Reusable Launch Vehicle Stage Recovery Glide Phase Attitude Adjustment Method and System

Abstract

This invention relates to a method and system for attitude adjustment during the gliding phase of a reusable launch vehicle stage recovery. The method allocates the duration of four sub-control segments within the gliding attitude adjustment phase to the rocket stage. These four sub-control segments include an uncontrolled segment, an angular velocity guidance segment, a quaternion programming segment, and an attitude maintenance segment. Attitude adjustment is performed using the initial angular velocity, thereby reducing attitude adjustment impulse consumption. Based on the initial angular velocity vector direction and attitude adjustment terminal constraints, the method solves for the optimal attitude adjustment direction online and plans the attitude adjustment path, ensuring that the initial angular velocity vector coincides as much as possible with the optimal attitude adjustment axis. This invention overcomes the shortcomings of traditional attitude adjustment methods, maximizing the utilization of initial angular momentum and reducing unnecessary control impulse consumption.

Description

Technical Field

[0001] This invention relates to a method and system for leveraging the glide phase of a reusable launch vehicle stage for attitude adjustment, belonging to the field of launch vehicle overall design technology. Background Technology

[0002] The typical profile of a reusable launch vehicle's return mission consists of four stages: the coasting attitude adjustment phase, the powered deceleration phase, the aerodynamic deceleration phase, and the landing phase. During the coasting attitude adjustment phase, the rocket's attitude needs to be adjusted from 0° to 180° to meet the attitude requirements for engine ignition during the powered deceleration phase. This large-angle attitude adjustment process consumes a significant amount of control impulse. The coasting attitude adjustment phase typically employs an auxiliary propulsion system consisting of a single-component hydrazine thruster or a cold nitrogen thruster to achieve this adjustment. Regardless of the type of auxiliary propulsion system used, the total amount of control impulse generated depends on the size of the gas cylinders and the mass of the working propellant. Therefore, it is necessary to employ technical means to reduce the total control impulse requirement, thereby reducing the size and mass of the auxiliary propulsion system, decreasing system design complexity, increasing the rocket's payload capacity, and improving the recovery success rate.

[0003] Compared to traditional attitude adjustment processes, the glide attitude adjustment during the first-stage reentry phase has two key characteristics: firstly, aerodynamic disturbances during initial separation cannot be ignored; and secondly, the plume disturbance to the first stage after second-stage ignition cannot be ignored. Both factors contribute to the rocket gaining a certain initial angular velocity shortly after separation. Traditional attitude adjustment planning methods treat this initial angular velocity as a disturbance, consuming control impulse to reduce it, and then using quaternions to plan the shortest attitude adjustment path to the final value. The drawback of this approach is that it wastes initial energy and additionally consumes control impulse. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a method and system for leveraging the glide phase of a reusable launch vehicle stage for attitude adjustment. This method overcomes the shortcomings of traditional attitude adjustment methods, maximizes the utilization of initial angular momentum, and reduces unnecessary control impulse consumption.

[0005] The above-mentioned objectives of the present invention are mainly achieved through the following technical solutions: Reusing the attitude adjustment method during the recovery glide phase of a launch vehicle stage includes: The duration of the four sub-control segments of the glide attitude adjustment phase is allocated to the rocket stage. The four sub-control segments include the uncontrolled phase, the angular velocity guidance phase, the quaternion programming phase, and the attitude maintenance phase. During the uncontrolled period, the attitude control system remains in an uncontrolled state, enabling the rocket body to accelerate its rotation. During the duration of the angular velocity pilot segment, the initial angular velocity vector is controlled by angular velocity. Guided to the expected value of the angular velocity vector ; During the duration of the quaternion programming segment, the quaternion of the pose adjustment process is used. The program uses quaternions and PD control to adjust the rocket's attitude towards the final attitude; the attitude adjustment process uses quaternions. The methods for obtaining this include: calculating the optimal pivot of the quaternion programming segment. and optimal turning angle According to the optimal shaft and optimal turning angle Quaternions in the design of posture adjustment process ; During the duration of the attitude holding segment, the programmed angle is maintained to stabilize the attitude.

