Five-axis redundant strapdown inertial measurement unit system and fault detection and reconstruction method thereof

Abstract

The present application relates to inertial navigation error compensation, in particular to a five-axis redundant strapdown inertial measurement unit system and fault detection and reconstruction method, for solving the problem of the existing redundant inertial navigation system, which has the problems of large volume, high cost and single fault detection method, which leads to the problem of navigation accuracy reduction caused by inevitable hardware failure. The present application comprises a power supply, a direct current power supply filtering circuit and a direct current power supply module, a five-axis inertial measurement unit, an inertial measurement unit computer circuit, an analog-to-digital conversion circuit, a five-axis redundant strapdown inertial measurement unit system; and through the steps of constructing an inertial measurement unit measurement coordinate system, parameter setting, fault detection and navigation information reconstruction, finally using the data of the gyroscope or accelerometer in the normal inertial instrument which is not isolated, through the corresponding reconstruction algorithm, the navigation information is calculated. The redundant inertial navigation system of the present application has the functions of fault detection and self-reconstruction, and has good reliability and good performance.

Description

Technical Field

[0001] This invention relates to an inertial navigation system error compensation system and method, specifically to a five-axis redundant strapdown inertial navigation system and its fault detection and reconstruction method. Background Technology

[0002] An inertial navigation system (INS) is an advanced navigation system that does not rely on external information. It measures the angular and linear acceleration of a vehicle using inertial sensors such as accelerometers and gyroscopes, and then calculates the vehicle's attitude, velocity, and position. In practical engineering applications, the system's reliability and accuracy depend heavily on the performance and operating status of the internal inertial instruments. Instrument malfunctions or performance degradation can directly lead to distorted navigation information or even system failure.

[0003] To improve the reliability of inertial navigation systems, the traditional approach is to select highly reliable and accurate inertial instruments to reduce the probability of failure at the hardware level. However, improving the performance of individual components faces challenges such as high technical barriers, complex processes, long development cycles, and significantly increased costs, which greatly limits their practical application. Therefore, the industry has gradually developed a technical approach combining "redundant configuration" with "fault diagnosis." This involves configuring more than three axes of inertial instruments in the system. When some instruments fail, the information from the remaining healthy instruments is used to reconstruct complete navigation parameters, thereby maintaining system functionality.

[0004] Among redundancy schemes, quad-axis redundant systems are an early and widely studied structure, typically employing a three-orthogonal-one-skewed instrument layout and utilizing algorithms such as the equivalent space method and the parity vector method for fault detection. However, these methods have limitations in fault isolation capabilities, making it difficult to accurately identify specific faulty instruments. To overcome the shortcomings of quad-axis redundancy, Chinese patent CN109813309A discloses a dual-fault isolation method for a six-gyroscope redundant strapdown inertial navigation system, employing a regular dodecahedral configuration and using methods such as generalized likelihood ratio and maximum likelihood estimation for dual-fault isolation. While this scheme can theoretically handle more complex fault scenarios, it results in a significant increase in system size, weight, power consumption, and cost, along with a sharp increase in algorithm complexity, while the improvement in system reliability and navigation accuracy is not proportional, leading to a low overall cost-effectiveness.

[0005] In summary, existing inertial navigation redundancy technologies still have the following shortcomings: First, four-axis redundancy schemes are limited by redundancy and algorithms, resulting in weak fault isolation capabilities and affecting reconstruction accuracy; second, while six-axis and above redundancy schemes improve fault tolerance, they require excessive hardware resources and have overly complex algorithms, limiting their potential for engineering applications; third, existing fault diagnosis methods mostly focus on software analysis of instrument output data, with insufficient monitoring of key hardware links such as power supplies, making it difficult to cover hardware faults caused by power supply anomalies, resulting in blind spots in diagnosis. Summary of the Invention

[0006] The purpose of this invention is to address the technical problems in existing inertial navigation systems, such as the weak fault isolation capability of four-axis schemes due to insufficient redundancy, the poor engineering applicability of six-axis and above schemes due to excessive hardware resource investment and high algorithm complexity, and the incomplete fault coverage of existing fault diagnosis methods due to the lack of hardware link monitoring dimensions. The invention provides a five-axis redundant strapdown inertial navigation system and its fault detection and reconstruction method.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a five-axis redundant strapdown inertial navigation system, comprising a power supply, a DC power filter circuit, and a DC power module connected in sequence; its special feature is that it also includes a five-axis inertial measurement unit, an inertial navigation computer, and an analog-to-digital conversion circuit; The five-axis inertial measurement unit includes three orthogonally mounted X, Y, and Z inertial instruments, and two obliquely mounted S and T inertial instruments. The X inertial instrument includes a Gx gyroscope and an Ax accelerometer; the Y inertial instrument includes a Gy gyroscope and an Ay accelerometer; the Z inertial instrument includes a Gz gyroscope and an Az accelerometer; the S inertial instrument includes a Gs gyroscope and an As accelerometer; and the T inertial instrument includes a Gt gyroscope and an At accelerometer. The DC power supply module includes modules MK1, MK2, MK3, MK4, MK5, and MK6. The output terminal of module MK1 is connected to the power input terminals of gyroscopes Gx and Gs, respectively; the output terminal of module MK2 is connected to the power input terminals of gyroscopes Gz and Gt, respectively; the output terminal of module MK3 is connected to the power input terminal of gyroscope Gy; the output terminal of module MK4 is connected to the power input terminals of accelerometers Ax and As, respectively; the output terminal of module MK5 is connected to the power input terminals of accelerometers Az and At, respectively; and the output terminal of module MK6 is connected to the power input terminal of accelerometer Gy. The output terminals of the MK4, MK5, and MK6 modules are all connected to the power input terminal of the analog-to-digital converter circuit; the data input terminal of the analog-to-digital converter circuit is connected to the data output terminals of the Ax, As, Az, At, and Ay accelerometers. The output terminals of the MK5 and MK6 modules are both connected to the power input terminal of the inertial navigation system (INS). The data input terminal of the INS is connected to the data output terminals of the Gx, Gs, Gz, Gt, and Gy gyroscopes and the analog-to-digital converter circuit, respectively. It is used to perform fault diagnosis based on the power supply voltage of each gyroscope and accelerometer, as well as the pulse signal emitted by each gyroscope and accelerometer. Then, based on the fault diagnosis results, it performs data reconstruction and error compensation calculations, and outputs navigation information.

