A four-axis strapdown inertial measurement unit fault detection and processing method

Abstract

The present invention relates to a fault detection and processing method for a four-axis strapdown inertial measurement device, and belongs to the field of inertial measurement. The present invention performs a reset process on an axis among the three axes X, Y, and Z when a fault occurs, and uses the A axis to replace the faulty axis for output, and no longer replaces the X, Y, and Z axes for output, and always uses the A axis to replace the faulty axis for output. After the faulty axis is reset, it is detected. If the faulty axis returns to normal after the reset, it is used as a backup axis, and is used to output when a subsequent axis fails; if the fault still exists after the faulty axis is reset, the axis is no longer used, and thereafter the four-axis inertial measurement device always uses the three measurement axes without faults for output. The present invention optimizes the output mode of the four-axis inertial measurement device, improves the working reliability of the four-axis strapdown inertial measurement device, and avoids the risks that may be caused by the unsuccessful reset of a faulty axis of the inertial measurement device.

Description

Technical Field

[0001] The invention belongs to the field of inertial measurement, and in particular relates to a fault detection and processing method for a four-axis strapdown inertial measurement device. Background Art

[0002] The strapdown inertial measurement unit (IMU) is the primary navigation and stability control device for aircraft, used to sense its position and attitude. Velocity is measured via inertial sensors called accelerometers, while attitude is measured via inertial sensors called fiber optic gyroscopes (FOGs). Traditional IMUs typically use fiber optic gyroscopes and accelerometers installed on the X, Y, and Z axes to sense angular velocity and acceleration. However, inertial measurement units (IMUs) designed for use outside the atmosphere utilize a four-axis IMU design to cope with complex environments and improve reliability. This design incorporates an additional, angled A-axis as a backup axis, which can be used to replace the faulty X, Y, and Z axes in the event of a failure.

[0003] The traditional fault detection and handling method for a four-axis strapdown inertial measurement unit (IMU) is as follows: the IMU defaults to using the X, Y, and Z axes of the fiber optic gyroscope and accelerometer for output. During each IMU operating cycle, the IMU detects faults in the four axes: X, Y, Z, and A. If a fault occurs in one of the three axes, the A axis is used to replace the faulty axis for output, and the faulty axis is reset. After the faulty axis is reset, the X, Y, and Z axes continue to be used for output. If a fault occurs in the A axis, the A axis is reset, and the IMU uses the X, Y, and Z axes for output.

[0004] A drawback of traditional methods is that when a measurement axis fails, the output is switched back to that axis after reset. However, if the reset fails and the fault persists, fault detection is the only way to identify the fault. If the fault is not identified, using that axis for output can result in erroneous output, causing malfunction of the inertial measurement unit and posing a risk. Summary of the Invention

[0005] (1) Technical issues to be solved

[0006] The technical problem to be solved by the present invention is how to provide a four-axis strapdown inertial measurement device fault detection and processing method to solve the problem of possible risks caused by the traditional fault detection method defaulting to using the three measurement axes XYZ for output.

[0007] (2) Technical solution

[0008] In order to solve the above technical problems, the present invention proposes a four-axis strapdown inertial measurement device fault detection and processing method, which includes the following steps:

[0009] S1. Check whether the X, Y, Z, and A four-axis fiber optic gyroscope and accelerometer have any faults in each sampling period.

[0010] S2. Reset the faulty axis in each communication cycle

[0011] The fault identification is judged in each external communication cycle of the four-axis strapdown inertial measurement device, and the three measurement axes XYZ are used for external output by default. If one of the three axes X, Y, and Z is judged to have a fault during the external communication cycle, it is reset by powering off and then powering on again, and the A-axis is used to replace the faulty axis for external communication output. If the A-axis fails, it is reset, and the three measurement axes XYZ are still used for external communication output.

[0012] S3: After the fault axis is reset, check whether the fault axis reset is successful.

[0013] Before the reset is completed, a check is performed to see if the reset is successful. If the faulty axis is one of the X, Y, and Z axes and the reset is successful, it will be used as a backup axis. At the same time, the system will not switch back to the XYZ measurement axis output mode. The A axis will still be used to replace the axis for external output. If one of the three axes currently outputting externally fails again, the backup axis will be used for external output and the faulty measurement axis will be reset.

[0014] If the faulty axis is A-axis and the reset is successful, the external communication still uses the three measurement axes XYZ, and A-axis still serves as the backup axis. When one of the three axes X, Y, and Z fails, A-axis will be used to replace the output and reset the faulty axis.

