Electro-hydraulic servo valve BIT test method for aircraft remote electronic unit

Abstract

The invention provides an electro-hydraulic servo valve BIT test method for an aircraft remote electronic unit, which relates to the technical field of aircraft control, and comprises the following steps: in a communication period, an instruction channel and a monitoring channel in the remote electronic unit respectively receive actuation instructions from a flight control computer through the same digital bus; the instruction channel and the monitoring channel respectively analyze the actuation instruction, and according to the analyzed actuation instruction, BIT test tasks of the high side and the low side of the servo valve are respectively executed based on an error integrator or a two-stage comparison strategy; and the instruction channel uploads BIT test result feedback of the two channels and actual state information of the servo valve through a digital bus. According to the invention, high integrity of the BIT test can be ensured, failure modes such as electro-hydraulic servo valve coil faults, remote electronic unit drive circuit faults and line faults can be effectively monitored, it is ensured that a remote electronic unit BIT test task in a flight control system does not have common-mode faults, and the fault detection coverage rate is improved.

Description

Technical Field

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

[0002] The BIT (Built-In Test) technology of the remote electronic unit electro-hydraulic servo valve in modern large passenger aircraft has been developed along with the continuous progress of avionics systems and flight control technology. In the flight control system of large passenger aircraft, the remote electronic unit is responsible for receiving instructions from the flight control system and controlling the electro-hydraulic servo valve to achieve precise control of the elevator, left and right ailerons, etc. As a key actuator in the flight control system, the stability and reliability of the electro-hydraulic servo valve itself and the control loop directly affect the control accuracy and flight safety of the aircraft. However, since the electro-hydraulic servo valve works in harsh environments such as high pressure, high speed, and high temperature for a long time, it is easily affected by various factors, resulting in performance degradation or failure. Therefore, it is increasingly important to perform real-time monitoring and fault detection on the control loop of the electro-hydraulic servo valve.

[0003] In the architecture design of modern fly-by-wire flight control, the remote electronic unit generally adopts a non-similar design to prevent common-mode problems in the control loop. Each electro-hydraulic servo valve actuator uses a command channel / 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 only a simple "command issuance - actuator execution - result upload" control logic. Since the flight control system is more sensitive to control feedback, this design method has the disadvantages of insufficient integrity, poor versatility, low fault detection capability, and 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 embodiment of the present application provides the following technical solution: a BIT test method for an electro-hydraulic servo valve of an aircraft remote electronic unit, comprising:

[0006] In one communication cycle, the command channel and the monitoring channel in the remote electronic unit receive the actuation command 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, respectively perform BIT test tasks of the high side and the low side of the servo valve based on an error integrator or a two-level 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 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 diff_t and the fault trigger threshold 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 according to 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, and the increment value is diff_th;

[0021] If it is satisfied, the integrator decreases, and the decrease 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 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 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. 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 an embodiment of the present application, the second-level instruction monitoring includes:

[0026] The command channel and the monitoring channel respectively calculate the servo valve theoretical current according to the displacement command in the BIT command content. The monitoring channel compares the servo valve theoretical current calculated by this channel with the servo valve theoretical current calculated 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, which reports the test fault. If the comparison result is normal, the third-level command monitoring is continued.

[0027] According to an 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 test failure is reported by the command channel.

[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 a digital bus to confirm whether the data is transmitted completely and effectively.

[0030] The embodiment of the present invention is a BIT test method for an electro-hydraulic servo valve for an aircraft remote electronic unit. Compared with the existing servo valve BIT test method, the present invention first compares and monitors the BIT command, the theoretical current drive command and the servo valve current / voltage value in sequence based on the dissimilarity between the command channel and the monitoring channel in the remote electronic unit, thereby effectively preventing the occurrence of single-point failures in the servo valve BIT test. Considering the differences between the maintenance BIT and periodic BIT test tasks, the error integrator method is combined to design the periodic BIT test logic, so that the periodic BIT test has a certain tolerance for errors / faults while ensuring effectiveness, and a two-level comparison strategy is used to complete the maintenance BIT test logic, and finally the BIT feedback information and two-channel status monitoring information data are uploaded. The present invention can ensure the high integrity of the BIT test and effectively monitor failure modes such as electro-hydraulic servo valve coil failure, remote electronic unit drive circuit failure and line failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. 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 paying creative work.

