A composite active control method for all aspects of a launch vehicle adapting to thrust drop failures

Abstract

The present invention discloses a full-link composite active control method for launch vehicles that adapts to thrust-drop failures. The method comprises obtaining fault diagnostic information; calculating control gains based on the fault diagnostic information; calculating the additional interference torque generated by the engine thrust-drop failure based on the fault diagnostic information, and generating additional control instructions based on the additional interference torque; superimposing the normal control instructions under normal engine operating conditions with the additional control instructions to obtain a total control instruction, and distributing the total control instruction to the servo mechanism of each engine to achieve closed-loop control. This invention forms a full-link fault-tolerant control method for launch vehicles, improving control quality and enhancing fault tolerance.

Description

Technical Field

[0001] The present invention belongs to the technical field of fault-tolerant control of launch vehicles, and in particular relates to a composite active control method for all links of a launch vehicle that is adaptable to engine thrust drop failures. Background Art

[0002] Current research on active fault-tolerant control technology for launch vehicles can be divided into two categories, based on the launch vehicle controller structure: control law reconstruction and control distribution law reconstruction. Currently, most research focuses on one aspect of these two, and a comprehensive fault-tolerant control approach for launch vehicles has not yet been developed. Both control law reconstruction and control distribution law reconstruction can only address the rationality of channel equivalent instructions or servo instructions, but cannot fully address the fault-tolerant control problem. The technical solution of the present invention can maximize the control loop's capabilities to solve the fault-tolerant control problem. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above-mentioned defects and provide a composite active control method for all links of a launch vehicle that is adaptable to thrust drop failures, thereby overcoming the technical problem that traditional active fault-tolerant control technology of launch vehicles cannot achieve fault-tolerant control of all links. The present invention forms a fault-tolerant control method for all links of a launch vehicle, improves the control quality, and enhances the fault-tolerant capability.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] A composite active control method for all aspects of a launch vehicle adapted to thrust drop failures, comprising:

[0006] Obtain fault diagnosis information;

[0007] Correcting the control gain according to the fault diagnosis information, and obtaining the basic control instruction under the fault condition according to the corrected control gain;

[0008] calculating the additional interference torque generated by the engine thrust reduction fault based on the fault diagnosis information, and generating additional control instructions based on the additional interference torque;

[0009] The basic control instructions and additional control instructions under fault conditions are superimposed to obtain the total control instructions, which are then distributed to the servo mechanism of each engine to complete closed-loop control.

[0010] Furthermore, the fault diagnosis information is the thrust coefficient of each engine;

[0011] When the jth engine fails, the thrust coefficients of each engine conform to the following model:

[0012] Among them, k i is the thrust coefficient of the i-th engine, k faultis the thrust coefficient of the faulty engine, 1≤i, j≤N, and N is the total number of engines.

[0013] Furthermore, the launch vehicle's engine layout consists of four booster engines bundled with two core stage engines;

[0014] Methods for correcting control gains based on fault diagnosis information include:

[0015] According to the fault diagnosis information, the control force coefficient expression is obtained:

[0016]

[0017]

[0018]

[0019]

[0020] in, Respectively represent the control force coefficients of the core stage engine and booster engine in the pitch channel and yaw channel, represents the pitch channel, ψ represents the yaw channel; k xj1 ,k xj2 ,k zt1 ,k zt2 ,k zt3 ,k zt4 are the thrust coefficients of the 1st and 2nd core stage engines and the 1st, 2nd, 3rd and 4th booster engines, respectively. xj1 ,P xj2 ,P zt1 ,P zt2 ,P zt3 ,P zt4 are the thrusts of the 1st and 2nd core stage engines and the 1st, 2nd, 3rd and 4th booster engines respectively, M is the mass of the launch vehicle, and V is the speed of the launch vehicle;

[0021] According to the fault diagnosis information, the control torque coefficient expression is obtained:

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028] in, They represent the control torque coefficients of the core stage engine and booster engine in the pitch channel and yaw channel respectively, Indicates the control torque coefficient of the core stage engine and booster engine in the rolling channel; X rxj is the distance between the engine swing point and the rocket theoretical tip; X rzt is the distance between the booster engine and the longitudinal axis of the rocket; X z J is the longitudinal center of mass of the rocket; x ,J y ,J z is the rocket's three-axis moment of inertia; Z rxj is the distance between the core stage engine swing point and the longitudinal axis; Z rzt is the distance between the booster engine swing point and the longitudinal axis;

[0029] Assuming that the three-channel control capabilities of a single engine under normal operating conditions and after a fault are equal, the following equations are obtained based on the control force coefficient expression and the control torque coefficient expression:

[0030]

[0031]