[0006] In the above-mentioned method for reusing the landing phase of a reusable launch vehicle stage for attitude adjustment, the duration of the uncontrolled phase is denoted as... That is, relative time 0s~ During the time period, the attitude control system remains uncontrolled, using aerodynamic forces and the force of the second-stage exhaust jet to accelerate the rotation of the rocket body; the relative time 0s refers to the moment of separation of the first stage of the rocket.

[0007] In the above-mentioned method for reusing the landing phase of a launch vehicle stage for attitude adjustment, the duration of the angular velocity guidance phase is denoted as... 0s after the uncontrolled segment ends During the time period, the initial angular velocity vector is controlled by angular velocity. Guided to the expected value of the angular velocity vector ; The expected value of the angular velocity vector The calculation method is as follows:

[0008] in, For the desired angular velocity, The initial angular velocity is represented by a unit vector.

[0009] In the aforementioned method for leveraging the glide phase of a reusable launch vehicle stage for attitude adjustment, the optimal rotation axis for calculating the quaternion programming segment is... and optimal turning angle The methods include: (1) Obtain the initial attitude angle and the target final attitude angle of the quaternion programming segment; (2) Convert the initial attitude angle and the target final attitude angle into corresponding quaternions. and ; (3) Calculate quaternions arrive The deviation quaternion; (4) Calculate the rotation angle and axis of rotation from the initial attitude angle to the target final attitude angle based on the deviation quaternion; (5) Obtain the initial angular velocity vector of the quaternion programming segment, obtain the initial angular velocity unit vector based on the initial angular velocity vector, and take the inner product of the rotation axis and the initial angular velocity unit vector; (6) Using the target final value of the rolling attitude angle to be optimized as the optimization variable, and the maximum inner product as the optimization objective, the optimization algorithm is used for iterative optimization. Steps (1) to (5) are repeated until the optimal result is obtained. The rotation angle and rotation axis calculated in step (4) are the optimal rotation angle. and optimal axis .

[0010] In the aforementioned method for leveraging the glide phase of a reusable launch vehicle stage for attitude adjustment, the optimal rotation axis for calculating the quaternion programming segment is... and optimal turning angle The method further includes: (a) Obtain the initial attitude angle of the quaternion programming segment and target final attitude angle as follows: ; ; in, , , These are the initial pitch, yaw, and roll attitude angles, respectively. , The final pitch and yaw attitude angles of the target; The target final value is the rolling attitude angle to be optimized; (b) Set the initial attitude angle and target final attitude angle Convert to the corresponding quaternion and as follows: ; ; (c) Calculate quaternions arrive The deviation quaternion of as follows: ; (d) Based on the aforementioned deviation quaternion Calculate the initial attitude angle Switch to target final attitude angle The corner and pivot as follows: ; ; (e) Obtain the initial angular velocity vector of the quaternion programming segment Its unit vector For the rotating shaft and the initial angular velocity unit vector Taking the inner product yields ; (f) Rolling attitude angle of the target final value to be optimized To optimize the variables, the inner product The optimization objective is to maximize the value of the rotation. An optimization algorithm is used for iterative optimization, repeating steps (a) to (e) until the optimal result is obtained. The rotation angle and axis of rotation calculated in step (d) are the optimal rotation angles. and optimal axis .

[0011] In the above-mentioned method for reusing the landing section of a reusable launch vehicle stage for attitude adjustment, the optimization algorithm adopts an arbitrary convex optimization algorithm.

