Design and Operational Elements of the Robotic Subsystem for the e.deorbit Debris Removal Mission

This paper presents a robotic capture concept that was developed as part of the e.deorbit study by ESA. The defective and tumbling satellite ENVISAT was chosen as a potential target to be captured, stabilized, and subsequently de-orbited in a controlled manner. A robotic capture concept was developed that is based on a chaser satellite equipped with a seven degrees-of-freedom dexterous robotic manipulator, holding a dedicated linear two-bracket gripper. The satellite is also equipped with a clamping mechanism for achieving a stiff fixation with the grasped target, following their combined satellite-stack de-tumbling and prior to the execution of the de-orbit maneuver. Driving elements of the robotic design, operations and control are described and analyzed. These include pre and post-capture operations, the task-specific kinematics of the manipulator, the intrinsic mechanical arm flexibility and its effect on the arm's positioning accuracy, visual tracking, as well as the interaction between the manipulator controller and that of the chaser satellite. The kinematics analysis yielded robust reachability of the grasp point. The effects of intrinsic arm flexibility turned out to be noticeable but also effectively scalable through robot joint speed adaption throughout the maneuvers. During most of the critical robot arm operations, the internal robot joint torques are shown to be within the design limits. These limits are only reached for a limiting scenario of tumbling motion of ENVISAT, consisting of an initial pure spin of 5 deg/s about its unstable intermediate axis of inertia. The computer vision performance was found to be satisfactory with respect to positioning accuracy requirements. Further developments are necessary and are being pursued to meet the stringent mission-related robustness requirements. Overall, the analyses conducted in this study showed that the capture and de-orbiting of ENVISAT using the proposed robotic concept is feasible with respect to relevant mission requirements and for most of the operational scenarios considered. Future work aims at developing a combined chaser-robot system controller. This will include a visual servo to minimize the positioning errors during the contact phases of the mission (grasping and clamping). Further validation of the visual tracking in orbital lighting conditions will be pursued

Atomoxetine Enhances Connectivity of Prefrontal Networks in Parkinson's Disease.

Cognitive impairment is common in Parkinson's disease (PD), but often not improved by dopaminergic treatment. New treatment strategies targeting other neurotransmitter deficits are therefore of growing interest. Imaging the brain at rest ('task-free') provides the opportunity to examine the impact of a candidate drug on many of the brain networks that underpin cognition, while minimizing task-related performance confounds. We test this approach using atomoxetine, a selective noradrenaline reuptake inhibitor that modulates the prefrontal cortical activity and can facilitate some executive functions and response inhibition. Thirty-three patients with idiopathic PD underwent task-free fMRI. Patients were scanned twice in a double-blind, placebo-controlled crossover design, following either placebo or 40-mg oral atomoxetine. Seventy-six controls were scanned once without medication to provide normative data. Seed-based correlation analyses were used to measure changes in functional connectivity, with the right inferior frontal gyrus (IFG) a critical region for executive function. Patients on placebo had reduced connectivity relative to controls from right IFG to dorsal anterior cingulate cortex and to left IFG and dorsolateral prefrontal cortex. Atomoxetine increased connectivity from the right IFG to the dorsal anterior cingulate. In addition, the atomoxetine-induced change in connectivity from right IFG to dorsolateral prefrontal cortex was proportional to the change in verbal fluency, a simple index of executive function. The results support the hypothesis that atomoxetine may restore prefrontal networks related to executive functions. We suggest that task-free imaging can support translational pharmacological studies of new drug therapies and provide evidence for engagement of the relevant neurocognitive systems.This work was funded by the Wellcome trust (103838), Parkinson’s UK, National Institute for Health Research’s Cambridge Biomedical Research Centre and the Medical Research Council (MC_US_A060_0016 and RG62761) and the James F McDonnell Foundation (21st century science initiative on Understanding Human Cognition). The BCNI is supported by a joint award from the Wellcome Trust and Medical Research Council.This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/npp.2016.1

e.Deorbit Mission: OHB Debris Removal Concepts

To stabilize the space debris problem in low Earth orbit(LEO), the performance of active debris removalmissions is required. To prepare for such missions, theEuropean Space Agency (ESA) has initiated thee.Deorbit mission as part of its Clean Space activities,with ENVISAT as a sizing case for a potential removaltarget.For the phase A of e.Deorbit, OHB System has led ateam with strong heritage in the key fields of missiondesign, space robotics, and guidance, navigation andcontrol (GNC). In this paper, the mission concepts for removing spacedebris with a rigid or flexible capture mechanism arepresented. While re-orbiting was also studied, it is notaddressed in this paper.A key focus of the study has been the creation of a cost-effective design, allowing the high number of futureremoval missions needed for the stabilization ofthe space debris environment while not sacrificing thenecessary levels of reliability and safety