[0032] in, They represent the control torque coefficients of the rocket as a whole in the pitch channel and the yaw channel respectively; d3 represents the control torque coefficient of the rocket as a whole in the roll channel; δ ψ , δ γ They represent the normal control instructions of pitch, yaw and roll channels under normal working conditions respectively; Represents the equivalent control swing angle of the core stage servo mechanism and booster servo mechanism of the pitch channel; Represents the equivalent control swing angle of the core stage servo mechanism and the booster servo mechanism of the yaw channel; Represents the equivalent control swing angle of the core stage servo mechanism and the booster servo mechanism of the rolling channel;

[0033] Substituting the three-channel control equation under normal operating conditions into the above equation, we can obtain the corrected control gain;

[0034] The control equation is: in, Represents the static control gains of pitch, yaw, and roll channels; represents the angular deviation and angular velocity of the pitch channel; ψ, Represents the angular deviation and angular velocity of the yaw channel; γ, Represents the angular deviation and angular velocity of the rolling channel; Represents the dynamic control gains of the pitch, yaw, and roll channels.

[0035] Furthermore, the corrected control gain is:

[0036]

[0037] in, The corrected static control gain for the pitch channel; Corrected dynamic control gain for the pitch channel; is the static control gain after correction of the yaw channel; is the corrected dynamic control gain of the yaw channel; is the static control gain after correction of the rolling channel; The corrected dynamic control gain of the rolling channel.

[0038] Substituting the corrected control gain under fault conditions into the control equation, we can obtain Then get They represent the basic control commands for pitch, yaw, and roll channels under thrust-down fault conditions respectively;

[0039] Furthermore, the additional interference force generated by the engine thrust reduction fault is calculated based on the fault diagnosis information, and the additional interference torque is obtained based on the additional interference force;

[0040] The additional disturbance force generated by the engine thrust reduction failure includes the Y-direction disturbance force F fy and the Z-direction interference force F of the rocket body coordinate system fz :

[0041]

[0042]

[0043] Among them, A zt 、A xj Represents the installation angle of the booster engine and core stage engine.

[0044] Furthermore, the interference torque generated by the engine thrust reduction failure is:

[0045]

[0046] Among them, M fz M is the disturbance torque generated in the pitch channel by the engine thrust reduction failure; fy is the disturbance torque generated in the yaw channel by the engine thrust reduction failure; Z C Y is the center of mass position of the rocket body in the Z-axis direction in the rocket body coordinate system; C It is the center of mass position of the rocket body in the Y-axis direction in the rocket body coordinate system.

[0047] Furthermore, the method for calculating the interference torque generated by the engine thrust reduction fault based on the fault diagnosis information includes:

[0048] When the booster engine thrust decreases, the interference torque M generated by the core stage engine in the pitch channel is fz_xj and the disturbance torque M generated by the yaw channel fy_xj for:

[0049]

[0050] When the booster engine thrust decreases, the interference torque M generated by the booster engine in the pitch channel is fz_zt and the disturbance torque M generated by the yaw channel fy_zt for:

[0051]

[0052] When the core stage engine thrust decreases, the interference torque M′ generated by the engine in the pitch channel fz and the disturbance torque M′ generated by the yaw channel fy for:

[0053]

[0054] M fz M fz_xj 、M fz_zt and M′ fz The sum, M fy M fy_xj 、M fy_zt and M′ fy sum.

[0055] Furthermore, the additional control instruction generated according to the additional interference torque is:

[0056]

[0057] in, and are additional control instructions for the pitch channel and yaw channel respectively; P xj 、P zt It is the rated thrust of the core stage engine and booster engine.

[0058] Furthermore, the total control instruction is obtained by linearly superimposing the basic control instruction and the additional control instruction under the engine fault condition.

[0059] Furthermore, the total control command is distributed to the servo mechanism of each engine using the pseudo-inverse method. The specific method is as follows:

[0060] According to the general control instruction, the swing angle synthesis formula of the core stage engine and the booster stage engine when the engine thrust drops is obtained:

[0061]

[0062] in, Equivalent control commands generated for the core stage engine in pitch, yaw and roll channels; Equivalent control commands generated for the booster engines in pitch, yaw, and roll channels.

[0063] By making the channel control torque of a single engine under normal operating conditions and after a fault equal to the control torque generated by the actual servo swing, the following equation is obtained:

[0064] Pitch channel:

[0065]

[0066]

[0067]

[0068]

[0069] Yaw channel:

[0070]

[0071]

[0072]

[0073]

[0074] Scroll channel:

[0075]

[0076]

[0077] in, Additional control instructions generated for the core stage engine in the pitch and yaw channels; Additional control instructions generated by the booster engine in the pitch and yaw channels; δ xjI , δ xjII , δ xjIII , δ xjIV is the swing angle instruction of the four servo mechanisms of the core stage engine; δ ztI , δ ztII , δ ztIII , δ ztIVTo provide the swing angle commands for the four servo mechanisms of the booster engine;

[0078] After transforming the swing angle synthesis formula of the core stage engine and the booster stage engine, the following formula is obtained:

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085] The pseudo-inverse method is used to obtain the control instruction redistribution formula for distributing the total control instruction to the servo mechanism of each engine.

