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

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Appendix I / Utilities / Digital Filters<br />

_ _<br />

χ<br />

k<br />

: =<br />

χ<br />

k − 1<br />

χ<br />

0<br />

⎛ X<br />

+<br />

⎜<br />

⎝<br />

22.8-3<br />

I<br />

− 1<br />

( k −1<br />

)<br />

− 2 ⋅ χ<br />

∆t<br />

+ 2 ⋅ t<br />

−1<br />

D<br />

: = χ : = 2 ⋅ X<br />

( t t ) ⋅ X ( k −1<br />

) − ( t t )<br />

k −1<br />

I<br />

⎞<br />

⎟ ⋅ ∆t<br />

⎠<br />

Equation 22.8-13<br />

Equation 22.8-14<br />

( −1<br />

) ⋅ ( χ + χ )<br />

yk : = N D I<br />

N D<br />

k k −1<br />

Equation 22.8-15<br />

If (I := 1), and on first use, the filter is re-initialised without integration<br />

using input (XI). Each filter is identified by a unique number (N).<br />

22.8.4 Digital Integration Filters<br />

D_INTEG propagates up to 50 digital integrators over time interval (∆t),<br />

with a time varying gain, starting from an initial state (X0).<br />

( X , X , ∆t<br />

, t , N , I ) ≡ ( X , t )<br />

y : = D_INTEG<br />

ϕ<br />

O<br />

I<br />

C<br />

DI<br />

I<br />

C<br />

Equation 22.8-16<br />

These filters are the discrete equivalent to the continuous transfer function:<br />

y<br />

⎛ X<br />

⎜<br />

⎝ s ⋅ t<br />

( ) ⎟ = + ⎜ I<br />

s : X<br />

χ : = χ −<br />

k<br />

k<br />

1<br />

χ0 = χ−<br />

1<br />

0<br />

C<br />

( k −1<br />

)<br />

⎛ XI<br />

+<br />

⎜<br />

⎝ 2 ⋅ t<br />

C<br />

: : = 0.<br />

5 ⋅ X<br />

yk : = χk<br />

+ χk<br />

−1<br />

⎞<br />

⎠<br />

⎞<br />

⎟ ⋅ ∆t<br />

⎠<br />

I<br />

Equation 22.8-17<br />

Equation 22.8-18<br />

Equation 22.8-19<br />

Equation 22.8-20<br />

If (I := 1), and on first use, the filter is re-initialised without integration<br />

using input (XI). Each filter is identified by a unique number (N).

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