Redundancy IRS common mode fault detection method based on installation position difference

Abstract

The invention provides a redundancy IRS common-mode fault detection method based on installation position difference, and belongs to the technical field of aviation navigation. According to the method, the common-mode fault generated by a three-redundancy inertial reference system (IRS) sensor can be detected, the principle is based on the characteristics of the common-mode fault, the installation direction of the IRS is adjusted and set, angular velocity and acceleration information under a coordinate system of the IRS are projected to an aircraft system and then are opposite in direction, the influence of the common-mode fault on a one-way shaft is amplified, and the detection accuracy of the common-mode fault is improved. Therefore, the angular velocity and acceleration information common-mode fault of the sensor can be monitored. The scheme is simple in implementation principle and easy to implement, redundant hardware modules do not need to be added, and the cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of civil aviation navigation, and in particular to a redundant IRS common mode fault detection method based on installation position difference. Background Art

[0002] The inertial navigation system is composed of an inertial measurement unit (IMU), a computer, a chassis, a bracket and other components. The IMU sensitively detects and outputs the acceleration and angular velocity information of the carrier to calculate the carrier's attitude, heading, speed, position and other navigation parameters. Generally, an IMU contains three orthogonally mounted gyroscopes and accelerometers.

[0003] At present, mainstream foreign aircraft models are generally equipped with triple-redundant inertial reference systems. Since there is no difference between the inertial sensors of the triple-redundant inertial reference system, it is possible to produce attitude errors caused by common mode failures. Since attitude directly affects the flight safety of the aircraft, it is very necessary to design a set of attitude faults that can detect common mode failures. Summary of the invention

[0004] The purpose of the present invention is to propose a redundant IRS common mode fault detection method based on installation position difference, by adjusting the installation direction of the inertial reference system, so that the angular velocity and acceleration information in the IRS coordinate system are projected to the aircraft system in the opposite direction, amplifying the influence of the common mode fault on the unidirectional axis, thereby realizing the monitoring of the common mode fault of the sensor angular velocity and acceleration information. The scheme has a simple implementation principle, is easy to implement, does not need to add redundant hardware modules, and has low cost.

[0005] The technical solution of the present invention is to monitor the angular velocity and acceleration information of the inertial reference system by using different installation positions, thereby ensuring the correctness of the attitude information output of the inertial reference system.

[0006] A redundant IRS common mode fault detection method based on installation position difference is proposed, including:

[0007] Define the body coordinate system. The b system represents the body coordinate system. The coordinate axes of the body coordinate system are fixed to the aircraft body. The longitudinal axis of the aircraft along the nose direction is selected as the b system Y b Positive axis direction, Z b The axis direction is perpendicular to the longitudinal axis of the aircraft, with the celestial direction as the positive direction, and the X b , Y b , Z b The axis conforms to the right-hand rule;

[0008] Set the s system as the inertial reference system coordinate system, whose coordinate axes are fixedly connected to the sensors in the inertial reference system; the X coordinates of the first inertial reference system IRS1 in the triple redundant inertial reference system are s1 Axis and Xb Axis reversal, Y s1 Axis and Y b Axis reversal; X of the second inertial reference system IRS2 s2 Axis and X b Axis in the same direction, Y s2 Axis and Y b The axes are in the same direction, and the installation direction of the third inertial reference system IRS3 is consistent with that of the first inertial reference system IRS1 or the second inertial reference system IRS2.

[0009] In a possible embodiment, the common mode fault detection method further includes the following steps:

[0010] S1, obtains the angular velocity information and acceleration information output by the gyro and accelerometer of the triple-redundant inertial reference system through the bus;

[0011] S2, judging the validity and rationality of the data according to the angular velocity information and acceleration information obtained in step S1; if the validity or rationality of the data fails to be judged, directly jump to step S6; otherwise, jump to step S3;

[0012] S3, comparing the angular velocity information output by the three-redundant inertial reference system, setting a detection threshold, and determining whether a common mode fault occurs in each redundant angular velocity information;

[0013] S4, comparing the acceleration information output by the triple-redundant inertial reference system, setting a detection threshold, and determining whether a common mode fault occurs in the accelerometer;

[0014] S5, when any detected amount of the angular velocity information and the acceleration information exceeds the detection threshold, jump to step S6;

[0015] S6: Fault information alarm.