[0012] In the above-mentioned method of reusing the landing phase of a reusable launch vehicle stage for attitude adjustment, based on the optimal rotation axis... and optimal turning angle Quaternions in the design of posture adjustment process include: (1) Select the angular velocity during the attitude adjustment process , The theoretical boundary is The theoretical lower bound is , The value is between and between; in, This is the nominal maximum angular acceleration that can be used for attitude adjustment; (2) Calculate the rotation angle during the attitude adjustment process as follows:

[0013] (3) Calculation The corresponding quaternion of the posture adjustment process as follows:

[0014] in, The symbol for quaternion multiplication. , For the rotating shaft Three components.

[0015] In the above-mentioned method for leveraging the glide phase of a reusable launch vehicle stage for attitude adjustment, the duration of the quaternion programming segment is denoted as... 0s after the angular velocity pilot segment ends During the time period, the quaternion of the posture adjustment process The program uses quaternions and PD control to adjust the rocket body attitude towards the final attitude. The duration of the attitude holding segment is denoted as The quaternion programming segment ends in 0s~ During the time period, maintain the program angle in a stable posture.

[0016] The above-mentioned method for reusing launch vehicle sub-stages for attitude adjustment during the recovery coasting phase also includes obtaining the basic state parameters, mission parameters, and initial condition parameters of the rocket sub-stage. The basic state parameters include the mass of the rocket substage, the center of mass, the moment of inertia of the orbiting system along the three axes, the layout of the auxiliary propulsion system thrusters, and the thrust configuration. The mission parameters include ballistic trajectory and ballistic data; the ballistic data includes at least: time, altitude, velocity, position, and attitude angle at the moment of stage separation, and time, altitude, velocity, position, and attitude angle at the moment of engine secondary ignition; The initial condition parameters include the attitude angle deviation, aerodynamic parameters, and the jet pattern of the second-stage exhaust at the moment of stage separation.

[0017] The above-mentioned method for reusing the attitude adjustment of the return slide of a launch vehicle stage also includes: randomly generating initial condition parameters again, repeating each step at least 1000 times, and obtaining the Monte Carlo target shooting results.

[0018] Reusable launch vehicle stage recovery glide phase attitude adjustment system, including: The duration allocation module allocates the duration of four sub-control segments of the gliding attitude adjustment phase to the rocket stage. The four sub-control segments include an uncontrolled segment, an angular velocity guidance segment, a quaternion programming segment, and an attitude maintenance segment. The first attitude control module maintains the attitude control system in an uncontrolled state during the uncontrolled period, thereby accelerating the rotation of the rocket body. The second attitude control module, during the duration of the angular velocity guidance segment, controls the initial angular velocity vector... Guided to the expected value of the angular velocity vector ; The third attitude control module, within the duration of the quaternion planning segment, uses the quaternion of the attitude adjustment process... The program uses quaternions and PD control to adjust the rocket's attitude towards the final attitude; the attitude adjustment process uses quaternions. The methods for obtaining this include: calculating the optimal pivot of the quaternion programming segment. and optimal turning angle According to the optimal shaft and optimal turning angle Quaternions in the design of posture adjustment process ; The fourth attitude control module maintains the programmed angle to stabilize the attitude during the duration of the attitude holding segment.

[0019] Compared with the prior art, the present invention has the following advantages: (1) The reusable launch vehicle stage recovery glide section attitude adjustment method proposed in this invention uses the initial angular velocity for attitude adjustment to reduce attitude adjustment impulse consumption. The method solves the optimal attitude adjustment direction and plans the attitude adjustment path online according to the initial angular velocity vector direction and attitude adjustment terminal constraint requirements, so that the initial angular velocity vector coincides with the optimal attitude adjustment axis as much as possible. The method of this invention overcomes the shortcomings of traditional attitude adjustment methods, can make the maximum use of initial angular momentum, and reduce unnecessary control impulse consumption.

