Evaluation of 3D CNN Semantic Mapping for Rover Navigation

Terrain assessment is a key aspect for autonomous exploration rovers, surrounding environment recognition is required for multiple purposes, such as optimal trajectory planning and autonomous target identification. In this work we present a technique to generate accurate three-dimensional semantic maps for Martian environment. The algorithm uses as input a stereo image acquired by a camera mounted on a rover. Firstly, images are labeled with DeepLabv3+, which is an encoder-decoder Convolutional Neural Networl (CNN). Then, the labels obtained by the semantic segmentation are combined to stereo depth-maps in a Voxel representation. We evaluate our approach on the ESA Katwijk Beach Planetary Rover Dataset.Comment: To be presented at the 7th IEEE International Workshop on Metrology for Aerospace (MetroAerospace

Metrological characterization of a vision-based system for relative pose measurements with fiducial marker mapping for spacecrafts

An improved approach for the measurement of the relative pose between a target and a chaser spacecraft is presented. The selected method is based on a single camera, which can be mounted on the chaser, and a plurality of fiducial markers, which can be mounted on the external surface of the target. The measurement procedure comprises of a closed-form solution of the Perspective from n Points (PnP) problem, a RANdom SAmple Consensus (RANSAC) procedure, a non-linear local optimization and a global Bundle Adjustment refinement of the marker map and relative poses. A metrological characterization of the measurement system is performed using an experimental set-up that can impose rotations combined with a linear translation and can measure them. The rotation and position measurement errors are calculated with reference instrumentations and their uncertainties are evaluated by the Monte Carlo method. The experimental laboratory tests highlight the significant improvements provided by the Bundle Adjustment refinement. Moreover, a set of possible influencing physical parameters are defined and their correlations with the rotation and position errors and uncertainties are analyzed. Using both numerical quantitative correlation coefficients and qualitative graphical representations, the most significant parameters for the final measurement errors and uncertainties are determined. The obtained results give clear indications and advice for the design of future measurement systems and for the selection of the marker positioning on a satellite surface

Simulation Framework for Mobile Robots in Planetary-Like Environments

In this paper we present a simulation framework for the evaluation of the navigation and localization metrological performances of a robotic platform. The simulator, based on ROS (Robot Operating System) Gazebo, is targeted to a planetary-like research vehicle which allows to test various perception and navigation approaches for specific environment conditions. The possibility of simulating arbitrary sensor setups comprising cameras, LiDARs (Light Detection and Ranging) and IMUs makes Gazebo an excellent resource for rapid prototyping. In this work we evaluate a variety of open-source visual and LiDAR SLAM (Simultaneous Localization and Mapping) algorithms in a simulated Martian environment. Datasets are captured by driving the rover and recording sensors outputs as well as the ground truth for a precise performance evaluation.Comment: To be presented at the 7th IEEE International Workshop on Metrology for Aerospace (MetroAerospace

Uncertainty analysis of image features for vision applications in space

A detailed uncertainty analysis for the position of image features is described. Three main uncertainty sources are identified and evaluated: image noise, lighting direction and image resolution. Since the proposed method does not need to acquire multiple images of the same scene in the same shooting conditions, it is particularly suited for applications with a relative motion between the camera and the scene and/or between the lighting source and the scene. The described method is applied to the images acquired during the recent asteroid Lutetia fly-by using the Narrow Angle Camera of the OSIRIS instrument. OSIRIS is a payload of the Rosetta ESA space mission. The obtained numerical results, including histograms and standard uncertainties, are depicted and discussed

