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

Chapter 2 / Target Modelling
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TGT_003.mtb
TGT_007.mtb
Figure 2-7 : Target Bearing
Accelerations provided by the user are treated as demands to be filtered so
as to obtain the reference target-state, thereby preventing unrealistic jumps
caused by changes in the elemental model characterisation. Eight elemental
motions are provided: stationary, independent accelerations in the
Alignment and Target Velocity frames, sinusoidal or “square” weaves,
accelerating PN track onto the Alignment axis origin with, or without,
superimposed weaves.
Square wave demanded acceleration profiles are important for assessing
performance against weaving targets as they represent the infinite spectral
case that is more representative of target motion than are sinusoidal weaves.
Idealised trajectories are provided for tuning the IMM. Weave and dog-leg
manoeuvres are provided for performance assessment as these are
notoriously difficult to track using fixed-gain and single filter formulations.
Three enhancements are proposed to the current target simulator:
• The initial phase of the weave models should be randomised as this can
significantly effect the miss distance attainable by low bandwidth guidance
laws.
• Target goal-orientated trajectories are currently constrained to the position
of the missile launcher. The facility would be greatly enhanced by
providing the target’s tracking point with PVA dynamics, starting from an
initial state defined in the Alignment frame.
• The last enhancement concerns intelligent targets. Given adequate
information a target could optimise its escape envelope on the basis of a 2player
pursuit-evasion game, Shinar [S.5&8] . Differential game theory
provides the direction the target must turn, and the time at which to stop the
turn, and fly in a direction maximising the probability of reaching a
perceived no-escape boundary. The target manoeuvre causes the missile to
turn and in doing so reduce speed as a tail-chase develops. Future targets