[0020] (2) The present invention reuses the launch vehicle stage recovery glide section leverage attitude adjustment method to make the most of the initial angular velocity to achieve the "turning" of the rocket body, thereby saving total impact consumption. That is, it can make the most of the initial angular velocity of the rocket body to complete large-angle attitude adjustment, thereby reducing the total impact consumption of attitude adjustment. Attached Figure Description

[0021] Figure 1 This is a flowchart of the attitude adjustment method using leverage during the gliding phase of a launch vehicle stage recovery, as described in this embodiment of the invention. Figure 2 This is a schematic diagram illustrating the allocation of four sub-control segments in the gliding attitude adjustment segment in an embodiment of the present invention; Figure 3 The magnitude of the angular velocity during the attitude adjustment process in this embodiment of the invention. Select a schematic diagram; Figure 4 The diagram shows the Monte Carlo target shooting results in an embodiment of the present invention. Figures a, b, and c are schematic diagrams of pitch attitude angle, yaw attitude angle, and roll attitude angle, respectively.

[0022] Figure 5 This is a schematic diagram of the synthesized angular velocity target hitting results in an embodiment of the present invention. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments: like Figure 1 The diagram shown is a flowchart of the attitude adjustment method for the coasting phase of a reusable launch vehicle stage recovery according to an embodiment of the present invention. The present invention is applicable to the attitude adjustment method for the coasting phase of a reusable launch vehicle stage recovery, and specifically includes the following steps: Step 1: Obtain the basic state parameters, mission parameters, and initial condition parameters of the rocket's first stage. The basic state parameters include the mass of the rocket stage, its center of mass, the moment of inertia of the three axes of the orbiting system, the layout of the auxiliary propulsion system thrusters, and the thrust configuration.

[0024] The mission parameters include the ballistic trajectory and ballistic data; the ballistic data includes at least: the time, altitude, velocity, position, and attitude angle at the moment of stage separation, and the time, altitude, velocity, position, and attitude angle at the moment of engine secondary ignition.

[0025] The initial condition parameters include the attitude angle deviation, aerodynamic parameters, and the characteristics of the second-stage exhaust jet at the time of stage separation.

[0026] Step 2: Allocate the duration of the four sub-control segments of the taxiing attitude adjustment segment. like Figure 2 The diagram shown is a schematic diagram of the allocation of four sub-control segments in the gliding attitude adjustment segment in an embodiment of the present invention. The four sub-control segments are the uncontrolled segment, the angular velocity guidance segment, the quaternion programming segment, and the attitude maintenance segment. The duration of the uncontrolled segment is recorded as ; The duration of the angular velocity pilot segment is denoted as... ; The duration of a quaternion programming segment is denoted as ; The duration of the attitude maintenance phase is denoted as .

[0027] Step 3: In the uncontrolled segment, i.e., relative time 0s~ During the period, the attitude control system remains uncontrolled, using aerodynamic force and the force of the second-stage exhaust jet to accelerate the rotation of the rocket body; The relative time of 0s refers to the moment of separation of the first stage of the rocket.

[0028] Step 4: 0s after the angular velocity guidance segment, i.e., the uncontrolled segment ends. During the time period, the initial angular velocity vector is controlled using an angular velocity control method. Guided to the expected value ; Initial angular velocity vector It refers to the angular velocity vector at the initial moment of the angular velocity pilot segment; Angular velocity vector expectation It can be calculated by the following formula.

[0029] in, For the desired angular velocity, The initial angular velocity unit vector; Step 5: Calculate the optimal rotation axis for the quaternion programming segment using an optimization algorithm. and optimal turning angle ; (a) Obtain the initial attitude angle of the quaternion programming segment and target final attitude angle ; in, , , These are the initial pitch, yaw, and roll attitude angles, respectively, which are obtained online by the onboard computer. , These are the target's final pitch and yaw attitude angles, obtained from a standard trajectory; The target final value is the rolling attitude angle to be optimized; (b) Euler angles and Convert to the corresponding quaternion and ; (c) Calculate quaternions arrive The deviation quaternion of ; (d) Based on the deviation quaternion Calculate Euler angles Go to The corner ; (e) Based on the deviation quaternion Calculate Euler angles Go to The shaft ; (f) Obtain the initial angular velocity vector of the quaternion programming segment online. Its unit vector For the rotating shaft and the initial angular velocity unit vector Taking the inner product yields ; (g) with To optimize variables, inner product The optimization objective is to maximize the value of the target value. An optimization algorithm is used for iterative optimization, repeating steps (a) to (f) until the optimal result is obtained. The angle calculated in step (d) is the optimal angle. The shaft calculated in step (e) is the optimal shaft. The optimization algorithm can be any commonly used convex optimization algorithm.