[0016] In a possible embodiment, in step S2, it is determined whether the received angular velocity information and acceleration information are valid according to the data valid bit.

[0017] In a possible embodiment, in step S2, it is determined whether the received angular velocity information and acceleration information are reasonable based on the actual flight maneuverability of the aircraft.

[0018] In a possible embodiment, in step 3, the following steps are specifically included:

[0019] S301, construct the transformation matrix from the s system to the b system of the first inertial reference system IRS1:

[0020]

[0021] Easy to know, is the conversion matrix from b system to s system of IRS1;

[0022] S302, construct the transformation matrix from the s system to the b system of the second inertial reference system IRS2:

[0023]

[0024] Similarly, is the conversion matrix from b system to s system of IRS2;

[0025] S303, when the gyro does not have a common mode failure, the outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 in the s system have the following relationship:

[0026]

[0027] where ω X_theory ,ω Y_theory represents the theoretical value of the angular velocity in frame b, ω X_s1 represents the X-axis angular velocity output of the first inertial reference system IRS1 at s, ω Y_s1 represents the Y-axis angular velocity output of the first inertial reference system IRS1 at s, ω X_s2 represents the X-axis angular velocity output of the second inertial reference system IRS2 at s, ω Y_s2 represents the Y-axis angular velocity output of the second inertial reference system IRS2 at s;

[0028] S304, when a gyro common mode failure occurs, the outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 are respectively

[0029]

[0030] Among them, δω err is the angular velocity error caused by common mode failure;

[0031] S305, convert the angular velocity information to the machine system b, and decouple the common mode angular velocity error from the machine system:

[0032]

[0033]

[0034] Substituting the matrix elements with numerical values, we get the decoupled numerical equation:

[0035] ω X_b1 =ω X_theory -δω err ω X_b2 =ωX_theory +δω err

[0036] ω Y_b1 =ω Y_theory -δω err ,ω Y_b2 =ω Y_theory +δω err

[0037] It can be obtained that after the IRS is installed in reverse, the common-mode angular velocity error is decoupled from the angular velocity of the b system, and the output difference of the two sets of IRS installed in opposite directions under the b system can be used to determine whether an angular velocity common-mode fault occurs;

[0038] S306, using the b-system outputs of two sets of IRS installed in opposite directions, construct the angular velocity common mode error detection quantity:

[0039]

[0040] S307, further introduce the third inertial reference system IRS3. When the installation direction of the third inertial reference system is consistent with that of the second inertial reference system IRS2, the conversion matrix from the s system to the b system of the third inertial reference system IRS3 is:

[0041]

[0042] It can be seen that is the conversion matrix from b system to s system of IRS3;

[0043] S308, when a gyro common mode failure occurs, the outputs of the first inertial reference system IRS1 and the third inertial reference system IRS3 are respectively

[0044]

[0045] Convert to machine system b, and get

[0046]

[0047] Substituting the matrix elements with numerical values, we get the decoupled numerical equation:

[0048] ω X_b1 =ω X_theory -δω err ω X_b3 =ω X_theory +δω err

[0049] ω Y_b1 =ω Y_theory -δω err ,ω Y_b3 =ωY_theory +δω err

[0050] S309, using the angular velocity outputs of the b-system of two sets of IRSs installed in the same direction, a set of angular velocity common mode error detection quantities can be constructed:

[0051]

[0052] S310, when δω err_X =δω err_Y ,δω′ err_X =δω′ err_Y , judging that there is a common mode fault.

[0053] In a possible embodiment, in order to avoid false alarms caused by zero bias errors, the fault detection threshold is further increased. ω , that is, when δω err_X =δω err_Y ,δω′ err_X =δω′ err_Y And |δω err_X |≥threshold ω1 、|δω′ err_X |≥threshold ω2 When , it is determined that the gyroscopes of the first inertial reference system IRS1, the second inertial reference system IRS2, and the third inertial reference system IRS3 have common mode failures.

