Vision-based rotational control of an agile observation satellite

International audienceRecent Earth observation satellites are now equipped with new instrument that allows image feedback in real-time. Problematic such as ground target tracking, moving or not, can now be addressed by precisely controlling the satellite attitude. In this paper, we propose to consider this problem using a visual servoing approach. While focusing on the target, the control scheme has also to take into account the satellite motion induced by its orbit, Earth rotational velocities, potential target own motion, but also rotational velocities and accelerations constraints of the system. We show the efficiency of our system using both simulation (considering real Earth image) and experiments on a robot that replicates actual high resolution satellite constraints

Visual servoing of an Earth observation satellite of the LION constellation

International audienceSatellites for observation missions, or imagery satellites, have increased drastically in number and performances since the beginning of the space age. Recent Earth observation satellites are now equipped with new instruments that allow image processing in real-time. Issues such as ground target tracking, moving or not, can now be addressed by controlling precisely the satellite attitude. The satellite "camera" can be used as an input sensor for real-time attitude control process. This can be addressed thanks to a closed loop control scheme that includes the image acquisition and image processing parts. Real-time attitude control using such sensors will then allow the tracking of static or moving ground targets. In this paper, we propose to consider this problem using a visual servoing (VS) approach. This work is thus focused on establishing a visual control law that allows to precisely control a low orbit Earth observation starer satellite attitude using images provided by its matrix sensor. The goal is to perform acquisition missions devoted to gaze on an object of interest that is visible in the image before the VS starts. The visual sensor is fixed to the satellite, and we have full control over its three rotational degrees of freedom subject to dynamic constraints, while the satellite is moving on an orbit that only influences its position (that is not controlled by our VS scheme). Compensating for the target motion in the image by explicitly embedding it in the control scheme becomes essential when it is significant. In our case, the satellite orbit is known, so we can determine accurately its translational motion, and compensate for it in the control law. When it comes to target motion, we propose to decompose it into a known displacement caused by Earth's dynamics and a residual motion due to its potential own motion. The contribution of this paper is a visual servoing scheme able to control the attitude of an agile Earth observation satellite for target tracking. Three visual features are selected for controlling the 3 attitude parameters, for achieving a centering task, and an orientation task. The control law allows for dealing with the satellite's high translational velocity induced by its orbit and other external motion including Earth's rotation and target own motion. A rate saturation algorithm is also proposed dealing with dynamic constraints. Simulations and experiments on an actual robot will be presented

Predictive computational phenotyping and biomarker discovery using reference-free genome comparisons

The antibiotic susceptibility data for the Clostridium difficile genomes. (XLSX 20.2 kb

Sensory stimulations potentializing digital therapeutics pain control

For the past two decades, using Digital Therapeutics (DTx) to counter painful symptoms has emerged as a novel pain relief strategy. Several studies report that DTx significantly diminish pain while compensating for the limitations of pharmacological analgesics (e.g., addiction, side effects). Virtual reality (VR) is a major component of the most effective DTx for pain reduction. Notably, various stimuli (e.g., auditory, visual) appear to be frequently associated with VR in DTx. This review aims to compare the hypoalgesic power of specific stimuli with or without a VR environment. First, this review will briefly describe VR technology and known elements related to its hypoalgesic effect. Second, it will non-exhaustively list various stimuli known to have a hypoalgesic effect on pain independent of the immersive environment. Finally, this review will focus on studies that investigate a possible potentialized effect on pain reduction of these stimuli in a VR environment

Identification of Susceptibility Pathways for the Role of Chromosome 15q25.1 in Modifying Lung Cancer Risk

Genome-wide association studies (GWAS) identified the chromosome 15q25.1 locus as a leading susceptibility region for lung cancer. However, the pathogenic pathways, through which susceptibility SNPs within chromosome 15q25.1 affects lung cancer risk, have not been explored. We analyzed three cohorts with GWAS data consisting 42,901 individuals and lung expression quantitative trait loci (eQTL) data on 409 individuals to identify and validate the underlying pathways and to investigate the combined effect of genes from the identified susceptibility pathways. The KEGG neuroactive ligand receptor interaction pathway, two Reactome pathways, and 22 Gene Ontology terms were identified and replicated to be significantly associated with lung cancer risk, with P values less than 0.05 and FDR less than 0.1. Functional annotation of eQTL analysis results showed that the neuroactive ligand receptor interaction pathway and gated channel activity were involved in lung cancer risk. These pathways provide important insights for the etiology of lung cancer