Occupancy grid mapping for rover navigation based on semantic segmentation

Obstacle mapping is a fundamental building block of the autonomous navigation pipeline of many robotic platforms such as planetary rovers. Nowadays, occupancy grid mapping is a widely used tool for obstacle perception. It foreseen the representation of the environment in evenly spaced cells, whose posterior probability of being occupied is updated based on range sensors measurement. In more classic approaches, the cells are updated to occupied at the point where the ray emitted by the range sensor encounters an obstacle, such as a wall. The main limitation of this kind of methods is that they are not able to identify planar obstacles, such as slippery, sandy, or rocky soils. In this work, we use the measurements of a stereo camera combined with a pixel labeling technique based on Convolution Neural Networks to identify the presence of rocky obstacles in planetary environment. Once identified, the obstacles are converted into a scan-like model. The estimation of the relative pose between successive frames is carried out using ORB-SLAM algorithm. The final step consists of updating the occupancy grid map using the Bayes' update Rule. To evaluate the metrological performances of the proposed method images from the Martian analogous dataset, the ESA Katwijk Beach Planetary Rover Dataset have been used. The evaluation has been performed by comparing the generated occupancy map with a manually segmented ortomosaic map, obtained by drones' survey of the area used as reference

EXPERIMENTAL VALIDATION OF A DEPLOYMENT MECHANISM FOR TAPE-TETHERED SATELLITES

The number of space debris orbiting our Earth has been continuously increasing since the beginning of the space era. The space community is converging on responsible conducts and self-regulations to address this serious problem that is degrading the near-Earth environment. In this context, green deorbiting technologies and strategies alternative to the traditional chemical propulsion are under investigation, including Electrodynamic Tethers (EDTs) because they are a promising option. To increase EDT technology maturity level, some critical points shall be addressed and experimentally evaluated, including the deployment of tape tethers, to demonstrate their reliability. This paper presents results of an experimental validation of the Deployment Mechanism (DM) proposed for the H2020 FET OPEN Project E.T.PACK \u2013 Electrodynamic Tether Technology for Passive Consumable-less Deorbit Kit. We developed a mockup that hosts the DM and other elements that are on board the tip mass of a tethered system, using off-the-shelf components. The DM is tested for the first part of the tether deployment maneuver employing the SPARTANS facility of the University of Padova. This facility includes a Testing Table where the mock-up can move with almost no friction and a Motion Capture system that provides an accurate estimation of the mock-up motion during this first part of the tether deployment maneuver

Investigation on the use of fused deposition modeling for the production of IR dosage forms containing Timapiprant

: The present work focused on evaluating the feasibility of fused deposition modeling (FDM) in the development of a dosage form containing Timapiprant (TMP), also known as CHF6532, which is a novel active molecule indicated in the potential treatment of eosinophilic asthma upon oral administration. The resulting product could be an alternative, with potential towards personalization, of immediate release (IR) tablets used in the clinical studies. Formulations based on different polymeric carriers were screened, leading to the identification of a polyvinyl alcohol-based one, which turned out acceptable for versatility in terms of active ingredient content, printability and dissolution performance (i.e. capability to meet the dissolution specification set, envisaging >80% of the drug dissolved within 30 min). Following an in-depth evaluation on the influence of TMP solid state and of the voids volume resulting from printing on dissolution, few prototypes with shapes especially devised for therapy customization were successfully printed and were compliant with the dissolution specification set

Subclassification of the “Grey Zone” of Thyroid Cytology; A Retrospective Descriptive Study with Clinical, Cytological, and Histological Correlation

Undetermined thyroid cytology precludes any definitive distinction between malignant and benign lesions. Recently several classifications have been proposed to split this category into two or more cytological subcategories related to different malignancy risk rates. The current study was performed retrospectively to investigate the results obtained separating “undetermined” cytologic reports into two categories: “follicular lesion” (FL) and “atypia of undetermined significance” (AUS). Biochemical, clinical, and echographic features of each category were also retrospectively analyzed. Altogether, 316 undetermined fine-needle aspirated cytologies (FNACs) were reclassified as 74 FL and 242 AUS. Histological control leads to a diagnosis of carcinomas, adenomas, and nonneoplastic lesions, respectively, in 42.2%, 20%, and 37.8% of AUS and in 8.3%, 69.4%, and 22.2% of FL. Among biochemical, clinical, cytological, and echographic outcomes, altered thyroid autoantibodies, multiple versus single nodule, AUS versus FL, and presence of intranodular vascular flow were statistically significant to differentiate adenoma from carcinoma and from nonneoplastic lesions, whereas no significant differences were found between carcinomas and nonneoplastic lesions for these parameters. The results of this retrospective study show that undetermined FNAC category can further be subclassified in AUS and FL, the former showing higher malignancy rate. Further prospective studies are needed to confirm our results

