Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

Chapter 6 / Missile Guidance
_ _
Augmented CLOS laws are obtained by setting GU_DM_CP as follows,
• Gravitational compensation Bit 0
• Linear target trajectory compensation Bit 10
• Missile longitudinal acceleration compensation Bit 11
• Missile body to target beam compensation Bit 12
MS_AUTOPILOT controls the activation of different missile autopilots
contained in modules AP_0, AP_1 etc. mapped to MS_TYPE. Setting bits in
GU_AP_ER activates the following errors and processes that act on the
guidance demand independently, or combined in the order listed:
• Guidance/Autopilot/Fin - lumped time delay Bit 1
• Low speed lateral acceleration demand limiting Bit 2
• General lateral acceleration demand limiting Bit 3
• Lateral acceleration demand noise filtering Bit 4
• Lateral acceleration aerodynamic filtering Bit 5
It is essential for CLOS stability that bit 4 is set so that the lateral
acceleration demands pass through the noise filter described in §. For all
guidance laws the low speed demand limiting bit 2 and bit 3 must be set. It
is also advisable when using the generic missile model that bit 5 is set to
smooth the accelerations used to determine the flight-path and body rates.
6.9 Launcher Dynamics
Only for ground launched missile systems is the concept of a trainable
launcher still relevant, as modern ships have universally adopted the vertical
launch concept. Prior to launch MS_LAUNCHER shown in Figure 6-11
constrains missile rotation to that of the launcher driven by demands from
one of the following sources:
• Reference target position
D B
E A : = ( π
T
ΘA
T
ΨA
)
• Ground radar measurement
D B
EA : = ( π
~ T
ΘA
~ T
ΨA
)
• Ground HMS measurement
D B
E A : = ( π
~ H
ΘA
~ H
ΨA
)
• Target observer (IMM tracking)
D B
E : = ( π ˆ T
Θ ˆ T
Ψ )
The target reference position is used by default if the radar, HMS and target
observer have been de-activated. If the target state observer is active it has
priority, followed by the radar in order of precedence. The launcher
dynamics are modelled using a 2 nd order lag with a damping ratio (ζL) of
0.7, and a natural frequency (ωL) of 3 Hz. Using reference data,
6-33
A
IMM
A
IMM
A