An online calibration method for wind vane type airflow sensor in aircraft spin state

Abstract

The present application belongs to the technical field of online calibration of aircraft airflow sensors, and particularly relates to a method for online calibration of a wind vane type airflow sensor in a state of aircraft spin. The method combines a satellite navigation system and an inertial navigation system to calibrate the wind vane type airflow sensor with large measurement error in the state of aircraft spin. The method can effectively improve the accuracy of functions or operations such as stall spin alarm, spin recovery control, spin system identification and parameter estimation, and further reduce the probability of serious flight safety accidents caused by false alarm, misjudgment or misoperation of the wind vane type airflow sensor with large measurement error in the state of spin.

Description

Technical Field

[0001] This invention belongs to the field of online calibration technology for aircraft airflow sensors, specifically relating to an online calibration method for a weather vane-type airflow sensor under aircraft spin conditions. Background Technology

[0002] When an aircraft enters a spin, it is often at a high angle of attack and a large sideslip angle, especially when it enters a horizontal spin, where the angle of attack can approach 90 degrees. Under these conditions, the measurement error of the weather vane-type airflow sensor increases dramatically, even causing the sensor to fail. This introduces significant errors into functions or operations such as aircraft stall spin warning, spin recovery control, spin system identification, and parameter estimation, leading to false alarms, misjudgments, or misoperations, and seriously threatening flight safety. For scenarios including manned aircraft spin recovery assisted piloting and fully autonomous UAV spin recovery, the accuracy of parameters such as angle of attack and sideslip angle measurements directly affects the timing and effectiveness of spin recovery. Therefore, accurately calibrating the aforementioned airflow sensors online in real time when the aircraft is in a spin becomes a crucial step before making a spin recovery decision.

[0003] Angle of attack and sideslip angle The measurement method used is a wind vane-type airflow sensor, which has a large measurement error in swirl conditions; pitch angle Yaw angle and roll angle The method for measuring constant attitude angles is an inertial navigation system. The measurement error is controllable in a spin state, so the latter can be used to calibrate the former through conversion. Summary of the Invention

[0004] The purpose of this invention is to provide an online calibration method for a weather vane-type airflow sensor in a tailspin state. This method can calibrate the weather vane sensor in real time when the aircraft is in a tailspin, reduce the measurement error of the angle of attack and sideslip angle in a tailspin state, provide more accurate tailspin state reference for manned aircraft pilots, and provide accurate parameters for the decision-making and control loop of tailspin recovery assistance or fully autonomous tailspin recovery of unmanned aerial vehicles.

[0005] This invention proposes an online calibration method for a weather vane-type airflow sensor under aircraft spin conditions. The online calibration steps are as follows: S1. Assuming the wind speed vector in the ground coordinate system Given the quantities, the origin of the ground coordinate system is determined as the aircraft's takeoff point, and the wind speed vector is... middle: Represents the ground coordinate system. Indicates wind speed. Bold text indicates vectors; S2, trajectory velocity vector in the ground coordinate system The airspeed vector in the ground coordinate system is obtained by measuring with a satellite navigation system and calculating based on the principle of vector triangles. ; S3. Determine the airspeed vector in the airflow coordinate system. ,in: This represents the airflow coordinate system. According to the definition of the airflow coordinate system, we know... , The transpose of a vector; Represents the airspeed vector in the ground coordinate system norm; S4, Airspeed vector in the airflow coordinate system Or by using the airspeed vector in the ground coordinate system We obtain the coordinates by performing a coordinate transformation. ; The and All are cosine transformation matrices. This is the transformation matrix from the body coordinate system to the airflow coordinate system. This is the transformation matrix from the ground coordinate system to the body coordinate system; S5. Combining the relationships in S3 and S4 into an equation, we have: ; S6. The simplified expression of the transformation matrix from the ground coordinate system to the body coordinate system described in S4 is shown in the following formula:

[0006] Combining S2 and simplifying, we get:

[0007]

[0008] S7. By performing inverse trigonometric function calculations on the relation obtained in S6, we can obtain:

[0009]

[0010] The and These are the angle of attack and sideslip angle to be calibrated, respectively, both of which are unknowns. The attitude angle , and These are pitch angle, yaw angle, and roll angle, respectively. The attitude angles are measured by the inertial navigation system and are all known quantities. The angle of attack and sideslip angle of the aircraft in spin state can be calculated in real time using the two relationships above, thus completing the online calibration of the wind vane sensor in spin state.

[0011] The ground coordinate system in S1 The axis points north. The axis points east. The axis points downwards according to the right-hand rule.

