A BIT test method for electro-hydraulic servo valves used in aircraft remote electronic units

Abstract

The present invention provides a BIT testing method for an electro-hydraulic servo valve in an aircraft remote electronic unit, relating to the field of aircraft control technology. The method comprises: within a communication cycle, a command channel and a monitoring channel in the remote electronic unit receive actuation commands from a flight control computer via the same digital bus; the command channel and the monitoring channel respectively parse the actuation commands, and based on the parsed actuation commands, execute BIT testing tasks for the high and low sides of the servo valve, respectively, using an error integrator or a two-stage comparison strategy; and the command channel transmits the BIT test results of the two channels and uploads the actual status information of the servo valve via a digital bus. The method ensures high integrity of the BIT test, effectively monitors failure modes such as electro-hydraulic servo valve coil faults, remote electronic unit drive circuit faults, and line faults, ensuring that common-mode faults do not occur during BIT testing of the remote electronic unit in the flight control system, thereby improving fault detection coverage.

Description

Technical Field

[0001] The present invention relates to the field of aircraft control technology, and in particular to a BIT testing method for an electro-hydraulic servo valve of an aircraft remote electronic unit. Background Art

[0002] BIT (Built-In Test) technology for remote electronic unit (REU) electro-hydraulic servo valves in modern large passenger aircraft has evolved alongside the continuous advancement of avionics systems and flight control technologies. In the flight control system of a large passenger aircraft, the REU is responsible for receiving commands from the flight control system and controlling the EMU to achieve precise control of the elevators, ailerons, and other components. As a key actuator in the flight control system, the stability and reliability of the EMU and its control circuits directly impact the aircraft's control accuracy and flight safety. However, due to the long-term operation of EMUs in harsh environments such as high pressure, high speed, and high temperature, EMUs are susceptible to various factors, leading to performance degradation or failure. Therefore, real-time monitoring and fault detection of EMU control circuits are becoming increasingly important.

[0003] In the architectural design of modern fly-by-wire flight control systems, remote electronic units generally adopt a non-similar design to prevent common-mode problems in the control loop. Each electro-hydraulic servo valve actuator uses a command channel and a monitoring channel for synchronous monitoring to improve the high integrity of the signal in the control loop. However, for BIT testing, it is generally implemented using a simple "command issuance - actuator execution - result upload" control logic. Since the flight control system is relatively sensitive to control feedback, this design method has shortcomings such as insufficient integrity, poor versatility, low fault detection capability, and the inability to quickly detect and isolate faults. Summary of the Invention

[0004] In view of this, an embodiment of the present application provides a BIT test method for an electro-hydraulic servo valve of an aircraft remote electronic unit to ensure that common mode failures do not occur in the BIT test task of the remote electronic unit in the flight control system, thereby improving the fault detection coverage.

[0005] The present application provides the following technical solution: a BIT testing method for an electro-hydraulic servo valve of an aircraft remote electronic unit, comprising:

[0006] In one communication cycle, the command channel and monitoring channel in the remote electronic unit receive the actuation commands from the flight control computer through the same digital bus respectively;

[0007] The command channel and the monitoring channel respectively analyze the actuation command, and according to the analyzed actuation command, perform BIT test tasks of the high side and the low side of the servo valve based on an error integrator or a two-stage comparison strategy;

[0008] The BIT test results feedback of the two channels and the actual status information of the servo valve are uploaded through the digital bus by the instruction channel;

[0009] Among them, during the process of performing the BIT test task, a three-level instruction monitoring mechanism is executed in real time. The three-level instruction monitoring mechanism successively includes: comparing the BIT instruction content corresponding to the actuation instruction parsed by the instruction channel and the monitoring channel, the theoretical current of the servo valve calculated according to the BIT instruction content, and the actual current / voltage of the servo valve collected by the two channels in sequence. If there is an abnormal comparison result, the BIT test task is aborted, and the test failure is reported by the instruction channel.

