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

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Chapter 6 / Missile Guidance
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Chapter 6
MISSILE GUIDANCE
Although the focus of this research is on real-time trajectory optimisation,
optimal guidance is rooted in the historical development of conventional PN
and CLOS laws. There are good reasons for considering these, not the least
being:
• Missile dynamic model verification is easier using a conventional guidance
law as the resulting missile trajectory characteristics are well established.
• Guidance laws derived analytically using simple PI provide a baseline
against which real-time optimisation algorithms can be verified. If viable
on-line optimisation must provide a basic performance that is better than
these simple, but robust, alternatives.
• Target tracking limitations, and performance improvement based on
manoeuvre detection linked to IMM mode probability are more easily
demonstrated and understood using simpler guidance laws.
The missile simulator with embedded trajectory optimiser is introduced.
The dynamics of a short-range, agile missile and launcher are developed,
dynamics generated by 2 nd order STT and BTT autopilots with speed
dependent acceleration limits for low speed stability.
A historical review is provided of PN laws and the introduction of optimally
derived laws including essential practical constraints for target capture.
Missile and target acceleration augmented PN laws are derived and the
critical part time-to-go plays in optimal guidance, and observer constraints
imposed by inertial stabilisation seekers emphasised.
The basics of CLOS guidance are established and extended to include
biasing associated with phased array beam forming. The accuracy required
for IMM weave frequency estimation is quantified using linear analysis and
steady-state weave tuned filters.
The importance of manoeuvre detection in conventional guidance laws is
discussed and its links to the IMM modal probability associated with the
constant velocity target-tracking filter introduced in §4.
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