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

Chapter 10 / Conclusions
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10.7 Missile Guidance
The missile simulator constructs guidance commands from basic TPN, PPN
and CLOS, introducing augmentations on requested. The infrastructure,
targets and missile model were verified using augmented TPN and CLOS
guidance against a crossing and a weaving target (Targets 3 and 7). Against
crossing targets the optimal PN gain was 2.5-3 minimising the miss distance
and effort, as expected. For weaving targets, bandwidth reduction according
to IMM filter probabilities is proposed providing that the IMM can
accurately discriminate between weaves and other types of target motion.
10.8 Trajectory Optimisation
Trajectory optimisation is performed in pseudo real-time for examining the
effect of limited processing on convergence from an initial trajectory, and in
response to changing boundary conditions. Pre-launch, a PN trajectory is
updated until the target is reachable. The optimiser then updates a fixed
number of controls from the initial state passing optimum pointing angles to
the launcher. In-flight, a dwindling number of controls are re-optimised,
scaled to accommodate the varying impact time, and split when the
processing load halves.
The optimisation algorithm uses Steepest Descent and an Armijo line search
to minimise the Hamiltonian formed by adjoining dynamic equality and
inequality constraints to the cost function. Control limits are applied using
an active set strategy. As cost reduction slows, conjugate directions are
explored at intervals using a Fibonacci line search.
10.9 Future Research
Although a great deal has been accomplished, the scale of the research is
ambitious and a considerable amount of simulation code verification and
system proving remains. The near-term evolution of this work is presented
in §11.
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