[0086] Compared with the prior art, the present invention has the following beneficial effects:

[0087] (1) The present invention creatively proposes a full-link composite active fault-tolerant control method covering control law reconstruction and control distribution law reconstruction. After obtaining engine fault information, the control gain can be adjusted online and interference compensation can be performed. The control effect of the present invention is significantly better than the traditional PD+network control method, and the control quality is improved.

[0088] (2) The present invention distributes the overall control instructions to the servo mechanism of each engine, realizes the redistribution of the swing angle, and further improves the control accuracy;

[0089] (3) The present invention is general and can be applied to the development of control reconstruction systems for various types of launch vehicles in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 This is a flow chart of the composite active control method for all aspects of a launch vehicle adapted to thrust drop failures according to the present invention;

[0091] Figure 2 This is a schematic diagram of the layout and swing of a first-stage engine of a certain type of rocket of the present invention (tail view);

[0092] Figure 3 Schematic diagram of the interference torque of the present invention (top view);

[0093] Figure 4 Schematic diagram of the interference torque of the present invention (side view);

[0094] Figure 5This is a schematic diagram of the online control reconstruction scheme of the present invention;

[0095] Figure 6 This is a rear view of the faulty engine position of the present invention;

[0096] Figure 7 is the thrust curve of the faulty engine of the present invention;

[0097] Figure 8 is the pitch angle deviation variation curve of the present invention;

[0098] Figure 9 is the yaw angle deviation change curve of the present invention;

[0099] Figure 10 is the roll angle deviation variation curve of the present invention;

[0100] Figure 11 is the pitch channel static control gain a0 curve of the present invention;

[0101] Figure 12 This is the pitch channel dynamic control gain a1 curve of the present invention;

[0102] Figure 13 is the static control gain a0 curve of the yaw channel of the present invention;

[0103] Figure 14 is the roll channel dynamic control gain a0 curve of the present invention;

[0104] Figure 15 This is the yaw channel dynamic control gain a1 curve of the present invention;

[0105] Figure 16 The dynamic control gain a1 curve of the roll channel of the present invention;

[0106] Figure 17 This is the equivalent swing angle change curve of the present invention, where (a), (b), and (c) are the equivalent control swing angles of the three channels of roll, yaw, and pitch, respectively. DETAILED DESCRIPTION

[0107] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0108] The word "exemplary" is used exclusively herein to mean "serving as an example, example, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0109] This paper proposes a comprehensive active fault-tolerant control method for a single engine under thrust loss conditions. This method involves online adjustment of control gains and additional compensation control in the control law reconstruction phase, and reallocation of control instructions in the control distribution law reconstruction phase. Simulations were conducted to verify the application of online control gain adjustment, additional compensation control instructions, and control instruction reallocation strategies for launch vehicle thrust loss failures. This completes a closed-loop active fault-tolerant solution for liquid launch vehicles, combining fault diagnosis with active fault-tolerant control.

[0110] According to the attached Figure 1 The algorithm flow chart of the active fault-tolerant control technology shown in FIG. 1 is a flowchart of the active fault-tolerant control technology shown in FIG. 1 , and the implementation steps of the present invention are as follows:

[0111] (1) Obtain fault information from the fault diagnosis system;

[0112] (2) Modify the control gain according to the fault condition and calculate the basic control command under the fault condition;

[0113] (3) Calculate the interference force and torque according to the fault situation, and then calculate the additional control instructions;

[0114] (4) The basic control instructions and additional control instructions under the engine fault condition are superimposed to obtain the total control instruction, and the total control instruction is distributed to each engine servo mechanism using the pseudo-inverse method to complete the closed-loop control.

[0115] The following takes the boost flight phase of a certain type of rocket as an example to illustrate the detailed calculation process of the algorithm proposed in the present invention, and verifies the effectiveness of the method proposed in the present invention through simulation.

[0116] (1) Obtain fault information from the fault diagnosis system:

[0117] The forms of engine failure are relatively complex. Except for catastrophic failures, from the perspective of input affecting rocket dynamics, all can be expressed as abnormal thrust. To facilitate problem research, it is assumed that the engine propellant (oxidizer and fuel) flow rate is proportional to the engine thrust. When the thrust drops by 100%, the propellant in the corresponding tank of the engine stops being consumed. This assumption is the worst case, because the propellant stops being discharged, and its center of mass deviation is greater than other leakage and slow discharge situations. Taking the engine thrust variation coefficient k i As the unknown coefficient, the model coefficient of the j-th engine failure is

[0118]

[0119] Where k fault is the thrust coefficient of the failed engine.