Biocompatibility of a Conjugated Polymer Retinal Prosthesis in the Domestic Pig

The progressive degeneration of retinal photoreceptors is one of the most significant causes of blindness in humans. Conjugated polymers represent an attractive solution to the field of retinal prostheses, and a multi-layer fully organic prosthesis implanted subretinally in dystrophic Royal College of Surgeons (RCS) rats was able to rescue visual functions. As a step toward human translation, we report here the fabrication and in vivo testing of a similar device engineered to adapt to the human-like size of the eye of the domestic pig, an excellent animal paradigm to test therapeutic strategies for photoreceptors degeneration. The active conjugated polymers were layered onto two distinct passive substrates, namely electro-spun silk fibroin (ESF) and polyethylene terephthalate (PET). Naive pigs were implanted subretinally with the active device in one eye, while the contralateral eye was sham implanted with substrate only. Retinal morphology and functionality were assessed before and after surgery by means of in vivo optical coherence tomography and full-field electroretinogram (ff-ERG) analysis. After the sacrifice, the retina morphology and inflammatory markers were analyzed by immunohistochemistry of the excised retinas. Surprisingly, ESF-based prostheses caused a proliferative vitreoretinopathy with disappearance of the ff-ERG b-wave in the implanted eyes. In contrast, PET-based active devices did not evoke significant inflammatory responses. As expected, the subretinal implantation of both PET only and the PET-based prosthesis locally decreased the thickness of the outer nuclear layer due to local photoreceptor loss. However, while the implantation of the PET only substrate decreased the ff-ERG b-wave amplitude with respect to the pre-implant ERG, the eyes implanted with the active device fully preserved the ERG responses, indicating an active compensation of the surgery-induced photoreceptor loss. Our findings highlight the possibility of developing a new generation of conjugated polymer/PET-based prosthetic devices that are highly biocompatible and potentially suitable for subretinal implantation in patients suffering from degenerative blindnes

In-lab characterization of HYPSOS, a novel stereo hyperspectral observing system: first results

HYPSOS (HYPerspectral Stereo Observing System, patented) is a novel remote sensing instrument able to extract the spectral information from the two channels of a pushbroom stereo camera; thus it simultaneously provides 4D information, spatial and spectral, of the observed features. HYPSOS has been designed to be a compact instrument, compatible with small satellite applications, to be suitable both for planetary exploration as well for terrestrial environmental monitoring. An instrument with such global capabilities, both in terms of scientific return and needed resources, is optimal for fully characterizing the observed surface of investigation. HYPSOS optical design couples a pair of folding mirrors to a modified three mirror anastigmat telescope for collecting the light beams from the optical paths of the two stereo channels; then, on the telescope focal plane, there is the entrance slit of an imaging spectrograph, which selects and disperses the light from the two stereo channels on a bidimensional detector. With this optical design, the two stereo channels share the large majority of the optical elements: this allowed to realize a very compact instrument, which needs much less resources than an equivalent system composed by a stereo camera and a spectrometer. To check HYPSOS actual performance, we realized an instrument prototype to be operated in a laboratory environment. The laboratory setup is representative of a possible flight configuration: the light diffused by a surface target is collimated on the HYPSOS channel entrance apertures, and the target is moved with respect to the instrument to reproduce the in- flight pushbroom acquisition mode. Here we describe HYPSOS and the ground support equipment used to characterize the instrument, and show the preliminary results of the instrument alignment activities