[0030] Step Six: Based on the optimal pivot and optimal turning angle Design the pose adjustment process of quaternion programming segments. ; (a) Select the magnitude of the angular velocity during the attitude adjustment process Its theoretical upper limit is The theoretical lower bound is ,in This is the nominal maximum angular acceleration that can be used for attitude adjustment; The value is between and Either is acceptable; such as Figure 3 The figure shows the magnitude of the angular velocity during the attitude adjustment process in an embodiment of the present invention. Select a schematic diagram.

[0031] (b) Calculate the rotation angle during the attitude adjustment process using the following formula. :

[0032] (c) Calculate using the following formula The corresponding quaternion of the posture adjustment process :

[0033] in, The symbol for quaternion multiplication. , For the rotating shaft Three components; Step 7: After 0s from the end of the quaternion programming segment, i.e., the angular velocity guiding segment... During the time period, the quaternions of the above posture adjustment process are used. The program uses quaternions and PD control to adjust the rocket body attitude towards the final attitude.

[0034] Step 8: During the attitude maintenance phase, i.e., 0s after the quaternion programming phase ends... During the time period, maintain the program angle in a stable posture.

[0035] Example This embodiment applies to the attitude adjustment technology during the glide phase of a reusable launch vehicle stage recovery, including the following steps: Step 1: Obtain the basic state parameters, mission parameters, and initial condition parameters of the rocket's first stage; The basic state parameters include the mass of the rocket stage, the center of mass, the moment of inertia of the orbiting system along the three axes, the layout of the auxiliary propulsion system thrusters, and the thrust configuration. The mission parameters include the ballistic trajectory and ballistic data; the ballistic data includes at least: the time, altitude, velocity, position, and attitude angle at the moment of stage separation, and the time, altitude, velocity, position, and attitude angle at the moment of engine secondary ignition; The initial condition parameters include the attitude angle deviation, aerodynamic parameters, and the characteristics of the second-stage exhaust jet at the time of stage separation.

[0036] Step 2: Allocate the duration of the four sub-control segments of the taxiing attitude adjustment segment, see [link / reference]. Figure 2 ; The four sub-control segments are the uncontrolled segment, the angular velocity guidance segment, the quaternion programming segment, and the attitude maintenance segment; The duration of the uncontrolled segment is recorded as The duration of the angular velocity pilot segment is denoted as... The duration of a quaternion programming segment is denoted as . The duration of the attitude maintenance phase is denoted as .

[0037] Step 3: In the uncontrolled segment, i.e., relative time 0s~ During the period, the attitude control system remains uncontrolled, using aerodynamic force and the force of the second-stage exhaust jet to accelerate the rotation of the rocket body; The relative time of 0s refers to the moment of separation of the first stage of the rocket.

[0038] Step 4: 0s after the angular velocity guidance segment, i.e., the uncontrolled segment ends. During the time period, an angular velocity control scheme is used to control the initial angular velocity vector. Guided to the expected value ; Initial angular velocity vector It refers to the angular velocity vector at the initial moment of the angular velocity pilot segment; Angular velocity vector expectation It can be calculated by the following formula.

[0039] in, For the desired angular velocity, The initial angular velocity is represented by a unit vector.

