An inertial platform fault injection and test method based on redundancy technology

Abstract

The application provides an inertial platform fault injection and testing method based on redundancy technology, aiming at an inertial platform accelerometer height measurement and altimeter combined error feedback compensation height measurement system adopting redundancy technology, four faults of platform noise interference fault, platform large interference torque fault signal, altimeter noise fault and altitude redundancy error feedback fault, adopting a time injection function mode, combining an inertial platform mechanical motion model, a direct current torque motor model and a gyroscope measurement model established by a transfer function method, organically combining the above faults and signals into a closed loop closed system, effectively simulating the altitude measurement output signal of the redundancy technology based on the fault state, thereby realizing the fault injection simulation of the inertial platform system and realizing the equivalent function of the testing system.

Description

Technical Field

[0001] This invention relates to the field of aircraft inertial navigation and platform inertial navigation test equivalence and fault injection, and more specifically, to an inertial platform fault injection and testing method based on redundancy technology. Background Technology

[0002] With the increasing demands on the reliability of measurement instruments in complex aircraft control systems, measurement components and systems designed based on redundancy technology have attracted extensive research and are being applied to an increasing number of flight control systems. However, using an inertial navigation platform and accelerometer to measure altitude inevitably introduces cumulative errors; while altimeter measurements, although free of cumulative errors, suffer from randomized accuracy, making further improvement difficult. Therefore, a combined altitude measurement system based on redundancy technology, using both inertial platforms, has been successfully applied in large-scale flight control systems due to its complementary advantages, despite its complexity. Given the system's complexity, testing is essential to ensure its proper functioning; however, testing often fails to expose faults, or only exposes one type of fault, making testing procedures and equipment training inconvenient. Therefore, a method of artificially injecting fault symptoms to create a test equivalent is proposed. This method avoids frequent power-on / off testing of expensive real systems, giving this research high engineering and economic value. Based on the above background reasons, the present invention proposes a method for fault injection and testing equivalent to four types of faults in inertial platforms based on redundancy technology, which has high engineering value.

[0003] It should be noted that the information in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide an inertial platform fault injection and testing method based on redundancy technology, thereby overcoming the problems of inertial platform faults and the lack of detailed and accurate simulation of height measurement faults based on redundancy technology due to the limitations and defects of related technologies.

[0005] According to one aspect of the present invention, a method for fault injection and testing of an inertial platform based on redundancy technology is provided, comprising the following steps:

[0006] Step S10: Set the initial value of the output angle of the inertial platform to zero; then establish the gyroscope measurement model using the transfer function method to obtain the gyroscope measurement angle signal of the inertial platform; then set the platform noise interference fault injection time function and set the platform input to a Gaussian distributed white noise signal, and combine them to obtain the platform input signal under fault injection; compare it with the inertial platform gyroscope measurement angle signal to obtain the inertial platform error signal, and integrate it to obtain the inertial platform error integral signal; then combine the inertial platform error signal and the inertial platform error integral signal to obtain the inertial platform proportional-integral control signal.

[0007] Step S20: Using the proportional-integral control signal of the inertial platform as the input to the DC motor of the platform, a DC motor model of the inertial platform is established using a first-order transfer function to obtain the motor output torque signal; then, a sine function is used to simulate the large disturbance torque fault signal experienced by the platform, and the injection time function of the large disturbance torque fault is designed and combined to obtain the platform disturbance torque signal under fault injection; then, the motor output torque signal is superimposed to obtain the total input torque signal of the inertial platform; then, a mechanical dynamics model of the inertial platform is established using a first-order transfer function and the total input torque signal of the inertial platform is input to obtain the angular velocity signal of the inertial platform; finally, integration is performed to obtain the output angle signal of the inertial platform.

[0008] Step S30: Calculate the interference signal of the inertial platform rotation on the accelerometer based on the equivalent arm parameters formed by the inertial platform angular velocity signal and the accelerometer installation position; then superimpose the translational vertical acceleration signal of the inertial platform to obtain the total acceleration input signal; then establish the accelerometer measurement model using a second-order transfer function, input the total acceleration input signal to obtain the acceleration measurement signal under the platform torque interference fault; then, based on the accelerometer measurement model, input the translational vertical acceleration signal of the inertial platform to obtain the vertical acceleration signal of the inertial platform, then integrate to obtain the vertical velocity signal of the inertial platform, and further integrate to obtain the position signal of the inertial platform.

[0009] Step S40: Use white noise signal to simulate the measurement noise fault of radio altimeter to obtain altimeter noise simulation signal, then establish a first-order low-pass filter to obtain altimeter noise fault signal; then design altimeter fault injection time function, combine to obtain altimeter fault comprehensive signal, and then superimpose inertial platform position signal to obtain altimeter measurement signal under fault injection.