[0010] According to an embodiment of the present application, the parsed actuation instruction includes a BIT instruction code, and the current BIT test task is determined to be a maintenance BIT test task or a periodic BIT test task through the BIT instruction code;

[0011] Among them, if it is determined that the current BIT test task is a maintenance BIT test task, the maintenance BIT test tasks of the high side and the low side of the servo valve are respectively executed based on the two-level comparison strategy; if it is determined that the current BIT test task is a periodic BIT test task, the periodic BIT test tasks of the high side and the low side of the servo valve are respectively executed based on the error integrator.

[0012] According to an embodiment of the present application, respectively executing the maintenance BIT test tasks of the high side and the low side of the servo valve based on the two-level comparison strategy includes:

[0013] Initializing the preset current comparison threshold parameter i_th and the position comparison threshold parameter d_th;

[0014] Receiving the current command I1 issued by the analog-to-digital converter, I1 = 0 mA, collecting the actual current value I2 of the servo valve actuator, and calculating and determining whether |I1 - I2| < i_th is satisfied;

[0015] If not satisfied, the maintenance BIT test fails and the test ends;

[0016] If satisfied, calculate the position change D of the servo valve actuator within two adjacent periods and confirm whether D < d_th is satisfied. If satisfied, the maintenance BIT test passes; if not satisfied, the maintenance BIT test fails and the test ends.

[0017] According to an embodiment of the present application, respectively executing the periodic BIT test tasks of the high side and the low side of the servo valve based on the error integrator includes:

[0018] After the remote electronic unit is powered on, the integrator and the preset single-cycle error comparison threshold value diff_t and the fault trigger threshold value trip_th in the remote electronic unit are initialized;

[0019] In each communication cycle, the theoretical current value I3 of the servo valve actuator is calculated based on the position difference, and the actual current value I4 of the servo valve actuator is collected to calculate and determine whether |I3-I4| is satisfied. <diff_th;

[0020] If it is not satisfied, the integrator is incremented by diff_th;

[0021] If it is satisfied, the integrator is decremented, and the decrement value is |I3-I4|;

[0022] When the value of the integrator reaches the fault trigger threshold trip_th, it indicates that the periodic BIT test fails, and the test ends after the fault is latched; if the value of the integrator does not reach trip_th during the test, it indicates that the periodic BIT test is normal, and the periodic test continues.

[0023] According to an embodiment of the present application, the three-level instruction monitoring mechanism is executed sequentially through the monitoring channel, wherein the first-level instruction monitoring includes:

[0024] The command channel sends the BIT command content obtained by parsing the current channel to the monitoring channel, and the monitoring channel compares the BIT command content obtained by parsing the current channel with the BIT command content obtained by parsing the command channel. If the comparison result is abnormal, the BIT test task is terminated, and the comparison result is transmitted back to the command channel, which reports the test failure. If the comparison result is normal and the actuation command is logic "1", the second-level command monitoring continues. If the comparison result is normal and the actuation command is logic "0", the current BIT test is not enabled.

[0025] According to one embodiment of the present application, the second-level instruction monitoring includes:

[0026] The instruction channel and the monitoring channel respectively calculate the servo valve theoretical current based on the displacement instruction in the BIT instruction content. The monitoring channel compares the servo valve theoretical current calculated by this channel with the servo valve theoretical current calculated by the instruction channel. If the comparison result is abnormal, the BIT test task is terminated and the comparison result is transmitted back to the instruction channel, which reports the test fault. If the comparison result is normal, the third-level instruction monitoring is continued.

[0027] According to one embodiment of the present application, the third-level instruction monitoring includes:

[0028] The command channel and the monitoring channel respectively collect the actual current / voltage of the servo valve. The monitoring channel compares the actual current / voltage of the servo valve collected by this channel with the actual current / voltage of the servo valve collected by the command channel. If the comparison result is abnormal, the BIT test task is terminated and the comparison result is transmitted back to the command channel, and the command channel reports the test failure.