[0120] (2) Calculate the control gain based on the fault diagnosis information, that is, correct the control gain online:

[0121] (2.1) Effect of engine failure on control force and torque

[0122] When the thrust is reduced, in addition to reducing the thrust and control torque, it will also generate a thrust imbalance torque. Take a certain type of rocket as an example, the configuration is a four-boost bundled core stage layout, the booster engines are tangentially swinging, and the core stage engines are in a "\" shape layout, all of which are cross-swinging, that is, the line connecting the 1st and 3rd booster engines is perpendicular to the line connecting the 2nd and 4th booster engines, and the line connecting the two core stage engines is 45 degrees to the above two lines. The engine layout is shown in Figure 1. Figure 2 , Figure 2 In the figure, the positive direction of engine swing is the direction indicated by the arrow, the bold line part is the servo mechanism actuator rod, z1~z4 represent the booster 1~4 engine numbers, and the Roman numerals represent the servo numbers.

[0123] The control force coefficient expression is expressed as:

[0124]

[0125]

[0126]

[0127]

[0128] In the formula represents the rocket control force coefficient; k xj1 ,k xj2 ,k zt1 ,k zt2 ,k zt3 ,k zt4 is the thrust coefficient of the core stage engine and booster engine; P xj1 ,P xj2 ,P zt1 ,P zt2 ,P zt3 ,P zt4 is the thrust of the 1st and 2nd core stage engines and the 1st, 2nd, 3rd and 4th booster engines; M, V are the mass and speed of the rocket.

[0129] The control torque coefficient expression is expressed as:

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136] In the formula represents the rocket control torque coefficient; X rxj is the distance between the engine swing point and the rocket theoretical tip; X z J is the longitudinal center of mass of the rocket; x ,J y ,J z is the rocket's three-axis moment of inertia; Z rxj is the distance between the rocket engine's swing point and the longitudinal axis.

[0137] (2.2) Control gain online adjustment method

[0138] The three-channel control equation under normal working conditions is:

[0139]

[0140] In the formula represents the angular deviation and angular velocity of the pitch channel; ψ, represents the angular deviation and angular velocity of the yaw channel; γ, Represents the angular deviation and angular velocity of the rolling channel; Represents the static control gains of pitch, yaw, and roll channels; Represents the dynamic control gains of pitch, yaw, and roll channels; δ ψ , δ γ Represents the normal control instructions of the pitch, yaw and roll channels under normal working conditions.

[0141] In order to ensure that the three-channel control capability remains unchanged after a single engine failure, the control force coefficient term and the torque coefficient term remain unchanged, that is:

[0142]

[0143]

[0144] In the formula Represents the equivalent control swing angle of the core stage servo mechanism and booster servo mechanism of the pitch channel; Represents the equivalent control swing angle of the core stage servo mechanism and the booster servo mechanism of the yaw channel; Represents the equivalent control swing angle of the core stage servo mechanism and the booster servo mechanism of the rolling channel.

[0145] Substituting the control equation into the pitch channel, we can get:

[0146]

[0147]

[0148] Where P xj ,P zt is the rated thrust of the core stage engine and booster engine; Represents the static control gain of the pitch channel after correction; Represents the corrected dynamic control gain of the pitch channel.

[0149] Yaw channel:

[0150]

[0151] In the formula Represents the static control gain after correction of the yaw channel; Represents the corrected dynamic control gain of the yaw channel.

[0152] Scroll channel:

[0153]

[0154] In the formula Represents the static control gain after rolling channel correction; Represents the corrected dynamic control gain of the rolling channel.

[0155] Ignoring the slight thrust deviation of the engine and assuming that the nominal thrust of each engine is equal, the online adjustment formula of the control gain can be directly obtained:

[0156]

[0157] It can be seen from this that as long as the fault diagnosis system can accurately identify the thrust coefficient of the faulty engine, the control gain can be adaptively adjusted through the above formula, thereby ensuring that the control capability remains basically unchanged.

[0158] (3) Generation of additional control instructions

[0159] (3.1) Additional interference force and torque analysis

[0160] In the event of an engine thrust drop failure, for example, when the thrust of booster engine No. 3 drops, the thrust of booster engines No. 1 and No. 3 are no longer equal, then booster engines No. 1 and No. 3 will inevitably generate additional interference torques due to the unequal thrusts, and the slower propellant consumption caused by the thrust drop of the booster engines will cause the center of mass to shift laterally, which will also introduce interference torques.

