Conception et intégration d'un capteur LIDAR 3D pour la navigation autonome des robots mobiles en terrain inconnu

Resume L’etude de la planete Mars suscite un interet grandissant au sein de la communaute scientifique. Etant donne la distance separant la Terre de cet astre, ainsi que l’environnement particulierement hostile y regnant, son exploration tire avantage de l’utilisation de robots mobiles (rovers). Les fenetres de communication peu nombreuses de meme que les delais importants justifient le deploiement d’intelligence artificielle sur ces plates-formes mobiles afin de maximiser leur autonomie. L’un des enjeux primordiaux est alors la capacite que possedent de tels robots de naviguer de facon autonome et donc de percevoir l’environnement au moyen de systemes de vision avances.Le projet de recherche dont il est question dans ce memoire s’articule autour de ce theme et est realise en collaboration avec l’Agence spatiale canadienne (ASC). L’objectif principal vise la conception d’un systeme de vision tridimensionnelle permettant a un robot mobile de naviguer de facon autonome. Il concerne plus particulierement la conception, l’integration et l’etude de CORIAS (COntinuous Range and Intensity Acquisition System), un systeme de vision utilisant la technologie lidar (LIght Detection And Ranging). Le systeme en question utilise comme capteur principal un lidar LMS111 de la compagnie SICK. L’appareil developpe au cours de cette recherche repond non seulement a l’objectif principal, mais il est egalement dote des caracteristiques suivantes : • La reproduction tridimensionnelle de l’environnement s’effectue dans un rayon maximum de 20 metres. • L’acquisition des donnees se fait a raison d’un debit maximal de 27 050 points par seconde. • Le temps requis pour balayer completement l’environnement avec des parametres d’operation typiques (une resolution de 0,25° en elevation et de 0,50° en azimut) est d’environ 29 secondes. • Le systeme peut transmettre les mesures d’intensite associees aux points acquis. • Les resolutions verticale (elevation) et horizontale (azimut) sont configurables et assez fines pour detecter des obstacles. • Le systeme presente un niveau raisonnable de protection face aux conditions environnementales hostiles (poussiere, pluie, neige, etc). ----------Abstract The study of Mars is of growing interest among the scientific community. Given the large distance between this planet and the Earth, as well as the hostile environment prevailing there, its exploration takes advantage of using rovers. The rare communication windows, along with the important delays occuring during communications, justify artificial intelligence deployment on these mobile platforms in order to maximize their autonomy. Hence, one of the crucial issues is the ability the rover has to autonomously navigate and thus, to properly detect its environment with the help of advanced vision systems. The research project discussed in this thesis focuses on this theme and is done in collaboration with the Canadian Space Agency (CSA). The main objective is to design a three-dimensional vision system enabling a mobile robot to navigate autonomously. It relates more particularly to the design, integration and study of CORIAS (COntinuous Range and Intensity Acquisition System), a vision system using lidar (LIght Detection And Ranging). The system uses a LMS111, manufactured by SICK, as its main sensor. The device developed in this research project not only meets the main objective, but it also has the following characteristics:• The three-dimensional reproduction of the environment is performed within a 20 meter radius. • The maximum data acquisition rate is 27 050 points per second. • The time required to complete a full-coverage scan performed with typical operation parameters (0,25° elevation and 0,50° azimuth resolutions) is around 29 seconds. • The system is able to transmit the intensity measurements associated with the acquired points. • Vertical (elevation) and horizontal (azimuth) resolutions are configurable and fine enough to detect obstacles. • The system has a reasonable level of protection against bad weather conditions (dust, rain, snow, etc.). CORIAS only requires a 24 volts DC power supply and an Ethernet link to be operated. It can be installed easily on a large variety of platforms. The rover’s on-board computer is responsible for communicating with the vision system and provides the commands it needs to accomplish. The microcontroller, which is the central part of the system, operates on Linux and acts as a TCP-IP server.