[0029] According to one embodiment of the present application, it also includes: the command channel returns the actuation command issued by the flight control computer to the flight control computer through the digital bus to confirm whether the data is transmitted completely and effectively.

[0030] An embodiment of the present invention provides a BIT testing method for an electro-hydraulic servo valve in an aircraft remote electronic unit. Compared to existing servo valve BIT testing methods, the present invention first compares and monitors BIT commands, theoretical current drive commands, and servo valve current / voltage values ​​sequentially based on the dissimilarity between the command channel and the monitoring channel in the remote electronic unit, effectively preventing single-point failures during servo valve BIT testing. Considering the differences between maintenance BIT and periodic BIT testing tasks, the periodic BIT test logic is designed using an error integrator method, ensuring effectiveness while maintaining a certain tolerance for errors / faults. A two-level comparison strategy is used to complete the maintenance BIT test logic. Finally, BIT feedback information and two-channel status monitoring data are uploaded. This method ensures high integrity in BIT testing and effectively monitors failure modes such as electro-hydraulic servo valve coil faults, remote electronic unit drive circuit faults, and line faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 A logic block diagram of an embodiment of the present invention;

[0033] Figure 2 This is a comparison monitoring logic block diagram of an embodiment of the present invention;

[0034] Figure 3 This is a comprehensive logic block diagram of comparison monitoring according to an embodiment of the present invention;

[0035] Figure 4 This is a logic flow chart of the maintenance BIT test according to an embodiment of the present invention;

[0036] Figure 5This is a logic flow chart of a periodic BIT test based on an error integrator according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0038] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0039] like Figure 1 As shown, an embodiment of the present invention provides a BIT testing method for an electro-hydraulic servo valve in an aircraft remote electronic unit. This method incorporates the operating state parameters of the electro-hydraulic servo valve into the BIT testing method, including key parameters such as valve core position, servo valve current, and voltage. Furthermore, it utilizes fault diagnosis methods to analyze and process the collected data, improving the integrity of the detection circuit and thus enabling real-time monitoring and fault detection of the electro-hydraulic servo valve control circuit.

[0040] Specifically, within a communication cycle, the command channel and monitoring channel in the remote electronic unit receive actuation commands from the flight control computer via the same digital bus. After completing and passing levels 1-3 of monitoring, the command channel and monitoring channel respectively perform high-side and low-side BIT testing of the servo valve using an error integrator or a two-level comparison strategy. Finally, the command channel rewinds the BIT commands, feeds back the BIT results from both channels, and uploads the actual servo valve status information via the digital bus. The command channel relays the actuation commands issued by the flight control computer back to the flight control computer via the digital bus to confirm that the data has been transmitted completely and effectively.

[0041] Among them, a three-level instruction monitoring mechanism is executed in real time during the process of performing the BIT test task, and the three-level instruction monitoring mechanism includes: comparing the BIT instruction content corresponding to the actuation instruction after analysis by the instruction channel and the monitoring channel, the servo valve theoretical current calculated according to the BIT instruction content, and the servo valve actual current / voltage collected by the two channels in sequence. If there is an abnormal comparison result, the BIT test task is terminated and the test fault is reported by the instruction channel.

[0042] Figure 1 This is a logic block diagram of an embodiment of the present invention. Within the entire communication loop, the command channel (COM Lane) and monitoring channel (MON Lane) in the remote electronic unit receive command data packets via the same digital bus. Each channel performs data parsing to obtain a BIT instruction code. The BIT instruction code in an actuation command packet can be either a maintenance BIT or a periodic BIT. The BIT instruction code determines whether the current BIT test task is a maintenance BIT test task or a periodic BIT test task. If the current BIT test task is determined to be a maintenance BIT test task, the maintenance BIT test tasks for the servo valve's high and low sides are executed separately based on the two-level comparison strategy. If the current BIT test task is determined to be a periodic BIT test task, the periodic BIT test tasks for the servo valve's high and low sides are executed separately based on the error integrator.