[0161] (3.1.1) Additional interference force analysis

[0162] When the thrust is unbalanced, due to the existence of the engine installation angle, the thrust component of the launch vehicle is no longer balanced in the transverse direction, causing the thrust component to generate interference force in the transverse direction. Figure 3 and Figure 4 By analyzing the geometric relationship, the disturbance force F in the Y direction of the rocket body coordinate system can be written as fy for:

[0163]

[0164] Where A zt ,A xj Represents the installation angle of the booster engine and core stage engine.

[0165] Write down the disturbance force F in the Z direction of the rocket body coordinate system fz for:

[0166]

[0167] Figure 3 In the figure, ZB represents the Z direction of the arrow system, and YB represents the Y direction of the arrow system.

[0168] (3.1.2) Additional interference torque analysis

[0169] When analyzing the additional interference torque, the decrease in booster thrust will cause the center of mass to shift laterally, while the decrease in core stage engine thrust will not cause the center of mass to shift laterally, but only slow down the longitudinal transformation of the center of mass. Therefore, it is necessary to discuss the two cases of core stage engine thrust decrease and booster engine thrust decrease separately.

[0170] a) Booster engine thrust decreases

[0171] Taking the thrust drop failure of the Booster 3 engine as an example, the slowdown of the propellant consumption of the Booster 3 engine will cause the center of mass to shift laterally. The interference torque generated by this on the attitude control system is as follows:

[0172] The two moments of the core stage engine in the yaw direction are exactly offset, and only the interference moment M is generated in the pitch direction. fz_xj :

[0173]

[0174] Where Y C Represents the center of mass position of the rocket body in the Y direction.

[0175] The interference torque generated by the thrust deviation of the booster engine is the pitch direction torque generated by the No. 1 and No. 3 engines, and the pitch direction torque generated by the No. 2 and No. 4 booster engines. The pitch direction torque arm is Figure 4 It can be seen that it is divided into two parts ①②. The whole does not generate interference torque on the yaw channel, and the interference torque M generated by the booster engine is obtained.fz_zt The form is as follows:

[0176]

[0177] Where X rzt is the distance between the rocket booster engine and the rocket's longitudinal axis;

[0178] b) Core stage engine thrust reduction

[0179] When the core stage engine has a thrust drop failure, the core stage propellant consumption slows down, and the axial change of the center of mass becomes slower than the nominal situation. However, the good thing is that it does not move laterally, so the interference torque generated on the attitude control system is only the lateral displacement Y of the center of mass. C , which can be expressed as follows:

[0180]

[0181] In summary, by combining the interference torques of the two core stage boost thrust reduction modes, the total additional interference torque generated by the engine thrust reduction failure can be obtained:

[0182]

[0183] Where Z C is the center of mass position of the rocket body in the Z-axis direction.

[0184] (3.2) Additional control instruction strategy

[0185] In order to eliminate the additional torque generated by the faulty engine, it is necessary to add interference compensation instructions on the basis of the stability control instructions. The interference compensation instructions for the pitch and yaw channels are and The calculation is as follows:

[0186]

[0187] (4) Obtain the total control instruction using the basic control instruction and additional control instruction under the fault condition, and redistribute the total control instruction

[0188] Under normal operating conditions, the core stage engine swing angle synthesis formula is:

[0189]

[0190] Where δ xjI ,δ xjII ,δ xjIII ,δ xjIV It is the swing angle instruction of the four servo mechanisms of the core stage.

[0191] The formula for the booster engine swing angle synthesis is:

[0192]

[0193] Where δ ztI ,δ ztII ,δ ztIII ,δ ztIV To assist in the swing angle instructions of the four servo mechanisms.

[0194] The formula for synthesizing the swing angles of the core stage and booster engine under engine failure conditions is:

[0195]

[0196] in, Equivalent control commands generated for the core stage engine in pitch, yaw and roll channels; Equivalent control commands generated for the booster engines in pitch, yaw, and roll channels.

[0197] By making the channel control torque of a single engine under normal operating conditions and after a fault equal to the control torque generated by the actual servo swing, the following equation is obtained:

[0198] Pitch channel:

[0199]

[0200]

[0201]

[0202]

[0203] Yaw channel:

[0204]

[0205]

[0206]

[0207]

[0208] Scroll channel:

[0209]

[0210]

[0211] Then there is

[0212]

[0213]

[0214]

[0215]

[0216]

[0217]

[0218] The control instruction reallocation formula can be obtained by using the pseudo-inverse method for the above formula.

[0219] When a launch vehicle experiences an engine thrust drop failure, the main impact of the failure on the attitude control system is a reduction in control torque and the generation of additional interference torque. To address the control torque reduction issue, an online control gain adjustment strategy was designed. To address the additional interference torque issue, an interference compensation command strategy was designed. In addition, to ensure the rationality of the swing angle command, a control command redistribution strategy was designed using the pseudo-inverse method. By combining these three strategies, an active fault-tolerant control scheme for engine thrust drop failures, namely the online reconstruction control scheme, was designed. The schematic diagram is shown in Figure 5 .

