Attitude stability of a dual-spin spacecraft on a stationary orbit around an asteroid subjected to gravity gradient torque

2015 ◽  
Vol 355 (2) ◽  
pp. 203-212 ◽  
Author(s):  
Ming-Jiang Zhang ◽  
Chang-Yin Zhao
2009 ◽  
Vol 104 (4) ◽  
pp. 337-353 ◽  
Author(s):  
Rodolpho Vilhena de Moraes ◽  
Regina Elaine Santos Cabette ◽  
Maria Cecília Zanardi ◽  
Teresinha J. Stuchi ◽  
Jorge Kennety Formiga

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Chunhui Liang ◽  
Yuanchun Li

Attitude stability analysis and robust control algorithms for spacecrafts orbiting irregular asteroids are investigated in the presence of model uncertainties and external disturbances. Rigid spacecraft nonlinear attitude models are considered and detailed attitude stability analysis of spacecraft subjected to the gravity gradient torque in an irregular central gravity field is included in retrograde orbits and direct orbits using linearized system model. The robust adaptive backstepping sliding mode control laws are designed to make the attitude of the spacecrafts stabilized and responded accurately to the expectation in the presence of disturbances and parametric uncertainties. Numerical simulations are included to illustrate the spacecraft performance obtained using the proposed control laws.


2020 ◽  
Vol 25 (3) ◽  
pp. 17-25 ◽  
Author(s):  
G. R. Ramazanov ◽  
L. B. Zavaliy ◽  
L. L. Semenov ◽  
S. A. Abudeev ◽  
A. O. Ptitsyn ◽  
...  

Abstract. Early rehabilitation (ER) of patients with acute cerebrovascular accident (ACA) is one of the priority tasks of the vascular centers; the issue of increasing the volume of rehabilitation measures in the resuscitation and intensive care units (ICU) is relevant. Objective. To evaluate the safety and effectiveness of the progressive ER program in patients with ACA. Material and research methods. The study included 129 patients with ACA in ICU. Each patient of the main group (MGr, n = 61) underwent progressive ER: at least 4–5 vertical adjustments per day, passive mode Kinesiotherapy 49 ± 9.3 minutes, a double load of physiotherapy exercises, preventive physiotherapy; the total time of classes reached 240 minutes per day. In the comparison group (СGr, n = 68), standard ER was performed no more than 120 minutes per day. The groups are comparable by sex, age, severity of the disease and comorbidity. The severity of ACA, the gravity gradient, patient mobility, functional status, degree of dependence, and the presence of complications were evaluated. Results. During a month of work with the MGr, 102 ICU bed-days, 94 days of the artificial lung ventilation use, p < 0.05 were saved. Mortality in MGr decreased -— 8 patients (13.1%) versus 14 (20.6%) in CGr (p < 0.05). In patients within CGr, pulmonary thromboembolism developed in 8.8%, in MGr – in 3.3%. The severity of the apoplectic attack decreased ( by 28% in MGr, and by 20% in CGr ), mobility increased. Comparing the modalities of post resuscitationsyndrome in MGr, it was noted that the score decreased by 2 times from 6 [5; 6] to 3 [2.3; 3.3], but it has not changed in the CGr. Patients in the MGr were 2-–3 days earlier adapted to the vertical adjustment. Conclusions. The progressive ER program in ICU is safe, effective, realisable, and allows reducing the number of bed-days in ICU, the number of days of the artificial lung ventilation use, complications, and mortality in comparison with standard medical care.


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