Robotic Capture and De-Orbit of a Heavy, Uncooperative and Tumbling Target in Low Earth Orbit

This paper presents a robotic capture concept for large spacecraft in low Earth orbit (LEO) that was developed as part of the the e.Deorbit feasibility study within the scope of the clean space initiative of the European Space Agency (ESA). The defective and tumbling satellite ENVISAT has been chosen as potential target to be captured, stabilized, and subsequently de-orbited in a controlled manner. Following a thorough target analysis including potential grasping points, a robotic capture concept was developed that is based on a 7-DoF dexterous robotic manipulator, a linear two-bracket gripper, and a clamping mechanism for achieving stiff fixation between target and chaser satellites prior to the de-tumbling and execution of the de-orbit maneuver. The robotic grasp concept includes a stereo-vision camera system featuring a visual servoing algorithm for camera-in-the-loop error correction. In addition, a platform-mounted camera system is utilized for target model building as well as relative motion and pose estimation. For concept validation, visual servoing, haptic grasp and capture simulations were performed. The task-specific kinematics of the manipulator and potential joint locks as contingency events were validated and analyzed using the method of capability maps. For the complete robotic capture maneuver, an error budget was created and evaluated. Geometric analysis and haptic grasp simulations showed that the gripper design and connected grasp approach is feasible and robust. In addition, the kinematics analysis yielded a sufficient reachability, even in the case of an improbable joint lock. FE-analyses were performed to show that a high compound stiffness can be achieved by the clamping device and that all required forces can be transmitted without damaging the target’s structure. Overall, the study showed that the capture and deorbiting of ENVISAT is feasible and robust using the developed robotic concept

Comprehensive Cardiovascular Magnetic Resonance‐Derived Myocardial Strain Analysis Provides Independent Prognostic Value in Acute Myocarditis

Background Late gadolinium enhancement and left ventricular (LV) ejection fraction on cardiovascular magnetic resonance (CMR) are prognostic markers, but their predictive value for incident heart failure or life‐threatening arrhythmias in acute myocarditis patients is limited. CMR‐derived feature tracking provides a more sensitive analysis of myocardial function and may improve risk stratification in myocarditis. In this study, the prognostic value of LV, right ventricular, and left atrial strain in acute myocarditis patients is evaluated. Methods and Results In this multicenter retrospective study, patients with CMR‐proven acute myocarditis were included. The primary end point was occurrence of major adverse cardiovascular events: all‐cause mortality, heart transplantation, heart failure hospitalizations, and life threatening arrhythmias. LV global longitudinal strain, global circumferential strain and global radial strain, right ventricular‐global longitudinal strain and left atrial strain were measured. Unadjusted and adjusted cox proportional hazard regression analysis were performed. In total, 162 CMR‐proven myocarditis patients were included (41 ± 17 years, 75% men). Mean LV ejection fraction was 51 ± 12%, and 144 (89%) patients had presence of late gadolinium enhancement. Major adverse cardiovascular events occurred in 29 (18%) patients during a follow‐up of 5.5 (2.2–8.3) years. All LV strain parameters were independent predictors of outcome beyond clinical features, LV ejection fraction and late gadolinium enhancement (LV‐global longitudinal strain: hazard ratio [HR] 1.07, P=0.02; LV‐global circumferential strain: HR 1.15, P=0.02; LV‐global radial strain: HR 0.98, P=0.03), but right ventricular or left atrial strain did not predict outcome. Conclusions CMR‐derived LV strain analysis provides independent prognostic value on top of clinical parameters, LV ejection fraction and late gadolinium enhancement in acute myocarditis patients, while left atrial and right ventricular strain seem to be of less importance

Comprehensive Cardiovascular Magnetic Resonance-Derived Myocardial Strain Analysis Provides Independent Prognostic Value in Acute Myocarditis

Background Late gadolinium enhancement and left ventricular (LV) ejection fraction on cardiovascular magnetic resonance (CMR) are prognostic markers, but their predictive value for incident heart failure or life-threatening arrhythmias in acute myocarditis patients is limited. CMR-derived feature tracking provides a more sensitive analysis of myocardial function and may improve risk stratification in myocarditis. In this study, the prognostic value of LV, right ventricular, and left atrial strain in acute myocarditis patients is evaluated. Methods and Results In this multicenter retrospective study, patients with CMR-proven acute myocarditis were included. The primary end point was occurrence of major adverse cardiovascular events: all-cause mortality, heart transplantation, heart failure hospitalizations, and life threatening arrhythmias. LV global longitudinal strain, global circumferential strain and global radial strain, right ventricular-global longitudinal strain and left atrial strain were measured. Unadjusted and adjusted cox proportional hazard regression analysis were performed. In total, 162 CMR-proven myocarditis patients were included (41 ± 17 years, 75% men). Mean LV ejection fraction was 51 ± 12%, and 144 (89%) patients had presence of late gadolinium enhancement. Major adverse cardiovascular events occurred in 29 (18%) patients during a follow-up of 5.5 (2.2-8.3) years. All LV strain parameters were independent predictors of outcome beyond clinical features, LV ejection fraction and late gadolinium enhancement (LV-global longitudinal strain: hazard ratio [HR] 1.07, P=0.02; LV-global circumferential strain: HR 1.15, P=0.02; LV-global radial strain: HR 0.98, P=0.03), but right ventricular or left atrial strain did not predict outcome. Conclusions CMR-derived LV strain analysis provides independent prognostic value on top of clinical parameters, LV ejection fraction and late gadolinium enhancement in acute myocarditis patients, while left atrial and right ventricular strain seem to be of less importance

