US 4,914,598 A · Integrated redundant reference system for the flight control and for generating heading and attitude informations · patentgrep

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Abstract

A plurality of two-axis rate gyros are arranged in relation to an aircraft-fixed coordinate system such that they redundantly supply angular rate information. A plurality of accelerometers supply correspondingly redundant acceleration information. First signal processing means comprise means for failure detection and elimination, such that angular rate and acceleration information subjected to error are eliminated. The angular rate and acceleration information thus cleared from errors supply stabilization signals for the autopilot. Second signal processing means obtain the angular rate and acceleration information cleared from errors and integrated if required, and therefrom supply heading and attitude reference signals.

Claims25

Dependent claims

An integrated, redundant reference system providing angular rate and heading and attitude information for the flight control of aircraft by means of an autopilot, comprising

(a) at least four strap-down, dynamically tuned gyros, each of said gyros having a spin axis and two mutually orthogonal input axes normal to said spin axis, the directions of said axes being defined by respective direction vectors, each of said dynamically tuned gyros providing two angular rate signals indicative of angular rates about said two input axes,
(b) said gyros being oriented with the direction vectors of their spin axes extending radially with respect to a common reference axis, the direction vectors of said input axes of all gyros being different and located on a notional cone having a cone angle of 90.degree., the axis of said cone coinciding with said reference axis,
(c) means equally operatively connected to all gyros for detecting deficiencies of said gyros and for eliminating signals from deficient gyros, the angular rate signals from all said gyros being supplied to said deficiency detecting and eliminating means, said deficiency detecting and eliminating means, in normal operation, providing a set of selected angular rate signals from operative gyros,
(d) first signal processing means to which said set of selected angular rate signals is applied for providing a set of corrected angular rate signals referenced to a vehicle-fixed coordinate system, said corrected angular rate signals being applied to said autopilot for stabilizing said aircraft, and
(e) second signal processing means to which said corrected angular rate signals are applied for providing heading and attitude reference signals.

2 more elements

An integrated, redundant reference system providing angular rate and heading and attitude information for the flight control of aircraft by means of an autopilot, comprising

(a) at least four strap-down, dynamically tuned gyros, each of said gyros having a spin axis and two mutually orthogonal input axes normal to said spin axis, the directions of said axes being defined by respective direction vectors, each of said dynamically tuned gyros providing two angular rate signals indicative of angular rates about said two input axes,
(b) said gyros being oriented with the direction vectors of their spin axes extending radially with respect to a common reference axis, the direction vectors of said input axes of all gyros being different and located on a notional cone having a cone angle of 90.degree., the axis of said cone coinciding with said reference axis,
(c) means equally operatively connected to all gyros for detecting deficiencies of said gyros and for eliminating signals from deficient gyros, the angular rate signals from all said gyros being supplied to said deficiency detecting and eliminating means, said deficiency detecting and eliminating means, in normal operation, providing a set of selected angular rate signals from operative gyros,
(d) first signal processing means to which said set of selected angular rate signals is applied for providing a set of corrected angular rate signals reference to a vehicle-fixed coordinate system, said corrected angular rate signals being applied to said autopilot for stabilizing said aircraft,
(e) second signal processing means to which said corrected angular rate signals are applied for providing heading and attitude reference signals, and
(f) strap-down acceleration sensor means for providing a plurality of acceleration signals
(1) said acceleration sensor means comprise means for sensing acceleration along more than three input axes, said input axes being oriented to provide redundant acceleration information,
(2) plurality of said acceleration signals from said acceleration sensor means providing redundant acceleration information being applied to acceleration failure detecting and eliminating means eliminating deficient accelerating signals and for selecting from said plurality of acceleration signals, in normal operation, a selected set of acceleration signals from operative acceleration sensors,
(3) said selected set of acceleration signals being applied to said first signal processing means for providing a set of corrected acceleration signals referenced to said vehicle fixed coordinate system, also said corrected acceleration signals being applied to said autopilot for stabilizing said aircraft, and
(4) said acceleration sensor means comprising a respective pair of accelerometers associated with each two-axis gyro, the input axes of which accelerometers are parallel to one of the input axes of the gyro.

