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US 5,617,317 AGranted
True north heading estimator utilizing GPS output information and inertial sensor system output information
AssigneeHoneywell Inc.
InventorMario B. Ignagni
Life of this patent
Estimating the term…
Abstract
Inertial sensor information is combined with GPS information derived from satellite information signals separately received by a pair of GPS antennae and separately processed. This information is processed in a manner to arrive at the offset angle between the inertial sensor heading angle and true north.
Claims12
A true north directional heading information apparatus for determining the true north heading of a platform, said apparatus comprising:
- global positioning system having,
- first and second antennae rigidly fixed to a platform, separated by a known separation distance, and there being a line passing through the positions of said antennae having a known orientation relative to a platform coordinate reference frame, said first and second antennae providing first and second electrical signals, respectively, in response to received satellite information signals transmitted from selected satellites, which form, in part, a satellite based global positioning system, and in which each satellite information signal is comprised of a carrier signal containing coded information therewith,
- signal receiver means responsive to said first and second electrical signals for deriving, therefrom, information representative of (i) an estimated geocentric position of said platform at specific measurement times, and (ii) the geocentric position of said plurality of selected satellites at said specific measurement times, and (iii) first satellite-specific relative range values corresponding to the satellite-specific range between said first antenna and each of said selected satellites at said specific measurement times, and (iv) second satellite-specific relative range values corresponding to the satellite-specific range between said second antenna and each of said selected satellites at said specific measurement times;
- range difference processor means responsive to said first and second satellite-specific relative range values for determining satellite-specific relative range difference values, where each satellite-specific relative range difference value is related to the difference between (a) the range between said first antenna and a specific satellite transmitting the corresponding satellite information signal and (b) the range between the second antenna and the same satellite, at substantially said specific measurement times;
- an inertial sensor system, having a plurality of inertial sensors rigidly fixed to said platform, for providing attitude information related to first, second, and third angles of rotation corresponding to the platform pitch, roll, and heading angles, respectively, of said platform relative to an initially established orthogonal computational coordinate reference frame;
- and
- information processing means for operating on said information representative of
- (i) said estimated geocentric position of said platform,
- (ii) said geocentric position of said selected satellites,
- (iii) said satellite-specific relative range difference values,
- (iv) said known antennae separation distance, and
- (iv) said attitude information, for determining a heading offset angle, where said heading offset angle is the difference between said platform heading angle and substantially the true north heading angle of said platform whereby said true north heading angle is determined.
9 more elements
A method of determining true North directional heading information comprising the steps of:
- receiving satellite information signals through first and second antennae rigidly fixed to a platform, separated by a known separation distance, and there being a line passing through the positions of said antennae having a known orientation relative to a platform coordinate reference frame, and in which said first and second antennae provides first and second electrical signals, respectively, in response to distinguishable satellite information signals transmitted from selected satellites, which form, in part, a satellite based global positioning system, and in which each satellite information signal is consists of a carrier signal containing coded information therewith;
- deriving from said first and second electrical signals information representative of (i) an estimated geocentric position of said platform at specific measurement times, (ii) the geocentric position of said plurality of selected satellites at said specific measurement times, and (iii) satellite-specific relative range difference values, where each satellite-specific relative range difference value is related to the difference between (a) the range between said first antenna and a specific satellite transmitting the corresponding satellite information signal and (b) the range between the second antenna and the same satellite, at substantially said specific measurement times;
- obtaining attitude information from an inertial sensor system related to first, second, and third angles of rotation corresponding to the platform pitch, roll, and heading angles, respectively, of said platform relative to an initially established orthogonal computational coordinate reference frame;
- and
- operating on said information representative of
- (i) said estimated geocentric position of said platform,
- (ii) said geocentric position of said selected satellites,
- (iii) said satellite-specific relative range difference values,
- (iv) said known antennae separation distance, and
- (iv) said attitude information, for determining a heading offset angle, where said heading offset angle is the difference between said platform heading angle and substantially the true north heading angle of said platform whereby said true north heading angle is determined.
7 more elements
Dependencies are inferred from the claim text.