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

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

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

[0035] Figure 4 A maintenance BIT test logic flow chart of an embodiment of the present invention;

[0036] Figure 5The figure 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 implementation methods 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 implementation methods, 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 following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0039] like Figure 1 As shown, an embodiment of the present invention provides a BIT test method for an electro-hydraulic servo valve for an aircraft remote electronic unit. The embodiment of the present invention integrates the working state parameters of the electro-hydraulic servo valve into the BIT test method, including key parameters such as valve core position, servo valve current, and voltage, and uses a fault diagnosis method to analyze and process the collected data to improve the high integrity of the detection circuit, thereby completing real-time monitoring and fault detection of the electro-hydraulic servo valve control circuit.

[0040] Specifically, within a communication cycle, the command channel and the monitoring channel in the remote electronic unit receive the actuation command from the flight control computer through the same digital bus; after completing and passing the 1st to 3rd level monitoring, the command channel and the monitoring channel respectively perform the servo valve high-side and low-side BIT test tasks based on the error integrator or the two-level comparison strategy; finally, the command channel rewinds the BIT command, feeds back the two-channel BIT results, and uploads the actual status information of the servo valve through the digital bus. 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 complete and effectively transmitted.

[0041] Among them, a three-level instruction monitoring mechanism is executed in real time during the BIT test task, and the three-level instruction monitoring mechanism includes: comparing the BIT instruction content corresponding to the actuation instruction after parsing 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 respectively. If the comparison result is abnormal, the BIT test task is terminated and the test fault is reported by the instruction channel.

[0042] Figure 1 It is a logic block diagram of an embodiment of the present invention. In the entire communication loop, the command channel (COM Lane) and the monitoring channel (MON Lane) in the remote electronic unit receive command data packets through the same digital bus, and the two channels perform data parsing to obtain BIT instruction codes. The BIT instruction code in an actuation instruction data packet can be one of a maintenance BIT and a periodic BIT. 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; wherein, if the current BIT test task is determined to be 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 the current BIT test task is determined to be 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.

[0043] Among them, the BIT test instructions are divided into maintenance BIT test and periodic BIT test. The two correspond to the same field of the actuation instruction data packet, but are distinguished by different BIT instruction codes. When the maintenance BIT test instruction is valid, the remote electronic unit enters the maintenance mode. At this time, the servo valve drive control instruction is triggered by the maintenance BIT task. The maintenance BIT test task is to test whether the shut-off function of the servo valve actuator is normal.

[0044] In the periodic BIT task, in each communication cycle (servo valve action cycle), the remote electronic unit monitors the real-time status information of the servo valve current and voltage and determines whether the servo valve control loop is normal based on the error integrator. The periodic BIT test task and the servo valve drive control task are executed in parallel without conflict.

[0045] In specific implementation, the maintenance BIT indicates that the remote electronic unit has entered the safety / maintenance mode. The maintenance BIT task is to drive the servo valve actuator to close to ensure the actuator's normal shutoff capability. The periodic BIT is to continuously monitor the current, voltage and other status information of the servo valve actuator online during the servo control process of the remote electronic unit.

[0046] In an embodiment, the remote electronic unit is a multi-circuit electronic controller in the aircraft flight control system, which is responsible for receiving instructions from the flight control system and controlling the electro-hydraulic servo valve to achieve precise control of the elevator, aileron, etc. COM Lane, servo valve, and MON Lane constitute a complete electrical circuit, in which the command channel completes the main control tasks such as servo valve high-side drive, high-side state acquisition, and data upload, and the monitoring channel completes the servo valve low-side drive, low-side state acquisition, and comparison monitoring tasks to ensure the high integrity of flight data information.

[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 through 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 comparison monitoring logic block diagram according to an embodiment of the present invention. The present invention includes three levels of comparison monitoring, the first level of comparison monitoring (i.e. the first level of instruction monitoring): compare the BIT instructions parsed from the data packets of the COM Lane and MON Lane channels; the second level of comparison monitoring (i.e. the second level of instruction monitoring): calculate the servo valve theoretical current drive instruction according to the actuation instruction, and compare the calculation results of the two channels; the third level of monitoring (i.e. the third level of instruction monitoring): compare 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 of the embodiment of the present invention. Level 1 comparison monitoring: The monitoring channel first uses the "XOR" logic to complete the comparison monitoring of the BIT instructions of the two channels. When the BIT instructions parsed by the two channels are the same, it indicates that the instruction is valid. When the instruction is valid and is "1", the BIT test continues to be performed, that is, the second level comparison monitoring. When the instruction is valid and is "0", the BIT test is not enabled; when the BIT instructions of the two channels are different, the BIT test task is terminated, and the test failure is reported by the instruction channel.