7 more elements

An integrated, redundant reference system providing angular rate and heading and attitude information for the fight control of aircraft by means of an autopilot, comprising

(a) at least four strap-down, dynamically tuned gyros, each of said gyros having a spin axis and two mutually orthogonal input axes normal to said spin axis, the directions of said axes being defined by respective direction vectors, each of said dynamically tuned gyros providing two angular rate signals indicative of angular rates about said two input axes,
(b) said gyros being oriented with the direction vectors of their spin axes extending radially with respect to a common reference axis, the direction vectors of said input axes of all gyros being different and located on a notional cone having a cone angle of 90.degree., the axis of said cone coinciding with said reference axis,
(c) means equally operatively connected to all gyros for detecting deficiencies of said gyros and for eliminating signals from deficient gyros, the angular rate signals from all said gyros being supplied to said deficiency detecting and eliminating means, said deficiency detecting and eliminating means, in normal operation, providing a set of selected angular rate signals from operative gyros,
(d) first signal processing means to which said set of selected angular rate signals is applied for providing a set of corrected angular rate signals reference to a vehicle-fixed coordinate system, said corrected angular rate signals being applied to said autopilot for stabilizing said aircraft,
(e) second signal processing means to which said corrected angular rate signals are applied for providing heading and attitude reference signals,
(f) strap-down acceleration sensor means for providing a plurality of acceleration signals being also applied to said first signal processing means for providing a set of corrected acceleration signals referenced to said vehicle fixed coordinate system, also said corrected acceleration signals being applied to said autopilot for stabilizing said aircraft,
(g) first means for the transformation of the true airspeed, which is the aerodynamically measured aircraft velocity relative to the surrounding air, into the aircraft-fixed coordinate system, on the basis of the angle of attack and angle of side-slip likewise measured by aerodynamical sensors,
(h) second means for determination of the aircraft velocity over ground in an aircraft-fixed coordinate system,
(i) difference forming means for determination of the wind velocity in the aircraft-fixed coordinate system as difference between the aircraft velocity relative to the surrounding air determined by the first means and the aircraft velocity over ground determined by the second means,
(j) memory means for memorizing the thus determined wind velocity,
(k) third means for forming estimated values of the angle of attack and the angle of side-slip from the wind velocity memorized in the memory means and the aircraft velocity over ground supplied from the second means, and
(l) conversion means, which, in case of failure of the aerodynamical sensors for angle of attack and angle of side-slip, is adapted to
separate the memory means from the difference forming means and
apply the estimated values of angle of attack and angle of side-slip formed by the third means, instead of the sensor signals, to the autopilot computer.

11 more elements

An integrated, redundant reference system providing angular rate and heading and attitude information for the flight control of aircraft by means of an autopilot, comprising

(a) at least four strap-down, dynamically tuned gyros, each of said gyros having a spin axis and two mutually orthogonal input axes normal to said spin axis, the directions of said axes being defined by respective direction vectors, each of said dynamically tuned gyros providing two angular rate signals indicative of angular rates about said two input axes,
(b) said gyros being oriented with the direction vectors of their spin axes extending radially with respect to a common reference axis, the direction vectors of said input axes of all gyros being different and located on a notional cone having a cone angle of 90.degree., the axis of said cone coinciding with said reference axis,
(c) means equally operatively connected to all gyros for detecting deficiencies of said gyros and for eliminating signals from deficient gyros, the angular rate signals from all said gyros being supplied to said deficiency detecting and eliminating means, said deficiency detecting and eliminating means, in normal operation, providing a set of selected angular rate signals from operative gyros,
(d) first signal processing means to which said set of selected angular rate signals is applied for providing a set of corrected angular rate signals reference to a vehicle-fixed coordinate system, said corrected angular rate signals being applied to said autopilot for stabilizing said aircraft, and
(e) second signal processing means to which said corrected angular rate signals are applied for providing heading and attitude reference signals,
wherein
(f) a first set of gyros is used for measuring the three components of the angular rate while they are operating properly, and
(g) when a failure appears a change-over is caused to a second set of gyros from a sequence of alternative sets with different combinations of gyros, none of which have failed.