[0054] In a possible embodiment, in step 4, the following steps are specifically included:

[0055] S401, the installation method of the accelerometers of the first inertial reference system IRS1 and the second inertial reference system IRS2 is the same as the installation method of the gyroscope. When there is no common mode failure, the outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 in the s system have the following relationship:

[0056]

[0057] where a X_theory 、a Y_theory represents the theoretical value of acceleration in system b, a X_s1 represents the X-axis acceleration output of the first inertial reference system IRS1 at s, a Y_s1 represents the Y-axis acceleration output of the first inertial reference system IRS1 at s, a X_s2 represents the X-axis acceleration output of the second inertial reference system IRS2 at s, a Y_s2 represents the Y-axis acceleration output of the second inertial reference system IRS2 at s;

[0058] S402, when a common mode fault of the accelerometer occurs, the acceleration outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 are respectively

[0059]

[0060] where δa err is the angular velocity error caused by common mode failure.

[0061] S403, convert the acceleration information to the machine system b system, and obtain

[0062]

[0063] Substituting the matrix elements with numerical values ​​yields the numerical equation:

[0064] a X_b1 =a X_theory -δa err a X_b2 =a X_theory +δa err

[0065] a Y_b1 =a Y_theory -δa err , a Y_b2 =a Y_theory +δa err

[0066] S404, using the b-series outputs of the two IRSs, construct a set of common-mode error detection quantities

[0067]

[0068] When there is a common-mode fault in the accelerometer, δa err_X =δa err_Y .

[0069] S405, further introducing a third inertial reference system IRS3, the installation direction of which is consistent with that of the second inertial reference system IRS2;

[0070] When a common-mode fault occurs in the accelerometer, the outputs of the first inertial reference system IRS1 and the third inertial reference system IRS3 are

[0071]

[0072] S406, convert the acceleration information to the machine system b system, and obtain

[0073]

[0074] S407, replace the matrix elements with numerical values ​​to obtain the numerical equation:

[0075] a X_b1 =a X_theory -δa err a X_b3 =a X_theory +δa err

[0076] a Y_b1 =a Y_theory -δa err , a Y_b3 =a Y_theory +δa err

[0077] S408, using the b-series outputs of two sets of IRS, a common mode error detection quantity can be constructed

[0078]

[0079] S409, when δa err_X =δa err_Y , δa′ err_X =δa′ err_Y , judging that there is a common mode fault in the accelerometer.

[0080] In a possible embodiment, in order to avoid false alarms caused by zero bias errors, the fault detection threshold may be further increased. a , that is, when δa err_X =δa err_Y , δa′ err_X =δa′ err_Y And |δa err_X |≥threshold a1 、|δa′ err_X |≥threshold a2 When , it is determined that the accelerometers of the first inertial reference system IRS1, the second inertial reference system IRS2, and the third inertial reference system IRS3 have common mode failures.

[0081] Beneficial technical effects of the present invention:

[0082] By adjusting the installation direction of the inertial reference system, the angular velocity and acceleration information in the IRS's own coordinate system are projected onto the aircraft's system in opposite directions, thereby amplifying the impact of common-mode failures on the unidirectional axis and monitoring common-mode failures of the sensor's angular velocity and acceleration information.

[0083] (1) The present invention solves the problem that a redundant inertial navigation system cannot be detected when a common mode failure occurs.

[0084] (2) The present invention can locate common mode failures from the system level to the sensor level, and accurately identify common mode failures occurring in gyroscopes or accelerometers. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] In order to more clearly explain the technical solution implemented by the present invention, the following will be a simple explanation of the drawings needed in the description of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0086] Figure 1 It is a flow chart of a redundant IRS common mode fault detection method based on installation position difference according to the present invention;

[0087] Figure 2 It is a principle diagram of a redundant IRS common mode fault detection method based on installation position difference according to the present invention. DETAILED DESCRIPTION

[0088] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0089] The features of various aspects of the embodiments of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to fully understand the present invention. However, it is obvious to those skilled in the art that the present invention can also be implemented without these specific details. The following description of the embodiments is only for a better understanding of the present invention by illustrating examples of the present invention. The present invention is not limited to any specific settings and methods provided below, but covers all product structures, any improvements, replacements, etc. of the methods covered without departing from the spirit of the present invention. In the various drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity of the present invention.