[0008] Furthermore, the Gx, Gs, Gz, Gt, and Gy gyroscopes are all fiber optic gyroscopes; The Ax, As, Az, At, and Ay accelerometers mentioned are all quartz accelerometers.

[0009] Meanwhile, this invention also provides a fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system, which is characterized by including the following steps: Step 1: Assemble the above-mentioned five-axis redundant strapdown inertial navigation system; Step 2: Construct the inertial measurement coordinate system An inertial measurement coordinate system is constructed using three orthogonally mounted X, Y, and Z inertial instruments as orthogonal axes. The X, Y, and Z inertial instruments are respectively located at... , , axis; Step 3, Parameter Setting S3.1 Set the fault voltage threshold for each power module; S3.2 Set the output data saturation threshold for each instrument; S3.3, Predefined multiple refactoring working modes; Step 4, Fault Detection S4.1 Power Supply Detection The inertial navigation computer detects the output voltage of each power module. When the output voltage of any power module exceeds the corresponding fault voltage threshold, all instruments powered by that module are determined to be faulty. S4.2 Data Saturation Detection The inertial navigation system computer performs saturation detection on the output data of each instrument. When the output data exceeds the set output data saturation threshold, the instrument is determined to be faulty. S4.3. Based on the detection results of steps S4.1 and S4.2, generate the corresponding fault status word; Step 5: Navigation Information Reconstruction S5.1. Based on the fault status word generated in step S4.3, select the corresponding instrument's output data to isolate; S5.2. Based on the fault status word, select the corresponding refactoring working mode from among the predefined multiple refactoring working modes; S5.3 The inertial computer uses data from normal instruments that are not isolated to calculate navigation information through the corresponding reconstruction algorithm, thus completing the fault detection and navigation information reconstruction of the five-axis redundant strapdown inertial group.

[0010] Furthermore, in step S5.3, the reconstruction algorithm is specifically as follows: When the gyroscopes and accelerometers in the three orthogonally mounted X, Y, and Z inertial instruments are all functioning correctly, their output data can be directly used for strapdown calculation to determine navigation information. When any of the gyroscopes or accelerometers in the three orthogonally mounted X, Y, and Z inertial instruments malfunctions, the corresponding normal gyroscopes and / or accelerometers in the obliquely mounted S and / or T inertial instruments are used to calculate the output data equivalent to the faulty component on the corresponding axis in the orthogonal three axes of the inertial measurement coordinate system through a projection synthesis algorithm.

[0011] Further, in step S5.3, the projection synthesis algorithm is specifically as follows: Using the output data of the corresponding normal gyroscopes and / or accelerometers in the obliquely mounted S-inertial instrument and / or T-inertial instrument, the components of the corresponding axes in the orthogonal three axes of the inertial measurement coordinate system are calculated through an orthogonal decomposition algorithm. These components are then used to replace the output data of the faulty gyroscopes and / or accelerometers to calculate navigation information.

[0012] Furthermore, in step S5.3, when all three orthogonally mounted accelerometers Ax, Ay, and Az are functioning correctly, the strapdown calculation formula is: ; In the formula, This represents the redundancy configuration matrix of the accelerometers in the inertial measurement coordinate system. , , These are the actual output values ​​of the Ax, Ay, and Az accelerometers along the measurement axes; , , The acceleration components of the orthogonal three axes of the inertial measurement coordinate system; , , , , , This is the installation error angular coefficient of the accelerometer relative to the inertial measurement coordinate system.

