The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Shengying Zhu - One of the best experts on this subject based on the ideXlab platform.
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prudent small Celestial Body landing strategy with risk precautions
Acta Astronautica, 2019Co-Authors: Pingyuan Cui, Shengying Zhu, He JiaAbstract:Abstract In small Body landing missions, the nominal landing scheme may turn out to be inapplicable in reality due to the limited prior information of the target and possible system errors after long-term operation. In this paper, a partial breakdown of the main thruster in the presence of large state deviations and complex terrain conditions at the landing site is considered. In order to ensure lander safety, a risk-precautionary landing strategy that identifies landing anomalies, generates onboard warnings, and plans an emergency transfer is proposed. First, lander safety is repetitively evaluated during descent through a computation of onboard deceleration capability and landing site safety. Upon a predicted landing risk, an emergency mode is activated. Three emergency modes are developed for the strategy, including an orbiting mode, a diverting mode, and a hovering mode. For each mode, a customized goal state is designated and a corresponding emergency transfer trajectory is generated in real-time. At last, an asteroid 433 Eros-based landing scenario is designed, and the effectiveness of the strategy is verified under three different thruster and terrain conditions.
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recent development of autonomous gnc technologies for small Celestial Body descent and landing
Progress in Aerospace Sciences, 2019Co-Authors: Pingyuan Cui, Shengying ZhuAbstract:Abstract As small Celestial Body exploration advances, higher requirements with regard to system safety and landing precision are proposed for future landing and sample return missions. However, due to limited prior information about the target, the complex dynamics environment, and significant time-delay, performing a descent and landing on the small Body surface is challenging. Among all the techniques required for achieving a safe landing, onboard guidance, navigation, and control (GNC) is of paramount importance in determining mission success. In this paper, a systematic survey of the autonomous GNC technologies for descent and landing on small bodies is carried out. First, based on an analysis of the technical challenges in the process, an overview of typical small Body landing and sample return missions is given. Then, an elaboration of the state-of-the-art GNC technologies is presented. Specifically, autonomous navigation methods in unknown environments with highly-nonlinear dynamics are introduced. Descent guidance and control algorithms that take into account landing performance optimization and system robustness against model uncertainties are discussed. Touchdown dynamics and control methods proposed for precise and safe surface contact under weak gravity are analyzed. And safe strategies for onboard detected emergencies such as collision threats and system malfunctions are explained. Besides the prevalent methods, innovative techniques with respect to observability-based optimization, edge curve matching, online landing site selection, collision probability-based hazard avoidance, and trajectory curvature guidance proposed for improving system safety and landing performance are elucidated. At last, based on the growing system autonomy and operational complexity demands, a prospect of future research directions for small Body GNC technologies is given.
Pingyuan Cui - One of the best experts on this subject based on the ideXlab platform.
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prudent small Celestial Body landing strategy with risk precautions
Acta Astronautica, 2019Co-Authors: Pingyuan Cui, Shengying Zhu, He JiaAbstract:Abstract In small Body landing missions, the nominal landing scheme may turn out to be inapplicable in reality due to the limited prior information of the target and possible system errors after long-term operation. In this paper, a partial breakdown of the main thruster in the presence of large state deviations and complex terrain conditions at the landing site is considered. In order to ensure lander safety, a risk-precautionary landing strategy that identifies landing anomalies, generates onboard warnings, and plans an emergency transfer is proposed. First, lander safety is repetitively evaluated during descent through a computation of onboard deceleration capability and landing site safety. Upon a predicted landing risk, an emergency mode is activated. Three emergency modes are developed for the strategy, including an orbiting mode, a diverting mode, and a hovering mode. For each mode, a customized goal state is designated and a corresponding emergency transfer trajectory is generated in real-time. At last, an asteroid 433 Eros-based landing scenario is designed, and the effectiveness of the strategy is verified under three different thruster and terrain conditions.
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recent development of autonomous gnc technologies for small Celestial Body descent and landing
Progress in Aerospace Sciences, 2019Co-Authors: Pingyuan Cui, Shengying ZhuAbstract:Abstract As small Celestial Body exploration advances, higher requirements with regard to system safety and landing precision are proposed for future landing and sample return missions. However, due to limited prior information about the target, the complex dynamics environment, and significant time-delay, performing a descent and landing on the small Body surface is challenging. Among all the techniques required for achieving a safe landing, onboard guidance, navigation, and control (GNC) is of paramount importance in determining mission success. In this paper, a systematic survey of the autonomous GNC technologies for descent and landing on small bodies is carried out. First, based on an analysis of the technical challenges in the process, an overview of typical small Body landing and sample return missions is given. Then, an elaboration of the state-of-the-art GNC technologies is presented. Specifically, autonomous navigation methods in unknown environments with highly-nonlinear dynamics are introduced. Descent guidance and control algorithms that take into account landing performance optimization and system robustness against model uncertainties are discussed. Touchdown dynamics and control methods proposed for precise and safe surface contact under weak gravity are analyzed. And safe strategies for onboard detected emergencies such as collision threats and system malfunctions are explained. Besides the prevalent methods, innovative techniques with respect to observability-based optimization, edge curve matching, online landing site selection, collision probability-based hazard avoidance, and trajectory curvature guidance proposed for improving system safety and landing performance are elucidated. At last, based on the growing system autonomy and operational complexity demands, a prospect of future research directions for small Body GNC technologies is given.
