Learning Pose Estimation for UAV Autonomous Navigation and Landing Using Visual-Inertial Sensor Data

In this work, we propose a robust network-in-the-loop control system for autonomous navigation and landing of an Unmanned-Aerial-Vehicle (UAV). To estimate the UAV’s absolute pose, we develop a deep neural network (DNN) architecture for visual-inertial odometry, which provides a robust alternative to traditional methods. We first evaluate the accuracy of the estimation by comparing the prediction of our model to traditional visual-inertial approaches on the publicly available EuRoC MAV dataset. The results indicate a clear improvement in the accuracy of the pose estimation up to 25% over the baseline. Finally, we integrate the data-driven estimator in the closed-loop flight control system of Airsim, a simulator available as a plugin for Unreal Engine, and we provide simulation results for autonomous navigation and landing

A robust extended H-infinity filtering approach to multi-robot cooperative localization in dynamic indoor environments

Multi-robot cooperative localization serves as an essential task for a team of mobile robots to work within an unknown environment. Based on the real-time laser scanning data interaction, a robust approach is proposed to obtain optimal multi-robot relative observations using the Metric-based Iterative Closest Point (MbICP) algorithm, which makes it possible to utilize the surrounding environment information directly instead of placing a localization-mark on the robots. To meet the demand of dealing with the inherent non-linearities existing in the multi-robot kinematic models and the relative observations, a robust extended H∞ filtering (REHF) approach is developed for the multi-robot cooperative localization system, which could handle non-Gaussian process and measurement noises with respect to robot navigation in unknown dynamic scenes. Compared with the conventional multi-robot localization system using extended Kalman filtering (EKF) approach, the proposed filtering algorithm is capable of providing superior performance in a dynamic indoor environment with outlier disturbances. Both numerical experiments and experiments conducted for the Pioneer3-DX robots show that the proposed localization scheme is effective in improving both the accuracy and reliability of the performance within a complex environment.This work was supported inpart by the National Natural Science Foundation of China under grants 61075094, 61035005 and 61134009

Vision-Aided Inertial Navigation

This document discloses, among other things, a system and method for implementing an algorithm to determine pose, velocity, acceleration or other navigation information using feature tracking data. The algorithm has computational complexity that is linear with the number of features tracked

Crumbling of the masonry of ancient settlements on Santorini caused by the Hymenoptera Anthophora crinipes and Osmia latreillei