[0013] Furthermore, in step S5.3, if one of the three orthogonally mounted accelerometers Ax, Ay, and Az fails, the output data of accelerometers As and / or At are used for strapdown calculation via projection synthesis; specifically as follows: When the Ax accelerometer malfunctions, the formula for strapdown calculation using the output data of the Ay, Az, As, and At accelerometers is as follows: ; In the formula, This represents the redundancy configuration matrix of the accelerometers in the inertial measurement coordinate system. , , , The actual output values ​​of the Ay, Az, As, and At accelerometers along the measurement axis; , , The acceleration components of the orthogonal three axes of the inertial measurement coordinate system; , , , This is the installation error angular coefficient of the accelerometer relative to the inertial measurement coordinate system; , , Let be the angles between the As accelerometer and the three orthogonal axes of the inertial measurement coordinate system; , , Let be the angles between the At accelerometer and the three orthogonal axes of the inertial measurement coordinate system; When accelerometers Ax and As malfunction, the formula for strapdown calculation using the output data of accelerometers Ay, Az, and At is as follows: ; When the Ay accelerometer malfunctions, the formula for strapdown calculation using the output data of the Ax, Az, As, and At accelerometers is as follows: ; In the formula, This represents the actual output value of the Ax accelerometer along the measurement axis; , The installation error angular coefficient of the accelerometer relative to the inertial measurement coordinate system; When the Az accelerometer malfunctions, the formula for strapdown calculation using the output data of the Ax, Ay, As, and At accelerometers is as follows: ; When accelerometers Az and At malfunction, the formula for strapdown calculation using the output data of accelerometers Ax, Ay, and As is as follows: .

[0014] Furthermore, in step S5.3, when all three orthogonally mounted gyroscopes Gx, Gy, and Gz are functioning correctly, the strapdown calculation formula is: ; In the formula, This represents the redundancy configuration matrix of the gyroscope in the inertial measurement coordinate system. , , These are the actual output values ​​of the Gx, Gy, and Gz gyroscopes along the measurement axes; , , To measure the angular velocity components of gyroscopes along the orthogonal three axes of the inertial measurement system; , , , , , This represents the installation error angle coefficient of the gyroscope relative to the inertial measurement coordinate system.

[0015] Furthermore, in step S5.3, if one of the three orthogonally mounted Gx, Gy, and Gz gyroscopes fails, the output data of the Gs and / or Gt gyroscopes are used for strapdown calculation via projection synthesis; specifically as follows: When the Gx gyroscope malfunctions, the formula for strapdown calculation using the output data of the Gy, Gz, Gs, and Gt gyroscopes is as follows: ; In the formula, This represents the redundancy configuration matrix of the gyroscope in the inertial measurement coordinate system. , , , These are the actual output values ​​of the Gy, Gz, Gs, and Gt gyroscopes along the measurement axes; , , To measure the angular velocity components of the orthogonal three-axis gyroscope in the inertial measurement coordinate system; , , , The installation error angle of the gyroscope relative to the inertial measurement coordinate system; , , The angles between the Gs gyroscope and the three orthogonal axes of the inertial measurement coordinate system are respectively. , , Let Gt be the angle between the gyroscope and the three orthogonal axes of the inertial measurement coordinate system; When the Gx and Gs gyroscopes malfunction, the formula for strapdown calculation using the output data of the Gy, Gz, and Gt gyroscopes is as follows: ; When the Gy gyroscope malfunctions, the formula for strapdown calculation using the output data of the Gx, Gz, Gs, and Gt gyroscopes is as follows: ; In the formula, This represents the actual output value of the Gx gyroscope along the measurement axis; , The installation error angle of the gyroscope relative to the inertial measurement coordinate system; When the Gz gyroscope malfunctions, the formula for strapdown calculation using the output data of the Gx, Gy, Gs, and Gt gyroscopes is as follows: ; When the Gz and Gt gyroscopes malfunction, the formula for strapdown calculation using the output data of the Gx, Gy, and Gs gyroscopes is as follows: .

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a five-axis redundant strapdown inertial measurement unit system. By adopting a "three-orthogonal + two-oblique" five-axis inertial measurement unit structure, it achieves the best balance between four-axis redundancy and six-axis or higher redundancy, achieving fault detection and isolation capabilities comparable to high-order redundant systems at a lower hardware cost. At the same time, through the synchronous parallel detection of power supply monitoring and data saturation detection, a dual fault diagnosis barrier of "hardware power link monitoring" and "software output data judgment" is formed, which can effectively identify hidden faults that cannot be detected by a single detection method and significantly reduce the fault missed rate. Based on the unique power redundancy topology, when a power module fails, the specific instrument combination it supplies can be directly and accurately located, realizing a fast and accurate mapping from power abnormality to specific fault channels and simplifying the fault decision-making logic.

[0017] (2) The present invention provides a five-axis redundant strapdown inertial navigation system, wherein power monitoring is performed by the inertial navigation computer to perform distributed monitoring of different power paths, and combined with two sets of detection results, it can not only determine the fault, but also accurately locate which power module or which specific instrument is faulty, providing key information for system maintenance and health management; at the same time, by using high-performance fiber optic gyroscopes and quartz accelerometers, and ensuring that the inclined instruments have the same angle with the orthogonal coordinate system, the system is provided with high-precision original measurement data and symmetrical redundancy structure, which is the fundamental guarantee for realizing high-precision navigation calculation and effective information reconstruction.

[0018] (3) The present invention provides a fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system. From coordinate system establishment and parameter setting to dual-channel fault detection and status word generation, and finally to mode selection and information reconstruction, a set of logically rigorous and clearly defined automated fault handling procedures are formed, which ensures the high feasibility and repeatability of the method in engineering.

