Design and Performance Assessment of Hazard Avoidance Techniques For Vision Based Landing
- Paper number
IAC-06-A3.P.2.01
- Author
Mr. Emanuele Di Sotto, DEIMOS Engenharia, Portugal
- Coauthor
Mr. Francisco Câmara, DEIMOS Engenharia, Portugal
- Coauthor
Mrs. Paola Rogata, DEIMOS Engenharia, Portugal
- Coauthor
Mr. Augusto Caramagno, DEIMOS Space, Spain
- Coauthor
Prof. José Manuel Rebordão, Portugal
- Coauthor
Mr. Salvatore Mancuso, European Space Agency/Headquarters, France
- Year
2006
- Abstract
Hazard Avoidance is a key technology for a safe landing of future planetary landing missions. The hazard avoidance function makes use of sensors and computers onboard the lander to detect hazards in the landing zone, autonomously select the most suitable region for landing, and generate the trajectory that retargets the lander to a safer landing site A HA system is responsible for the detection of any hazards that put in risk the landing mission and path-planning to avoid the identified hazards. Hazard detection implies the lander to be equipped with a proper sensing device. In the frame of this study, an optical sensor, onboard camera, is used to detect hazards (e.g. craters, rocks, boulders, high slopes, etc.) in the landing zone. In the presented work algorithms are described for vision-based hazard detection, safe site selection and powered landing guidance designed for landing in planets without atmosphere. The algorithms are validated in a realistic simulated scenario representing a landing on Mercury. The simulation environment includes an image generation module that provides realistic landing scenarios through the generation of an artificial surface representative of the cratered planet. Craters distribution, boulders and terrain roughness can be set to generate different risk levels in the landing area. An image processing function is also implemented being in charge of resolving both: the terrain slope and roughness using “shape from shading” algorithms. These algorithms allow deriving a first mapping of the hazard extracting from the image three basic data set: shadow, texture and slope. This preliminary risk map is modified through the piloting function that, on real-time, is responsible for evaluating if the current landing site is considered unsafe and, whenever this happens, to provide a new safe LS. Piloting function selects a LS that is, not only ‘safer’ but also reachable. This attainability is addressed considering system requirements and mission constraints such as: available on-board propellant, landing site visibility, propulsion system limitations and guidance algorithms restrictions. Finally a terminal point guidance system, based on the E-Guidance, is also implemented to steer the lander towards the landing site by the piloting module. Several scenarios have been simulated and the obtained results show a very effective and robust behaviour of the proposed Hazard Avoidance function. The overall retargeting capability, towards a new landing site safer than the nominal one, has been validated with respect to the a-priori known topography. The work presented in this paper was done under the ESA/ESTEC contract for the study of Vision Based Relative Navigation Techniques Framework (VBRNAV).
- Abstract document
- Manuscript document
IAC-06-A3.P.2.01.pdf (🔒 authorized access only).
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