Augmented Proportional Guidance (APNG)

Advanced guidance laws reduce acceleration requirements and miss distance but require more information (e. g., time — to-go and missile-target range) (19). In an attempt to take into account a constant target acceleration maneuver at, guidance engineers developed augmented proportional guidance (APNG). For APNG, the commanded acceleration is given by

acA PNG(t) = NVcX(t) + — Nat = acpng(0 + ^ Nat (15)

for stability robustness which implies that the guidance-control-seeker bandwidth bandwidth ю must be small when Vm is small, (R!, N, Vc) are large, or юа is small (high altitude and low missile speed V ).

m

From the above, it follows that we require the guidance — control-seeker bandwidth ю to satisfy

RNVc

юа<ю<Є

ZEM

V

m

or acAPNG(t) = N( 2 ), where ZEM = y + ytgo + — attgo is

^go. 2

the associated zero effort miss distance. Equation (15) shows that APNG is essentially PNG with an extra term to account for the maneuvering target. For this guidance law,

(16)

1——

tf

at

acPNGmax — ["

N — 2

larger maximum acceleration but less acceleration than PNG for t > 0.2632tf. As a result, APNG is more fuel effi­cient for exoatmospheric applications than PNG. Finally, it should be noted that APNG minimizes Jjf a2c(T)dT subject to zero miss distance, linear dynamics, and constant target acceleration (8).

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