[0010] Step S50: Set the initial value of the height redundancy error signal under fault injection to 0. Superimpose the acceleration measurement signal under platform torque interference fault with the amplified signal of the height redundancy error signal under fault injection to obtain a redundancy-corrected acceleration signal. Then, integrate to obtain a velocity signal based on redundancy technology. Then, superimpose the amplified signal of the height redundancy error signal under fault injection to obtain a redundancy-corrected velocity signal. Then, integrate to obtain a height measurement signal based on redundancy technology. Compare the height measurement signal based on redundancy technology with the altimeter measurement signal under fault injection to obtain the height redundancy error signal. Then, design the injection time function of the height redundancy error feedback fault to obtain the height redundancy error signal under fault injection.

[0011] Step S60: Based on the injection time function of the height redundancy error feedback fault, the altimeter fault injection time function, the platform noise interference fault injection time function, and the large disturbance torque fault injection time function, select one or more faults to inject simultaneously, calculate the height measurement signal based on redundancy technology under multiple platform fault injections, realize the fault injection simulation of the inertial platform accelerometer and altimeter redundancy measurement process, and complete the test equivalent function of the inertial platform redundancy measurement process.

[0012] In one example embodiment of the present invention, the initial value of the output angle of the inertial platform is set to zero; then, a gyroscope measurement model is established using the transfer function method to obtain the gyroscope measurement angle signal of the inertial platform; next, a platform noise interference fault injection time function is set, and the platform input is set to a Gaussian distributed white noise signal, and the combination is used to obtain the platform input signal under fault injection; this signal is compared with the inertial platform gyroscope measurement angle signal to obtain the inertial platform error signal, and then integrated to obtain the inertial platform error integral signal; finally, the inertial platform proportional-integral control signal is obtained by combining the inertial platform error signal and the inertial platform error integral signal, including:

[0013]

[0014]

[0015] r0 = r a n a1 f0;

[0016] e a =r0-y a ;

[0017] s a =∫e a dt;

[0018] u a =k b1 e a +kb2 s a ;

[0019] Where θ a The initial value of the output angle for the inertial platform is zero; ε t Here, ω is the damping ratio parameter of the gyroscope, and ω is a constant coefficient. t Here, represents the natural frequency parameter of the gyroscope, and represents a constant coefficient. Here, s represents the gyroscope measurement model, and y represents the differential operator of the model transfer function. a f0 represents the angle signal measured by the gyroscope of the inertial platform; f0 represents the time function injected by the platform noise interference fault; t 0s The injection start time for platform noise interference faults; t 0e The injection end time for platform noise interference faults; n a1 The signal is a Gaussian-distributed white noise signal, r a Here, r is the noise intensity coefficient; r0 is the platform input signal under fault injection; e a For the inertial platform error signal, s a The integral signal of the inertial platform error; u a For the proportional-integral control signal of the inertial platform; k b1 k b2 These are constant control parameters.

[0020] In one exemplary embodiment of the present invention, the proportional-integral control signal of the inertial platform is used as the input of the platform's DC motor. A first-order transfer function is used to establish a DC motor model of the inertial platform to obtain the motor output torque signal. Then, a sine function is used to simulate the large disturbance torque fault signal experienced by the platform, and an injection time function for the large disturbance torque fault is designed and combined to obtain the platform disturbance torque signal under fault injection. The motor output torque signal is then superimposed to obtain the total input torque signal of the inertial platform. A mechanical dynamics model of the inertial platform is then established using a first-order transfer function, and the total input torque signal of the inertial platform is input to obtain the angular velocity signal of the inertial platform. Finally, integration is performed to obtain the output angle signal of the inertial platform, including:

[0021]

[0022] M a3 =m a sin(ω1t);

[0023]

[0024] M a2 =f1M a3 ;

[0025] M a =M a1 +Ma2 ;

[0026]

[0027] θ a =∫ω g dt;

[0028] in For the DC motor model of the inertial platform, k2 is the equivalent amplification factor of the motor model, T2 is the equivalent time constant of the motor model, and M is a constant parameter; a1 M is the torque signal output by the motor. a3 For large disturbance torque fault signals, m a ω1 is the amplitude parameter of the large disturbance torque, which is a constant; ω2 is the frequency parameter of the large disturbance torque, which is a constant; t 1s The injection start time for a large disturbance torque fault; t 1e f1 is the injection end time for the large disturbance torque fault; f1 is the injection time function for the large disturbance torque fault, M a2 The platform interference torque signal injected under fault conditions; M a Input the total torque signal to the inertial platform; ω is the first-order transfer function of the mechanical dynamics model of the inertial platform; T1 is the equivalent time constant of the mechanical dynamics model of the inertial platform, a constant parameter; k1 is the equivalent magnification factor of the mechanical dynamics model of the inertial platform, a constant parameter; g The angular velocity signal of the inertial platform; θ a Output angle signals to the inertial platform.