[0220] Example:

[0221] This invention addresses the situation where an engine thrust-down failure primarily impacts the attitude control system by reducing control torque and generating additional interference torque. To address this reduction, an online control gain adjustment strategy is designed; to address the additional interference torque, an interference compensation command strategy is designed; and to ensure reasonable swing angle commands, a control command redistribution strategy is designed using the pseudo-inverse method. Combining these three strategies creates a comprehensive, composite, active, fault-tolerant control scheme for engine thrust-down failures.

[0222] See the attached algorithm flow chart Figure 1 , the specific steps are as follows:

[0223] (1) Obtain fault diagnosis information;

[0224] (2) Modify the control gain according to the fault condition and calculate the basic control instructions under the fault condition;

[0225] (3) Calculate additional interference forces and torques based on the fault conditions, and then generate additional control instructions;

[0226] (4) According to the basic control instructions and additional control instructions under the engine fault condition, the synthetic control instructions are obtained and the control instructions are allocated using the pseudo-inverse method.

[0227] In order to verify the effectiveness of the online control reconstruction scheme proposed in this section, the fault setting is that the thrust of the booster engine No. 3 drops by 100% in 50 seconds, and a simulation analysis is performed. The location of the faulty engine is shown in Figure 6 The upper engine is the faulty engine. The thrust curve of the faulty engine is shown in Figure 7 .

[0228] The simulation results are shown in Figures 8 to 17 , the analysis is as follows:

[0229] Depend on Figure 8 It can be seen that when the booster engine has a thrust drop failure, the traditional PD+ network control method increases the pitch attitude angle deviation instantly, and then oscillates and diverges, indicating that the rocket is out of control; while the active fault-tolerant control system of the present invention (AFTC shown in the figure, which means active fault-tolerant control in Chinese) can better maintain stability and control the three-channel attitude angle deviation within 1 degree. Although the traditional control method of the yaw and roll channels does not diverge and lose control, the attitude angle deviation increases significantly compared to normal flight, and the control quality deteriorates. After the present invention adopts the active fault-tolerant control method, the attitude angle deviation is significantly improved, see for details. Figure 9 and Figure 10 .

[0230] When a thrust drop failure occurs during the rocket boost and first stage flight, a full-link composite active fault-tolerant control method, including control law reconstruction and control distribution law reconstruction, is used to improve control quality and enhance fault tolerance. This is analyzed from three specific strategic aspects:

[0231] Control gain online adjustment: Because the No. 3 engine swing controls the yaw and roll channels, the pitch control gain does not change. See Figures 11 and 12 , a0 in the figure represents the static control gain; a1 represents the dynamic control gain.

[0232] In the yaw and roll channels, the control gain values ​​of the two channels increase from the moment the fault occurs (see Figures 13 to 16 ) so that the control torque still meets the rated design conditions, that is, the rocket can still fly stably.

[0233] Additional control instructions: via Figure 17 It can be seen (where DeltaX / Y / Z are the equivalent control swing angles of the roll, yaw, and pitch channels, respectively) that after a fault occurs, the total control instructions of the two methods differ greatly. The equivalent swing angle curve using the active fault-tolerant control method of the present invention has a smaller amplitude and is smoother. This is partly because the gain is adjusted online, and partly because the active fault-tolerant control method introduces interference compensation instructions.

[0234] Control allocation reconstruction module verification: passed Figure 17It can be found that the thrust of the Booster No. 3 engine dropped by 100% in 50 seconds. The swing angle of the Booster No. 3 engine using the traditional (PD+correction network) control method still had an output, indicating that the control system failed to respond to the engine failure; while the swing angle of the Booster No. 3 engine using the active fault-tolerant control method was 0, indicating that after the active fault-tolerant control method identified the fault, the swing angle command of the Booster No. 3 engine was reconstructed and the swing angle output was solidified to 0 degrees.

[0235] The present invention takes the thrust drop of the boost and first-stage flight phase as the fault condition and proposes a full-link composite active fault-tolerant control method covering the reconstruction of control law and control distribution law. The method mainly includes:

[0236] 1) The impact of a launch vehicle engine thrust-drop failure on the attitude control system was analyzed. This failure primarily resulted in a reduction in control torque and the generation of additional disturbance torque. To address the reduction in control torque, an online control gain adjustment strategy was designed. To address the additional disturbance torque, a disturbance compensation command strategy was developed. To ensure reasonable swing angle commands, a control command redistribution strategy was designed using the pseudo-inverse method. These three strategies were combined to form a comprehensive, active, and fault-tolerant control scheme for engine thrust-drop failures.