[0015] If the faulty axis fails to be reset, that axis will no longer be used for output. The four-axis strapdown inertial measurement unit will switch to three-axis output mode, always using the three fault-free measurement axes for external output, and no fault processing will be performed.

[0016] Furthermore, the external communication cycle of the four-axis strapdown inertial measurement unit is generally 2.5ms.

[0017] Furthermore, the external communication cycle of the four-axis strapdown inertial measurement unit is usually 5ms.

[0018] Furthermore, the internal sampling period of the gyroscope and accelerometer data of the four-axis strapdown inertial measurement unit is 0.25ms.

[0019] Furthermore, the internal sampling period of the gyroscope and accelerometer data of the four-axis strapdown inertial measurement unit is 0.5 ms.

[0020] Furthermore, the faults in step S1 include: no communication, repeated data, over-range and data mutation faults.

[0021] Furthermore, in step S3, if the X-axis fails, it is reset and the AYZ measuring axis is used for external output. After the X-axis is reset, it is detected that there is no fault and it serves as a backup axis; if the Y-axis fails again, the XAZ measuring axis is used for output and the Y-axis is reset. After the Y-axis is successfully reset, it serves as a backup axis; if the Z-axis fails again, the XYA measuring axis is used for output and the Z-axis is reset. After the Z-axis is successfully reset, it serves as a backup axis.

[0022] Furthermore, in step S3, if the Y axis fails, it is reset and the XAZ measuring axis is used for external output. After the Y axis is reset, it is detected that there is no fault and it serves as a backup axis; if the X axis fails again, the AYZ measuring axis is used for output and the X axis is reset. After the X axis is successfully reset, it serves as a backup axis; if the Z axis fails again, the XYA measuring axis is used for output and the Z axis is reset. After the Z axis is successfully reset, it serves as a backup axis.

[0023] Furthermore, in step S3, if the Z axis fails, it is reset and the XYA measuring axis is used to output externally. After the Z axis is reset, it is detected that there is no fault and it serves as a backup axis; if the Y axis fails again, the XAZ measuring axis is used to output and the Y axis is reset. After the Y axis is successfully reset, it serves as a backup axis; if the X axis fails again, the AYZ measuring axis is used to output and the X axis is reset. After the X axis is successfully reset, it serves as a backup axis.

[0024] Furthermore, in step S3, if a fault occurs on the X-axis and it is reset, the AYZ measurement axis output is used to measure the output. If the X-axis is still faulty after being reset, the X-axis output is no longer used, and the AYZ measurement axis output is always used thereafter; if a fault occurs on the Y-axis and it is reset, the XAZ measurement axis output is used to measure the output. If the Y-axis is still faulty after being reset, the Y-axis output is no longer used, and the XAZ measurement axis output is always used thereafter; if a fault occurs on the Z-axis and it is reset, the XYA measurement axis output is used to measure the output. If the Z-axis is still faulty after being reset, the Z-axis output is no longer used, and the XYA measurement axis output is always used thereafter.

[0025] (3) Beneficial effects

[0026] The present invention provides a fault detection and processing method for a four-axis strapdown inertial measurement device. The present invention provides a fault detection and processing method for a four-axis strapdown inertial measurement device. After the faulty axis is reset, whether the reset is successful is detected, the output mode of the four-axis inertial measurement device is optimized, the working reliability of the four-axis strapdown inertial measurement device is improved, and the risks that may be caused by the unsuccessful reset of a faulty axis of the inertial measurement device are avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A state transition diagram of a four-axis strapdown inertial measurement device according to the present invention;

[0028] Figure 2 This is a flow chart of fault detection and processing of a four-axis strapdown inertial measurement device according to the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0030] The technical problem to be solved by the present invention is how to implement high-reliability design for fault detection and processing of a four-axis strapdown inertial measurement device, resolve the risks that may be caused by the traditional fault detection method defaulting to the three measurement axes X, Y, and Z for output, avoid the risks that may be caused by resetting a faulty axis of the four-axis inertial measurement device, and improve the reliability of the four-axis inertial measurement device.

[0031] The four-axis strapdown inertial measurement device fault detection and processing method of the present invention comprises the following steps:

[0032] S1. Check whether the X, Y, Z, and A four-axis fiber optic gyroscope and accelerometer have any faults in each sampling cycle.

[0033] The external communication cycle of a four-axis strapdown inertial measurement unit is typically 2.5ms or 5ms. The internal sampling cycle for gyro and accelerometer data is even shorter, typically 0.25ms or 0.5ms. During each sampling cycle, the gyro and accelerometer are tested for faults such as no communication, duplicate data, over-range, or data mutation. If a fault occurs, the corresponding fault flag is set.