5 more elements

An integrated, redundant reference system providing angular rate and heading and attitude information for the flight control of aircraft by means of an autopilot, comprising

(a) at least four strap-down, dynamically tuned gyros, each of said gyros having a spin axis and two mutually orthogonal input axes normal to said spin axis, the directions of said axes being defined by respective direction vectors, each of said dynamically tuned gyros providing two angular rate signals indicative of angular rates about said two input axes,
(b) said gyros being oriented with the direction vectors of their spin axes extending radially with respect to a common reference axis, the direction vectors of said input axes of all gyros being different and located on a notional cone having a cone angle of 90.degree., the axis of said cone coinciding with said reference axis,
(c) means equally operatively connected to all gyros for detecting deficiencies of said gyros and for eliminating signals from deficient gyros, the angular rate signals from all said gyros being supplied to said deficiency detecting and eliminating means, said deficiency detecting and eliminating means, in normal operation, providing a set of selected angular rate signals from operative gyros,
(d) first signal processing means to which said set of selected angular rate signals is applied for providing a set of corrected angular rate signals reference to a vehicle-fixed coordinate system, said corrected angular rate signals being applied to said autopilot for stabilizing said aircraft,
(e) second signal processing means to which said corrected angular rate signals are applied for providing heading and attitude reference signals,
(f) strap-down acceleration sensor means for providing a plurality of acceleration signals being also applied to said first signal processing means for providing a set of corrected acceleration signals referenced to said vehicle fixed coordinate system, also said corrected acceleration signals being applied to said autopilot for stabilizing said aircraft,
wherein
(g) the first signal processing means supply
transformation parameters for the transformation of vectors from an aircraft-fixed coordinate system into an earth-fixed coordinate system to attitude outputs, which transformation parameters result from integration of angular rate information,
velocity values to velocity outputs, which velocity values result from integration of acceleration information in a vehicle-fixed coordinate system,
(h) the second signal processing means comprise
initial aligning means for determination of initial values of the transformation parameters,
means for determination of correcting values for taking earth rotation and transport rate into consideration,
correcting means for correction of the transformation parameters with respect to initial values, earth rotation and transport rate, and
means for calculation and output of the heading and attitude angles from the thus corrected transformation parameters,
a coordinate transformation circuit which operates with the corrected transformation parameters from said correcting means, and which is arranged to transform said velocity values into an earth-fixed coordinate system, and
(i) the velocity components measured with the vehicle at rest by integration of acceleration componenets are applied to the initial aligning means, which velocity components form a measure of the initial inclination of the vehicle, and velocity computer means
to which the velocity values transformed by the coordinate transformation circuit and
flying speed as well as angle of attack and angle of side-slip are supplied, and
which apply velocity components to the means for determination of correcting values for taking the earth rotation and transport rate into consideration, and
which apply velocity components to a vertical channel aided by the pressure altitude, which vertical channel supplies flight altitude and vertical velocity.

18 more elements

An integrated, redundant reference system providing angular rate and heading and attitude information for the flight control of aircraft by means of an autopilot, comprising

(a) at least four strap-down, dynamically tuned gyros, each of said gyros having a spin axis and two mutually orthogonal input axes normal to said spin axis, the directions of said axes being defined by respective direction vectors, each of said dynamically tuned gyros providing two angular rate signals indicative of angular rates about said two input axes,
(b) said gyros being oriented with the direction vectors of their spin axes extending radially with respect to a common reference axis, the direction vectors of said input axes of all gyros being different and located on a notional cone having a cone angle of 90.degree., the axis of said cone coinciding with said reference axis,
(c) means equally operatively connected to all gyros for detecting deficiencies of said gyros and for eliminating signals from deficient gyros, the angular rate signals from all said gyros being supplied to said deficiency detecting and eliminating means, said deficiency detecting and eliminating means, in normal operation, providing a set of selected angular rate signals from operative gyros,
(d) first signal processing means to which said set of selected angular rate signals is applied for providing a set of corrected angular rate signals reference to a vehicle-fixed coordinate system, said corrected angular rate signals being applied to said autopilot for stabilizing said aircraft,
(e) second signal processing means to which said corrected angular rate signals are applied for providing heading and attitude reference signals,
(f) strap-down acceleration sensor means for providing a plurality of acceleration signals being also applied to said first signal processing means for providing a set of corrected acceleration signals referenced to said vehicle fixed coordinate system, also said corrected acceleration signals being applied to said autopilot for stabilizing said aircraft,
wherein
(g) the first signal processing meaNs supply
transformation parameters for the tranrformation of vectors from an aircraft-fixed coordinate system into an earth-fixed coordinate system to attitude outputs, which transformation parametars result from integration of angular rate information,
velocity vlues to velocity outputs, which velocity values result from integration of acceleration information In a vehicle-fixed coordinate system,
(h) the second signal processing means comprise
initial aligning means for determination of initial values of the transformation parameters,
means for determination of correcting values for taking earth rotation and transport rate into consideration,
correcting means for correction of the transformation parameters with respect to initial values, earth rotation and transport rate, and
means for calculation and output of the heading and attitude angles from the thus corrected transformation parameters,
coordinate transformation circuit which operates with the corrected transformation parameters from said correcting means, which is arranged to transform said velocity values into an earth-fixed coordinate system, and
(i) the velocity components measured with the vehicle at rest by integration of acceleration components are applied to the initial aligning means, which velocity components form a measure of the initial inclination of the vehicle, furthermore an external initial heading information is applied to the initial aligning means.

