Patent ID: 6082666
Filing Date: 2000-07-04
Classification: G05D

Abstract:
A system for providing an accurate estimate of missile vertical velocity comprising:first means for obtaining radar range measurements;second means for tracking changes in missile acceleration without the use of radar range measurements and providing a signal in response thereto, said second means including an inertial reference unit (IRU); andthird means for combining said signal and said radar range measurements to provide said accurate estimate of missile vertical velocity,third means for combining said signal and said radar range measurements to provide said accurate estimate of missile vertical velocity, said third means including a Kalman filter and said Kalman filter being a two state Kalman filter, each state corresponding to one of the following state equations:h.sub.msl (t.sub.k+1)=h.sub.msl (t.sub.k)+V.sub.msl (t.sub.k)(t.sub.k+1 -t.sub.k),where h.sub.msl (t.sub.k+1) is a pseudo measurement estimate of the current altitude linearly extrapolated from a previous pseudo measurement altitude estimate h.sub.msl (t.sub.k) using an estimate of vertical missile velocity V.sub.msl (t.sub.k); andV.sub.bias (t.sub.k)=V.sub.IRU (t.sub.k)-V.sub.msl (t.sub.k)where V.sub.bias (t.sub.k) is the bias error in the IRU's estimate of vertical velocity, V.sub.IRU (t.sub.k) is the IRU's estimate of vertical velocity, and V.sub.msl (t.sub.k) is a vertical velocity estimate obtained by differentiating average range measurements.