[0040] Step 5: Calculate the optimal rotation axis for the quaternion programming segment using an optimization algorithm. and optimal turning angle ; (a) Obtain the initial attitude angle of the quaternion programming segment and target final attitude angle , , , These are the initial pitch, yaw, and roll attitude angles, respectively, which are obtained online by the onboard computer. , The final pitch and yaw attitude angles of the target are obtained from the standard trajectory. The target final value is the rolling attitude angle to be optimized; (b) Euler angles and Convert to the corresponding quaternion and ; (c) Calculation arrive The deviation quaternion of ; (d) Calculation Go to The corner ; (e) Calculation Go to The shaft ; (f) Obtain the initial angular velocity vector of the quaternion programming segment online. Its unit vector For the rotating shaft and the initial angular velocity unit vector Taking the inner product yields ; (g) with To optimize the variables, the inner product The optimization objective is to maximize the value of the target value. An optimization algorithm is used for iterative optimization, repeating steps (a) to (f) until the optimal result is obtained. The angle calculated in step (d) is the optimal angle. The shaft calculated in step (e) is the optimal shaft. The optimization algorithm can be any commonly used convex optimization algorithm.

[0041] Step Six: Design the attitude adjustment process of the quaternion programming segment. ; (a) Select the magnitude of the angular velocity during the attitude adjustment process Its theoretical upper limit is The theoretical lower bound is ,in The nominal maximum angular acceleration that can be used for attitude adjustment; The value is between and Either is acceptable, see Figure 3 ; (b) Calculate the rotation angle during the attitude adjustment process using the following formula. ;

[0042] (c) Calculate using the following formula The corresponding quaternion of the posture adjustment process :

[0043] in, The symbol for quaternion multiplication. , For the rotating shaft Three components.

[0044] Step 7: After 0s from the end of the quaternion programming segment, i.e., the angular velocity guiding segment... During the time period, the quaternions of the above posture adjustment process are used. The program uses quaternions and PD control to adjust the rocket body attitude towards the final attitude.

[0045] Step 8: During the attitude maintenance phase, i.e., 0s after the quaternion programming phase ends... During the time period, maintain the program angle in a stable posture.

[0046] Step 9: Regenerate initial condition parameters randomly, and repeat steps 3-8 1000 times to obtain the Monte Carlo shooting results. Figure 4 and Figure 5 It is noted that attitude "turning around" is achieved through multiple means, including traditional pitch "nose-down," pitch "nose-up," pure yaw "turning around," and a "combined turn" of pitch and yaw, with both pitch and yaw final attitude values ​​converging. Furthermore, by... Figure 5 The results of the composite angular velocity target shooting show obvious monotonicity and convergence. Regardless of the actual angular velocity direction, the composite results are similar, indicating that the attitude adjustment method proposed in this invention makes full use of the initial angular velocity to achieve the "turning" of the rocket body, thereby saving total impact consumption.