[0019] (4) The present invention provides a fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system. The reconstruction algorithm intelligently distinguishes between two situations: "normal orthogonal axis" and "orthogonal axis fault". The former uses the highest precision direct calculation, while the latter uses the projection synthesis method based on the installation matrix to maximize the use of the oblique axis information, thereby providing the system with the best navigation accuracy under the current conditions in various fault modes. At the same time, the calculation formula based on the redundant configuration matrix and the installation error angle is a high-precision reconstruction method that has been rigorously mathematically derived. It fully considers the specific spatial geometric relationship of the instrument and can recover the orthogonal three-axis navigation parameters of the inertial navigation measurement coordinate system with the greatest accuracy from the remaining normal instrument information. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a first embodiment of a five-axis redundant strapdown inertial navigation system according to the present invention; Figure 2 This is a schematic diagram of the inertial measurement coordinate system constructed in step 2 of an embodiment of the fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system of the present invention.

[0021] Figure 3 This is a partial flowchart of step 4, fault detection, in Embodiment 2 of the fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system of the present invention. Detailed Implementation

[0022] To better understand the purpose, structure, and function of this invention, the following detailed description, in conjunction with the accompanying drawings, provides an explanation of a five-axis redundant strapdown inertial navigation system and its fault detection and reconstruction method.

[0023] Example 1 This invention provides a five-axis redundant strapdown inertial navigation system, such as... Figure 1 As shown, it includes a power supply, a DC power filter circuit, a DC power module, a five-axis inertial measurement unit, an inertial computer, and an analog-to-digital conversion circuit.

[0024] The power supply is a 28V primary power supply, whose output terminal is connected to the input terminal of the DC power supply filter circuit. The output terminal of the DC power supply filter circuit is connected to the input terminal of the DC power supply module, which supplies power to the internal components of the five-axis redundant strapdown inertial navigation system.

[0025] The five-axis inertial measurement unit includes three orthogonally mounted X, Y, and Z inertial instruments (hereinafter referred to as X, Y, and Z inertial instruments) and two obliquely mounted S and T inertial instruments (hereinafter referred to as S and T inertial instruments). The X inertial instrument includes a Gx fiber optic gyroscope and an Ax quartz accelerometer; the Y inertial instrument includes a Gy fiber optic gyroscope and an Ay quartz accelerometer; the Z inertial instrument includes a Gz fiber optic gyroscope and an Az quartz accelerometer; the S inertial instrument includes a Gs fiber optic gyroscope and an As quartz accelerometer; and the T inertial instrument includes a Gt fiber optic gyroscope and an At quartz accelerometer.

[0026] The DC power supply modules include MK1, MK2, MK3, MK4, MK5 and MK6 (hereinafter referred to as MK1, MK2, MK3, MK4, MK5 and MK6 modules), which are used to output ±5.2V, ±15V and +5V secondary power supplies respectively to power the five-axis inertial measurement unit, inertial computer and digital-to-analog conversion circuit.

[0027] The output of module MK1 is connected to the power input of fiber optic gyroscopes Gx and Gs, respectively, to power these gyroscopes. The output of module MK2 is connected to the power input of fiber optic gyroscopes Gz and Gt, respectively, to power these gyroscopes. The output of module MK3 is connected to the power input of fiber optic gyroscope Gy, respectively, to power this gyroscope. The output of module MK4 is connected to the power input of quartz accelerometers Ax and As, respectively, to power these quartz accelerometers. The output of the MK5 module is connected to the power input of the Az and At quartz accelerometers, respectively, to power them. The output of the MK6 module is connected to the power input of the Ay quartz accelerometer, to power it. Together, they form a 2-1-2 combination for redundant secondary power supply design. If the power supply of one quartz accelerometer or fiber optic gyroscope malfunctions, the remaining three quartz accelerometers or fiber optic gyroscopes can still be powered normally, ensuring the normal operation of the five-axis redundant strapdown inertial navigation system. The outputs of the MK5 and MK6 modules are both connected to the power input of the inertial navigation computer, to power it. The outputs of the MK4, MK5, and MK6 modules are all connected to the power input of the analog-to-digital converter circuit, to power it.

[0028] The data output terminals of the Ax, As, Az, At, and Ay quartz accelerometers are connected to the data input terminals of the analog-to-digital converter (ADC); the data output terminal of the ADC is connected to the data input terminal of the inertial navigation system (INS); the data input terminal of the INS is connected to the data output terminals of the Gx, Gs, Gz, Gt, and Gy fiber optic gyroscopes and the ADC, respectively. This is used to perform fault diagnosis based on the power supply voltage of each gyroscope and accelerometer, as well as the pulse signals emitted by each gyroscope and accelerometer. Then, based on the fault diagnosis results, data reconstruction and error compensation calculations are performed before outputting navigation information.

[0029] This invention discloses a fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system, the specific steps of which are as follows: Step 1: Prepare the above-mentioned five-axis redundant strapdown inertial navigation system; Step 2: Construct the inertial measurement coordinate system Build as Figure 2 The inertial measurement coordinate system shown is constructed using three orthogonally mounted X, Y, and Z inertial instruments as orthogonal axes. The X, Y, and Z inertial instruments are respectively positioned at... , , Axis; Let S be the angle between the orthogonal three axes of the inertial instrument and the inertial measurement coordinate system. , , The angles between the orthogonal three axes of the T inertial instrument and the inertial measurement coordinate system are respectively , , .

