Patent ID: 11879969
Assignee: HONEYWELL INTERNATIONAL INC.
Field: Measurement (Instruments)
Classification: CPC G  B | IPC G

Claim 0:
1. A system comprising:
one or more aiding sensors onboard a vehicle;
an onboard inertial measurement unit (IMU) operative to produce inertial measurements for the vehicle;
an onboard radar altimeter operative to produce radar altimeter measurements for the vehicle;
an onboard map database comprising one or more terrain and object maps;
an onboard navigation system operative to receive aiding data from the one or more aiding sensors and inertial data from the IMU, the navigation system including a navigation filter operative to generate estimated kinematic state statistics for the vehicle based on the aiding data and the inertial data; and
at least one processor onboard the vehicle, the at least one processor operative to execute processor readable instructions to perform a method comprising:
inputting horizontal position statistics and vertical position statistics from the navigation filter into the map database; and
computing an estimated ground/object height, an estimated ground/object velocity, an estimated ground/object acceleration, and error statistics thereof, based on terrain and object map data from the map database;

wherein the at least one processer includes a radar altimeter inertial vertical loop (RIVL) filter, wherein the RIVL filter is operative to perform a method comprising:
receiving the estimated ground/object height, the estimated ground/object velocity, the estimated ground/object acceleration, and the error statistics thereof;
receiving radar altimeter measurements from the radar altimeter;
determining a relative vertical acceleration based on a difference between a vehicle vertical acceleration and a ground/object vertical acceleration;
determining a relative vertical velocity based on a difference between a vehicle vertical velocity and a ground/object vertical velocity;
performing a consistency check on the relative vertical acceleration based on non-zero relative vertical acceleration conditions, and on conditions comparing an integrated relative vertical acceleration to the relative vertical velocity;
performing a consistency check on the relative vertical velocity based on zero relative vertical acceleration conditions and non-zero relative vertical velocity conditions; and
outputting estimated vertical position and vertical velocity statistics of the vehicle for compensation of estimated vertical position and vertical velocity statistics from the navigation filter;

wherein the navigation filter is configured to output the compensated estimated vertical position and vertical velocity statistics to provide landing guidance for the vehicle.