ESA GNC Conference Papers Repository
Real-time implementation of the hybrid camera-LiDAR hazard detection and avoidance software in space qualified hardware
The Hybrid Hazard Detection and Avoidance System (H2DAS) is a complete camera-LIDAR Hazard Detection and Avoidance (HDA) software that uses information from different sensors to perform hazard mapping and safe site selection thus enabling safe planetary and small body landings, anytime, anywhere. The software has been tested extensively, through Monte Carlo simulation campaigns, in the context of landing on Mars, Phobos and Moon south pole. Results demonstrated high probability of safe site selection (>99%). The capability of running H2DAS software in real-time is a key factor for safe landing, in particular on Mars, where landing dynamics are fast. This paper discusses the real-time implementation of the H2DAS in a space qualified hardware, which comprises a soft-core LEON2 and an RTAX-2000 FPGA. Focus is on the porting of H2DAS into real-time environment and on the CPU/FPGA code partitioning for runtime optimization. It addresses the modifications applied to the HDA methods to make them suitable for FPGA implementation, running in a stream wise fashion, exploiting a deep pipeline of data processing blocks, and hence achieving high throughput. H2DAS is ported into flight compatible hardware and tested via Processor-In-the-Loop (PIL) Monte Carlo campaigns. Monte Carlo simulations are run in 6 DOF for two mission scenarios: Mars Precision Lander Mission and Terrestrial Demonstration mission. The simulation tool includes all the relevant dynamics, kinematics, environment, sensors and actuators models. The GNC model features a guidance with re-targeting capability and a vision-based navigation function. The simulation tool interfaces with ESA's Planet and Asteroid Natural Scene Generation Utility (PANGU) for terrain sensors image simulation and interfaces with the space qualified hardware running the real-time H2DAS software through a spacewire connection. PIL test results demonstrate H2DAS real-time running capability with unchanged probability of performing safe site selection, enabling the execution of a flight test campaign on a terrestrial demonstration platform in 2017, with the objective of validating the H2DAS real-time performance against a natural landscape representative of a landing area on Mars surface. At the end of the flight test campaigns, the H2DAS system will have reached a TRL of 5-6.