[0034] S2. Reset the faulty axis in each communication cycle

[0035] The four-axis strapdown inertial measurement unit (SIMU) detects faults during each external communication cycle, with the default output being the X, Y, and Z axes. If a fault is detected on one of the X, Y, and Z axes during an external communication cycle, it is reset by powering it off and then back on, and the A-axis replaces the faulty axis for external communication output. If the A-axis fails, it is reset, and external communication continues using the X, Y, and Z axes.

[0036] S3: After the fault axis is reset, check whether the fault axis reset is successful.

[0037] Before the reset is completed, a check is performed to see if the reset is successful. If the faulty axis is one of the X, Y, and Z axes and the reset is successful, it will be used as a backup axis. At the same time, the mode will not be switched back to the XYZ measurement axis output mode, and the A axis will still be used to replace the axis for external output. When one of the three axes currently outputting to the outside fails again, the backup axis will be used for external output, and the faulty measurement axis will be reset.

[0038] For example: if the X-axis fails, it is reset and the AYZ measuring axis is used for external output. After the X-axis is reset and tested to be fault-free, it serves as the backup axis. If the Y-axis fails again, the XAZ measuring axis is used for output and the Y-axis is reset. After the Y-axis is successfully reset, it serves as the backup axis. If the Z-axis fails again, the XYA measuring axis is used for output and the Z-axis is reset. After the Z-axis is successfully reset, it serves as the backup axis.

[0039] If the Y-axis fails, it will be reset and the XAZ measuring axis will be used for external output. After the Y-axis is reset and detected to be fault-free, it will serve as the backup axis. If the X-axis fails again, the AYZ measuring axis will be used for output to reset the X-axis. After the X-axis is successfully reset, it will serve as the backup axis. If the Z-axis fails again, the XYA measuring axis will be used for output to reset the Z-axis. After the Z-axis is successfully reset, it will serve as the backup axis.

[0040] If the Z axis fails, reset it and use the XYA measuring axis to output externally. After the Z axis is reset and detected to be fault-free, it will serve as the backup axis. If the Y axis fails again, use the XAZ measuring axis to output and reset the Y axis. After the Y axis is successfully reset, it will serve as the backup axis. If the X axis fails again, use the AYZ measuring axis to output and reset the X axis. After the X axis is successfully reset, it will serve as the backup axis.

[0041] If the faulty axis is A-axis and is successfully reset, external communication still uses the three measurement axes XYZ, and A-axis still serves as the backup axis. When one of the three axes X, Y, and Z fails, A-axis is used to replace the output and reset the faulty axis.

[0042] If a faulty axis fails to be reset, that axis will no longer be used for output. The four-axis strapdown inertial measurement unit will switch to three-axis output mode, always using the three healthy measurement axes for external output, and no further fault handling will be performed. For example: If an X-axis fault occurs and is reset, the AYZ measurement axes will be used for output. If the X-axis is still faulty after reset, the X-axis output will no longer be used, and the AYZ measurement axes will always be used for output. If a Y-axis fault occurs and is reset, the XAZ measurement axes will be used for output. If the Y-axis is still faulty after reset, the Y-axis output will no longer be used, and the XAZ measurement axes will always be used for output. If a Z-axis fault occurs and is reset, the XYA measurement axes will be used for output. If the Z-axis is still faulty after reset, the Z-axis output will no longer be used, and the XYA measurement axes will always be used for output.

[0043] To address the above technical issues, the present invention proposes a fault detection and processing method for a four-axis strapdown inertial measurement device. This method resets one of the X, Y, and Z axes when it fails, and uses axis A to replace the faulty axis for output. The output is no longer switched back to the X, Y, and Z axes, but is always replaced by axis A. After the faulty axis is reset, it is tested. If the faulty axis returns to normal after the reset, it is used as a backup axis to be used for output when a subsequent axis fails. If the faulty axis still remains faulty after reset, it is no longer used. Thereafter, the four-axis inertial measurement device always uses the three healthy measurement axes for output.

[0044] The present invention proposes a fault detection and processing method for a four-axis strapdown inertial measurement device. By detecting whether the reset of a faulty axis is successful after the reset is completed, the output mode of the four-axis inertial measurement device is optimized, the working reliability of the four-axis strapdown inertial measurement device is improved, and the risks that may be caused by the unsuccessful reset of a faulty axis of the inertial measurement device are avoided.

