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Designing robust pose estimator for non-cooperative space targets for visual servoing during approach maneuvers

Mishra, Hrishik (2016) Designing robust pose estimator for non-cooperative space targets for visual servoing during approach maneuvers. Master's. DLR-Interner Bericht. DLR-IB-RM-OP-2017-123, 95 S.

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For on-orbit autonomous grasping of an uncooperative spacecraft using visual servo control of a robotic manipulator, it is imperative that the pose estimation algorithm provide accurate estimates of relative motion parameters from the noisy vision measurements. These non-uniformly sampled measurements have variable noise characteristics and represent a past state owing to the processing time. In this thesis, an event-driven and Out of Sequence Measurement (OOSM)-capable Extended Kalman Filter (EKF) observer with adaptive behavior is derived for estimating motion, inertial and geometric characteristics of an uncooperative Target spacecraft with an objective of grasping while using the measurements of the kind mentioned above. Observability and stability analyses have been presented with conclusions about target inertia and geometry that affect the estimation process. Special focus has been laid on the vision sensor’s noise and time-response characteristics to improve the estimator’s robustness and optimality. Robustness is analysed in terms of convergence, immunity towards outliers and adaptive behaviour in the face changing noise characteristics. The adaptive behaviour in the EKF is achieved using a Variational Bayesian (VB) approach and an assessment is presented for a step-change in noise characteristics. A nonlinear state-space model for relative dynamics between the OOS’s end-effector and the tumbling target have been derived which incorporate orbital dynamics and manipulator’s servoing motion. In order to avoid rank-deficiency variances for the attitude quaternion, a Multiplicative Extended Kalman Filter (MEKF) approach with a reduced state-vector is used. The small angular rotation and the Gibbs vector were used as candidates and an evaluation of both of these representations is provided. A Software In Loop (SIL) has been developed which allows fast prototyping of estimation/control algorithms for the grasping problem using an eye-in-hand topology for position-based servo control.

Item URL in elib:https://elib.dlr.de/113119/
Document Type:Monograph (DLR-Interner Bericht, Master's)
Title:Designing robust pose estimator for non-cooperative space targets for visual servoing during approach maneuvers
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Mishra, Hrishikhrishik.mishra (at) dlr.dehttps://orcid.org/0000-0002-5025-2447
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Number of Pages:95
EditorsEmailEditor's ORCID iD
Lampariello, RobertoRoberto.Lampariello@dlr.deUNSPECIFIED
Schmidt, PhillipPhillip.Schmidt@dlr.deUNSPECIFIED
Keywords:Extended Kalman Filter (EKF), Visual Servoing, On Orbit Servicing, Pose estimation
Institution:Technische Universität München
Department:Ingenieurfakultät Bau Geo Umwelt
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space System Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Space System Technology
DLR - Research theme (Project):On-Orbit Servicing (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Robotics and Mechatronics (since 2013) > Analysis and Control of Advanced Robotic Systems
Deposited By: Mishra, Hrishik
Deposited On:31 Jul 2017 16:22
Last Modified:31 Jul 2019 20:10

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