Speaker
Mr
Konstantinos Konstantinidis
(Universität der Bundeswehr München)
Description
The Institute for Space Technology and Space Applications (ISTA) of Bundeswehr University Munich is investigating mission concepts for the in-situ astrobiological exploration of the icy moons of the outer solar system. A concept studied in the context of the DLR funded Enceladus Explorer project (EnEx) aimed to place a lander near one of the plume sources on the bottom of a “tiger stripe” canyon on the south pole of Saturn’s moon Enceladus. Once there, the lander would deploy a melting probe to sample relatively shallow liquid water in the ice under the plume source. The lander would have to achieve a landing accuracy of 50 m and manage to land safely on an extremely challenging terrain interspersed with landing hazards like ice blocks, but also uncertain terrain like soft and unconsolidated snow or hard ice. To achieve this, a landing Guidance, Navigation, and Control (GN&C) system would be necessary to allow for autonomous landing operations. To achieve the required accuracy, terrain relative navigation can use sensors such as optical and thermal cameras, LIDAR, etc. to navigate relative to detected terrain features. To ensure a safe landing the system must be able to assess if the originally planned landing site is safe and if not, to then autonomously command a retargeting to another, safer spot. The guidance and control function must then calculate a viable trajectory and thrust arc to the newly chosen landing site.
To validate that the landing satisfies the accuracy and reliability requirements we are developing a tool in Matlab/Simulink to simulate the operation of the autonomous landing GN&C system.
In this paper we present a first version of this tool, used to simulate the final phase of landing operations as described above. It comprises the following parts:
• Terrain simulation block: Generates a simple terrain model based on a given Digital Elevation Model (DEM) file. The topology can be modified using fractal algorithms and arbitrary simple shapes can be added to represent hazards. Terrain texture is also simulated.
• Simultaneous Localization and Mapping (SLAM) block: Simulates Terrain Relative Navigation (TRN)/feature matching, whereby features are extracted from the simulated terrain and a SLAM approach is followed for accurate navigation.
• Hazard Detection and Avoidance (HDA) block: Creates fused hazard maps from the output of camera and LIDAR sensors based on the simulated interaction of these sensors with the terrain. A fuzzy logic approach is used to evaluate landing safety and command a retargeting if necessary.
• Guidance and control block: Implements E-guidance and D’Souza guidance algorithms to generate a thrust arc and trajectory to a new landing spot if commanded by HDA.
Using this tool we will attempt to show the feasibility of an adequately accurate and safe landing near a plume source on the bottom of a tiger stripe canyon on the south pole of Enceladus.
| Applicant type | First author |
|---|
Primary author
Mr
Konstantinos Konstantinidis
(Universität der Bundeswehr München)
Co-authors
Mr
Julian Adler
(Bundeswehr University)
Mr
Manuel Thies
(Bundeswehr University)
Mr
Martin Rudolph
(Bundeswehr University)
Mr
Robert Jacob
(Bundeswehr University)
Prof.
Roger Förstner
(Bundeswehr University)
