The SURPRISE demonstrator: a super-resolved compressive instrument in the visible and medium infrared for Earth Observation

While Earth Observation (EO) data has become ever more vital to understanding the planet and addressing societal challenges, applications are still limited by revisit time and spatial resolution. Though low Earth orbit missions can achieve resolutions better than 100 m, their revisit time typically stands at several days, limiting capacity to monitor dynamic events. Geostationary (GEO) missions instead typically provide data on an hour-basis but with spatial resolution limited to 1 km, which is insufficient to understand local phenomena. In this paper, we present the SURPRISE project - recently funded in the frame of the H2020 programme – that gathers the expertise from eight partners across Europe to implement a demonstrator of a super-spectral EO payload - working in the visible (VIS) - Near Infrared (NIR) and in the Medium InfraRed (MIR) and conceived to operate from GEO platform -with enhanced performance in terms of at-ground spatial resolution, and featuring innovative on-board data processing and encryption functionalities. This goal will be achieved by using Compressive Sensing (CS) technology implemented via Spatial Light Modulators (SLM). SLM-based CS technology will be used to devise a super-resolution configuration that will be exploited to increase the at-ground spatial resolution of the payload, without increasing the number of detector’s sensing elements at the image plane. The CS approach will offer further advantages for handling large amounts of data, as is the case of superspectral payloads with wide spectral and spatial coverage. It will enable fast on-board processing of acquired data for information extraction, as well as native data encryption on top of native compression. SURPRISE develops two disruptive technologies: Compressive Sensing (CS) and Spatial Light Modulator (SLM). CS optimises data acquisition (e.g. reduced storage and transmission bandwidth requirements) and enables novel onboard processing and encryption functionalities. SLM here implements the CS paradigm and achieves a super-resolution architecture. SLM technology, at the core of the CS architecture, is addressed by: reworking and testing off-the-shelf parts in relevant environment; developing roadmap for a European SLM, micromirror array-type, with electronics suitable for space qualification. By introducing for the first time the concept of a payload with medium spatial resolution (few hundreds of meters) and near continuous revisit (hourly), SURPRISE can lead to a EO major breakthrough and complement existing operational services. CS will address the challenge of large data collection, whilst onboard processing will improve timeliness, shortening time needed to extract information from images and possibly generate alarms. Impact is relevant to industrial competitiveness, with potential for market penetration of the demonstrator and its components

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

Closed-loop magnetic bearing and angular velocity control of a reaction sphere actuator

This article presents the first closed-loop magnetic bearing and angular velocity experimental results of a reaction sphere actuator for satellite attitude control. The proposed reaction sphere is a permanent magnet spherical actuator whose rotor is supported by magnetic bearing and can be torqued electronically about any desired axis. The spherical actuator is composed of an 8-pole permanent magnet spherical rotor and of a 20-pole stator with electromagnets. The electromechanical model of the reaction sphere is summarized together with procedures to estimate the rotor magnetic state, the back-EMF voltage, and the rotor angular velocity, which are all fundamental ingredients for controller design. Dynamic controllers are developed to levitate the rotor inside the stator (magnetic bearing) and to control the rotor angular velocity. The magnetic bearing is based on a state-space controller with reduced-order displacement velocity estimator whereas the angular velocity controller is a simple proportional controller with a dedicated angular velocity estimator. The developed control algorithms are experimentally validated using the developed laboratory prototype showing the ability of simultaneously levitating the rotor while rotating it about a given arbitrary axis

Linear Parameter-Varying Kalman Filter for angular velocity estimation of a reaction sphere actuator for satellite attitude control

This paper presents a novel angular velocity estimation strategy of a Reaction Sphere (RS) for satellite attitude control based on a Linear Parameter-Varying (LPV) Kalman Filter. The reaction sphere is a permanent magnet synchronous spherical actuator whose rotor is magnetically levitated and can be accelerated about any desired axis. The spherical actuator is composed of an 8-pole permanent magnet spherical rotor and of a 20-coil stator. The proposed technique relies on the implementation of a Kalman Filter observer over a LPV state-space model based on the rotor dynamics and the spherical harmonic decomposition of the magnetic flux density generated by the rotor. First, a theoretical development of the aforementioned estimator will be exposed, followed by a description of simulation and experimental set-ups for the tests. Finally, the proposed estimator is compared with the previous method used for angular velocity estimation based on the estimation of the back-EMF voltages induced in the coils, obtaining a significant reduction in amplitude and frequency of oscillations in the angular velocity control loop

Novel Generalised Notch Filter for Harmonic Vibration Suppression in Magnetic Bearing Systems

Magnetic bearings represent an important alternative to conventional ball bearings for applications that require very low noise and vibrations. The absence of contact and friction between rotor and stator parts, combined with the use of active vibration control techniques result in rotating machinery that can greatly outperform their passive counterparts. One of the main disadvantages of these systems is the increased complexity of requiring the active control of the rotor, including sensors actuators and computing power. Furthermore, active vibration control techniques are generally difficult to implement over a broad speed range due to requirement of choosing and adapting different parameters to guarantee its stability. For this reason, this article presents a novel generalised notch filter for harmonic suppression control for magnetically-levitated rotors which features improved stability properties. The proposed harmonic or unbalance force rejection control (UFRC) is based on an unbalance and resonance suppression technique originally developed for piezoelectric active bearings for rotating machinery, and it is successfully adapted and its performance validated for machines featuring magnetic bearings. The formulation of the harmonic suppression control technique is introduced, its stability for magnetic bearing systems analysed, and experimentally implemented and tested on a fully active slotless Lorentz-type magnetic bearing motor obtaining a reduction of at least one order of magnitude in the level of generated vibrations

Efficiency Optimisation of Slotless Magnetic Bearing Machines

Efficiency is one of the key performance indexes in the design of electric motors. When considering fully active magnetic bearing machines, this aspect gain further relevance due to the necessity of actively controlling all the remaining degrees of freedom of the rotor in addition to its rotation. This article presents a strategy for efficiency maximisation of rotating machinery featuring slotless active magnetic bearings and motor. The efficiency optimisation maximises the motor and bearing constants, allowing the combined minimisation of losses and maximisation of the generated forces and torques. Due to the inherently complexity of active magnetic bearings, where multiple actuators are required for controlling different degrees of freedom of the rotor, a general optimisation procedure is proposed allowing a combined optimisation of several actuators. This approach is executed and validated using a 50-W and 20-krpm fully active magnetic bearing motor designed for space applications, resulting in a manufactured system featuring an efficiency increase between 33% and 58% with respect to the original machine

Force and Torque Model of Ironless Passive Magnetic Bearing Structures

This article presents the development and validation of a three-dimensional force and torque semi-analytical model for ironless permanent magnet structures. This method relies on the definition of the magnetic flux density generated by permanent magnets in terms of elliptic integrals, allowing a fast computation when compared with finite element methods (FEM). The approach is validated and shown for two ironless passive magnetic bearing configurations by studying the applied force, torque and stiffness when small displacements and tilting are present