[0090] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0091] The method may include the following steps:

[0092] Step 1: Define the body coordinate system. The b system represents the body coordinate system. Its coordinate axis is fixed to the aircraft body. The longitudinal axis of the aircraft along the nose direction is selected as the b system Y b Positive axis direction, Z b The axis direction is perpendicular to the longitudinal axis of the aircraft, with the celestial direction as the positive direction, and the X b , Y b , Z b The axis conforms to the right-hand rule, such as Figure 2 As shown;

[0093] Step 2, select the installation direction of the inertial reference system, set the s system as the inertial reference system coordinate system, and its coordinate axis is fixedly connected to the sensor in the inertial reference system; the X axis of the first inertial reference system IRS1 in the three-redundant inertial reference system s1 Axis and X b Axis reversal, Y s1 Axis and Y b Axis reversal; X of the second inertial reference system IRS2 s2 Axis and X b Axis in the same direction, Y s2 Axis and Y b The axes are in the same direction, and the installation direction of the third inertial reference system IRS3 is consistent with that of the first inertial reference system IRS1 or the second inertial reference system IRS2;

[0094] Step 3, obtaining the angular velocity information and acceleration information output by the gyroscope and accelerometer of the triple-redundant inertial reference system through the bus;

[0095] Step 4: After each IRS receives data, it first performs validity judgment according to the valid bits specified in the bus data protocol. If the data is valid, it performs rationality judgment. Otherwise, it is considered that the current data is unavailable and waits for the next data. The rationality of the data is judged according to the actual maneuverability of the civil aircraft. The continuous angular velocity change should not exceed the set threshold, preferably 5° / s. The continuous angular velocity change should not exceed the set threshold, preferably 3m / s. 2 If the difference between the current angular velocity and acceleration and the previous angular velocity and acceleration exceeds the threshold, the data is considered unreasonable, the system issues an alarm, and the process ends;

[0096] Step 5: compare the angular velocity information output by the triple-redundant IRS, set a detection threshold, and determine whether a common mode fault occurs in the angular velocity information.

[0097] Construct the transformation matrix from the s system to the b system of the first inertial reference system IRS1:

[0098]

[0099] Easy to know, is the transformation matrix from the b system to the s system of IRS1.

[0100] Construct the transformation matrix from the s system to the b system of the second inertial reference system IRS2:

[0101]

[0102] Similarly, is the conversion matrix from the b system to the s system of IRS2.

[0103] When there is no common mode failure, the outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 in the s system have the following relationship:

[0104]

[0105] where ω X_theory ,ω Y_theory represents the theoretical value of the angular velocity in frame b, ω X_s1 represents the X-axis angular velocity output of the first inertial reference system IRS1 at s, ω Y_s1 represents the Y-axis angular velocity output of the first inertial reference system IRS1 at s, ω X_s2 represents the X-axis angular velocity output of the second inertial reference system IRS2 at s, ω Y_s2 It represents the Y-axis angular velocity output of the second inertial reference system IRS2 at s.

[0106] When a gyro common mode failure occurs, the outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 are

[0107]

[0108] where δω err is the angular velocity error caused by common mode failure.

[0109] Convert the angular velocity information to the machine system b system and decouple the common mode angular velocity error from the machine system:

[0110]

[0111] Substituting the matrix elements with numerical values, we get the decoupled numerical equation:

[0112] ω X_b1 =ω X_theory -δω err ω X_b2 =ω X_theory +δω err

[0113] ω Y_b1 =ωY_theory -δω err ,ω Y_b2 =ω Y_theory +δω err

[0114] It can be obtained that after the IRS is installed in reverse, the common-mode angular velocity error is decoupled from the b system, and the output difference of the two sets of IRS under the b system can be used to determine whether an angular velocity common-mode fault occurs.

[0115] Using the b-series outputs of two sets of IRS, the angular velocity common-mode error detection quantity can be constructed:

[0116]

[0117] The third inertial reference system IRS3 is further introduced. When the installation direction of the third inertial reference system is consistent with that of the second inertial reference system IRS2, the transformation matrix from the s system to the b system of the third inertial reference system IRS3 is:

[0118]

[0119] It can be seen that It is the conversion matrix from b system to s system of IRS3.