[0030] The installation polarities of each instrument in the inertial measurement coordinate system are as follows: Three orthogonal fiber optic gyroscopes (Gx, Gy, and Gz) are positioned along each of the three orthogonal axes of the inertial measurement system (INS). Two obliquely positioned fiber optic gyroscopes (Gs and Gt) are positioned along the S-axis and T-axis, respectively. Three orthogonal quartz accelerometers (Ax, Ay, and Az) are positioned along each of the three orthogonal axes of the INS. Two obliquely positioned quartz accelerometers (As and At) are positioned along the S-axis and T-axis, respectively. The angles and orientations between the sensitive axes of the As and At quartz accelerometers and the three orthogonal axes of the INS are consistent with those of the Gs and Gt fiber optic gyroscopes.

[0031] Step 3, Parameter Setting S3.1 Set the fault voltage threshold for modules MK1, MK2, MK3, MK4, MK5 and MK6 respectively; S3.2 Set the saturation threshold for the output data of the gyroscope and accelerometer in the X inertial instrument, Y inertial instrument, Z inertial instrument, S inertial instrument and T inertial instrument respectively; S3.3, and then predefine at least several refactoring working modes; Step 4, Fault Detection S4.1 Power Supply Detection The inertial navigation computer detects the output voltages of modules MK1, MK2, MK3, MK4, MK5, and MK6 respectively. When the output voltage of any power module exceeds the corresponding fault voltage threshold, all instruments powered by that module are deemed to be faulty.

[0032] S4.2 Data Saturation Detection The inertial navigation system computer performs saturation detection on the output data of the Ax, As, Az, At and Ay quartz accelerometers and the Gx, Gs, Gz, Gt and Gy fiber optic gyroscopes respectively. When the output data exceeds the set saturation threshold, the instrument is determined to be faulty. S4.3. Based on the detection results of steps S4.1 and S4.2, generate the corresponding fault status word. The fault status word corresponds one-to-one with the various reconfiguration working modes predefined in step S3.3.

[0033] Step 5: Navigation Information Reconstruction Based on the aforementioned fault detection results, the system reconstructs navigation information according to the following steps: Step 5.1: Based on the fault status word generated in step 4.3, select the corresponding instrument's output data to isolate; Step 5.2: Based on the fault status word, select the corresponding refactoring working mode from the predefined multiple refactoring working modes; Step 5.3: The inertial navigation computer uses the output data of the unisolated normal inertial instruments and the corresponding reconstruction algorithm to calculate navigation information, completing the fault detection and navigation information reconstruction of the five-axis redundant strapdown inertial group. The specific reconstruction algorithm is as follows: When the gyroscopes and accelerometers in the three orthogonally mounted X, Y, and Z inertial instruments are all functioning correctly (i.e., X, Y, and Z inertial instruments or X, Y, Z, S, and T inertial instruments), their output data are directly used for strapdown calculation to determine navigation information.

[0034] When any of the gyroscopes or accelerometers in the three orthogonally mounted X, Y, and Z inertial instruments malfunctions, the corresponding normal gyroscopes and / or accelerometers in the obliquely mounted S and / or T inertial instruments are used to calculate the output data equivalent to the faulty component on the corresponding axis in the orthogonal three axes of the inertial measurement coordinate system through a projection synthesis algorithm.

[0035] The specific algorithm for overall projection synthesis is as follows: Using the output data of the corresponding normal gyroscopes and / or accelerometers in the obliquely mounted S-inertial instrument and / or T-inertial instrument, the components of the corresponding axes in the orthogonal three axes of the inertial measurement coordinate system are calculated through an orthogonal decomposition algorithm. These components are then used to replace the output data of the faulty gyroscopes and / or accelerometers to calculate navigation information.

[0036] The following uses an accelerometer as an example to illustrate the acceleration components of the actual accelerometer output that are orthogonal to the three axes of the inertial measurement coordinate system. , , The calculation relationship is shown in formula (1): (1); in, This represents the redundancy configuration matrix of the accelerometers in the inertial measurement coordinate system. , , , , These are the actual output values ​​of the accelerometers Ax, Ay, Az, As, and At along the measurement axis; , , The acceleration components of the orthogonal three axes of the inertial measurement coordinate system; , , , , , The installation error angular coefficient of the accelerometer relative to the inertial measurement coordinate system; , , Let be the angles between the As accelerometer and the three orthogonal axes of the inertial measurement coordinate system; , , Let be the angles between the At accelerometer and the three orthogonal axes of the inertial measurement coordinate system.

[0037] When all three orthogonally mounted accelerometers Ax, Ay, and Az of the inertial navigation system are found to be fault-free, the data from the Ax, Ay, and Az accelerometers are directly used to perform strapdown calculations using formula (2) to calculate the navigation information: (2).

