applications to autonomous asteroid close-proximity operations

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ACTA ASTRONAUTICA 2020年 171卷 1-13页

作者： Gaudet, Brian Linares, Richard Furfaro, Roberto Univ Arizona Dept Syst & Ind Engn Tucson AZ 85721 USA MIT Dept Aeronaut & Astronaut Cambridge MA 02139 USA

Current practice for asteroid close proximity maneuvers requires extremely accurate characterization of the environmental dynamics and precise spacecraft positioning prior to the maneuver. This creates a delay of several months between the spacecraft's arrival and the ability to safely complete close proximity maneuvers. In this work we develop an adaptive integrated guidance, navigation, and control system that can complete these maneuvers in environments with unknown dynamics, with initial conditions spanning a large deployment region, and without a shape model of the asteroid. The system is implemented as a policy optimized using reinforcement meta-learning. The lander is equipped with an optical seeker that locks to either a terrain feature, reflected light from a targeting laser, or an active beacon, and the policy maps observations consisting of seeker angles and LIDAR range readings directly to engine thrust commands. The policy implements a recurrent network layer that allows the deployed policy to adapt real time to both environmental forces acing on the agent and internal disturbances such as actuator failure and center of mass variation. We validate the guidance system through simulated landing maneuvers in a six degrees-of-freedom simulator. The simulator randomizes the asteroid's characteristics such as solar radiation pressure, density, spin rate, and nutation angle, requiring the guidance and control system to adapt to the environment. We also demonstrate robustness to actuator failure, sensor bias, and changes in the lander's center of mass and inertia tensor. Finally, we suggest a concept of operations for asteroid close proximity maneuvers that is compatible with the guidance system.

关键词： Reinforcement learning Asteroid missions guidance Navigation artificial intelligence Autonomous maneuvers

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3D Profile Reconstruction and guidance for the Terminal Area Energy Management Phase of an Unpowered RLV with Aerosurface Failure

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JOURNAL OF AEROSPACE ENGINEERING 2020年第3期33卷 1-10页

作者： Lan, Xuejing Xu, Wenbiao Wang, Yongji Guangzhou Univ Sch Mech & Elect Engn Guangzhou 510006 Peoples R China Guangdong Inst Metrol Guangdong Prov Key Lab Modern Geometr & Mech Metr Guangzhou 510405 Peoples R China Huazhong Univ Sci & Technol Sch Artificial Intelligence & Automat Wuhan 430074 Peoples R China

This paper focuses on the guidance of an unpowered reusable launch vehicle (RLV) with aerosurface failure in the terminal area energy management (TAEM) phase. The aerosurface failure will limit the bank capability, and has a great influence on the range and turning radius of RLV. To this end, a new TAEM guidance scheme with the ability of online profile reconstruction is proposed in this paper for the bank-constrained RLV. The 3-dimensional (3D) profile is reconstructed online by directly adjusting the parameters of the dynamic pressure profile and the two-external-tangent-circle-based ground track profile. As the coupling between vertical and lateral motion is considered in the trajectory propagation, the reconstruction accuracy is guaranteed. Then, a closed-loop TAEM guidance law is proposed to track the reconstructed 3D profile. The effectiveness and robustness of the guidance scheme are verified by numerical simulations with a variety of initial states and model deviations.

关键词： Reusable launch vehicle Terminal area energy management Trajectory reconstruction guidance Aerosurface failure

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Path planning and guidance algorithms for SAR formation reconfiguration: Comparison between centralized and decentralized approaches

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ACTA ASTRONAUTICA 2020年第0期167卷 404-417页

作者： Sarno, S. D'Errico, M. Guo, J. Gill, E. Univ Campania L Vanvitelli Dept Engn Via Roma 29 I-81031 Aversa CE Italy Delft Univ Technol Fac Aerosp Engn NL-2629 HS Delft Netherlands

This paper presents innovative approaches for guidance of spacecraft formations during reconfiguration, developed under the paradigms of duster autonomy and safe maneuverability. A task-assignment algorithm identifies those satellites that need to be rearranged in order to minimize the total propellant consumption. The decision process relies on convex optimization procedures which estimate control laws and maneuvering trajectories, accounting for thruster technology constraints and collision avoidance. The path-planning has a twofold implementation. In the centralized approach, the reconfiguration strategy is elaborated by a single unit: the maneuvering trajectories are generated considering solely collision avoidance constraints at expenses of computational costs. The alternative method is conceived such that each satellite autonomously determines its tasks. This de-centralized architecture allows the algorithm to tun faster, but entails a higher traffic on the intersatellite communication link. In addition, collision avoidance is approximated to make each optimization independent from the other. For preliminary validation of the developed routines, a specific mission scenario is considered, with a distributed Synthetic Aperture Radar in a low Earth orbit that has to be reconfigured for tomographic applications. Simulation results show that, once remote-sensing requirements are specified within the limits set by standard products, the developed algorithms can manage autonomously the maneuver towards the corresponding operative pattern. In details, the centralized approach allows the reconfiguration to be handled with mean delta-v savings around 30%. On the contrary, strategies are elaborated by the decentralized planners about 7 times faster.