[0012] The airspeed vector in S2 ; The Indicates airspeed. , and The airspeed vector in the ground coordinate system is respectively axis, and The velocity component of the shaft.

[0013] The origin of the airflow coordinate system in S3 is the center of mass of the aircraft. The axis points in the direction of airspeed. The axis points downwards along the plane of symmetry of the aircraft. The axis is determined according to the right-hand rule.

[0014] The S4 described and All The direction cosine transformation matrix.

[0015] The origin of the body coordinate system mentioned in S4 is the aircraft's center of mass. The axis points towards the nose along the axis of symmetry of the fuselage. The axis points downwards along the plane of symmetry of the fuselage. The axis is determined according to the right-hand rule.

[0016] The origin of the airflow coordinate system in S4 is the aircraft's center of mass. The shaft coincides with the airspeed. The axis points downwards along the plane of symmetry of the fuselage. The axis is determined according to the right-hand rule.

[0017] The transformation matrix from the body coordinate system to the airflow coordinate system in S4 for: .

[0018] The transformation matrix from the ground coordinate system to the body coordinate system in S4 for: .

[0019] The beneficial effects of this invention are: During an aircraft spin, the measurement error of the wind vane-type airflow sensor increases significantly or even fails, bringing unpredictable impacts to spin recovery judgment, decision-making, and specific recovery control operations. Inaccurate measurements can easily lead to missed spin recovery opportunities, further increasing the physiological and psychological burden on pilots, or even causing the failure of fully autonomous spin recovery by the UAV. However, the measurement accuracy of satellite navigation and inertial navigation systems is not affected by airflow characteristics such as large angles of attack and sideslip angles during an aircraft spin. Therefore, multi-source data fusion based on satellite navigation and inertial navigation system data can effectively calibrate the measurement results of relevant parameters of the aircraft's wind vane-type airflow sensor, improving the measurement accuracy of angle of attack and sideslip angle during a spin. Attached Figure Description

[0020] Appendix Figure 1 A schematic diagram of a wind vane-type airflow sensor, including an angle-of-attack sensor and a sideslip angle sensor.

[0021] Appendix Figure 2 Flowchart of online calibration method for weather vane airflow sensor under aircraft spin conditions Detailed Implementation The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. The embodiments of the present invention provide an online calibration method for a weather vane-type airflow sensor under aircraft spin conditions, thus concretizing the online calibration method for airflow sensors of the present invention. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0022] Example S1. Assuming the wind speed vector in the ground coordinate system Let be a known quantity, where: Represents the ground coordinate system. Indicates wind speed. Bold text indicates vectors; The origin of the ground coordinate system is the aircraft's takeoff point. The axis points north. The axis points east. The axis points downwards according to the right-hand rule; S2, trajectory velocity vector in the ground coordinate system The airspeed vector in the ground coordinate system is obtained by measuring with a satellite navigation system and calculating based on the principle of vector triangles. ; The Indicates airspeed. , and The airspeed vector in the ground coordinate system is respectively axis, and The velocity component of the shaft; S3, airspeed vector in the airflow coordinate system ,in: This represents the airflow coordinate system. According to the definition of the airflow coordinate system, we know... , Represents the transpose of a vector; The origin of the airflow coordinate system is at the aircraft's center of mass. The axis points in the direction of airspeed. The axis points downwards along the plane of symmetry of the aircraft. The axis is determined according to the right-hand rule; The Represents the airspeed vector in the ground coordinate system norm; S4, Airspeed vector in the airflow coordinate system Or by using the airspeed vector in the ground coordinate system We obtain the result by performing a coordinate transformation, which satisfies... ; The and All The direction cosine transformation matrix, This is the transformation matrix from the body coordinate system to the airflow coordinate system. This is the transformation matrix from the ground coordinate system to the body coordinate system; The origin of the body coordinate system is the aircraft's center of mass. The axis points towards the nose along the axis of symmetry of the fuselage. The axis points downwards along the plane of symmetry of the fuselage. The axis is determined according to the right-hand rule; The origin of the airflow coordinate system is the aircraft's center of mass. The shaft coincides with the airspeed. The axis points downwards along the plane of symmetry of the fuselage. The axis is determined according to the right-hand rule; The transformation matrix from the body coordinate system to the airflow coordinate system for:

[0023] The transformation matrix from the ground coordinate system to the body coordinate system for:

[0024] The and These are the angle of attack and sideslip angle to be calibrated, respectively, both of which are unknowns. The attitude angle , and These are pitch angle, yaw angle, and roll angle, respectively. The attitude angles are measured by the inertial navigation system and are all known quantities. S5. Combining the relationships in S3 and S4 into an equation, we have:

[0025] S6. The simplified expression of the transformation matrix from the ground coordinate system to the body coordinate system described in S4 is shown in the following formula:

[0026] Combining S2 and simplifying, we get:

[0027]

[0028] S7. By performing inverse trigonometric function calculations on the relation obtained in S6, we can obtain:

[0029]

[0030] The angle of attack and sideslip angle of the aircraft in spin state can be calculated in real time using the two relationships above, thus completing the online calibration of the weather vane sensor in spin state.