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The present status and prospects in the research of orbital dynamics and control near small Celestial bodies
Theoretical and Applied Mechanics Letters, 2014Co-Authors: Pingyuan Cui, Dong QiaoAbstract:Small Celestial Body exploration is of great significance to deep space activities. The dynamics and control of orbits around small Celestial bodies is of top priority in the exploration research. It includes the modeling of dynamics environment and the orbital dynamics mechanism. This paper introduced state-of-the-art researches, major challenges, and future trends in this field. Three topics are mainly discussed: the gravitational field modeling of irregular-shaped small Celestial bodies, natural orbital dynamics and control, and controlled orbital dynamics. Finally, constructive suggestions are made for China's future space exploration missions.
Qiao Dong - One of the best experts on this subject based on the ideXlab platform.
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State-of-the-art and prospects for orbital dynamics and control near small Celestial bodies
Advances in Mechanics, 2013Co-Authors: Cui Pingyuan, Qiao DongAbstract:Small Celestial Body exploration is one of the key areas of deep space exploration in the future.The orbital dynamics and control problem near small Celestial bodies is crucial in such explorations, and urgent to be treated. This problem involves the modeling of dynamics environment around an irregularshaped small Celestial Body, and the orbital dynamics mechanism near the small Celestial Body. In this paper, we survey the gravitational field modeling of irregular-shaped small Celestial Body, natural orbital dynamics and control, and controlled orbital dynamics near small Celestial Body. We introduce state-ofthe-art and trends for the development of orbital dynamics and control near small Celestial bodies. The challenges and difculties encountered are analyzed. Finally, we discuss the prospects for the development direction and key issues of orbital dynamics and control for Chinese future mission for exploring small Celestial bodies.
Cui Pingyuan - One of the best experts on this subject based on the ideXlab platform.
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State-of-the-art and prospects for orbital dynamics and control near small Celestial bodies
Advances in Mechanics, 2013Co-Authors: Cui Pingyuan, Qiao DongAbstract:Small Celestial Body exploration is one of the key areas of deep space exploration in the future.The orbital dynamics and control problem near small Celestial bodies is crucial in such explorations, and urgent to be treated. This problem involves the modeling of dynamics environment around an irregularshaped small Celestial Body, and the orbital dynamics mechanism near the small Celestial Body. In this paper, we survey the gravitational field modeling of irregular-shaped small Celestial Body, natural orbital dynamics and control, and controlled orbital dynamics near small Celestial Body. We introduce state-ofthe-art and trends for the development of orbital dynamics and control near small Celestial bodies. The challenges and difculties encountered are analyzed. Finally, we discuss the prospects for the development direction and key issues of orbital dynamics and control for Chinese future mission for exploring small Celestial bodies.
Guangjun Zhang - One of the best experts on this subject based on the ideXlab platform.
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Accurate and Robust Synchronous Extraction Algorithm for Star Centroid and Nearby Celestial Body Edge
IEEE Access, 2019Co-Authors: Yong Zhang, Jie Jiang, Guangjun ZhangAbstract:Celestial Body features are important navigation information in deep space exploration. This study provides a synchronous high-precision extraction algorithm for star centroid and nearby Celestial Body edges for a miniaturized independent optical navigation sensor, which combines the functions of a star tracker and a navigation camera. The image is filtered by a ring filter template to eliminate the interference information of background and improve the contrast between the target and the background. The second-order directional derivative and specific area characteristic method aim to roughly extract and distinguish the features (star centroid and the nearby Celestial Body edge). In local area template where feature points are located, the 1D energy deviation effect is proposed to extract the features of the two different light intensity distribution models. The accuracy and robustness of our algorithm are verified by simulation and ground-based experiments. The algorithm has certain reference significance for other types of dim target and edge detections, such as infrared detection, medical image, target measurement, and machine vision.
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High-Accuracy Synchronous Extraction Algorithm of Star and Celestial Body Features for Optical Navigation Sensor
IEEE Sensors Journal, 2018Co-Authors: Jie Jiang, Hao Wang, Guangjun ZhangAbstract:This paper provides an optimal high-performance image processing algorithm for a miniaturized independent optical navigation sensor, which combines the functions of a star tracker and a navigation camera. This novel image processing algorithm is capable of extracting two different types of optical navigation measurements from a raw image. The aim is to simultaneously extract stars and target Celestial Body features with high accuracy and reliability to estimate observer-to-Body relative position in subsequent navigation process. This paper presents star and Celestial Body imaging models and a novel slope edge model. We propose an high-performance algorithm to achieve the synchronous extraction of star and Celestial Body image features based on the aforementioned models. Double-window variance difference method is proposed to segment and classify stars and edge image regions of a Celestial Body with strong robustness. The sub-pixel level position of star centroid and Celestial Body edges are then simultaneously extracted by using the same operator on the basis of the consistency of the derivative distribution of star and Celestial Body edge profiles. The edge extraction deviation when using the slope edge model is also analyzed and compensated, and the accuracy of the Celestial Body edge extraction is improved to a higher level. The proposed algorithm has excellent feature extraction performance in terms of qualitative and quantitative measurements. This paper has established a technical foundation for the development of the miniaturized independent optical navigation sensor, which is low cost, light weight and has flexible applicability due to its high accuracy and robustness.