[0043] BIT test commands are divided into maintenance BIT tests and periodic BIT tests. Both correspond to the same field in the actuation command data packet but are distinguished by different BIT command codes. When the maintenance BIT test command is active, the remote electronic unit enters maintenance mode. At this point, the servo valve drive control command is triggered by the maintenance BIT task. The maintenance BIT test task tests the servo valve actuator's shutoff function.

[0044] During each communication cycle (servo valve operation cycle), the remote electronic unit monitors the servo valve's current and voltage status in real time and uses an error integrator to determine whether the servo valve control loop is functioning properly. The periodic BIT test task executes in parallel with the servo valve drive control task, ensuring they do not conflict with each other.

[0045] In practice, the Maintenance BIT indicates that the remote electronics unit has entered safety / maintenance mode. Its task is to drive the servo valve actuator to close to ensure its shutoff capability. The Periodic BIT continuously monitors the servo valve actuator's current, voltage, and other status information online during the remote electronics unit's servo control process.

[0046] In one embodiment, the remote electronic unit (REU) is a multi-circuit electronic controller within an aircraft's flight control system. It receives commands from the flight control system and controls the electro-hydraulic servovalves to achieve precise control of the elevators, ailerons, and other components. The COM Lane, servovalves, and MON Lane form a complete electrical circuit. The command channel performs master control tasks such as servovalves' high-side drive, high-side status acquisition, and data upload. The monitoring channel performs servovalves' low-side drive, low-side status acquisition, and comparative monitoring to ensure high integrity of flight data.

[0047] Optionally, the command channel can also complete tasks such as high-side status collection, and the monitoring channel can complete tasks such as low-side status collection to ensure the high integrity of flight data information.

[0048] MON Lane sends its own BIT result feedback and status monitoring information to COM Lane, and COM Lane uploads BIT instructions, its own BIT results, and status monitoring information via the digital bus.

[0049] Optionally, the above specific tasks are not limited to be executed on a certain channel, and channels can be exchanged to complete tasks such as driving, monitoring, comparing, and data uploading.

[0050] Figure 2 This is a logic block diagram of a comparison monitoring system according to an embodiment of the present invention. The present invention includes three levels of comparison monitoring. Level 1 comparison monitoring (i.e., the first-level instruction monitoring) compares the BIT instructions parsed from data packets by the COM Lane and MON Lane channels. Level 2 comparison monitoring (i.e., the second-level instruction monitoring) calculates the theoretical current drive instruction for the servo valve based on the actuation instruction and compares the calculated results from the two channels. Level 3 monitoring (i.e., the third-level instruction monitoring) compares the actual current / voltage of the servo valve collected by the COM Lane and MON Lane channels, respectively.

[0051] Figure 3 This is a comprehensive logic block diagram of the comparison monitoring embodiment of the present invention. Level 1 comparison monitoring: The monitoring channel first uses "exclusive OR" logic to perform comparative monitoring of the BIT instructions of the two channels. If the BIT instructions parsed by the two channels are identical, the instructions are valid. If the instruction is valid and the value is "1," the BIT test continues, i.e., level 2 comparison monitoring. If the instruction is valid and the value is "0," the BIT test is disabled. If the BIT instructions of the two channels are different, the BIT test task is aborted, and the instruction channel reports a test failure.

[0052] Level 2 comparison monitoring: The level 2 comparison monitoring task is triggered by the level 1 monitoring result. When the level 1 monitoring result indicates that the BIT test enable is valid, the monitoring channel uses "exclusive OR" logic to complete the comparison monitoring of the theoretical current drive instructions of the two-channel servo valve actuators. When the theoretical current drive instructions calculated by the two channels based on the displacement instructions are the same (the error is within an acceptable range), it indicates that the current drive instruction is valid and the BIT test continues to be executed, that is, the level 3 comparison monitoring; when the current drive instructions of the two channels are different, the BIT test task is terminated and the test fault is reported by the instruction channel.