Claims

1. A method for online calibration of a weather vane-type airflow sensor under aircraft spin conditions, characterized in that, The online calibration steps are as follows: S1. Assuming the wind speed vector in the ground coordinate system Given the quantities, the origin of the ground coordinate system is determined as the aircraft's takeoff point, and the wind speed vector is... middle: Represents the ground coordinate system. Indicates wind speed. Bold text indicates vectors; S2, trajectory velocity vector in the ground coordinate system The airspeed vector in the ground coordinate system is obtained by measuring with a satellite navigation system and calculating based on the principle of vector triangles. ; S3. Determine the airspeed vector in the airflow coordinate system. ,in: This represents the airflow coordinate system. According to the definition of the airflow coordinate system, we know... , The transpose of a vector; Represents the airspeed vector in the ground coordinate system norm; S4, Airspeed vector in the airflow coordinate system Or by using the airspeed vector in the ground coordinate system We obtain the coordinates by performing a coordinate transformation. ; The and All are cosine transformation matrices. This is the transformation matrix from the body coordinate system to the airflow coordinate system. This is the transformation matrix from the ground coordinate system to the body coordinate system; S5. Combining the relationships in S3 and S4 into an equation, we have: ； S6. The simplified expression of the transformation matrix from the ground coordinate system to the body coordinate system described in S4 is shown in the following formula: Combining S2 and simplifying, we get: S7. By performing inverse trigonometric function calculations on the relation obtained in S6, we can obtain: The and These are the angle of attack and sideslip angle to be calibrated, respectively, both of which are unknowns. attitude angle , and These are pitch angle, yaw angle, and roll angle, respectively. The attitude angles are measured by the inertial navigation system and are all known quantities. The angle of attack and sideslip angle of the aircraft in spin state can be calculated in real time using the two relationships above, thus completing the online calibration of the weather vane sensor in spin state.

2. The online calibration method for a weather vane-type airflow sensor under aircraft spin conditions according to claim 1, characterized in that, The ground coordinate system in S1 The axis points north. The axis points east. The axis points downwards according to the right-hand rule.

3. The online calibration method for a weather vane-type airflow sensor under aircraft spin conditions according to claim 1, characterized in that, The airspeed vector in S2 ; The Indicates airspeed. , and The airspeed vector in the ground coordinate system is respectively axis, and The velocity component of the shaft.

4. The online calibration method for a weather vane-type airflow sensor under aircraft spin conditions according to claim 1, characterized in that, The origin of the airflow coordinate system in S3 is the center of mass of the aircraft. The axis points in the direction of airspeed. The axis points downwards along the plane of symmetry of the aircraft. The axis is determined according to the right-hand rule.

5. The online calibration method for a weather vane-type airflow sensor under aircraft spin conditions according to claim 1, characterized in that, The S4 described and All The direction cosine transformation matrix.

6. The online calibration method for a weather vane-type airflow sensor under aircraft spin conditions according to claim 1, characterized in that, The origin of the body coordinate system mentioned in S4 is the aircraft's center of mass. The axis points towards the nose along the axis of symmetry of the fuselage. The axis points downwards along the plane of symmetry of the fuselage. The axis is determined according to the right-hand rule.

7. The online calibration method for a weather vane-type airflow sensor under aircraft spin conditions according to claim 1, characterized in that, The origin of the airflow coordinate system in S4 is the aircraft's center of mass. The shaft coincides with the airspeed. The axis points downwards along the plane of symmetry of the fuselage. The axis is determined according to the right-hand rule.

8. The online calibration method for a weather vane-type airflow sensor under aircraft spin conditions according to claim 1, characterized in that, The transformation matrix from the body coordinate system to the airflow coordinate system in S4 for: 。 9. The online calibration method for a weather vane-type airflow sensor under aircraft spin conditions according to claim 1, characterized in that, The transformation matrix from the ground coordinate system to the body coordinate system in S4 for: 。

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