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.

High-definition mapping of the atria using a novel multipolar mapping catheter in patients with complex adult congenital heart disease

Background The Advisor™ HD Grid Mapping Catheter (Abbott Technologies, Minneapolis, MN) has been recently introduced. Although the clinical use of HD Grid mapping catheter is well described in adults with no congenital heart disease, there is limited data on the feasibility of using the HD Grid multipolar catheter to create voltage and activation mapping in adults with congenital heart disease. The purpose of this study was to evaluate the safety and technical feasibility of using the Advisor™ HD Grid mapping catheter during the catheter ablation of atrial arrhythmias in adults with congenital heart disease. We included 6 consecutive adults with congenital heart disease suffering from atrial arrhythmias in our study. The HD Grid mapping catheter was used to perform voltage and activation mapping. Results Six patients with congenital heart diseases (d-TGA n = 1, Tricuspid atresia n = 1, atrioventricular defect repair n = 1, secundum atrial septal defect n = 1, double-inlet single-ventricle n = 1, Tetralogy of Fallot = 1); majority (84%) male, with the mean age was 35 ± 10 years included in our series. The mean ablation duration and the fluoroscopy time were 789 ± 433 and 502 ± 355 s, respectively. The mean radiation dose was 7.52 ± 9 milliGy/cm2. The HD Grid mapping catheter was used successfully for entire arrhythmia mapping in 5 out of 6 cases. During one procedure, HD Grid mapping catheter could not be used for the entire mapping due to suboptimal reach through baffle puncture. The acute success rate of ablation was 100% with no immediate complications. Conclusions The use of HD Grid mapping catheter is a safe and valuable adjunct to accurately create voltage and activation mapping in ACHD patients undergoing radiofrequency catheter ablation. However, a contact force-sensing ablation catheter should be considered in conjunction to supplement data acquisition in challenging anatomy and substrates.

Challenges and limitations of modelling historical spatial data on nature: 19th century flora and fauna of Peloponnese, Greece

The aim of the study is the consolidation of a methodology suitable for organizing, utilizing and visualizing information regarding species distribution provided as text in historical sources. The work of the French Scientific Expedition in 1829 in Peloponnese, Greece, was used as a case study. We propose a system organized in three geographical levels: for information referring to a certain locality the form of a grid is appropriate, otherwise polygons depicting historical administrative areas or the whole region of Peloponnese should be preferred. There are three important caveats to avoid. First, species presence referring to an administrative area or region does not equal with presence in every locality and should not be transferred to the level of grid mapping, respectively reference of presence in the region should not be transferred to the administrative units’ level. Second, historical sources refer to species names that often are no longer valid; this kind of data must be referred to currently valid species names. Third, absence of reference of species presence should not be misinterpreted as absence of the species.