[0038] When a fault is detected in one of the three orthogonally mounted accelerometers Ax, Ay, and Az, the output data of the As and / or At accelerometers are used for strapdown calculation via projection synthesis; the specifics are as follows: When the Ax accelerometer fails, the output data of the Ay, Az, As and At accelerometers can be used to perform strapdown calculation using formula (3); (3); When accelerometers Ax and As malfunction, the output data of accelerometers Ay, Az, and At can be used for strapdown calculation using formula (4): (4); When the Ay accelerometer fails, the output data of the Ax, Az, As and At accelerometers can be used to perform strapdown calculations using formulas (5) and (6); (5); (6); When the Az accelerometer malfunctions, the output data of the Ax, Ay, As, and At accelerometers can be used for strapdown calculation using formula (7): (7); When accelerometers Az and At malfunction, the output data of accelerometers Ax, Ay, and As can be used for strapdown calculation using formula (8): (8); Similarly, the principle for gyroscope reconstruction is the same as that for accelerometer reconstruction. The inertial navigation system (INS) uses data from the unisolated normal gyroscopes to calculate angular velocity information through a corresponding reconstruction algorithm.

[0039] In step 5.3, when all three orthogonally mounted Gx, Gy and Gz gyroscopes are functioning correctly, their output data is used directly for strapdown calculation.

[0040] When one of the three orthogonally mounted Gx, Gy, and Gz gyroscopes fails, the output data of the Gs and / or Gt gyroscopes are used for strapdown calculation via projection synthesis; the calculated relationship between the actual output of the five-axis gyroscope and the angular velocity components of the orthogonal three axes of the inertial measurement coordinate system is as follows: , , Consistent with the form of the accelerometer, its general relationship is as shown in equation (9): (9); in, This represents the redundancy configuration matrix of the gyroscope in the inertial measurement coordinate system. , , , , These are the actual output values ​​of the Gx, Gy, Gz, Gs, and Gt gyroscopes along the measurement axes; , , To measure the angular velocity components of the orthogonal three-axis gyroscope in the inertial measurement coordinate system; , , , , , The installation error angle of the gyroscope relative to the inertial measurement coordinate system; , , The angles between the Gs gyroscope and the three orthogonal axes of the inertial measurement coordinate system are respectively. , , Let Gt be the angle between the gyroscope and the three orthogonal axes of the inertial measurement coordinate system.

[0041] Example 2 In this embodiment, the structure of the five-axis redundant strapdown inertial navigation system is the same as that in Embodiment 1, and will not be described again. The difference between the two is: In the steps of the five-axis redundant strapdown inertial navigation system fault detection and reconstruction method, there are seven predefined reconstruction modes in step S3.3, as shown in Table 1. Table 1 Seven Refactoring Working Modes ; In Table 1 above, "normal inertial instruments" indicates that both the gyroscope and accelerometer are functioning correctly. The table shows the seven reconfiguration modes: Mode 1: X, Y, Z, S, and T inertial instruments are all functioning normally; Mode 2: X, Y, and Z inertial instruments are functioning normally; Mode 3: X, Y, S, and T inertial instruments are functioning normally; Mode 4: Y, Z, S, and T inertial instruments are functioning normally; Mode 5: X, Z, S, and T inertial instruments are functioning normally; Mode 6: Y, Z, and T inertial instruments are functioning normally; Mode 7: X, Y, and S inertial instruments are functioning normally.

[0042] Another difference is in the steps of the five-axis redundant strapdown inertial navigation system fault detection and reconstruction method, where step 4 involves fault detection, such as... Figure 3 As shown, fault detection can generate seven reconfiguration working modes and corresponding fault status words.

[0043] The fault status words generated in step S4.3 are also seven types, namely 0x01, 0x02, 0x03, 0x04, 0x05, 0x06 and 0x07, as shown in Table 2, which shows the correspondence between the fault status words and the working modes of the gyroscope and accelerometer. Table 2. Correspondence between fault status words and operating modes of gyroscopes and accelerometers ; As shown in Table 2, the fault status words correspond one-to-one with the various predefined reconfiguration working modes in step S3.3; among them, the fault status word 0x01 corresponds to the first reconfiguration working mode; the fault status word 0x02 corresponds to the second reconfiguration working mode; the fault status word 0x03 corresponds to the third reconfiguration working mode; the fault status word 0x04 corresponds to the fourth reconfiguration working mode; the fault status word 0x05 corresponds to the fifth reconfiguration working mode; the fault status word 0x06 corresponds to the sixth reconfiguration working mode; and the fault status word 0x07 corresponds to the seventh reconfiguration working mode.

[0044] The alignment accuracy is calculated using seven reconstruction modes. The testing method is as follows: First, the five-axis redundant strapdown inertial navigation system is aligned with the inertial measurement coordinate system. The axis is fixed upward on the turntable. The turntable is fixed at a position every 45°, for a total of 8 positions. At each position, the five-axis redundant strapdown inertial navigation system is statically drifted for 8 minutes, and the attitude angles are calculated to obtain the heading angle and alignment accuracy (3σ).

[0045] The measurement results are shown in the table below: Table 3 shows the alignment accuracy of the five-axis redundant strapdown inertial navigation system under different fault modes. Tables 4-1 and 4-2 show the alignment data results for eight positions under the seven reconstruction working modes of this embodiment.

[0046] Data analysis showed that the five-axis redundant strapdown inertial navigation system could work normally and the alignment function was normal under all seven reconfiguration modes.