[0120] When a gyro common mode failure occurs, the outputs of the first inertial reference system IRS1 and the third inertial reference system IRS3 are

[0121]

[0122] Convert to machine system b and get

[0123]

[0124] Substituting the matrix elements with numerical values, we get the decoupled numerical equation:

[0125] ω X_b1 =ω X_theory -δω err ω X_b3 =ω X_theory +δω err

[0126] ω Y_b1 =ω Y_theory -δω err ,ω Y_b3 =ω Y_theory +δω err

[0127] Using the angular velocity outputs of the b-system of two IRSs installed in the same direction, a set of angular velocity common-mode error detection quantities can be constructed:

[0128]

[0129] When there is a gyro common mode fault, δω err_X =δω err_Y ,δω′ err_X =δω′ err_Y At the same time, in order to avoid false alarms caused by zero bias errors, the fault detection threshold is further increased. ω , that is, when δω err_X =δω err_Y ,δω′ err_X =δω′ err_Y And |δω err_X |≥threshold ω1 、|δω′ err_X |≥threshold ω2 When , it is determined that the gyroscopes of the first inertial reference system IRS1, the second inertial reference system IRS2, and the third inertial reference system IRS3 have common mode failures, an alarm is issued, and the process ends; otherwise, step 6 is performed.

[0130] Step 6: Compare the acceleration information output by the triple-redundant IRS, set a detection threshold, and determine whether the accelerometer has a common mode fault.

[0131] The installation method of the accelerometers of the first inertial reference system IRS1 and the second inertial reference system IRS2 is the same as the installation method of the gyroscope. When there is no common mode failure, the output of the first inertial reference system IRS1 and the second inertial reference system IRS2 in the s system has the following relationship:

[0132]

[0133] where a X_theory 、a Y_theory represents the theoretical value of acceleration in system b, a X_s1 represents the X-axis acceleration output of the first inertial reference system IRS1 at s, a Y_s1 represents the Y-axis acceleration output of the first inertial reference system IRS1 at s, a X_s2 represents the X-axis acceleration output of the second inertial reference system IRS2 at s, a Y_s2 It represents the Y-axis acceleration output of the second inertial reference system IRS2 at s.

[0134] When a common mode fault occurs in the accelerometer, the acceleration outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 are

[0135]

[0136] where δa err is the angular velocity error caused by common mode failure.

[0137] Convert the acceleration information to the machine system b system, and get

[0138]

[0139] Substituting the matrix elements with numerical values ​​yields the numerical equation:

[0140] a X_b1 =a X_theory -δa err a X_b2 =a X_theory +δa err

[0141] a Y_b1 =a Y_theory -δa err , a Y_b2 =a Y_theory +δa err

[0142] Using the b-series outputs of two IRSs, a common-mode error detection device can be constructed.

[0143]

[0144] When there is a common-mode fault in the accelerometer, δa err_X =δa err_Y .

[0145] A third inertial reference system IRS3 is further introduced, and its installation direction is consistent with that of the second inertial reference system IRS2;

[0146] When a common-mode fault occurs in the accelerometer, the outputs of the first inertial reference system IRS1 and the third inertial reference system IRS3 are

[0147]

[0148] Convert the acceleration information to the machine system b system, and get

[0149]

[0150] Substituting the matrix elements with numerical values ​​yields the numerical equation:

[0151] a X_b1 =a X_theory -δa err a X_b3 =a X_theory +δa err

[0152] a Y_b1 =a Y_theory -δa err , a Y_b3 =a Y_theory +δa err

[0153] Using the b-series outputs of two IRSs, a set of common-mode error detection quantities can be constructed:

[0154]

[0155] When there is a common-mode fault in the accelerometer, δa err_X =δa err_Y ,δa′ err_X =δa′ err_Y At the same time, in order to avoid false alarms caused by zero bias errors, the fault detection threshold can be further increased. a , that is, when δa err_X =δa err_Y ,δa′ err_X =δa′ err_Y And |δa err_X |≥threshold a1 、|δa′ err_X |≥threshold a2 When , it is determined that the accelerometers of the first inertial reference system IRS1, the second inertial reference system IRS2, and the third inertial reference system IRS3 have common mode failures, and the system alarms.