[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 "XOR" 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 actual current / voltage acquisition is valid, and the BIT test continues to be executed; when the actual current / voltage values collected by the two channels are different, the BIT test task is aborted, and the test fault 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, to ensure the high integrity of the test, a two-level comparison strategy is adopted. 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 measured current value, and the difference between the theoretical voltage value of the servo valve actuator and the actually measured voltage. The periodic BIT mainly continuously monitors the actual state of the servo valve actuator under the normal working condition of the remote electronic unit. In the execution logic of the periodic BIT, the upper limit threshold up_th of the integrator, the fault trigger threshold trip_th, and the single-cycle error comparison threshold diff_th 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 measured. If the relationship between the two does not satisfy |I3 - I4| < diff_th, the integrator increases by the increment value of diff_th. If |I3 - I4| < diff_th is satisfied, the integrator decreases by the value of |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 the fault is latched. 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 increment value and the decrement value of the integrator can be set according to the actual accuracy and sensitivity requirements. In this embodiment, the difference comparison threshold diff_th is selected as the increment value of the integrator, and the calculated error difference in the current cycle is selected as the decrement value of the integrator.

[0062] The embodiment of the present invention is a BIT test method for an electro-hydraulic servo valve for an aircraft remote electronic unit. Compared with the existing servo valve BIT test method, the present invention first compares and monitors the BIT command, the theoretical current / voltage drive command, and the actual current / voltage value of the servo valve in sequence based on the dissimilarity between the command channel and the monitoring channel in the remote electronic unit, thereby effectively preventing the occurrence of single-point failures in the servo valve BIT test. Considering the differences between the maintenance BIT and the periodic BIT test tasks, the error integrator method is combined to design the periodic BIT test logic, so that the periodic BIT test has a certain tolerance for errors / faults while ensuring effectiveness, and a two-level comparison strategy is used to complete the maintenance BIT test logic, and finally the BIT feedback information and two-channel status monitoring information data are uploaded. The present invention can ensure the high integrity of the BIT test and effectively monitor failure modes such as electro-hydraulic servo valve coil failure, remote electronic unit drive circuit failure, and line failure.

[0063] Those skilled in the art of the present invention should recognize that the implementation of the method of the present invention can be implemented by hardware, software or a combination thereof. In hardware implementation, CPU, DSP, FPGA and other hardware components can be used to perform the functions and operations described in the present invention. In software implementation, it can be implemented in the form of computer program products, which can be stored in a computer-accessible storage medium and used as executable code to implement specific functions. The storage medium is, for example, a disk, a flash memory, a ROM, a memory, etc.

[0064] The detailed description of the present invention is mainly based on the flowcharts and / or block diagrams of the methods and computer program products of the embodiments. It should be clearly pointed out that each process and / or box presented in the flowchart and / or block diagram, as well as their combination, can be implemented by computer program instructions, which fully demonstrates that the implementation methods of these steps and modules are highly flexible.

[0065] In practical applications, there is no need to be limited to the specific execution order shown in the flow chart and / or block diagram. According to actual needs, the execution order of the steps can be flexibly adjusted, and they can even be allocated to different integrated circuit modules. In addition, in order to improve resource utilization efficiency, multiple steps or modules can also be merged into a single integrated circuit module. Therefore, the embodiments of the present invention have a high degree of flexibility and scalability, and are not limited to a specific form of hardware, software or a combination of hardware and software.

[0066] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope 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: Within a communication cycle, the command channel and the monitoring channel in the remote electronic unit receive actuation commands from the flight control computer through the same digital bus respectively; The command channel and the monitoring channel respectively parse the actuation commands, and based on the parsed actuation commands, execute 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-stage 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 sequentially 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 fault.

2. The BIT test 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-stage 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 test 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-stage comparison strategy includes: Initializing the preset current comparison threshold parameter i_th and position comparison threshold parameter d_th; Receiving the current commands I1 and I2 issued by the analog-to-digital converter, where 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; 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 test 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 fault trigger threshold trip_th; Within 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 determine 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 test 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 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. 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 test 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 command channel and the monitoring channel respectively calculate the servo valve theoretical current according to the displacement command in the BIT command content. The monitoring channel compares the servo valve theoretical current calculated by this channel with the servo valve theoretical current calculated 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, which reports the test fault. If the comparison result is normal, the third-level command monitoring is continued.

7. The BIT test 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 test failure is reported by the command channel.

8. The BIT test 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 through the digital bus to confirm whether the data is transmitted completely and effectively.

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