[0047] Table 3 Alignment accuracy of a five-axis redundant strapdown inertial navigation system under different reconfiguration modes ; Table 4-1 Results of omnidirectional alignment data under the first to third reconstruction working modes ; Table 4-2 Results of omnidirectional alignment data under the fourth to seventh reconstruction working modes .

[0048] The fault detection and reconstruction technology of this invention can ensure the normal operation of a five-axis redundant strapdown inertial navigation system under single-table and partial two-table failures. Using the reconstruction technology, the five-axis redundant strapdown inertial navigation system of this invention achieves an alignment accuracy of 2.2' in normal orthogonal table mode and 4' in abnormal orthogonal table mode, further verifying the improved system reliability.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A five-axis redundant strapdown inertial navigation system, characterized in that: It includes a power supply, a DC power filter circuit and a DC power module connected in sequence, as well as a five-axis inertial measurement unit, an inertial computer and an analog-to-digital conversion circuit; The five-axis inertial measurement unit includes three orthogonally mounted X, Y, and Z inertial instruments, and two obliquely mounted S and T inertial instruments. The X inertial instrument includes a Gx gyroscope and an Ax accelerometer; the Y inertial instrument includes a Gy gyroscope and an Ay accelerometer; the Z inertial instrument includes a Gz gyroscope and an Az accelerometer; the S inertial instrument includes a Gs gyroscope and an As accelerometer; and the T inertial instrument includes a Gt gyroscope and an At accelerometer. The DC power supply module includes modules MK1, MK2, MK3, MK4, MK5, and MK6. The output terminal of module MK1 is connected to the power input terminals of gyroscopes Gx and Gs, respectively; the output terminal of module MK2 is connected to the power input terminals of gyroscopes Gz and Gt, respectively; the output terminal of module MK3 is connected to the power input terminal of gyroscope Gy; the output terminal of module MK4 is connected to the power input terminals of accelerometers Ax and As, respectively; the output terminal of module MK5 is connected to the power input terminals of accelerometers Az and At, respectively; and the output terminal of module MK6 is connected to the power input terminal of accelerometer Ay. The output terminals of the MK4, MK5, and MK6 modules are all connected to the power input terminal of the analog-to-digital converter circuit; the data input terminal of the analog-to-digital converter circuit is connected to the data output terminals of the Ax, As, Az, At, and Ay accelerometers. The output terminals of the MK5 and MK6 modules are both connected to the power input terminal of the inertial navigation system (INS). The data input terminal of the INS is connected to the data output terminals of the Gx, Gs, Gz, Gt, and Gy gyroscopes and the analog-to-digital converter circuit, respectively. It is used to perform fault diagnosis based on the power supply voltage of each gyroscope and accelerometer, as well as the pulse signal emitted by each gyroscope and accelerometer. Then, based on the fault diagnosis results, it performs data reconstruction and error compensation calculations, and outputs navigation information.

2. The five-axis redundant strapdown inertial navigation system according to claim 1, characterized in that: The Gx, Gs, Gz, Gt and Gy gyroscopes mentioned are all fiber optic gyroscopes; The Ax, As, Az, At, and Ay accelerometers mentioned are all quartz accelerometers.

3. A fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system, characterized in that, Includes the following steps: Step 1: Assemble the five-axis redundant strapdown inertial navigation system as described in claim 1 or 2; Step 2: Construct the inertial measurement coordinate system An inertial measurement coordinate system is constructed using three orthogonally mounted X, Y, and Z inertial instruments as orthogonal axes. The X, Y, and Z inertial instruments are respectively located at... , , axis; Step 3, Parameter Setting S3.1 Set the fault voltage threshold for each power module; S3.2 Set the output data saturation threshold for each instrument; S3.3, Predefined multiple refactoring working modes; Step 4, Fault Detection S4.1 Power Supply Detection The inertial navigation computer detects the output voltage of each power module. When the output voltage of any power module exceeds the corresponding fault voltage threshold, all instruments powered by that module are determined to be faulty. S4.2 Data Saturation Detection The inertial navigation system computer performs saturation detection on the output data of each instrument. When the output data exceeds the set output data saturation threshold, the instrument is determined to be faulty. S4.

3. Based on the detection results of steps S4.1 and S4.2, generate the corresponding fault status word; Step 5: Navigation Information Reconstruction S5.

1. Based on the fault status word generated in step S4.3, select the corresponding instrument's output data to isolate; S5.

2. Based on the fault status word, select the corresponding refactoring working mode from among the predefined multiple refactoring working modes; S5.3 The inertial computer uses data from normal instruments that are not isolated to calculate navigation information through the corresponding reconstruction algorithm, thus completing the fault detection and navigation information reconstruction of the five-axis redundant strapdown inertial group.

4. The fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system according to claim 3, characterized in that, In step S5.3, the reconstruction algorithm is as follows: When the gyroscopes and accelerometers in the three orthogonally mounted X, Y, and Z inertial instruments are all functioning correctly, their output data can be directly used for strapdown calculation to determine navigation information. When any of the gyroscopes or accelerometers in the three orthogonally mounted X, Y, and Z inertial instruments malfunctions, the corresponding normal gyroscopes and / or accelerometers in the obliquely mounted S and / or T inertial instruments are used to calculate the output data equivalent to the faulty component on the corresponding axis in the orthogonal three axes of the inertial measurement coordinate system through a projection synthesis algorithm.