14 more elements

An integrated, redundant reference system providing angular rate and heading and attitude information for the flight control of aircraft by means of an autopilot, comprising

(a) at least four strap-down, dynamically tuned gyros, each of said gyros having a spin axis and two mutually orthogonal input axes normal to said spin axis, the directions of said axes being defined by respective direction vectors, each of said dynamically tuned gyros providing two angular rate signals indicative of angular rates about said two input axes,
(b) said gyros being oriented with the direction vectors of their spin axes extending radially with respect to a common reference axis, the direction vectors of said input axes of all gyros being different and located on a notional cone having a cone angle of 90.degree., the axis of said cone coinciding with said reference axis,
(c) means equally operatively connected to all gyros for detecting deficiencies of said gyros and for eliminating signals from deficient gyros, the angular rate signals from all said gyros being supplied to said deficiency detecting and eliminating means, said deficiency detecting and eliminating means, in normal operation, providing a set of selected angular rate signals from operative gyros,
(d) first signal processing means to which said set of selected angular rate signals is applied for providing a set of corrected angular rate signals reference to a vehicle-fixed coordinate system, said corrected angular rate signals being applied to said autopilot for stabilizing said aircraft,
(e) second signal processing means to which said corrected angular rate signals are applied for providing heading and attitude reference signals,
(f) strap-down acceleration sensor means for providing a plurality of acceleration signals being also applied to said first signal processing means for providing a set of corrected acceleration signals referenced to said vehicle fixed coordinate system, also said corrected acceleration signals being applied to said autopilot for stabilizing said aircraft,
wherein
(g) the first signal processing means supply
transformation parameters for the transformation of vectors from an aircraft-fixed coordinate system into an earth-fixed coordinate system to attitude outputs, which transformation parameters result from integration of angular rate information,
velocity values to velocity outputs, which velocity values result from integration of acceleration information in a vehicle-fixed coordinate system,
(h) the second signal processing means comprise
initial aligning means for determination of initial values of the transformation parameters,
means for determination of correcting values for taking earth rotation and transport rate into consideration,
correcting means for correction of the transformation parameters with respect to initial values, earth rotation and transport rate,
means for calculation and output of the heading and attitude angles from the thus corrected transformation parameters, and
a coordinate transformation circuit which operates with the corrected transformation parameters from said correcting means, and which is arranged to transform said velocity values into an earth-fixed coordinate system, and
(i) the velocity components measured with the vehicle at rest by integration of acceleration components are applied to the initial aligning means, which velocity components form a measure of the initial inclination of the vehicle, wherein the initial aligning means comprise
(1) fast responding coarse leveling means, to which velocity increment signals from the acceleration sensor means are applied and which supply an initial direction cosine matrix for transformation from an aircraft-fixed system into an earth-fixed system,
(2) means for updating the direction cosine matrix, to which angular increment signals from the angular rate sensor means are applied,
(3) velocity transformation means, to which the velocity increment signals are applied and which supply a velocity vector transformed with the direction cosine matrix in an earth-fixed coordinate system,
(4) fine leveling means, to which the transformed velocity vector and the geographical latitude are applied, and which apply attitude correction signals to the means for updating the direction cosine matrix and which supply signals, which are determined by the influence of the earth rotation on the angular rate sensors, and
(5) means for determining the heading from said signals determined by the earth rotation.

19 more elements

Dependencies are inferred from the claim text.