[0029] In one exemplary embodiment of the present invention, the interference signal of the inertial platform rotation on the accelerometer is calculated based on the equivalent arm parameters formed by the angular velocity signal of the inertial platform and the installation position of the accelerometer; then, the translational vertical acceleration signal of the inertial platform is superimposed to obtain the total acceleration input signal; then, an accelerometer measurement model is established using a second-order transfer function, and the total acceleration input signal is input to obtain the acceleration measurement signal under the platform torque interference fault; then, the translational vertical acceleration signal of the inertial platform is input according to the accelerometer measurement model to obtain the vertical acceleration signal of the inertial platform, and then integration is performed to obtain the vertical velocity signal of the inertial platform, and further integration is performed to obtain the position signal of the inertial platform, including:

[0030] a h2 =ω g r g ;

[0031] a h =a h1 +a h2 ;

[0032]

[0033]

[0034] v c1 =∫a c1 dt;

[0035] s c1 =∫v c1 dt;

[0036] Where r g For the equivalent force arm parameters formed by the accelerometer mounting position, a h2 The interference signal of the inertial platform rotation on the accelerometer; a h1 For the translational vertical acceleration signal of the inertial platform, a h ω2 is the total input signal for acceleration; ω2 is the natural frequency of the accelerometer, a constant parameter; ε2 is the damping ratio of the accelerometer, a constant parameter. For the accelerometer measurement model, a c The acceleration measurement signal under platform torque interference fault; a c1 For the vertical acceleration signal of the inertial platform, v c1 The vertical velocity signal of the inertial platform, s c1 This is the position signal of the inertial platform.

[0037] In one exemplary embodiment of the present invention, white noise signal is used to simulate the measurement noise fault of the radio altimeter to obtain an altimeter noise simulation signal. Then, a first-order low-pass filter is established to obtain an altimeter noise fault signal. Next, an altimeter fault injection time function is designed and combined to obtain a comprehensive altimeter fault signal. Finally, the inertial platform position signal is superimposed to obtain the altimeter measurement signal under fault injection, including:

[0038] s n3 =w1n1;

[0039]

[0040]

[0041] s n1 =f2s n2 ;

[0042] s c1a =s c1 +s n1 ;

[0043] Where n1 is the white noise signal, w1 is the measurement noise fault intensity of the radio altimeter, and s n3 T is the analog signal for altimeter noise. n1 Let s be the time constant of the first-order low-pass filter.n2 f1 is the altimeter noise fault signal; f2 is the altimeter fault injection time function, t 2s The start time for injecting fault information into the altimeter, t 2e End time for altimeter fault injection; s n1 For altimeter fault comprehensive signal, s c1a The altimeter measurement signal is injected under fault conditions.

[0044] In one exemplary embodiment of the present invention, the initial value of the height redundancy error signal under fault injection is set to 0. An amplified signal of the height redundancy error signal under fault injection is superimposed on the acceleration measurement signal under platform torque interference fault to obtain a redundancy-corrected acceleration signal. This is then integrated to obtain a velocity signal based on redundancy technology. Next, the amplified signal of the height redundancy error signal under fault injection is superimposed to obtain a redundancy-corrected velocity signal. This is then integrated to obtain a height measurement signal based on redundancy technology. The height measurement signal based on redundancy technology is compared with the altimeter measurement signal under fault injection to obtain the height redundancy error signal. Then, an injection time function for the height redundancy error feedback fault is designed. The height redundancy error signal under fault injection includes:

[0045] a cz =a c -k s1 e s ;

[0046] v c =∫a cz dt;

[0047] v cz =v c -k s2 e s ;

[0048] s cz =∫v cz dt;

[0049]

[0050] e s0 =s cz -s c1a ;

[0051] e s =f3e s0 ;

[0052] Where e s The height redundancy error signal is injected under fault conditions; k s1 k s2 a is a constant amplification factor; czCorrect the acceleration signal for redundancy; v c For velocity signals based on redundancy techniques; v cz For redundancy correction of the speed signal; s cz For height measurement signals based on redundancy technology; e s0 f3 is the height redundancy error signal; f3 is the injection time function of the height redundancy error feedback fault; t 3s The start time for injecting the high redundancy error feedback fault; t 3e The termination time for the high redundancy error feedback fault injection.

[0053] Beneficial effects

[0054] This invention discloses a fault injection and testing method for inertial platforms based on redundancy technology. Its main innovations are as follows: First, it simulates faults in the combined accelerometer and altimeter height measurement system of the entire inertial platform, simulating feedback gain failures. This allows for accurate closed-loop calculation of the height signal under fault conditions, providing a more in-depth and precise analysis than traditional open-loop fault calculation methods, and better reflecting the actual height measurement output under real-world faults. Second, it systematically analyzes and injects faults in the dual-redundancy height measurement system of the inertial platform under large disturbance torque faults, realistically reflecting the overall output of a single measurement channel affected by a fault under redundancy technology. Third, it performs fault injection and calculation on the redundancy-based height measurement system of the altimeter and inertial platform under large noise interference faults, simulating the height output performance under these faults. This provides a more realistic test object, enabling the system to function as a test equivalent, replacing the real system, and reducing the losses from multiple tests on expensive real systems, thus possessing high economic value.

