Laufzeit: 12/2004 - 08/2005
Mitarbeiter: Dr.-Ing. V. Tchernkyh, Dipl.-Ing. M. Beck
Wissenschaftl. Zusammenarbeit: Astrium SAS, Toulouse
- The feasibility of proposed concept of visual navigation system for planetary lander has been proved in open-loop simulation experiment, considering the Mercury landing scenario as a reference mission. During simulated Visual Guidance Phase, RMS error of position determination has been determined to be within 1% of distance to landing site; RMS attitude error ? about 0.5 degrees and RMS velocity error ? about 1%. Obtained accuracy can be further improved by appropriate filtering of navigation data The effect of the resolution of the reference 3D model of landing site on the accuracy of the obtained navigation data has been investigated. Standard deviation of position error, caused by insufficient resolution of the reference model, has been found to be within one half of the sampling distance of the model.
- The effect of the errors of rough estimation of position/attitude/velocity prior to the start of visual navigation phase on the navigation data accuracy has been investigated. A good estimation convergence has been obtained, when the initial estimation errors were within the following limits:
position estimation error ? 22% of the initial distance to landing site; attitude estimation error ? 14 degrees;
velocity estimation error ? 45% of initial velocity
In this case the effect of initial errors was practically compensated after 3 to 4 measurements.