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Inertia tensor estimation for a rigid nadir pointing satellite based on star tracker
Cheriet, Mohammed E.A.,Bellar, Abdellatif,Ghaffour, Mohammed Y.,Adnane, Akram,Mohammed, Mohammed A. SI Techno-Press 2021 Advances in aircraft and spacecraft science Vol.8 No.2
Accurate inertia properties information is important to reach an optimized estimation of attitude and precise control of a rigid spacecraft. Unfortunately, the satellite is succumbing several influences that can affect the inertia properties, such as fuel consumption and sloshing. Thus, this work inspects the use of star tracker to estimate the attitude, angular velocity and moment of inertia for a rigid nadir pointing satellite by employing extended Kalman filter, without any prior information about the nominal inertia matrix. The proposed estimator is applied in nadir pointing mode and without any constant control torque to avoid the attitude tumbling during the estimation phase, which in turn leads to a catastrophic failure of the satellite mission. The simulation results are compared to three other approaches and validated by Monte Carlo method that elucidates the good performance of the suggested approach and demonstrates its efficiency in satellite inertia tensor and attitude estimation even in worst situations.
Inertia tensor estimation for a rigid nadir pointing satellite based on star tracker
Cheriet, Mohammed E.A.,Bellar, Abdellatif,Ghaffour, Mohammed Y.,Adnane, Akram,Mohammed, Mohammed A. SI Techno-Press 2021 Advances in aircraft and spacecraft science Vol.8 No.2
Accurate inertia properties information is important to reach an optimized estimation of attitude and precise control of a rigid spacecraft. Unfortunately, the satellite is succumbing several influences that can affect the inertia properties, such as fuel consumption and sloshing. Thus, this work inspects the use of star tracker to estimate the attitude, angular velocity and moment of inertia for a rigid nadir pointing satellite by employing extended Kalman filter, without any prior information about the nominal inertia matrix. The proposed estimator is applied in nadir pointing mode and without any constant control torque to avoid the attitude tumbling during the estimation phase, which in turn leads to a catastrophic failure of the satellite mission. The simulation results are compared to three other approaches and validated by Monte Carlo method that elucidates the good performance of the suggested approach and demonstrates its efficiency in satellite inertia tensor and attitude estimation even in worst situations.
Siddhartha Das,Sandeep Gurav,Vivek Soni,Arvind Ingle,Bhabani S. Mohanty,Pradip Chaudhari,Kiran Bendale,Kanchan Dholam,Jayesh R. Bellare 한국조직공학과 재생의학회 2018 조직공학과 재생의학 Vol.15 No.2
A titanium implant surface when coated with biodegradable, highly porous, osteogenic nanofibrous coating has shown enhanced intrinsic osteoinductive and osteoconductive properties. This coating mimics extracellular matrix resulting in differentiation of stem cells present in the peri-implant niche to osteoblast and hence results in enhanced osseointegration of the implant. The osteogenic nanofibrous coating (ONFC) consists of poly-caprolactone, gelatin, nano- sized hydroxyapatite, dexamethasone, ascorbic acid and beta-glycerophosphate. ONFC exhibits optimum mechanical properties to support mesenchymal stem cells and steer their osteogenic differentiation. ONFC was subjected to various characterization tests like scanning electron microscopy, Fourier-transform infrared spectroscopy, x-ray diffractometry, thermal degradation, biomineralization, mechanical properties, wettability and proliferation assay. In pre-clinical animal trials, the coated implant showed enhanced new bone formation when placed in the tibia of rabbit. This novel approach toward implant bone integration holds significant promise for its easy and economical coating thus marking the beginning of new era of electrospun osteogenic nanofibrous coated bone implants.