[0055] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0056] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0057] Figure 1 This is a flowchart of a fault injection and testing method for an inertial platform based on redundancy technology provided by the present invention;

[0058] Figure 2It is the proportional-integral control signal (unitless) of the inertial platform provided in the embodiments of the present invention;

[0059] Figure 3 It is the inertial platform error signal (unit: degrees) of the method provided in the embodiments of the present invention;

[0060] Figure 4 It is the inertial platform angular velocity signal (unit: degrees per second) provided by the method in the embodiments of the present invention;

[0061] Figure 5 The inertial platform outputs an angle signal (unit: degrees) according to the method provided in the embodiments of the present invention.

[0062] Figure 6 It is the vertical acceleration signal of the inertial platform (unit: meters per second squared) provided by the method in the embodiments of the present invention;

[0063] Figure 7 It is the vertical velocity signal of the inertial platform (unit: meters per second) provided by the method in the embodiments of the present invention;

[0064] Figure 8 This is the inertial platform position signal (unit: meters) provided by the method in the embodiments of the present invention;

[0065] Figure 9 The altimeter measurement signal (unit: meters) under fault injection provided by the method in the embodiments of the present invention;

[0066] Figure 10 It is the injection time function (unitless) for the height redundancy error feedback fault of the method provided in the embodiments of the present invention;

[0067] Figure 11 It is the height measurement signal (unit: meters) based on redundancy technology provided in the embodiments of the present invention;

[0068] Figure 12 It is the height redundancy error signal (unit: meters) under fault injection of the method provided in the embodiments of the present invention. Detailed Implementation

[0069] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the technical solutions of the invention may be practiced with one or more of these specific details omitted, or other methods, components, apparatus, steps, etc., may be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of the invention.

[0070] This invention provides a fault injection and testing method for inertial platforms based on redundancy technology. It addresses four types of faults in inertial platform altimeter and altimeter combination error feedback compensation systems employing redundancy technology: platform noise interference, platform subjected to large disturbance torque fault signals, altimeter noise faults, and altitude redundancy error feedback faults. The method utilizes a time injection function approach, combined with an inertial platform mechanical motion model, a DC torque motor model, and a gyroscope measurement model established using the transfer function method. This organically combines the aforementioned faults and signals into a closed-loop system, effectively simulating the altitude measurement output signal based on redundancy technology under fault conditions. This achieves fault injection simulation of the inertial platform system, realizing the equivalent function of the testing system. The advantage of this method is that it uses a transfer function to describe the differential relationship between signals, making the entire fault simulation closely resemble the real situation, with high reliability and accuracy.

[0071] The following will further explain and illustrate the present invention's method for fault injection and testing of an inertial platform based on redundancy technology, with reference to the accompanying drawings. (Reference) Figure 1 As shown, this inertial platform fault injection and testing method based on redundancy technology may include the following steps:

[0072] Step S10: Set the initial value of the output angle of the inertial platform to zero; then establish the gyroscope measurement model using the transfer function method to obtain the gyroscope measurement angle signal of the inertial platform; then set the platform noise interference fault injection time function and set the platform input to a Gaussian distributed white noise signal, and combine them to obtain the platform input signal under fault injection; compare it with the inertial platform gyroscope measurement angle signal to obtain the inertial platform error signal, and integrate it to obtain the inertial platform error integral signal; then combine the inertial platform error signal and the inertial platform error integral signal to obtain the inertial platform proportional-integral control signal.

[0073] Specifically, this can be broken down into the following three steps. First, set the initial value of the inertial platform's output angle to zero; then, use the transfer function method to establish a gyroscope measurement model, obtaining the inertial platform gyroscope measurement angle signal as follows:

[0074]

[0075] Where θ a The initial value of the output angle for the inertial platform is zero; ε t Here, ω is the damping ratio parameter of the gyroscope, and ω is a constant coefficient. t Here, represents the natural frequency parameter of the gyroscope, and represents a constant coefficient. Here, s represents the gyroscope measurement model, and y represents the differential operator of the model transfer function. a This is for measuring angle signals from the gyroscope of an inertial platform.

[0076] The second step involves setting the platform noise interference fault injection time function and setting the platform input to a Gaussian-distributed white noise signal. After combining these signals, the platform input signal under fault injection is obtained. This signal is then compared with the inertial platform gyroscope measurement angle signal to obtain the inertial platform error signal, as follows:

[0077]

[0078] r0 = r a n a1 f0;

[0079] e a =r0-y a ;

[0080] Where f0 is the platform noise interference fault injection time function, t 0s The injection start time for platform noise interference faults; t 0e The injection end time for platform noise interference faults; n a1 The signal is a Gaussian-distributed white noise signal, r a Here, r is the noise intensity coefficient; r0 is the platform input signal under fault injection; e a This is the error signal of the inertial platform.

