ESA Document - Emits - ESA

s
Initial and final
conditions
Vehicle
characteristics
and environment
State vector measured
using sensors
Reference
trajectory
MEV MEV Model
Model
Thruster activation:
Number, duration,
and frequency
State vector
errors
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 346 of 422
Figure 4-86: MEV CDF Model
The parameters that can be optimised are the initial flight path angle, initial azimuth, initial flight
path velocity and the time duration for the entry. The purpose of the study is to select the
appropriate values of those parameters. This study is also concerned to establish not only the
3DoF optimal entry trajectory but also the corresponding 6DoF full closed loop controlled
trajectory.
4.4.5.2 Assumptions and trade-offs
4.4.5.2.1 MEV GNC design cyle
Figure 4-87 shows the design cycle of the GNC of the MEV:
Entry Entry corridor corridor design,
design,
Equipment Equipment design,
design,
Modes Modes design
design
Guidance Guidance law law generation
generation
Compute Compute optimal
optimal
3DoF 3DoF controlled
controlled
entry entry trajectory
trajectory
Boundary Boundary and
and
path path constraints
constraints
Vehicle Vehicle features
features
Mars Mars environment
environment
Control Control law law generation
generation
MonteCarlo MonteCarlo for
for
performance
performance
verification
verification
Figure 4-87: GNC design cycle
Compute Compute optimal
optimal
6DoF 6DoF controlled
controlled
entry entry trajectory
trajectory
Final Final 6DoF
6DoF
trajectory
trajectory
and and GNC GNC design
design