[0053] Level 3 comparison monitoring: The Level 3 comparison monitoring task is triggered by the monitoring results of Level 2. When the monitoring results of Level 2 are valid, the monitoring channel uses the "XNOR" logic to complete the comparison monitoring of the actual current / voltage values of the actuator servo valves in two channels. When the actual current / voltage values obtained by parsing the two channels are the same (the error is within the acceptable range), it indicates that the acquisition of the actual current / voltage is valid, and the BIT test is continued; when the actual current / voltage values collected by the two channels are different, the BIT test task is aborted, and the test failure is reported by the command channel.

[0054] In one embodiment, the specific execution logic of the maintenance BIT test task is as Figure 4 shown. The purpose of the maintenance BIT is to test whether the actuator servo valve can be normally shut off when the current drive command is 0 mA. In the execution logic of the maintenance BIT test task, a two-level comparison strategy is adopted to ensure the high integrity of the test. First, the current comparison threshold parameter i_th and the position comparison threshold parameter d_th are initialized, and then the current command I1 = 0 mA is issued by the digital-to-analog converter (DAC). Then, the actual current value I2 of the servo valve actuator is collected to confirm whether the first-level comparison condition |I1 - I2| < i_th is satisfied. If this condition is not satisfied, the maintenance BIT fails and the test ends; if this condition is satisfied, the position change D of the actuator within two adjacent periods is calculated and it is confirmed whether the second-level comparison condition D < d_th is satisfied. If this condition is satisfied, the maintenance BIT passes and the test ends; if this condition is not satisfied, the maintenance BIT fails.

[0055] Optionally, the current comparison threshold and the position comparison threshold can be set according to the actual accuracy and sensitivity requirements.

[0056] In one embodiment, the specific execution logic of the periodic BIT based on the error integrator is as Figure 5As shown. Among them, the error refers to the difference between the theoretical current command calculated from the servo valve actuator displacement command and the actually collected current value, and the difference between the theoretical voltage value of the servo valve actuator and the actually collected voltage. The periodic BIT mainly continuously monitors the actual state of the servo valve actuator under the normal working state of the remote electronic unit. In the periodic BIT execution logic, the upper limit threshold up_th, the fault trigger threshold trip_th, and the single-cycle error comparison threshold diff_th of the integrator are preset; first, the integrator is initialized once after the remote electronic unit is powered on. Secondly, in each cycle, the theoretical current value I3 is calculated according to the position difference, and the actual current value I4 of the actuator is collected. If the relationship between the two does not satisfy |I3 - I4| < diff_th, the integrator increases, and the increment value is diff_th. If |I3 - I4| < diff_th is satisfied, the integrator decreases, and the decrement value is |I3 - I4|. When the integrator value reaches the fault trigger threshold trip_th, it indicates that the periodic BIT has a fault, and the test ends after latching the fault. If the integrator does not reach trip_th during the test, it indicates that the periodic BIT is normal, and the periodic test continues according to Figure 5 the execution logic to maintain the periodic test.

[0057] Optionally, if the current value of the integrator is not greater than de_value, the integrator value remains 0.

[0058] Optionally, if the current value of the integrator is not less than up_th, the integrator value remains up_th.

[0059] Optionally, the servo valve voltage detection logic is the same as the current detection logic, and the corresponding threshold parameters can be set according to the actual accuracy requirements.

[0060] Among them, the position difference refers to the difference between the expected position and the current actual position of the actuator.

[0061] Optionally, initializing the integrator includes setting the initial value of the integrator to 0, the fault trigger threshold trip_th of the integrator, the upper limit threshold up_th of the integrator, the difference comparison threshold diff_th. The integrator increment value and the integrator decrement value can be set according to the actual accuracy and sensitivity requirements. In this embodiment, the difference comparison threshold diff_th is selected as the integrator increment value, and the current cycle calculation error difference is selected as the integrator decrement value.