[0081] The third step is to integrate the inertial platform error signal to obtain the inertial platform error integral signal; then, combine the inertial platform error signal and the inertial platform error integral signal to obtain the inertial platform proportional-integral control signal as follows:

[0082] s a =∫e a dt;

[0083] u a =k b1 ea +k b2 s a ;

[0084] Where s a The integral signal of the inertial platform error; u a For the proportional-integral control signal of the inertial platform; k b1 k b2 These are constant control parameters.

[0085] Step S20: Using the proportional-integral control signal of the inertial platform as the input to the DC motor of the platform, a DC motor model of the inertial platform is established using a first-order transfer function to obtain the motor output torque signal; then, a sine function is used to simulate the large disturbance torque fault signal experienced by the platform, and the injection time function of the large disturbance torque fault is designed and combined to obtain the platform disturbance torque signal under fault injection; then, the motor output torque signal is superimposed to obtain the total input torque signal of the inertial platform; then, a mechanical dynamics model of the inertial platform is established using a first-order transfer function and the total input torque signal of the inertial platform is input to obtain the angular velocity signal of the inertial platform; finally, integration is performed to obtain the output angle signal of the inertial platform.

[0086] Specifically, this can be broken down into the following three steps. First, using the proportional-integral control signal of the inertial platform as the input to the platform's DC motor, a first-order transfer function is used to establish the DC motor model of the inertial platform, yielding the motor output torque signal as follows:

[0087]

[0088] in For the DC motor model of the inertial platform, k2 is the equivalent amplification factor of the motor model, T2 is the equivalent time constant of the motor model, and M is a constant parameter; a1 This provides the torque signal for the motor output.

[0089] The second step involves simulating the large disturbance torque fault signal experienced by the platform using a sinusoidal function, designing the injection time function for the large disturbance torque fault, and combining these functions to obtain the platform disturbance torque signal under fault injection as follows:

[0090] M a3 =m a sin(ω1t);

[0091]

[0092] M a2 =f1M a3 ;

[0093] Where M a3 For large disturbance torque fault signals, m aω1 is the amplitude parameter of the large disturbance torque, which is a constant; ω2 is the frequency parameter of the large disturbance torque, which is a constant; t 1s The injection start time for a large disturbance torque fault; t 1e f1 is the injection end time for the large disturbance torque fault; f1 is the injection time function for the large disturbance torque fault, M a2 The platform interference torque signal is injected under fault conditions.

[0094] The third step involves superimposing the platform interference torque signal under fault injection with the motor output torque signal to obtain the total input torque signal of the inertial platform. Then, a first-order transfer function is used to establish the mechanical dynamics model of the inertial platform, and the total input torque signal is input to obtain the inertial platform angular velocity signal. Finally, integration is performed to obtain the inertial platform output angle signal as follows:

[0095] M a =M a1 +M a2 ;

[0096]

[0097] θ a =∫ω g dt;

[0098] Where M a Input the total torque signal to the inertial platform; ω is the first-order transfer function of the mechanical dynamics model of the inertial platform; T1 is the equivalent time constant of the mechanical dynamics model of the inertial platform, a constant parameter; k1 is the equivalent magnification factor of the mechanical dynamics model of the inertial platform, a constant parameter; g The angular velocity signal of the inertial platform; θ a Output angle signals to the inertial platform.

[0099] Step S30: Calculate the interference signal of the inertial platform rotation on the accelerometer based on the equivalent arm parameters formed by the inertial platform angular velocity signal and the accelerometer installation position; then superimpose the translational vertical acceleration signal of the inertial platform to obtain the total acceleration input signal; then establish the accelerometer measurement model using a second-order transfer function, input the total acceleration input signal to obtain the acceleration measurement signal under the platform torque interference fault; then, based on the accelerometer measurement model, input the translational vertical acceleration signal of the inertial platform to obtain the vertical acceleration signal of the inertial platform, then integrate to obtain the vertical velocity signal of the inertial platform, and further integrate to obtain the position signal of the inertial platform.

[0100] Specifically, this can be broken down into the following three steps. First, calculate the interference signal of the inertial platform's rotation on the accelerometer based on the equivalent arm parameters formed by the inertial platform's angular velocity signal and the accelerometer's installation position; then, superimpose the translational vertical acceleration signal of the inertial platform to obtain the total acceleration input signal as follows:

[0101] a h2 =ω g r g ;

[0102] a h =a h1 +a h2 ;

[0103] Where r g For the equivalent force arm parameters formed by the accelerometer mounting position, a h2 The interference signal of the inertial platform rotation on the accelerometer; a h1 For the translational vertical acceleration signal of the inertial platform, a h This is the total input signal for acceleration.