Ένα από τα σπουδαιότερα αρχαιολογικά ευρήματα της εποχής του Χαλκού στο Ακρωτήρι της Σαντορίνης έχει υποστεί ζημιές από δύο Hymenoptera, τα Anthophora crinipes και Osmia (Chalcosmia) latreillei. Τα έντομα αυτά εγκαθιστούν τις αποικίες τους ανοίγοντας στοές στους πλήθινους τοίχους των κτιρίων του οικισμού. Κατά την κατασκευή των στοών εξορύσσουν το υλικό  των τοίχων όταν δε τα έντομα εισέρχονται και εξέρχονται προκαλούν αποσάθρωση των τοιχωμάτων. Λεπτή θηραϊκή γη υπάρχει σε σωρούς κάτω από τις στοές. Η μορφή της προσβολής είναι εμφανής από τις πολυάριθμες οπές που υπάρχουν στους τοίχους. Η προκαλούμενη ζημιά από αυτά τα έντομα στο αρχαιολογικό μνημείο είναι πολύ επικίνδυνη για τη διατήρηση της μορφής του και εάν συνεχιστεί υπάρχει κίνδυνος παραμόρφωσης κατά θέσεις μερών της τοιχοποιίας.One of the most important archaeological findings of recent years has been the discovery of complete buildings of a Bronze Age settlement at Akrotiri on the island of Santorini (Thera). The settlement covers an area of over 200,000 square metres. The excavations conducted by Spyros Marinates brought to light a large number of buildings constructed of stones, mud and straw, with earth roofs. The walls were faced with clay. Almost every exposed mass of masonry in the settlement has been invaded by colonies of Hymenopterous insects consisting nests which are wreaking havoc on the walls, because they bore through the masonry to build their nests and then every time they go in and out of the tunnels, they wear away the dust of the walls which they have build for their own nests. Observations were carried out at Akrotiri in the spring and summer of 1985, 1986 and 1988. Glass collecting-tubes were placed at entry and exit points and at various places in the tunnels, to sellect the insects when the adults emerged in the spring, and insects also were collected with sweeping nets from the surrounding area and from light traps. Plants which were visited by adults of these species for pollen and nectar were also collected from round about. The insect species collected by these various methods were the following: Osmia (Chalcosinia) latredlei Spinola, 1806 (Hymenoptera: Megachilidae), Anthophora crinipes Smith, 1884 (Hymenoptera: Apidae), and Melecta albifrons albovaria Erichson 1840 ( Hymenoptera : Megachilidae). These three species were collected in all observation years in glass collectintubes. Of these A. crinipes and O. latreillei, which are solitary species, both build colonies with tunnels a short distance appart but not actually touching each other. The number of such colonies in the walls of the Akrotiri settlement is fairly large, and conspicuous through the holes of entrance and exit of the insects. M. albifrons albovaria is a predator on A. crinipes. It is known from the literature that all species of the genus Melecta prey on Anthophora species. The tunnels of both species are made by the females. At the end of each tunnel the female hollows out a number of cells and lays in supplies of pollen and nectar on which she deposits her eggs after mating. She then seals off each cell with a mixture of earth and saliva. Finally, when eggs have been deposited in all the cells, she closes the outer entrance of the tunnel. The larvae start developing once the tunnel has been sealed off. Thus after the hatching of the eggs, the insects spend more than thirty days as larvae, later on as prepupae. In this stage they overwinter and early in the spring enter the pupal stage. The first adults appeared from the last days of March. The females mate with the males and then start making tunnels and cells for their eggs. Adults of both sexes visit flowers to feed and also, in the case of the females, to collect pollen and nectar for the cells in which the larvae will develop. In the neighbourhood of Akrotiri we have observed adults of both species in question visiting flowers of the following species: Reichardia picroide(L.) Roth (Compositae), Echhon angustifolium Miller (Boraginaceae), Vicia vilosa Roth (Leguminosae), Euphorbia spp. (Euphorbiaceae), Salvia  verticillata L. (Labiatae),Rosinarinuin officinalis L. (Labiatae), Morina persica L. (Dipsacaceae). Fahringer reported only Anthophora crinipes in Asia Minor and observed that adults visited the flowers of Salvia verticillata and Morina persica, but it is not clear if the insects collect pollen or nectar or both of these plants. The adults usually choose sunny days to fly out to the flowers, and during their flight a caracteristic buzzing is heard. The flying season be­gins in late March and goes on until the end of June, or some time later. The damage done by these insects to the fabric of the ancient settlement at Akrotiri is posing a serious problem for the preservation of the ruins in their present form. If it continues there is danger that parts of the masonry will be permanently deformed. Little heaps of fine pozzolana dust made by the insects going in and out of the tunnels is found on the ground below the entrance holes. In the last two years the team of archeaeologists  has used light traps in and around the ruins, thereby apparently reducing the populations of these insects and limiting the damage done by them. On the basis of the insects collected in May 1988, the population of A. crinipes outnumbers that of O. larreillei (ratio 79:21)

Crumbling of the masonry of ancient settlements on Santorini caused by the Hymenoptera Anthophora crinipes and Osmia latreillei