[0062] An embodiment of the present invention discloses a BIT testing method for an electro-hydraulic servo valve in an aircraft remote electronic unit. Compared to existing servo valve BIT testing methods, the present invention first compares and monitors BIT commands, theoretical current / voltage drive commands, and actual servo valve current / voltage values ​​sequentially based on the dissimilarity between the command channel and the monitoring channel in the remote electronic unit, effectively preventing single-point failures during servo valve BIT testing. Taking into account the differences between maintenance BIT and periodic BIT testing tasks, the periodic BIT test logic is designed in conjunction with an error integrator method, ensuring effectiveness while maintaining a certain tolerance for errors / faults. A two-level comparison strategy is employed to complete the maintenance BIT test logic. Finally, BIT feedback information and two-channel status monitoring data are uploaded. This method ensures high BIT test integrity and effectively monitors failure modes such as electro-hydraulic servo valve coil faults, remote electronic unit drive circuit faults, and line faults.

[0063] Those skilled in the art will recognize that the methods described in the present invention can be implemented through hardware, software, or a combination thereof. In hardware implementation, the various functions and operations described in the present invention can be performed using hardware components such as a CPU, DSP, and FPGA. In software implementation, the methods can be implemented in the form of computer program products. These products can be stored in a computer-accessible storage medium, such as a disk, flash memory, ROM, or memory, and can be implemented as executable code to implement specific functions.

[0064] The detailed description of the present invention is primarily based on the flowcharts and / or block diagrams of the methods and computer program products of the embodiments. It should be explicitly noted that each process and / or block shown in the flowcharts and / or block diagrams, as well as combinations thereof, can be implemented using computer program instructions, demonstrating the high degree of flexibility in the implementation of these steps and modules.

[0065] In practical applications, there is no need to be limited to the specific execution order presented in the flowcharts and / or block diagrams. The execution order of the steps can be flexibly adjusted based on actual needs, and they can even be distributed to different integrated circuit modules. Furthermore, to improve resource utilization efficiency, multiple steps or modules can be combined into a single integrated circuit module. Therefore, the embodiments of the present invention are highly flexible and scalable and are not limited to a specific hardware, software, or combination of hardware and software.

[0066] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A BIT test method for an electro-hydraulic servo valve of an aircraft remote electronic unit, characterized in that: including: During a communication cycle, the command channel and the monitoring channel in the remote electronic unit respectively receive the actuation commands from the flight control computer through the same digital bus; The command channel and the monitoring channel respectively parse the actuation commands, and based on the parsed actuation commands, perform the BIT test tasks for the high side and the low side of the servo valve respectively based on the error integrator or the two-level comparison strategy; The command channel uploads the BIT test results feedback of the two channels and the actual status information of the servo valve through the digital bus; Among them, during the process of performing the BIT test task, a three-level command monitoring mechanism is executed in real time. The three-level command monitoring mechanism successively includes: comparing the BIT instruction content corresponding to the actuation commands parsed by the command channel and the monitoring channel, the theoretical current of the servo valve calculated according to the BIT instruction content, and the actual current / voltage of the servo valve collected by the two channels in sequence. If there is an abnormal comparison result, the BIT test task is aborted, and the command channel reports the test failure.

2. The BIT testing method for an electro-hydraulic servo valve of an aircraft remote electronic unit according to claim 1, characterized in that: The parsed actuation command includes a BIT instruction code, and the current BIT test task is determined as a maintenance BIT test task or a periodic BIT test task through the BIT instruction code; Among them, if it is determined that the current BIT test task is a maintenance BIT test task, the maintenance BIT test tasks for the high side and the low side of the servo valve are respectively executed based on the two-level comparison strategy; if it is determined that the current BIT test task is a periodic BIT test task, the periodic BIT test tasks for the high side and the low side of the servo valve are respectively executed based on the error integrator.