[0104] The second step involves establishing an accelerometer measurement model using a second-order transfer function. The total acceleration input signal is then used to obtain the acceleration measurement signal under platform torque interference fault conditions, as follows:

[0105]

[0106] Where ω2 is the natural frequency of the accelerometer, a constant parameter; ε2 is the damping ratio of the accelerometer, a constant parameter; For the accelerometer measurement model, a c This is the acceleration measurement signal under platform torque interference fault.

[0107] The third step involves obtaining the vertical acceleration signal of the inertial platform based on the translational vertical acceleration signal input to the accelerometer measurement model. This signal is then integrated to obtain the vertical velocity signal of the inertial platform. Further integration yields the position signal of the inertial platform, as follows:

[0108]

[0109] v c1 =∫a c1 dt;

[0110] s c1 =∫v c1 dt;

[0111] Where a c1 For the vertical acceleration signal of the inertial platform, v c1 The vertical velocity signal of the inertial platform, s c1 This is the position signal of the inertial platform.

[0112] Step S40: Use white noise signal to simulate the measurement noise fault of radio altimeter to obtain altimeter noise simulation signal, then establish a first-order low-pass filter to obtain altimeter noise fault signal; then design altimeter fault injection time function, combine to obtain altimeter fault comprehensive signal, and then superimpose inertial platform position signal to obtain altimeter measurement signal under fault injection.

[0113] Specifically, this can be broken down into the following three steps. The first step is to simulate the measurement noise fault of the radio altimeter using white noise, resulting in the following simulated altimeter noise signal:

[0114] s n3 =w1n1;

[0115] Where n1 is the white noise signal, w1 is the measurement noise fault intensity of the radio altimeter, and s n3 This is a simulated noise signal from the altimeter.

[0116] The second step involves establishing a first-order low-pass filter to obtain the altimeter noise fault signal as follows:

[0117]

[0118] Where T n1 Let s be the time constant of the first-order low-pass filter. n2 This is a noise fault signal for the altimeter.

[0119] The third step involves designing the altimeter fault injection time function, combining the functions to obtain the comprehensive altimeter fault signal, and then superimposing it with the inertial platform position signal to obtain the altimeter measurement signal under fault injection, as follows:

[0120]

[0121] s n1 =f2s n2 ;

[0122] s c1a =s c1 +s n1 ;

[0123] Where f2 is the altimeter fault injection time function, t 2s The start time for injecting fault information into the altimeter, t 2e End time for altimeter fault injection; s n1 For altimeter fault comprehensive signal, s c1a The altimeter measurement signal is injected under fault conditions.

[0124] Step S50: Set the initial value of the height redundancy error signal under fault injection to 0. Superimpose the acceleration measurement signal under platform torque interference fault with the amplified signal of the height redundancy error signal under fault injection to obtain a redundancy-corrected acceleration signal. Then, integrate to obtain a velocity signal based on redundancy technology. Then, superimpose the amplified signal of the height redundancy error signal under fault injection to obtain a redundancy-corrected velocity signal. Then, integrate to obtain a height measurement signal based on redundancy technology. Compare the height measurement signal based on redundancy technology with the altimeter measurement signal under fault injection to obtain the height redundancy error signal. Then, design the injection time function of the height redundancy error feedback fault to obtain the height redundancy error signal under fault injection.

[0125] Specifically, this can be broken down into the following three steps. First, set the initial value of the height redundancy error signal under fault injection to 0. Then, superimpose the acceleration measurement signal under platform torque interference fault conditions with the amplified signal of the height redundancy error signal under fault injection to obtain the redundancy-corrected acceleration signal. Finally, integrate this signal to obtain the velocity signal based on redundancy technology, as follows:

[0126] a cz =a c -k s1 e s ;

[0127] v c =∫a cz dt;

[0128] Where e s The height redundancy error signal is injected under fault conditions; k s1 a is a constant amplification factor; cz Correct the acceleration signal for redundancy; v c This is a speed signal based on redundancy technology.

[0129] The second step involves obtaining a redundancy-corrected speed signal by superimposing the speed signal based on redundancy technology with the amplified signal of the height redundancy error signal under fault injection. This corrected speed signal is then integrated to obtain the height measurement signal based on redundancy technology, as follows:

[0130] v cz =v c -k s2 e s ;

[0131] s cz =∫v cz dt;

[0132] Where k s2 v is a constant amplification factor. cz For redundancy correction of the speed signal; s czThis is a height measurement signal based on redundancy technology.

[0133] The third step involves comparing the height measurement signal based on redundancy technology with the altimeter measurement signal under fault injection to obtain the height redundancy error signal. Then, the injection time function for the height redundancy error feedback fault is designed. The height redundancy error signal under fault injection is obtained as follows:

[0134]

[0135] e s0 =s cz -s c1a ;

[0136] e s =f3e s0 ;

[0137] Where e s0 f3 is the height redundancy error signal; f3 is the injection time function of the height redundancy error feedback fault; t 3s The start time for injecting the high redundancy error feedback fault; t 3e The termination time for the high redundancy error feedback fault injection.

