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

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Chapter 6 / Missile Guidance<br />

_ _<br />

η<br />

FF<br />

: = 2 ⋅ η ⋅ µ<br />

6-29<br />

FF<br />

UL<br />

1<br />

1<br />

0<br />

Equation 6.6-20<br />

Inherent in this expression is the assumption that a probability of 0.5 means<br />

a particular tracking mode is dominant, an assumption that needs<br />

exploration even though it is often encountered in literature.<br />

6.6.7 Command Off LOS Feed Forward Demands<br />

When using electro-optical target tracking sensors it is better if the missile<br />

plume does not obscure the target. To force the missile to fly a constant<br />

distance off the target LOS the guidance demands are augmented by,<br />

−<br />

−<br />

COLOS<br />

COLOS<br />

P<br />

COLOS<br />

P<br />

YT<br />

m<br />

YT<br />

m<br />

⋅<br />

⋅ Ψ&<br />

&<br />

α<br />

T<br />

( ) T<br />

YT<br />

ZT<br />

− A , A<br />

: =<br />

−<br />

COLOS<br />

m<br />

COLOS<br />

m<br />

Equation 6.6-21<br />

T 2<br />

ZT T T T T<br />

( Ψ&<br />

) + P ⋅ ( Ψ&<br />

& + 2 ⋅ Ψ&<br />

⋅ Θ&<br />

⋅ cos Θ )<br />

T<br />

A<br />

I<br />

⋅ sin Θ<br />

T<br />

A<br />

−<br />

COLOS<br />

COLOS<br />

COLOS<br />

COLOS<br />

A<br />

m<br />

A<br />

P<br />

YT<br />

m<br />

ZT<br />

m<br />

ZT<br />

m<br />

⋅<br />

: =<br />

: =<br />

A<br />

A<br />

A<br />

A<br />

Equation 6.6-22<br />

T 2 T 2 2 T<br />

( Θ&<br />

) − ( Ψ&<br />

) ⋅ sin Θ<br />

A<br />

A<br />

A<br />

Equation 6.6-23<br />

If the missile seeker acquires the target in-flight the hand-over from midcourse<br />

CLOS guidance to terminal guidance needs to be smooth. This<br />

might be implemented by computing a PN demand from missile referenced<br />

CLOS parameters derived from ground radar and IMU measurements.<br />

Alternatively the COLOS off-boresight distance can be computed so that the<br />

CLOS and PN demands are the same, a topic that is outside the scope of this<br />

research.<br />

6.6.8 Missile Longitudinal Acceleration Compensation Demand<br />

CLOS demands assume that the uncontrolled longitudinal acceleration of<br />

the missile lies along the target LOS. This is rarely the case, and the<br />

following CLOS demand compensation is required,<br />

α<br />

T<br />

AXB<br />

≡<br />

( ) T<br />

YT<br />

ZT<br />

A , A<br />

AXB<br />

m<br />

AXB<br />

m<br />

Equation 6.6-24

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