[0047] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

[0048] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for reusing the attitude adjustment during the gliding phase of a reusable launch vehicle stage recovery, characterized in that... include: The duration of the four sub-control segments of the glide attitude adjustment phase is allocated to the rocket stage. The four sub-control segments include the uncontrolled phase, the angular velocity guidance phase, the quaternion programming phase, and the attitude maintenance phase. During the uncontrolled period, the attitude control system remains in an uncontrolled state, enabling the rocket body to accelerate its rotation. During the duration of the angular velocity pilot segment, the initial angular velocity vector is controlled by angular velocity. Guided to the expected value of the angular velocity vector ; During the duration of the quaternion programming segment, the quaternion of the pose adjustment process is used. The program uses quaternions and PD control to adjust the rocket's attitude towards the final attitude; the attitude adjustment process uses quaternions. The methods for obtaining this include: calculating the optimal pivot of the quaternion programming segment. and optimal turning angle According to the optimal shaft and optimal turning angle Quaternions in the design of posture adjustment process ; During the duration of the attitude holding segment, the programmed angle is maintained to stabilize the attitude; The optimal pivot for calculating the quaternion programming segment. and optimal turning angle The methods include: (1) Obtain the initial attitude angle and the target final attitude angle of the quaternion programming segment; (2) Convert the initial attitude angle and the target final attitude angle into corresponding quaternions. and ; (3) Calculate quaternions arrive The deviation quaternion; (4) Calculate the rotation angle and axis of rotation from the initial attitude angle to the target final attitude angle based on the deviation quaternion; (5) Obtain the initial angular velocity vector of the quaternion programming segment, obtain the initial angular velocity unit vector based on the initial angular velocity vector, and take the inner product of the rotation axis and the initial angular velocity unit vector; (6) Using the target final value of the rolling attitude angle to be optimized as the optimization variable, and the maximum inner product as the optimization objective, the optimization algorithm is used for iterative optimization. Steps (1) to (5) are repeated until the optimal result is obtained. The rotation angle and rotation axis calculated in step (4) are the optimal rotation angle. and optimal axis ; According to the optimal shaft and optimal turning angle Quaternions in the design of posture adjustment process include: (7) Select the angular velocity during the attitude adjustment process , The theoretical boundary is The theoretical lower bound is , The value is between and between; in, This is the nominal maximum angular acceleration that can be used for attitude adjustment; (8) Calculate the rotation angle during the attitude adjustment process as follows: (9) Calculation The corresponding quaternion of the posture adjustment process as follows: in, The symbol for quaternion multiplication. , For the rotating shaft Three components.

2. The method for reusable launch vehicle stage recovery using leverage during the coasting phase, as described in claim 1, is characterized in that... The duration of the uncontrolled segment is denoted as That is, relative time 0s~ During the time period, the attitude control system remains uncontrolled, using aerodynamic forces and the force of the second-stage exhaust jet to accelerate the rotation of the rocket body; the relative time 0s refers to the moment of separation of the first stage of the rocket.

3. The method for reusable launch vehicle stage recovery using leverage during the coasting phase, as described in claim 1, is characterized in that... The duration of the angular velocity guidance segment is denoted as 0s after the uncontrolled segment ends During the time period, the initial angular velocity vector is controlled by angular velocity. Guided to the expected value of the angular velocity vector ; The expected value of the angular velocity vector The calculation method is as follows: in, For the desired angular velocity, The initial angular velocity is represented by a unit vector.

4. The method for reusable launch vehicle stage recovery using leverage during the coasting phase, as described in claim 1, is characterized in that... The optimal pivot for calculating the quaternion programming segment. and optimal turning angle The method further includes: (a) Obtain the initial attitude angle of the quaternion programming segment and target final attitude angle as follows: ； ； in, , , These are the initial pitch, yaw, and roll attitude angles, respectively. , The final pitch and yaw attitude angles of the target; The target final value is the rolling attitude angle to be optimized; (b) Set the initial attitude angle and target final attitude angle Convert to the corresponding quaternion and as follows: ； ； (c) Calculate quaternions arrive The deviation quaternion of as follows: ； (d) Based on the aforementioned deviation quaternion Calculate the initial attitude angle Switch to target final attitude angle The corner and pivot as follows: ； ; (e) Obtain the initial angular velocity vector of the quaternion programming segment Its unit vector For the rotating shaft and the initial angular velocity unit vector Taking the inner product yields ; (f) Rolling attitude angle of the target final value to be optimized To optimize the variables, the inner product The optimization objective is to maximize the value of the rotation. An optimization algorithm is used for iterative optimization, repeating steps (a) to (e) until the optimal result is obtained. The rotation angle and axis of rotation calculated in step (d) are the optimal rotation angles. and optimal axis .

5. The method for reusable launch vehicle stage recovery using leverage during the coasting phase, as described in claim 4, is characterized in that... The optimization algorithm used is an arbitrary convex optimization algorithm.