[0138] Step S60: Based on the injection time function of the height redundancy error feedback fault, the altimeter fault injection time function, the platform noise interference fault injection time function, and the large disturbance torque fault injection time function, select one or more faults to inject simultaneously, calculate the height measurement signal based on redundancy technology under multiple platform fault injections, realize the fault injection simulation of the inertial platform accelerometer and altimeter redundancy measurement process, and complete the test equivalent function of the inertial platform redundancy measurement process.

[0139] Case Implementation and Computer Simulation Results Analysis

[0140] In step S10, select ε t =0.2, ω t =50,k b1 =1.5, k b2 =0.3, thus obtaining the proportional-integral control signal for the inertial platform as follows: Figure 2 As shown; the inertial platform error signal is as follows Figure 3 As shown.

[0141] In step S20, T2 = 0.001, k2 = 219.5, and m are selected. a =2000, ω1=40, t 1e =10, t 1s =15, T1=1.05, k1=0.01 to obtain the angular velocity signal of the inertial platform as follows: Figure 4As shown; the inertial platform outputs the angle signal as follows: Figure 5 As shown.

[0142] In step S30, ω2 = 1000 and ε2 = 0.15 are selected to obtain the vertical acceleration signal of the inertial platform as follows: Figure 6 As shown, the vertical velocity signal of the inertial platform is as follows: Figure 7 As shown; the inertial platform position signal is as follows Figure 8 As shown.

[0143] In step S40, select t 2s =30, t 2e =35, the altimeter measurement signal under fault injection is obtained as follows Figure 9 As shown.

[0144] In step S50, t is selected. 3s =20, t 3e =25, the injection time function for the height redundancy error feedback fault is obtained as follows: Figure 10 As shown; the height measurement signal obtained based on redundancy technology is as follows. Figure 11 As shown; the height redundancy error signal obtained under fault injection is as follows: Figure 12 As shown.

[0145] Depend on Figure 8 and Figure 9 It can be seen that the difference between the two images is very small, only between 30 and 35 seconds. This difference is caused by a fault injection in the altimeter. Figure 12 It can also be seen that there are burrs in this part of the time period. And from Figure 10 The injection time for the height redundancy error feedback fault is given; its impact is not significant, but... Figure 11 This shows that the height measurement and the previous trend differ between 20 and 25 seconds. Figure 4 It can be seen that between 10 and 15 seconds, the platform's angular velocity exhibits dense flutter due to the influence of a large disturbance torque; at this time, from Figure 2 , 3 As can be seen from point 5, it has a significant impact on the platform system, and also a significant impact on the platform's output angle; while by Figure 12 It can be seen that during this period, the altitude measurement exhibited severe sinusoidal fluctuations, mainly due to the interference of faults. The experimental results above demonstrate that the entire closed-loop solution is rigorous and flawless, capable of improving the acceleration, velocity, and position signals of all inertial platforms; moreover, it can simulate corresponding faults and calculate the state responses of each component of the system under fault conditions, thereby achieving the purpose of test equivalence. This also indicates high accuracy and reliability, thus giving the invention significant engineering practical value.

