METHOD AND SYSTEM FOR ESTIMATING THE ANGULAR SPEED OF A MOBILE

• US 20100268414A1
• Filed: 06/09/2008
• Published: 10/21/2010
• Est. Priority Date: 06/08/2007
• Status: Active Grant

• Current Assignee: Airbus Helicopters
• Original Assignee: Eurocopter
• Inventors: Salesse-Lavergne, Marc, Petillon, Jean-Paul
• Granted Patent: US 8,543,281 B2
• Time in Patent Office: Days
• US Class Current: 701/34
• CPC Class Codes: G01C 19/00 Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
• CPC Class Codes: G01C 21/183 Compensation of inertial measurements, e.g. for temperature effects
• CPC Class Codes: G01P 15/034 for indicating angular accelerations G01P15/036 takes precedence
• CPC Class Codes: G01P 15/0888 for indicating angular acceleration
• CPC Class Codes: G01P 15/18 in two or more dimensions

Abstract

A method of determining an angular velocity of an aircraft includes measuring the angular velocity using at least one gyro delivering a measured angular velocity signal affected by stochastic noise; measuring the angular acceleration of the aircraft using at least one accelerometer delivering a signal representing the angular acceleration of the aircraft; and using a filtering complementary in a frequency domain to combine a sum of the measured angular velocity signal and the angular acceleration signal so as to obtain a hybrid estimated angular velocity signal with reduced stochastic noise.

Claims

1-22. -22. (canceled)

23. A method of determining an angular velocity of an aircraft comprising:

measuring the angular velocity using at least one gyro delivering a measured angular velocity signal affected by stochastic noise;

measuring the angular acceleration of the aircraft using at least one accelerometer delivering a signal representing the angular acceleration of the aircraft; and

using a filtering complementary in a frequency domain to combine a sum of the measured angular velocity signal and the angular acceleration signal so as to obtain a hybrid estimated angular velocity signal with reduced stochastic noise.

24. The method as recited in claim 23, wherein the complementary filtering includes a lowpass filter for the gyro signals and a highpass filter for the accelerometer signals.

25. The method as recited in claim 23, further comprising attenuating high frequencies of the measured angular velocity signals and attenuating low frequencies of angular velocity signals obtained by an integration of the angular acceleration signals.

26. The method as recited in claim 23, wherein the at least one acceleratometer includes a cluster of linear accelerometers, wherein the measuring of the angular acceleration includes calculating at least one component of the angular acceleration as a function of a plurality of scalar acceleration measurements delivered by the cluster of linear accelerometers.

27. The method as recited in claim 26, wherein the cluster of linear accelerometers includes at least one of a single-axis and a two-axis accelerometer.

28. The method as recited in claim 23, wherein the at least one accelerometer includes an excess number of accelerometers, and further comprising comparing a difference between the angular velocity signal and the hybrid estimated angular velocity signal with at least one reference value over a plurality of successive cycles.

29. The method as recited in claim 28, further comprising producing a failure detection signal when the reference value is exceeded during the plurality of successive cycles.

30. The method as recited in claim 23, wherein the obtaining of the hybrid estimated angular velocity signal is performed using a program running on an aircraft computer, wherein the measuring the angular velocity includes determining angular velocity data from signals delivered by the gyro using a first code segment, the measuring the angular acceleration includes determining angular acceleration data from signals delivered using the gyro by a second code segment, and the obtaining a hybrid estimated angular velocity signal includes hybridizing the measured angular velocity data and the measured angular acceleration data using a third code segment.

31. A system for determining an angular velocity of an aircraft comprising:

at least one gyro configured to deliver measured angular velocity signals affected by stochastic noise;

at least one accelerometer configured to deliver angular acceleration signals of the aircraft; and

a hybridizing module coupled to the at least one gyro and to the at least one accelerometer configured to hybridize and to filter completely in the frequency domain, the hybridizing module including;

a subtractor configured to receive the measured angular velocity signal and a previously-estimated angular velocity;

a filter connected to the subtractor configured to receive as input a difference between the angular velocity sign and the hybrid estimated angular velocity signal produced by the subtractor and configured to deliver as output a bias correction;

a summing circuit connected to the filter and configured to receive as input the output of the filter and the angular acceleration signals of the aircraft; and

an integrator connected to the summing circuit and configured to receive as input a sum from the summing circuit and to deliver as output a hybrid estimated angular velocity having reduced stochastic noise.

32. The system as recited in claim 31, wherein the system is configured to measure the angular velocity using at least one gyro configured to deliver a measured angular velocity signal affected by stochastic noise, measure the angular acceleration of the aircraft using at least one accelerometer configured to deliver a signal representing the angular acceleration of the aircraft;

and use a filtering complementary in a frequency domain to combine a sum of the measured angular velocity signal and the angular acceleration signal so as to obtain a hybrid estimated angular velocity signal with reduced stochastic noise, wherein the hybridizing module is configured to perform complementary filtering and includes a lowpass filter characteristic for the gyro signals and a highpass filter characteristic for the accelerometer signals.

33. The system as recited in claim 31, wherein the at least one gyro is configured to produce a noise of power spectrum density (PSD) that is substantially uniform in a frequency band from about 0.1 Hz to about 10 Hz.

34. The system as recited in claim 31, wherein the at least one gyro is configured to produce a noise of power density (PSD) that is substantially proportional to frequency in a frequency band from about 1 Hz to about 10 Hz.

35. The system as recited in claim 31, wherein the at least one accelerometer is configured to produce a noise of power spectrum (PSD) that is substantially uniform regardless of frequency in a frequency band from about 0.1 Hz to about 10 Hz.

36. The system as recited in claim 31, wherein the at least one accelerometer includes at least six linear accelerometers.

37. The system as recited in claim 31, wherein the at least six linear accelerometers are secured rigidly to one another in a configuration having central symmetry.

38. The system as recited in claim 31, wherein the at least one accelerometer includes at least six single-axis linear accelerometers disposed in a configuration, the at least six single-axis linear accelerometers each including a sensitive point and a sensitivity axis, wherein each sensitive point is disposed in a center of an edge of a regular tetrahedron and each the sensitivity axis is oriented along the edge.

39. The system as recited in claim 31, wherein the at least one accelerometer includes at least four two-axis linear accelerometers each disposed at a vertex of a tetrahedron.

40. The system as recited in claim 31, wherein the at least one accelerometer includes at least three linear accelerometers disposed in a trihedron configuration and at least three angular accelerometers disposed in a trihedron configuration.

41. The system as recited in claim 31, wherein the at least one gyro includes a microelectromechanical system (MEMS).

42. The system as recited in claim 31, wherein the at least one accelerometer includes a microelectromechanical system (MEMS).

43. The system as recited in claim 31, wherein the filter includes a proportional gain 1/τ

, a low integral gain 1/τ

i, where τ

<

<

τ

i, and a cutoff frequency of less than 1 Hz.

44. The system as recited in claim 31, includes a comparator configured to compare difference between the angular velocity signal and the hybrid estimated angular velocity signal with a threshold and a failure-confirmation logic circuit connected to the comparator.