5. The fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system according to claim 4, characterized in that, In step S5.3, the projection synthesis algorithm is as follows: Using the output data of the corresponding normal gyroscopes and / or accelerometers in the obliquely mounted S-inertial instrument and / or T-inertial instrument, the components of the corresponding axes in the orthogonal three axes of the inertial measurement coordinate system are calculated through an orthogonal decomposition algorithm. These components are then used to replace the output data of the faulty gyroscopes and / or accelerometers to calculate navigation information.

6. The fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system according to claim 5, characterized in that: In step S5.3, when all three orthogonally mounted accelerometers Ax, Ay, and Az are functioning correctly, the strapdown calculation formula is: ； In the formula, This represents the redundancy configuration matrix of the accelerometers in the inertial measurement coordinate system. , , These are the actual output values ​​of the Ax, Ay, and Az accelerometers along the measurement axes; , , The acceleration components of the orthogonal three axes of the inertial measurement coordinate system; , , , , , This is the installation error angular coefficient of the accelerometer relative to the inertial measurement coordinate system.

7. The fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system according to claim 5, characterized in that: In step S5.3, if one of the three orthogonally mounted accelerometers Ax, Ay, and Az fails, the output data of accelerometers As and / or At are used for strapdown calculation via projection synthesis; specifically as follows: When the Ax accelerometer malfunctions, the formula for strapdown calculation using the output data of the Ay, Az, As, and At accelerometers is as follows: ； In the formula, This represents the redundancy configuration matrix of the accelerometers in the inertial measurement coordinate system. , , , The actual output values ​​of the Ay, Az, As, and At accelerometers along the measurement axis; , , The acceleration components of the orthogonal three axes of the inertial measurement coordinate system; , , , This is the installation error angular coefficient of the accelerometer relative to the inertial measurement coordinate system; , , Let be the angles between the As accelerometer and the three orthogonal axes of the inertial measurement coordinate system; , , Let be the angles between the At accelerometer and the three orthogonal axes of the inertial measurement coordinate system; When accelerometers Ax and As malfunction, the formula for strapdown calculation using the output data of accelerometers Ay, Az, and At is as follows: ； When the Ay accelerometer malfunctions, the formula for strapdown calculation using the output data of the Ax, Az, As, and At accelerometers is as follows: ； In the formula, This represents the actual output value of the Ax accelerometer along the measurement axis; , The installation error angular coefficient of the accelerometer relative to the inertial measurement coordinate system; When the Az accelerometer malfunctions, the formula for strapdown calculation using the output data of the Ax, Ay, As, and At accelerometers is as follows: ； When accelerometers Az and At malfunction, the formula for strapdown calculation using the output data of accelerometers Ax, Ay, and As is as follows: 。 8. The fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system according to claim 5, characterized in that: In step S5.3, when all three orthogonally mounted gyroscopes Gx, Gy, and Gz are functioning correctly, the strapdown calculation formula is as follows: ； In the formula, This represents the redundancy configuration matrix of the gyroscope in the inertial measurement coordinate system. , , These are the actual output values ​​of the Gx, Gy, and Gz gyroscopes along the measurement axes; , , To measure the angular velocity components of gyroscopes along the orthogonal three axes of the inertial measurement system; , , , , , This represents the installation error angle coefficient of the gyroscope relative to the inertial measurement coordinate system.

9. The fault detection and reconstruction method for a five-axis redundant strapdown inertial navigation system according to claim 5, characterized in that: In step S5.3, if one of the three orthogonally mounted Gx, Gy, and Gz gyroscopes fails, the output data of the Gs and / or Gt gyroscopes are used for strapdown calculation via projection synthesis; specifically as follows: When the Gx gyroscope malfunctions, the formula for strapdown calculation using the output data of the Gy, Gz, Gs, and Gt gyroscopes is as follows: ； In the formula, This represents the redundancy configuration matrix of the gyroscope in the inertial measurement coordinate system. , , , These are the actual output values ​​of the Gy, Gz, Gs, and Gt gyroscopes along the measurement axes; , , To measure the angular velocity components of the orthogonal three-axis gyroscope in the inertial measurement coordinate system; , , , The installation error angle of the gyroscope relative to the inertial measurement coordinate system; , , The angles between the Gs gyroscope and the three orthogonal axes of the inertial measurement coordinate system are respectively. , , Let Gt be the angle between the gyroscope and the three orthogonal axes of the inertial measurement coordinate system; When the Gx and Gs gyroscopes malfunction, the formula for strapdown calculation using the output data of the Gy, Gz, and Gt gyroscopes is as follows: ； When the Gy gyroscope malfunctions, the formula for strapdown calculation using the output data of the Gx, Gz, Gs, and Gt gyroscopes is as follows: ； In the formula, This represents the actual output value of the Gx gyroscope along the measurement axis; , The installation error angle of the gyroscope relative to the inertial measurement coordinate system; When the Gz gyroscope malfunctions, the formula for strapdown calculation using the output data of the Gx, Gy, Gs, and Gt gyroscopes is as follows: ； When the Gz and Gt gyroscopes malfunction, the formula for strapdown calculation using the output data of the Gx, Gy, and Gs gyroscopes is as follows: 。

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