Claims

1. A fault injection and testing method for an inertial platform based on redundancy technology, characterized by the following steps: Step S10: Set the initial value of the inertial platform output angle to zero; then, establish a gyroscope measurement model using the transfer function method to obtain the inertial platform gyroscope measurement angle signal; next, set the platform noise interference fault injection time function and set the platform input to a Gaussian-distributed white noise signal, combining them to obtain the platform input signal under fault injection; compare this signal with the inertial platform gyroscope measurement angle signal to obtain the inertial platform error signal, and integrate it to obtain the inertial platform error integral signal; finally, combine the inertial platform error signal and the inertial platform error integral signal to obtain the inertial platform proportional-integral control signal as follows: ； ； ； ； ； ； in The initial value of the output angle for the inertial platform is zero; Here is the damping ratio parameter of the gyroscope, and is a constant coefficient; Here, represents the natural frequency parameter of the gyroscope, and represents a constant coefficient. This is a gyroscope measurement model. Differential operators for the model's transfer function; For measuring angle signals of the inertial platform gyroscope; Inject a time function to address platform noise interference faults. The injection start time for platform noise interference faults; The injection end time for platform noise interference faults; The signal is a Gaussian-distributed white noise signal. is a constant sub-parameter, and is the noise intensity coefficient; Input signals to the platform under fault injection; This is the error signal of the inertial platform. This is the integral signal of the inertial platform error; For the proportional-integral control signal of the inertial platform; , These are constant control parameters; Step S20: Using the proportional-integral control signal of the inertial platform as the input to the platform's DC motor, a first-order transfer function is used to establish the DC motor model of the inertial platform, obtaining the motor output torque signal. Then, a sine function is used to simulate the large disturbance torque fault signal experienced by the platform, and the injection time function of the large disturbance torque fault is designed and combined to obtain the platform disturbance torque signal under fault injection. The motor output torque signal is then superimposed to obtain the total input torque signal of the inertial platform. A first-order transfer function is then used to establish the mechanical dynamics model of the inertial platform, and the total input torque signal of the inertial platform is input to obtain the inertial platform angular velocity signal. Finally, integration is performed to obtain the inertial platform output angle signal as follows: ； ； ； ； ； ； ； in This is a DC motor model for an inertial platform. This represents the equivalent magnification factor of the motor model. is the equivalent time constant of the motor model, and is a constant parameter; This provides the motor with a torque signal. This is a large disturbance torque fault signal. This is the amplitude parameter of the large disturbance torque, and it is a constant value; The frequency parameter for the large disturbance torque is a constant value. The injection start time for a large disturbance torque fault; The injection end time for large disturbance torque faults; The injection time function for large disturbance torque faults. The platform interference torque signal injected under fault conditions; Input the total torque signal to the inertial platform; This is the first-order transfer function of the mechanical dynamics model of the inertial platform; is the equivalent time constant of the mechanical dynamics model of the inertial platform, and is a constant parameter; is the equivalent magnification factor for the mechanical dynamics model of the inertial platform, and is a constant parameter; This is the angular velocity signal of the inertial platform; Output angle signals to the inertial platform; Step S30: The interference signal of the inertial platform rotation on the accelerometer is calculated based on the equivalent arm parameters formed by the inertial platform angular velocity signal and the accelerometer installation position. Then, the translational vertical acceleration signal of the inertial platform is superimposed to obtain the total acceleration input signal. Next, a second-order transfer function is used to establish an accelerometer measurement model, and the total acceleration input signal is input to obtain the acceleration measurement signal under platform torque interference fault. Then, based on the accelerometer measurement model, the translational vertical acceleration signal of the inertial platform is input to obtain the vertical acceleration signal of the inertial platform. Integration is then performed to obtain the vertical velocity signal of the inertial platform, and further integration yields the inertial platform position signal as follows: ； ； ； ； ； ； in The equivalent force arm parameters formed by the accelerometer installation position, This is the interference signal of the inertial platform rotation on the accelerometer; This is the translational vertical acceleration signal of the inertial platform. The total input signal for acceleration; is the natural frequency of the accelerometer, and is a constant parameter; Here is the damping ratio of the accelerometer, and is a constant parameter; For accelerometer measurement model, This is the acceleration measurement signal under platform torque interference fault; This is the vertical acceleration signal of the inertial platform. This is the vertical velocity signal of the inertial platform. This is the position signal of the inertial platform; Step S40: Use white noise signal to simulate the measurement noise fault of radio altimeter to obtain altimeter noise simulation signal, then establish a first-order low-pass filter to obtain altimeter noise fault signal; then design altimeter fault injection time function, combine to obtain altimeter fault comprehensive signal, and then superimpose inertial platform position signal to obtain altimeter measurement signal under fault injection. ； ； ； ； ； in It is a white noise signal. For measuring the noise fault intensity of the radio altimeter, This is an analog signal for altimeter noise. The time constant of the first-order low-pass filter. This is a noise fault signal for the altimeter. Inject a time function to address altimeter malfunctions. The start time injected for altimeter malfunction. End time for injecting fault information into altimeter; This is a comprehensive signal indicating a fault in the altimeter. The altimeter measurement signal is injected under fault conditions; Step S50: Set the initial value of the height redundancy error signal under fault injection to 0, and superimpose the acceleration measurement signal under platform torque interference fault with the amplified signal of the height redundancy error signal under fault injection to obtain the redundancy correction acceleration signal. Then, the speed signal based on redundancy technology is obtained by integration; then, the amplified signal of the height redundancy error signal under fault injection is superimposed to obtain the redundancy-corrected speed signal. The height measurement signal based on redundancy technology is then obtained by integration. This redundancy-based height measurement signal is compared with the altimeter measurement signal under fault injection to obtain the height redundancy error signal. The injection time function for the height redundancy error feedback fault is then designed. The height redundancy error signal under fault injection is obtained as follows: ； ； ； ； ； ； ； in The height redundancy error signal is injected under fault conditions; , This is a constant amplification factor; Correct the acceleration signal for redundancy; The speed signal is based on redundancy technology; The speed signal is corrected for redundancy. This is a height measurement signal based on redundancy technology; This is the height redundancy error signal; The injection time function for the high redundancy error feedback fault; The start time for injecting feedback faults for height redundancy errors; Termination time for high redundancy error feedback fault injection; Step S60: Based on the injection time function of the height redundancy error feedback fault, the altimeter fault injection time function, the platform noise interference fault injection time function, and the large disturbance torque fault injection time function, select one or more faults to inject simultaneously, calculate the height measurement signal based on redundancy technology under multiple platform fault injections, realize the fault injection simulation of the inertial platform accelerometer and altimeter redundancy measurement process, and complete the test equivalent function of the inertial platform redundancy measurement process.

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