14.02.2013 Views

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

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

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

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Chapter 5 / Missile State Observer<br />

_ _<br />

RD<br />

H<br />

TL<br />

≡<br />

∂<br />

∂<br />

RD<br />

IMM<br />

Z<br />

X<br />

T<br />

TL<br />

: =<br />

⎛<br />

⎜<br />

⎝<br />

The range measurement Jacobian,<br />

∂ P<br />

XT<br />

t<br />

∂ X<br />

TL<br />

∂ P<br />

∂ X<br />

: =<br />

4-21<br />

XT<br />

t<br />

The target bearing measurement Jacobian,<br />

∂ Ψ<br />

T<br />

A<br />

TL<br />

⎛<br />

⎜<br />

⎝<br />

TL<br />

,<br />

∂ P&<br />

∂ X<br />

XT<br />

t<br />

TL<br />

,<br />

∂ Ψ<br />

∂ X<br />

T<br />

A<br />

TL<br />

A T<br />

T<br />

( P ) ⎞<br />

t Po,<br />

t , 06<br />

⎟<br />

⎠<br />

hA −2<br />

YA XA T<br />

( P ) ⋅ ( P , P , 0 )<br />

∂ X : =<br />

−<br />

The target elevation measurement Jacobian,<br />

∂ Θ<br />

T<br />

A<br />

∂ X<br />

TL<br />

: =<br />

⎛<br />

⎜ P<br />

⎜<br />

⎝ P<br />

XA<br />

t<br />

hA<br />

t<br />

t<br />

⋅ Pt<br />

⋅ P<br />

ZA<br />

2<br />

o,<br />

t<br />

The range-rate measurement Jacobian,<br />

∂ P&<br />

XT<br />

t<br />

∂ X<br />

TL<br />

: =<br />

⎛<br />

⎜<br />

⎜<br />

⎝<br />

,<br />

P<br />

t<br />

YA<br />

t<br />

hA<br />

t<br />

P<br />

⋅ P<br />

⋅ P<br />

ZA<br />

t<br />

2<br />

o,<br />

t<br />

,<br />

t<br />

Pt<br />

−<br />

P<br />

A T<br />

XT A T<br />

( P&<br />

t ) P&<br />

t ⋅ ( Pt<br />

) A<br />

−<br />

, ( P )<br />

o,<br />

t<br />

The measurement covariance,<br />

RD<br />

R : =<br />

T<br />

P<br />

diag<br />

P<br />

2<br />

o,<br />

t<br />

t<br />

hA<br />

2<br />

o,<br />

t<br />

T<br />

,<br />

∂ Θ<br />

∂ X<br />

T<br />

A<br />

TL<br />

⎞<br />

⎟<br />

⎠<br />

T<br />

Equation 4.6-3<br />

Equation 4.6-4<br />

7<br />

Equation 4.6-5<br />

,<br />

0<br />

T<br />

6<br />

⎞<br />

⎟<br />

⎟<br />

⎠<br />

Equation 4.6-6<br />

P<br />

o,<br />

t<br />

2 2<br />

2<br />

2<br />

( 10 , 4 , 0.<br />

003 , 0.<br />

003 )<br />

,<br />

0<br />

T<br />

3<br />

⎞<br />

⎟<br />

⎟<br />

⎠<br />

Equation 4.6-7<br />

Equation 4.6-8<br />

Frequency agility reduces any time dependent error correlation so each<br />

measurement can be considered as independent. Phased array radar<br />

generally maintain a near-constant SNR which means the measurement<br />

errors are independent of range and can be treated as constants rather than<br />

functions of the radar SNR.<br />

4.7 IMM Initialisation<br />

Assuming that target-tracking starts at long-range and is quiescent, the<br />

individual filter weights are biased towards the constant velocity filter,

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!