Additional diagnostic value of CMR to the European Society of Cardiology (ESC) position statement criteria in a large clinical population of patients with suspected myocarditis

Aims: To determine the diagnostic yield of tissue characterization by cardiovascular magnetic resonance (CMR) in a large clinical population of patients with suspected acute myocarditis (AM) and to establish its diagnostic value within the 2013 European Society of Cardiology position statement criteria (ESC-PSC) for clinically suspected myocarditis. Methods and results: In this retrospective study, CMR examinations of 303 hospitalized patients referred for work-up of suspected AM in two tertiary referral centres were analysed. CMR was performed at median 7 days (interquartile range 4-20 days) after clinical presentation and included cine imaging, T2-weighted imaging, and late gadolinium enhancement. CMR images were evaluated to assign each patient to a diagnosis. By using non-CMR criteria only, the 2013 ESC-PSC were positive for suspected myocarditis in 151 patients and negative in 30. In the remaining 122 patients, there was insufficient information available for ESC-PSC assessment, mostly due to lack of coronary angiography (CAG) before the CMR examination (n = 116, 95%). There were no in-hospital deaths. CMR provided a diagnosis in 158 patients (52%), including myocarditis in 104 (34%), myocardial infarction in 44 (15%), and other pathology in 10 patients (3%). Non-urgent CAG (>24 h after presentation) was performed before the CMR examination in 85 patients, of which 20 (24%) were done in patients with subsequently confirmed AM, which could potentially have been avoided if CMR was performed first. ESC-PSC was correct in diagnosing AM before the CMR in 50 of the 151 patients (33%) and was correct in ruling out AM in all the 30 patients (100%). However, ESC-PSC provided an incorrect diagnosis of AM in 27 of the 151 patients (18%), which was corrected by CMR through the identification of new cardiac disease that could explain the clinical syndrome. Patients with insufficient ESC-PSC information had a relatively low pre-test probability of coronary artery disease. In this group, CMR confirmed the diagnosis of AM in a relatively high percentage (44%) but still revealed myocardial infarction in 8% of them. Conclusion: Tissue characterization by CMR provided a good diagnostic yield in this large clinical population of patients with suspected AM. CMR provided incremental diagnostic value to the ESC-PSC by ruling out the diagnosis of AM on one hand and by potentially sparing AM patients from CAG on the other

Usefulness of Left Atrial Emptying Fraction to Predict Ventricular Arrhythmias in Patients With Implantable Cardioverter Defibrillators

Impaired left atrial emptying fraction (LAEF) is an important predictor of mortality in patients with heart failure. As it may reflect increased LV wall stress, it might predict ventricular arrhythmia (VA) specifically. This study evaluated the predictive value of LAEF assessed with cardiovascular magnetic resonance (CMR) imaging with respect to appropriate device therapy (ADT) for VA and compared its role with CMR assessed scar size and other risk factors. In total, 229 patients (68% male, 63 ± 10 years, 61% ischemic cardiomyopathy) with LV ejection fraction ≤35% who underwent CMR and implantable cardioverter defibrillator (ICD) implantation for primary prevention in 2005 to 2012 were included. CMR was used to quantify LV volumes and function. LV scar size was quantified when late gadolinium enhancement was available (n = 166). Maximum and minimum left atrial volumes and LAEF were calculated using the biplane area-length method. The occurrence of ADT and mortality was assessed during a median follow-up of 3.9 years. Sixty-two patients (27%) received ADT. Univariable Cox analysis showed that male gender, creatinine level, minimum left atrial volume, LAEF, and total scar size were significant predictors of ADT. In multivariable Cox analysis, LAEF (hazard ratio 0.75 per 10%, p median and scar size median experienced 40% ADT at 5 years (log-rank p = 0.01). In conclusion, LAEF independently predicts ADT in patients with primary prevention ICDs. Combined assessment of LAEF and scar size identifies a group with low risk of ADT. Therefore, LAEF assessment could assist in risk stratification for VA to select patients with the highest benefit from ICD implantation

Myocardial adaptation after surgical therapy differs for aortic valve stenosis and hypertrophic obstructive cardiomyopathy

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