[0237] 2) Using a full-link composite active fault-tolerant control method, a simulation analysis was conducted for a specific fault in which the thrust of the booster engine No. 3 dropped by 100% within 50 seconds. The results showed that the conventional PD+network control method resulted in a momentary increase in pitch attitude angle deviation, followed by oscillation and divergence, indicating a loss of rocket control. However, the active fault-tolerant control system of the present invention maintained good stability and controlled the three-channel attitude angle deviation to within 1 degree. Although the conventional control method for the yaw and roll channels did not diverge and lose control, the attitude angle deviation increased significantly compared to normal flight, resulting in poor control quality. The active fault-tolerant control method of the present invention significantly improved control quality.

[0238] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

[0239] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

[0240] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A composite active control method for all aspects of a launch vehicle adapted to thrust drop failures, characterized in that: include: Obtain fault diagnosis information; Correcting the control gain according to the fault diagnosis information, and obtaining the basic control instruction under the fault condition according to the corrected control gain; calculating the additional interference torque generated by the engine thrust reduction fault based on the fault diagnosis information, and generating additional control instructions based on the additional interference torque; The basic control instructions under fault conditions and the additional control instructions are superimposed to obtain the total control instruction, which is then distributed to the servo mechanism of each engine to complete closed-loop control. The corrected control gain is: in, The corrected static control gain for the pitch channel; Corrected dynamic control gain for the pitch channel; is the static control gain after correction of the yaw channel; is the corrected dynamic control gain of the yaw channel; is the static control gain after correction of the rolling channel; The corrected dynamic control gain for the rolling channel; Substituting the corrected control gain under fault conditions into the control equation, we can obtain Then get They represent the basic control commands for pitch, yaw, and roll channels under thrust-down fault conditions respectively; Represents the static control gains of pitch, yaw, and roll channels; represents the angular deviation and angular velocity of the pitch channel; ψ, Represents the angular deviation and angular velocity of the yaw channel; γ, Represents the angular deviation and angular velocity of the rolling channel; Represents the dynamic control gains of pitch, yaw, and roll channels; Z rxj is the distance between the core stage engine swing point and the longitudinal axis; Z rzt k is the distance between the booster engine swing point and the longitudinal axis; xj1 ,k xj2 ,k zt1 ,k zt2 ,k zt3 ,k zt4 These are the thrust coefficients of the 1st and 2nd core stage engines and the 1st, 2nd, 3rd and 4th booster engines respectively.

2. The method for all-link composite active control of a launch vehicle adapted to thrust drop failure according to claim 1, characterized in that: The fault diagnosis information is the thrust coefficient of each engine; When the jth engine fails, the thrust coefficients of each engine conform to the following model: Among them, k i is the thrust coefficient of the i-th engine, k fault is the thrust coefficient of the faulty engine, 1≤i, j≤N, and N is the total number of engines.

3. The method for all-link composite active control of a launch vehicle adapted to thrust drop failure according to claim 2, characterized in that: The launch vehicle's engine layout consists of four booster engines bundled with two core stage engines; Methods for correcting control gains based on fault diagnosis information include: According to the fault diagnosis information, the control force coefficient expression is obtained: in, Respectively represent the control force coefficients of the core stage engine and booster engine in the pitch channel and yaw channel, represents the pitch channel, ψ represents the yaw channel; k xj1 ,k xj2 ,k zt1 ,k zt2 ,k zt3 ,k zt4 are the thrust coefficients of the 1st and 2nd core stage engines and the 1st, 2nd, 3rd and 4th booster engines, respectively. xj1 ,P xj2 ,P zt1 ,P zt2 ,P zt3 ,P zt4 are the thrusts of the 1st and 2nd core stage engines and the 1st, 2nd, 3rd and 4th booster engines respectively, M is the mass of the launch vehicle, and V is the speed of the launch vehicle; According to the fault diagnosis information, the control torque coefficient expression is obtained: in, They represent the control torque coefficients of the core stage engine and booster engine in the pitch channel and yaw channel respectively, Indicates the control torque coefficient of the core stage engine and booster engine in the rolling channel; X rxj is the distance between the engine swing point and the rocket theoretical tip; X rzt is the distance between the booster engine and the longitudinal axis of the rocket; X z J is the longitudinal center of mass of the rocket; x ,J y ,J z is the rocket's three-axis moment of inertia; Z rxj is the distance between the core stage engine swing point and the longitudinal axis; Z rzt is the distance between the booster engine swing point and the longitudinal axis; Assuming that the three-channel control capabilities of a single engine under normal operating conditions and after a fault are equal, the following equations are obtained based on the control force coefficient expression and the control torque coefficient expression: in, They represent the control torque coefficients of the rocket as a whole in the pitch channel and the yaw channel respectively; d3 represents the control torque coefficient of the rocket as a whole in the roll channel; δ ψ , δ γ They represent the normal control instructions of pitch, yaw and roll channels under normal working conditions respectively; Represents the equivalent control swing angle of the core stage servo mechanism and booster servo mechanism of the pitch channel; Represents the equivalent control swing angle of the core stage servo mechanism and the booster servo mechanism of the yaw channel; Represents the equivalent control swing angle of the core stage servo mechanism and the booster servo mechanism of the rolling channel; Substituting the three-channel control equation under normal operating conditions into the above equation, we can obtain the corrected control gain; The control equation is: in, Represents the static control gains of pitch, yaw, and roll channels; represents the angular deviation and angular velocity of the pitch channel; ψ, Represents the angular deviation and angular velocity of the yaw channel; γ, Represents the angular deviation and angular velocity of the rolling channel; Represents the dynamic control gains of the pitch, yaw, and roll channels.