Ένα από τα σπουδαιότερα αρχαιολογικά ευρήματα της εποχής του Χαλκού στο Ακρωτήρι της Σαντορίνης έχει υποστεί ζημιές από δύο Hymenoptera, τα Anthophora crinipes και Osmia (Chalcosmia) latreillei. Τα έντομα αυτά εγκαθιστούν τις αποικίες τους ανοίγοντας στοές στους πλήθινους τοίχους των κτιρίων του οικισμού. Κατά την κατασκευή των στοών εξορύσσουν το υλικό  των τοίχων όταν δε τα έντομα εισέρχονται και εξέρχονται προκαλούν αποσάθρωση των τοιχωμάτων. Λεπτή θηραϊκή γη υπάρχει σε σωρούς κάτω από τις στοές. Η μορφή της προσβολής είναι εμφανής από τις πολυάριθμες οπές που υπάρχουν στους τοίχους. Η προκαλούμενη ζημιά από αυτά τα έντομα στο αρχαιολογικό μνημείο είναι πολύ επικίνδυνη για τη διατήρηση της μορφής του και εάν συνεχιστεί υπάρχει κίνδυνος παραμόρφωσης κατά θέσεις μερών της τοιχοποιίας.One of the most important archaeological findings of recent years has been the discovery of complete buildings of a Bronze Age settlement at Akrotiri on the island of Santorini (Thera). The settlement covers an area of over 200,000 square metres. The excavations conducted by Spyros Marinates brought to light a large number of buildings constructed of stones, mud and straw, with earth roofs. The walls were faced with clay. Almost every exposed mass of masonry in the settlement has been invaded by colonies of Hymenopterous insects consisting nests which are wreaking havoc on the walls, because they bore through the masonry to build their nests and then every time they go in and out of the tunnels, they wear away the dust of the walls which they have build for their own nests. Observations were carried out at Akrotiri in the spring and summer of 1985, 1986 and 1988. Glass collecting-tubes were placed at entry and exit points and at various places in the tunnels, to sellect the insects when the adults emerged in the spring, and insects also were collected with sweeping nets from the surrounding area and from light traps. Plants which were visited by adults of these species for pollen and nectar were also collected from round about. The insect species collected by these various methods were the following: Osmia (Chalcosinia) latredlei Spinola, 1806 (Hymenoptera: Megachilidae), Anthophora crinipes Smith, 1884 (Hymenoptera: Apidae), and Melecta albifrons albovaria Erichson 1840 ( Hymenoptera : Megachilidae). These three species were collected in all observation years in glass collectintubes. Of these A. crinipes and O. latreillei, which are solitary species, both build colonies with tunnels a short distance appart but not actually touching each other. The number of such colonies in the walls of the Akrotiri settlement is fairly large, and conspicuous through the holes of entrance and exit of the insects. M. albifrons albovaria is a predator on A. crinipes. It is known from the literature that all species of the genus Melecta prey on Anthophora species. The tunnels of both species are made by the females. At the end of each tunnel the female hollows out a number of cells and lays in supplies of pollen and nectar on which she deposits her eggs after mating. She then seals off each cell with a mixture of earth and saliva. Finally, when eggs have been deposited in all the cells, she closes the outer entrance of the tunnel. The larvae start developing once the tunnel has been sealed off. Thus after the hatching of the eggs, the insects spend more than thirty days as larvae, later on as prepupae. In this stage they overwinter and early in the spring enter the pupal stage. The first adults appeared from the last days of March. The females mate with the males and then start making tunnels and cells for their eggs. Adults of both sexes visit flowers to feed and also, in the case of the females, to collect pollen and nectar for the cells in which the larvae will develop. In the neighbourhood of Akrotiri we have observed adults of both species in question visiting flowers of the following species: Reichardia picroide(L.) Roth (Compositae), Echhon angustifolium Miller (Boraginaceae), Vicia vilosa Roth (Leguminosae), Euphorbia spp. (Euphorbiaceae), Salvia  verticillata L. (Labiatae),Rosinarinuin officinalis L. (Labiatae), Morina persica L. (Dipsacaceae). Fahringer reported only Anthophora crinipes in Asia Minor and observed that adults visited the flowers of Salvia verticillata and Morina persica, but it is not clear if the insects collect pollen or nectar or both of these plants. The adults usually choose sunny days to fly out to the flowers, and during their flight a caracteristic buzzing is heard. The flying season be­gins in late March and goes on until the end of June, or some time later. The damage done by these insects to the fabric of the ancient settlement at Akrotiri is posing a serious problem for the preservation of the ruins in their present form. If it continues there is danger that parts of the masonry will be permanently deformed. Little heaps of fine pozzolana dust made by the insects going in and out of the tunnels is found on the ground below the entrance holes. In the last two years the team of archeaeologists  has used light traps in and around the ruins, thereby apparently reducing the populations of these insects and limiting the damage done by them. On the basis of the insects collected in May 1988, the population of A. crinipes outnumbers that of O. larreillei (ratio 79:21)

Loss of Ptpn11 (Shp2) drives satellite cells into quiescence

The equilibrium between proliferation and quiescence of myogenic progenitor and stem cells is tightly regulated to ensure appropriate skeletal muscle growth and repair. The non-receptor tyrosine phosphatase Ptpn11 (Shp2) is an important transducer of growth factor and cytokine signals. Here we combined complex genetic analyses, biochemical studies and pharmacological interference to demonstrate a central role of Ptpn11 in postnatal myogenesis of mice. Loss of Ptpn11 drove muscle stem cells out of the proliferative and into a resting state during muscle growth. This Ptpn11 function was observed in postnatal but not fetal myogenic stem cells. Furthermore, muscle repair was severely perturbed when Ptpn11 was ablated in stem cells due to a deficit in stem cell proliferation and survival. Our data demonstrate a molecular difference in the control of cell cycle withdrawal in fetal and postnatal myogenic stem cells, and assign to Ptpn11 signaling a key function in satellite cell activity