6. The method for attitude adjustment during the coasting phase of a reusable launch vehicle stage recovery as described in claim 1, characterized in that, The duration of the quaternion programming segment is denoted as 0s after the angular velocity pilot segment ends During the time period, the quaternion of the posture adjustment process The program uses quaternions and PD control to adjust the rocket body attitude towards the final attitude. The duration of the attitude holding segment is denoted as The quaternion programming segment ends in 0s~ During the time period, maintain the program angle in a stable posture.

7. The method for reusable launch vehicle stage recovery using leverage during the coasting phase as described in claim 1, characterized in that, It also includes obtaining the basic state parameters, mission parameters, and initial condition parameters of the rocket substage; The basic state parameters include the mass of the rocket substage, the center of mass, the moment of inertia of the orbiting system along the three axes, the layout of the auxiliary propulsion system thrusters, and the thrust configuration. The mission parameters include ballistic trajectory and ballistic data; the ballistic data includes at least: time, altitude, velocity, position, and attitude angle at the moment of stage separation, and time, altitude, velocity, position, and attitude angle at the moment of engine secondary ignition; The initial condition parameters include the attitude angle deviation, aerodynamic parameters, and the jet pattern of the second-stage exhaust at the moment of stage separation.

8. The method for reusable launch vehicle stage recovery using leverage during the coasting phase according to claim 1, characterized in that, Also includes: Regenerate initial condition parameters randomly, repeat each step at least 1000 times, and obtain the Monte Carlo shooting results.

9. A reusable launch vehicle stage recovery glide section attitude adjustment system, characterized in that, include: The duration allocation module allocates the duration of four sub-control segments of the gliding attitude adjustment phase to the rocket stage. The four sub-control segments include an uncontrolled segment, an angular velocity guidance segment, a quaternion programming segment, and an attitude maintenance segment. The first attitude control module maintains the attitude control system in an uncontrolled state during the uncontrolled period, thereby accelerating the rotation of the rocket body. The second attitude control module, during the duration of the angular velocity guidance segment, controls the initial angular velocity vector... Guided to the expected value of the angular velocity vector ; The third attitude control module, within the duration of the quaternion planning segment, uses the quaternion of the attitude adjustment process... The program uses quaternions and PD control to adjust the rocket's attitude towards the final attitude; the attitude adjustment process uses quaternions. The methods for obtaining this include: calculating the optimal pivot of the quaternion programming segment. and optimal turning angle According to the optimal shaft and optimal turning angle Quaternions in the design of posture adjustment process ; The fourth attitude control module maintains the programmed angle to stabilize the attitude during the duration of the attitude holding segment. The optimal pivot for calculating the quaternion programming segment. and optimal turning angle The methods include: (1) Obtain the initial attitude angle and the target final attitude angle of the quaternion programming segment; (2) Convert the initial attitude angle and the target final attitude angle into corresponding quaternions. and ; (3) Calculate quaternions arrive The deviation quaternion; (4) Calculate the rotation angle and axis of rotation from the initial attitude angle to the target final attitude angle based on the deviation quaternion; (5) Obtain the initial angular velocity vector of the quaternion programming segment, obtain the initial angular velocity unit vector based on the initial angular velocity vector, and take the inner product of the rotation axis and the initial angular velocity unit vector; (6) Using the target final value of the rolling attitude angle to be optimized as the optimization variable, and the maximum inner product as the optimization objective, the optimization algorithm is used for iterative optimization. Steps (1) to (5) are repeated until the optimal result is obtained. The rotation angle and rotation axis calculated in step (4) are the optimal rotation angle. and optimal axis ; According to the optimal shaft and optimal turning angle Quaternions in the design of posture adjustment process include: (7) Select the angular velocity during the attitude adjustment process , The theoretical boundary is The theoretical lower bound is , The value is between and between; in, This is the nominal maximum angular acceleration that can be used for attitude adjustment; (8) Calculate the rotation angle during the attitude adjustment process as follows: (9) Calculation The corresponding quaternion of the posture adjustment process as follows: in, The symbol for quaternion multiplication. , For the rotating shaft Three components.

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