4. The method for all-link composite active control of a launch vehicle adapted to thrust drop failure according to claim 3, characterized in that: The additional interference force generated by the engine thrust reduction fault is calculated according to the fault diagnosis information, and the additional interference torque is obtained according to the additional interference force; The additional disturbance force generated by the engine thrust reduction failure includes the Y-direction disturbance force F fy and the Z-direction interference force F of the rocket body coordinate system fz : Among them, A zt 、A xj Represents the installation angle of the booster engine and core stage engine.

5. The method for all-link composite active control of a launch vehicle adapted to thrust drop failure according to claim 4 is characterized in that: The disturbance torque generated by the engine thrust reduction failure is: Among them, M fz M is the disturbance torque generated in the pitch channel by the engine thrust reduction failure; fy is the disturbance torque generated in the yaw channel by the engine thrust reduction failure; Z C Y is the center of mass position of the rocket body in the Z-axis direction in the rocket body coordinate system; C It is the center of mass position of the rocket body in the Y-axis direction in the rocket body coordinate system.

6. The method for all-link composite active control of a launch vehicle adapted to thrust drop failure according to claim 5, characterized in that: The method for calculating the interference torque generated by the engine thrust reduction fault based on the fault diagnosis information includes: When the booster engine thrust decreases, the interference torque M generated by the core stage engine in the pitch channel is fz_xj and the disturbance torque M generated by the yaw channel fy_xj for: When the booster engine thrust decreases, the interference torque M generated by the booster engine in the pitch channel is fz_zt and the disturbance torque M generated by the yaw channel fy_zt for: When the thrust of the core stage engine decreases, the interference torque M′ generated by the engine in the pitch channel fz and the disturbance torque M′ generated by the yaw channel fy for: M fz M fz_xj 、M fz_zt and M′ fz The sum, M fy M fy_xj 、M fy_zt and M′ fy sum.

7. The method for all-link composite active control of a launch vehicle adapted to thrust drop failure according to claim 5, characterized in that: The additional control instructions generated according to the additional interference torque are: in, and are additional control instructions for the pitch channel and yaw channel respectively; P xj 、P zt It is the rated thrust of the core stage engine and booster engine.

8. The method for all-link composite active control of a launch vehicle adapted to thrust drop failure according to claim 7, characterized in that: The total control instruction is obtained by linearly superimposing the basic control instruction and the additional control instruction under the engine fault condition.

9. The method for all-link composite active control of a launch vehicle adapted to thrust drop failure according to claim 8, characterized in that: The total control command is distributed to the servo mechanism of each engine using the pseudo-inverse method. The specific method is as follows: According to the general control instruction, the swing angle synthesis formula of the core stage engine and the booster stage engine when the engine thrust drops is obtained: in, Equivalent control commands generated for the core stage engine in pitch, yaw and roll channels; Equivalent control commands generated for the booster engines in pitch, yaw, and roll channels; By making the channel control torque of a single engine under normal operating conditions and after a fault equal to the control torque generated by the actual servo swing, the following equation is obtained: Pitch channel: Yaw channel: Scroll channel: in, Additional control instructions generated for the core stage engine in the pitch and yaw channels; Additional control instructions generated by the booster engine in the pitch and yaw channels; δ xjI , δ xjII , δ xjIII , δ xjIV is the swing angle instruction of the four servo mechanisms of the core stage engine; δ ztI , δ ztII , δ ztIII , δ ztIV To provide the swing angle commands for the four servo mechanisms of the booster engine; After transforming the swing angle synthesis formula of the core stage engine and the booster stage engine, the following formula is obtained: The pseudo-inverse method is used to obtain the control instruction redistribution formula for distributing the total control instruction to the servo mechanism of each engine.

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