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A four-axis strapdown inertial measurement device fault detection and processing method, characterized in that: The method comprises the following steps: S1. Check whether the X, Y, Z, and A four-axis fiber optic gyroscope and accelerometer have any faults in each sampling period. S2. Reset the faulty axis in each communication cycle The fault identification is judged in each external communication cycle of the four-axis strapdown inertial measurement device, and the three measurement axes XYZ are used for external output by default. If one of the three axes X, Y, and Z is judged to have a fault during the external communication cycle, it is reset by powering off and then powering on again, and the A-axis is used to replace the faulty axis for external communication output. If the A-axis fails, it is reset, and the three measurement axes XYZ are still used for external communication output. S3: After the fault axis is reset, check whether the fault axis reset is successful. Before the reset is completed, a check is performed to see if the reset is successful. If the faulty axis is one of the X, Y, and Z axes and the reset is successful, it will be used as a backup axis. At the same time, the system will not switch back to the XYZ measurement axis output mode. The A axis will still be used to replace the axis for external output. If one of the three axes currently outputting externally fails again, the backup axis will be used for external output and the faulty measurement axis will be reset. If the faulty axis is A-axis and the reset is successful, the external communication still uses the three measurement axes XYZ, and A-axis still serves as the backup axis. When one of the three axes X, Y, and Z fails, A-axis will be used to replace the output and reset the faulty axis. If the faulty axis fails to be reset, that axis will no longer be used for output. The four-axis strapdown inertial measurement unit will switch to three-axis output mode, always using the three fault-free measurement axes for external output, and no fault processing will be performed.

2. The four-axis strapdown inertial measurement device fault detection and processing method according to claim 1, wherein: The external communication cycle of a four-axis strapdown inertial measurement unit is usually 2.5ms.

3. The four-axis strapdown inertial measurement device fault detection and processing method according to claim 1, wherein: The external communication cycle of a four-axis strapdown inertial measurement unit is usually 5ms.

4. The four-axis strapdown inertial measurement device fault detection and processing method according to claim 1, wherein: The internal sampling period of the gyroscope and accelerometer data of the four-axis strapdown inertial measurement unit is 0.25ms.

5. The four-axis strapdown inertial measurement device fault detection and processing method according to claim 1, wherein: The internal sampling period of the gyroscope and accelerometer data of the four-axis strapdown inertial measurement unit is 0.5ms.

6. The four-axis strapdown inertial measurement device fault detection and processing method according to any one of claims 1 to 5, characterized in that: The faults in step S1 include: no communication, repeated data, over-range and data mutation faults.

7. The four-axis strapdown inertial measurement unit fault detection and processing method according to claim 6, wherein: In step S3, if the X-axis fails, it is reset and the AYZ measuring axis is used for external output. After the X-axis is reset and tested to be fault-free, it serves as a backup axis. If the Y axis fails again, the XAZ measuring axis will be used for output to reset the Y axis. After the Y axis is successfully reset, it will serve as a backup axis. If the Z axis fails again, use the XYA measuring axis for output and reset the Z axis. After the Z axis is successfully reset, it will serve as a backup axis.

8. The four-axis strapdown inertial measurement device fault detection and processing method according to claim 6, wherein: In step S3, if the Y axis fails, it is reset and the XAZ measuring axis is used to output externally. After the Y axis is reset, it is detected that there is no fault and it serves as a backup axis. If the X axis fails again, the AYZ measuring axis is used to output and reset the X axis. After the X axis is successfully reset, it serves as a backup axis. If the Z axis fails again, use the XYA measuring axis for output and reset the Z axis. After the Z axis is successfully reset, it will serve as a backup axis.

9. The four-axis strapdown inertial measurement device fault detection and processing method according to claim 6, wherein: In step S3, if the Z axis fails, it is reset and the XYA measuring axis is used to output externally. After the Z axis is reset and tested to be fault-free, it serves as a backup axis. If the Y axis fails again, the XAZ measuring axis will be used for output to reset the Y axis. After the Y axis is successfully reset, it will serve as a backup axis. If the X-axis fails again, the AYZ measuring axis is used for output to reset the X-axis. After the X-axis is successfully reset, it serves as a backup axis.

10. The four-axis strapdown inertial measurement device fault detection and processing method according to claim 6, wherein: In step S3, if the X-axis fails and is reset, the AYZ measurement axis output is used. If the X-axis is still faulty after being reset, the X-axis output is no longer used, and the AYZ measurement axis output is always used subsequently. If the Y-axis fails and is reset, the XAZ measurement axis output is used. If the Y-axis is still faulty after being reset, the Y-axis output is no longer used, and the XAZ measurement axis output is always used subsequently. If the Z-axis fails and is reset, the XYA measurement axis output is used. If the Z-axis is still faulty after being reset, the Z-axis output is no longer used, and the XYA measurement axis output is always used subsequently.

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