3. The BIT testing method for an electro-hydraulic servo valve of an aircraft remote electronic unit according to claim 2, characterized in that: Respectively executing the maintenance BIT test tasks for the high side and the low side of the servo valve based on the two-level comparison strategy includes: Initializing the preset current comparison threshold parameter i_th and the position comparison threshold parameter d_th; Receiving the current commands I1 and I2 issued by the analog-to-digital converter, I1 = 0 mA, collecting the actual current value I2 of the servo valve actuator, and calculating and judging whether |I1 - I2| < i_th is satisfied; If not satisfied, the maintenance BIT test fails and the test ends; If satisfied, calculate the position change D of the servo valve actuator within two adjacent cycles and confirm whether D < d_th is satisfied. If satisfied, the maintenance BIT test passes; if not satisfied, the maintenance BIT test fails and the test ends.

4. The BIT testing method for an electro-hydraulic servo valve of an aircraft remote electronic unit according to claim 2, characterized in that: Respectively executing the periodic BIT test tasks for the high side and the low side of the servo valve based on the error integrator includes: After the remote electronic unit is powered on, initializing the integrator in the remote electronic unit and the preset single-cycle error comparison threshold diff_t and the fault trigger threshold trip_th; In each communication cycle, calculate the theoretical current value I3 of the servo valve actuator according to the position difference, collect the actual current value I4 of the servo valve actuator, and calculate and judge whether |I3 - I4| < diff_th is satisfied; If not satisfied, the integrator increments, and the increment value is diff_th; If satisfied, the integrator decrements, and the decrement value is |I3 - I4|; When the value of the integrator reaches the fault trigger threshold trip_th, it indicates that the periodic BIT test fails, and the test ends after the fault is latched; if the value of the integrator does not reach trip_th during the test, it indicates that the periodic BIT test is normal, and the periodic test continues.

5. The BIT testing method for an electro-hydraulic servo valve of an aircraft remote electronic unit according to claim 1, characterized in that: The three-level instruction monitoring mechanism is executed sequentially through the monitoring channel, wherein the first-level instruction monitoring includes: The command channel sends the BIT command content obtained by parsing this channel to the monitoring channel, and the monitoring channel compares the BIT command content obtained by parsing this channel with the BIT command content obtained by parsing the command channel. If there is an abnormal comparison result, the BIT test task is terminated and the comparison result is returned to the command channel, and the command channel reports the test failure. If the comparison result is normal and the actuation command is logic "1", the second-level command monitoring continues. If the comparison result is normal and the actuation command is logic "0", the current BIT test is not enabled.

6. The BIT testing method for an electro-hydraulic servo valve of an aircraft remote electronic unit according to claim 5, characterized in that: The second level instruction monitoring includes: The instruction channel and the monitoring channel respectively calculate the servo valve theoretical current based on the displacement instruction in the BIT instruction content. The monitoring channel compares the servo valve theoretical current calculated by this channel with the servo valve theoretical current calculated by the instruction channel. If the comparison result is abnormal, the BIT test task is terminated and the comparison result is transmitted back to the instruction channel, which reports the test fault. If the comparison result is normal, the third-level instruction monitoring is continued.

7. The BIT testing method for an electro-hydraulic servo valve of an aircraft remote electronic unit according to claim 6, characterized in that: The third level instruction monitoring includes: The command channel and the monitoring channel respectively collect the actual current / voltage of the servo valve. The monitoring channel compares the actual current / voltage of the servo valve collected by this channel with the actual current / voltage of the servo valve collected by the command channel. If the comparison result is abnormal, the BIT test task is terminated and the comparison result is transmitted back to the command channel, and the command channel reports the test failure.

8. The BIT testing method for an electro-hydraulic servo valve of an aircraft remote electronic unit according to claim 1, characterized in that: Also includes: The command channel transmits the actuation command issued by the flight control computer back to the flight control computer via the digital bus to confirm whether the data is transmitted completely and effectively.

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