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

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Chapter 6 / Missile Guidance<br />

_ _<br />

M<br />

B<br />

A<br />

: = M<br />

B<br />

v<br />

+ M<br />

B<br />

ω<br />

+ M<br />

B<br />

δ<br />

: =<br />

⎛<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎝<br />

m<br />

n<br />

6-40<br />

w<br />

v<br />

0<br />

⋅ P&<br />

⋅ P&<br />

ZB<br />

o,<br />

m<br />

YB<br />

o,<br />

m<br />

⎞ ⎛ l<br />

⎜ p ⋅ ω<br />

⎟<br />

⎟ ⎜<br />

⎟ ⎜<br />

+<br />

⎟ ⎜ mq<br />

⋅ ω<br />

⎟ ⎜<br />

⎟ ⎜<br />

⎠ ⎝ n r ⋅ ω<br />

XB<br />

A,<br />

B<br />

YB<br />

A,<br />

B<br />

ZB<br />

A,<br />

B<br />

⎞<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

+<br />

⎟<br />

⎟<br />

⎠<br />

⎛<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎝<br />

l<br />

m<br />

n<br />

ξ<br />

η<br />

ζ<br />

⋅ ξ<br />

⋅ η<br />

⋅ ζ<br />

⎞<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎠<br />

Equation 6.10-25<br />

The control surface deflections are dealt with in §3.11. For an agile missile<br />

the derivatives are functions of Mach number, height and lateral<br />

acceleration. The generic missile rotational dynamics are simpler and are<br />

determined by the speed and incidence dependent incidence lag (TI) where,<br />

For BTT missiles,<br />

YB ZB<br />

( T , T ) : = ( − 1 y , 1 z )<br />

I<br />

ω<br />

YR<br />

A,<br />

B<br />

I<br />

: =<br />

−<br />

ZR<br />

ZB Po,<br />

m<br />

( 1 + TI<br />

⋅ s ) ⋅ XB<br />

v<br />

&<br />

P&<br />

o,<br />

m<br />

w<br />

Equation 6.10-26<br />

Equation 6.10-27<br />

The angular acceleration is determined by differentiating smooth angular<br />

rates. The missile orientation quaternion is propagated using the 1 st order<br />

derivatives followed by normalisation. For STT missiles,<br />

P&<br />

YB ZB<br />

( ω , ω )<br />

ZB ZB<br />

YB YB<br />

( − ( 1 + T ⋅ s ) ⋅ &P<br />

& , ( 1 + T ⋅ s ) ⋅ &P<br />

& )<br />

I<br />

XB<br />

o,<br />

m<br />

⋅<br />

A,<br />

B<br />

o,<br />

m<br />

A,<br />

B<br />

I<br />

: =<br />

o,<br />

m<br />

Equation 6.10-28<br />

Jerk is also obtained by differences at 4 kHz. The incidence lag for both<br />

types of missile control depends on Mach number limited to [1,3] and body<br />

incidence limited to ± 40°,<br />

⎛<br />

⎜<br />

⎝<br />

T<br />

1<br />

YB<br />

I<br />

,<br />

T<br />

1<br />

ZB<br />

I<br />

⎞<br />

⎟<br />

⎠<br />

: =<br />

ϕ<br />

1<br />

⋅<br />

S<br />

( ϕ , ϕ ) : =<br />

⋅ ( ϕ , ϕ )<br />

2<br />

3<br />

5969 ⋅<br />

P<br />

S<br />

T<br />

2<br />

Equation 6.10-29<br />

3

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