[0156] Step 7, fault information alarm. When any detection value of the angular velocity information and the acceleration information exceeds the detection threshold, the system sends out an alarm message and the process ends.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A redundant IRS common mode fault detection method based on installation position difference, characterized in that: include: Define the body coordinate system. The b system represents the body coordinate system. The coordinate axes of the body coordinate system are fixed to the aircraft body. The longitudinal axis of the aircraft along the nose direction is selected as the b system Y b Positive axis direction, Z b The axis direction is perpendicular to the longitudinal axis of the aircraft, with the celestial direction as the positive direction, and the X b , Y b , Z b The axis conforms to the right-hand rule; the s system is set as the inertial reference system coordinate system, and its coordinate axis is fixedly connected to the sensor in the inertial reference system; the X s1 Axis and X b Axis reversal, Y s1 Axis and Y b Axis reversal; X of the second inertial reference system IRS2 s2 Axis and X b Axis in the same direction, Y s2 Axis and Y b The axes are in the same direction, and the installation direction of the third inertial reference system IRS3 is consistent with that of the first inertial reference system IRS1 or the second inertial reference system IRS2.

2. The redundant IRS common mode fault detection method based on installation position difference according to claim 1 is characterized in that: The common mode fault detection method further comprises the following steps: S1, obtains the angular velocity information and acceleration information output by the gyro and accelerometer of the triple-redundant inertial reference system through the bus; S2, judging the validity and rationality of the data according to the angular velocity information and acceleration information obtained in step S1; if the validity or rationality of the data fails to be judged, directly jump to step S6; otherwise, jump to step S3; S3, comparing the angular velocity information output by the three-redundant inertial reference system, setting a detection threshold, and determining whether a common mode fault occurs in each redundant angular velocity information; S4, comparing the acceleration information output by the triple-redundant inertial reference system, setting a detection threshold, and determining whether a common mode fault occurs in the accelerometer; S5, when any detected amount of the angular velocity information and the acceleration information exceeds the detection threshold, jump to step S6; S6: Fault information alarm.

3. The redundant IRS common mode fault detection method based on installation position difference according to claim 2 is characterized in that: In step S2, whether the received angular velocity information and acceleration information are valid is determined according to the data valid bit.

4. The redundant IRS common mode fault detection method based on installation position difference according to claim 2 is characterized in that: In step S2, whether the received angular velocity information and acceleration information are reasonable is determined based on the actual flight maneuverability of the aircraft.

5. The redundant IRS common mode fault detection method based on installation position difference according to claim 2 is characterized in that: In the step 3, the following steps are specifically included: S301, construct the transformation matrix from the s system to the b system of the first inertial reference system IRS1: Easy to know, is the conversion matrix from b system to s system of IRS1; S302, construct the transformation matrix from the s system to the b system of the second inertial reference system IRS2: Similarly, is the conversion matrix from b system to s system of IRS2; S303, when the gyro does not have a common mode failure, the outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 in the s system have the following relationship: where ω X_theory ,ω Y_theory represents the theoretical value of the angular velocity in frame b, ω X_s1 represents the X-axis angular velocity output of the first inertial reference system IRS1 at s, ω Y_s1 represents the Y-axis angular velocity output of the first inertial reference system IRS1 at s, ω X_s2 represents the X-axis angular velocity output of the second inertial reference system IRS2 at s, ω Y_s2 represents the Y-axis angular velocity output of the second inertial reference system IRS2 at s; S304, when a gyro common mode failure occurs, the outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 are respectively Among them, δω err is the angular velocity error caused by common mode failure; S305, convert the angular velocity information to the machine system b, and decouple the common mode angular velocity error from the machine system: Substituting the matrix elements with numerical values, we get the decoupled numerical equation: oh X_b1 =ω X_theory -here err oh X_b2 =ω X_theory +see err oh Y_b1 =ω Y_theory -here err Oh, oh Y_b2 =ω Y_theory +see err It can be obtained that after the IRS is installed in reverse, the common-mode angular velocity error is decoupled from the angular velocity of the b system, and the output difference of the two sets of IRS installed in opposite directions under the b system can be used to determine whether an angular velocity common-mode fault occurs; S306, using the b-system outputs of two sets of IRS installed in opposite directions, construct the angular velocity common mode error detection quantity: S307, further introduce the third inertial reference system IRS3. When the installation direction of the third inertial reference system is consistent with that of the second inertial reference system IRS2, the conversion matrix from the s system to the b system of the third inertial reference system IRS3 is: It can be seen that is the conversion matrix from b system to s system of IRS3; S308, when a gyro common mode failure occurs, the outputs of the first inertial reference system IRS1 and the third inertial reference system IRS3 are respectively Convert to machine system b, and get Substituting the matrix elements with numerical values, we get the decoupled numerical equation: oh X_b1 =ω X_theory -here err oh X_b3 =ω X_theory +see err oh Y_b1 =ω Y_theory -here err Oh, oh Y_b3 =ω Y_theory +see err S309, using the angular velocity outputs of the b system of two sets of IRSs installed in the same direction, a set of angular velocity common mode error detection quantities can be constructed: S310, when δω err_X =δω err_Y ,δω′ err_X =δω′ err_Y , judging that there is a common mode fault.

