US 5,948,044 A · Hybrid GPS/inertially aided platform stabilization system

Abstract

A hybrid system for stabilizing the attitude of an instrument relative to a dynamic platform includes a plurality of (roll, pitch and yaw) inertial rate sensors, whose outputs are sampled at a rate sufficient to provide real time tracking of changes in orientation of the platform, and a global positioning system (GPS) receiver, whose precision platform attitude output is updated periodically, but at a rate less than the rate of change of attitude of the platform. The inertial rate sensors provide effectively continuous motion (e.g., angular rate) data signals representative of three-dimensional changes in attitude (position derivative signals) of the platform. The inertial rate output are integrated to provide output signals representative of the dynamic orientation of the platform. Sequential outputs of the integration-processing circuitry are also coupled to a sample buffer, which is controllably read-out in accordance with the periodic updates from the GPS receiver. The integrated inertial sensor (attitude) data is compared with the GPS update data to generate error signals which are used to adjust the inertial sensor data. By employing a sample buffer in an inertial sensor output integration feedback loop with the GPS receiver, the hybrid system of the present invention avoids what would otherwise be a staleness problem with the data provided by the GPS receiver.

Claims30

Dependent claims

A system for stably positioning the attitude of an instrument relative to a platform upon which the instrument is mounted, said platform having an orientation that is subject to dynamic variations, comprising:

at least one rate of motion sensor attached to said platform, each rate of motion sensor being operative to provide a first, real-time signal representative of rate of change of a respective attitude parameter of said platform;
a platform position sensor which attached to said platform and is operative to generate second signals representative of at least one attitude parameter of said platform;
and
a signal processor which is operative to adjust said first signals in accordance with said second signals, and wherein
said platform position sensor comprises a global positioning system (GPS) based platform position sensor, which is operative to periodically generate said second signals at a rate less than that at which said first signals are produced, and wherein said signal processor is operative to generate third signals representative of said attitude parameter of said platform based upon said first signals, and to compare selected ones of said second signals with third signals to derive error signals through which said first signals are adjusted.

2 more elements

A method of stably orienting an instrument relative to a platform upon which the instrument is mounted, said platform having an orientation that is subject to dynamic variations, comprising the steps of:

(a) attaching a plurality of rate of motion sensors to said platform, each of said motion sensors being operative to provide a first, real-time signal representative of rate of change of a respectively different attitude parameter of said platform;
(b) providing a platform position sensor which is operative to generate second signals representative of respectively different attitude parameters of said platform;
(c) adjusting said first signals in accordance with said second signals;
and
(d) controlling the orientation of said instrument relative to said platform in accordance with said adjusted first signals, and wherein step (c) comprises
(c1) coupling said first signals to an integration operator, which provides output signals representative of the dynamic roll, pitch and yaw orientation of said platform,
(c2) storing said output signals in memory,
(c3) controllably reading out selected ones of said stored output signals from said memory in accordance with periodic updates of said GPS receiver, and
(c4) modifying said first signals in accordance with differences between said selected ones of said output signals and associated ones of said second signals.

6 more elements

A method of stably positioning an instrument relative to a platform upon which the instrument is mounted, said platform having a position and orientation that are subject to dynamic variations, comprising the steps of:

(a) providing at least one inertial rate sensor on said platform, said sensor being operative to generate first signals representative of a rate of change of an attitude parameter of said platform;
(b) providing a global positioning system (GPS) receiver which is operative to generate second signals representative of said attitude parameter of said platform;
and
(c) adjusting said first signals in accordance with said second signals, and wherein
said global positioning system (GPS) receiver is operative to periodically generate said second signals at a rate less than that at which said first signals are produced, and wherein step (c) comprises generating third signals representative of said attitude parameter of said platform in accordance with said first signals, and comparing selected ones of said second signals with third signals to derive error signals through which said first signals are corrected.

2 more elements

Dependencies are inferred from the claim text.

Hybrid GPS/inertially aided platform stabilization system

Life of this patent

Hybrid GPS/inertially aided platform stabilization system

Life of this patent

Abstract

Claims30