关键词： Distributed space systems Autonomous reconfiguration Path-planning guidance

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Chest CT tomography vs. intracavitary electrocardiogram guidance in predicting the length of PICC placement

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BMC SURGERY 2022年第1期22卷 197-197页

作者： Dong, Huimin Zhu, Yuxin Zhang, Xin Yin, Xinxin Liu, Fude Shijiazhuang Gen Hosp Myasthenia Gravis Ctr Shijiazhuang Hebei Peoples R China Shijiazhuang Gen Hosp Venous Catheter Clin 365 Jiahua South St Shijiazhuang 05000 Hebei Peoples R China Shijiazhuang Gen Hosp Shijiazhuang Hebei Peoples R China

Background To evaluate chest computed tomography (CT) compared to intracavitary electrocardiogram (ECG) in predicting the length of peripherally inserted central catheter (PICC) placement and analyzing the accuracy of the positioning methods. Methods This study included a total number of 436 patients who underwent PICC placement. The patients enrolled were randomly divided into two groups: ECG group (n = 218, received IC-ECG) and chest CT group (n = 218, received chest CT). The tip length of the catheter in the superior vena cava, the measured length of the catheter and the actual insertion length of the catheter were observed and recorded in the two groups. Results The best catheterization rate of tip positioning and the one-time placement rate of tip positioning in ECG group were significantly higher than that in the chest CT group (all P < 0.05). The comfort level and satisfaction rate in ECG group was significantly higher than that of chest CT group (all P < 0.05). Conclusion Accurate catheterization length could be achieved by both chest CT and intracavitary electrocardiogram guidance in the process of predicting PICC placement length. However, IC-ECG guided procedure was more worthy of promotion in clinic.

关键词： Chest CT tomography Intracavitary electrocardiogram guidance PICC placement Length Comparison

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guidance command generation and nonlinear dynamic inversion control for reusable launch vehicles

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ACTA ASTRONAUTICA 2020年 174卷 334-346页

作者： Acquatella, Paul B. Briese, Lale Evrim Schnepper, Klaus German Aerosp Ctr DLR Inst Syst Dynam & Control D-82234 Oberpfaffenhofen Germany

Future launch vehicle concepts and technologies for expendable and reusable launch vehicles are currently investigated by the DLR research projects AKIRA and X-TRAS. In particular, the winged Liquid Fly-back Booster concept LFBB based on an LOX/LH2 propellant combination for vertical takeoff and vertical landing (VTVL), as well as the delta-winged horizontal takeoff and horizontal landing (HTHL) concept AURORA based on an LOX/Kerosene propellant combination are considered in these projects. Because of the complexity and risks involved in on-line trajectory optimization, off-line reference trajectories are still considered important for tracking purposes. In that sense, the goal of this paper is to investigate an off-line and general-purpose guidance and control (G&C) architecture for preliminary studies of reusable launch vehicles. This is done by using trajectory optimization combined with MODELICA models for the generation of optimal guidance commands, and then trajectory tracking is performed by means of inner-loop feedback controls in terms of nonlinear dynamic inversion with prescribed desired dynamics. We showcase the advantages of this baseline G&C architecture in terms of early stability and controllability aspects during the preliminary design studies of an example configuration of a reusable launch vehicle investigated in the context of the research projects above mentioned.

关键词： Trajectory optimization guidance Nonlinear control Dynamic inversion Reusable space launchers

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L1 Penalized Sequential Convex Programming for Fast Trajectory Optimization: With Application to Optimal Missile guidance

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INTERNATIONAL JOURNAL OF AERONAUTICAL AND SPACE SCIENCES 2020年第2期21卷 493-503页

作者： Roh, Heekun Oh, Young-Jae Tahk, Min-Jea Kwon, Ki-Jeong Kwon, Hyuck-Hoon Korea Adv Inst Sci & Technol Daejeon 34141 South Korea ADD Daejeon 34186 South Korea LIG Nex1 Gyeonggi Do 16911 South Korea

In this paper, an L1 penalized sequential convex programming (LPSCP) method for trajectory optimization is proposed. Sequential convex methods dramatically reduce computation time for nonlinear trajectory optimizations, based on the desirable properties of convex optimization algorithms. Due to its fast convergence speed, the sequential convex method is considered as a near-future candidate for real-time optimal online guidance. However, the generic sequential convex method seldom suffers from poor robustness to crude the initial trajectory estimates and constraint perturbations, which limits its application to real-world systems. Suggested LPSCP method resolves the robustness issue of generic sequential convex methods, by addressing the convex subproblem infeasibility. While improving its robustness, proposed LPSCP method maintains its fast convergence property. Consequently, LPSCP method enhances overall versatility of sequential convex method for trajectory optimization, which includes ameliorated robustness toward initial trajectory estimates, and improved stability to state and constraint perturbations. Throughout the paper, details of LPSCP method are outlined along with an application example to missile trajectory optimization problems. Desirable properties of LPSCP method are demonstrated through several simulated examples. Optimized trajectories are compared with results from the pseudospectral method. Numerical simulation and Monte Carlo analysis show that LPSCP method accelerates optimization process dramatically (-98.2% on average) while producing the same optimal trajectory.

关键词： Trajectory optimization Convex optimization guidance

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Optimal guidance laws with prescribed degree of stability

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AEROSPACE SCIENCE AND TECHNOLOGY 2020年 99卷 105780-105780页

作者： Rusnak, Ilan Weiss, Haim Hexner, Gyorgy RAFAEL POB 2250 IL-3102102 Haifa Israel

The prescribed degree of stability criterion is used. This quadratic criterion involves an increasing exponential time dependent term in the integral part of the criterion. This criterion is used for derivation of guidance laws. The derived guidance law has the classical structure of guidance gain times the zero-effort miss. The important issue is the fact that initially the guidance gain and thus the commanded acceleration are larger than in the conventional Proportional Navigation guidance law, but near the end, the commanded acceleration is smaller. The new guidance law attempts to close the zero effort miss earlier in the scenario than the conventional guidance law. (C) 2020 Elsevier Masson SAS. All rights reserved.

关键词： guidance Zero-effort-miss Quadratic criterion Proportional navigation

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