6. The redundant IRS common mode fault detection method based on installation position difference according to claim 2 is characterized in that: Set the fault detection threshold ω , that is, when δω err_X =δω err_Y ,δω′ err_X =δω′ err_Y And |δω err_X |≥threshold ω1 、|δω′ err_X |≥threshold ω2 When , it is determined that the gyroscopes of the first inertial reference system IRS1, the second inertial reference system IRS2, and the third inertial reference system IRS3 have common mode failures.

7. The redundant IRS common mode fault detection method based on installation position difference according to claim 2 is characterized in that: In step 4, the following steps are specifically included: S401, the installation method of the accelerometers of the first inertial reference system IRS1 and the second inertial reference system IRS2 is the same as the installation method of the gyroscope. When there is no common mode failure, the outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 in the s system have the following relationship: where a X_theory 、a Y_theory represents the theoretical value of acceleration in system b, a X_s1 represents the X-axis acceleration output of the first inertial reference system IRS1 at s, a Y_s1 represents the Y-axis acceleration output of the first inertial reference system IRS1 at s, a X_s2 represents the X-axis acceleration output of the second inertial reference system IRS2 at s, a Y_s2 represents the Y-axis acceleration output of the second inertial reference system IRS2 at s; S402, when a common mode fault of the accelerometer occurs, the acceleration outputs of the first inertial reference system IRS1 and the second inertial reference system IRS2 are respectively where δa err is the angular velocity error caused by common mode failure. S403, convert the acceleration information to the machine system b system, and obtain Substituting the matrix elements with numerical values ​​yields the numerical equation: in X_b1 = yes X_theory -δa err in X_b2 = yes X_theory +δa err in Y_b1 = yes Y_theory -δa err ,in Y_b2 = yes Y_theory +δa err S404, using the b-series outputs of the two IRSs, construct a set of common-mode error detection quantities When there is a common-mode fault in the accelerometer, δa err_X =δa err_Y . S405, further introducing a third inertial reference system IRS3, the installation direction of which is consistent with that of the second inertial reference system IRS2; When a common-mode fault occurs in the accelerometer, the outputs of the first inertial reference system IRS1 and the third inertial reference system IRS3 are S406, convert the acceleration information to the machine system b system, and obtain S407, replace the matrix elements with numerical values ​​to obtain the numerical equation: in X_b1 = yes X_theory -δa err in X_b3 = yes X_theory +δa err in Y_b1 = yes Y_theory -δa err ,in Y_b3 = yes Y_theory +δa err S408, using the b-series outputs of two sets of IRS, a common mode error detection quantity can be constructed S409, when δa err_X =δa err_Y ,δa′ err_X =δa′ err_Y , it is determined that there is a common mode failure of the accelerometer.

8. The redundant IRS common mode fault detection method based on installation position difference according to claim 2 is characterized in that: Set the fault detection threshold a , that is, when δa err_X =δa err_Y ,δa′ err_X =δa′ err_Y And |δa err_X |≥threshold a1 、|δa′ err_X |≥threshold a2 When , it is determined that the accelerometers of the first inertial reference system IRS1, the second inertial reference system IRS2, and the third inertial reference system IRS3 have common mode failures.

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