A RCS compound control-based pose adjustment path planning method

Abstract

The application relates to a RCS composite control-based attitude adjustment path planning method, which plans a program angular velocity interpolation matrix according to the size of an initial pitching angular velocity; interpolates the program angular velocity matrix to obtain a current program angular velocity, and solves a current program quaternion; calculates a current attitude deviation; and calculates and outputs current RCS nozzle control signals of each channel. The application considers adjusting the path planning according to the initial angular velocity of a rocket body, so that fuel consumption is minimized under the condition of meeting the attitude adjustment requirement.

Description

Technical Field

[0001] This invention belongs to the field of launch vehicle design and relates to an attitude adjustment path planning method based on RCS composite control, which is particularly suitable for attitude adjustment planning methods under the condition of large initial angular rate in the unpowered section based on RCS nozzle. Background Technology

[0002] Compared to traditional expendable launch vehicles, reusable launch vehicles require return phase control, which includes unpowered ascent, unpowered descent, powered deceleration, aerodynamic deceleration, and powered landing. The powered deceleration phase requires restarting the rocket's main engines, and the rocket must reach a predetermined attitude before the engines are ignited. This necessitates planned attitude control during the unpowered phase.

[0003] During the unpowered descent phase, since the engine is not operating, attitude control is achieved using RCS nozzles, configured as follows: Figure 1 As shown.

[0004] When a launch vehicle is in the unpowered reentry phase, it is subject to significant disturbances and experiences a high angular velocity. Due to the relatively weak nozzle control capability and the fact that the yaw and roll channels are a composite control mechanism, the traditional single-channel attitude adjustment path planning method cannot adapt to the large initial angular velocity. This would lead to excessive nozzle fuel consumption and, in extreme cases, potentially cause attitude instability. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose an attitude adjustment path planning method based on RCS composite control for the unpowered phase of a launch vehicle, thereby solving the problem of excessive fuel consumption in the traditional attitude adjustment path planning method during composite nozzle control in the return phase.

[0006] The solution of the present invention is: A pose adjustment path planning method based on RCS composite control includes: The initial pitch angular velocity of the rocket body is obtained based on the inertial navigation system calculation results, and the program angular velocity interpolation matrix is ​​planned based on the magnitude of the initial pitch angular velocity. The current program angular velocity is obtained by interpolating the program angular velocity matrix, and the current program quaternion is calculated based on the program angular velocity. Calculate the current quaternion deviation based on the current navigation quaternion calculated by the inertial navigation system and the programmed quaternion; calculate the current angular velocity deviation based on the current angular velocity and the programmed angular velocity. The switch command signal for each channel is calculated based on the deviation calculation results of each channel and the set switch threshold, and then output to the RCS nozzle.

[0007] Preferably, the program angular velocity interpolation matrix is ​​planned based on the initial pitch angular velocity magnitude, as follows: Determine the initial pitch angular velocity With angular velocity threshold Relationship: like Then the angular velocity is planned to be 0, and the program angular velocity interpolation matrix is ​​used. as follows

[0008] Otherwise, the angular velocity interpolation matrix for the planning program is as follows:

[0009] in: This is the start time for posture adjustment. For maximum posture adjustment time, The time required for posture adjustment Angular velocity is designed for attitude adjustment. For the maximum permissible angular acceleration, It is a symbolic function.

[0010] Preferably, the current program angular velocity is obtained by interpolating the program angular velocity matrix, as follows: If the arrow timing is less than the attitude adjustment start time The pitch channel program angular velocity is the element in the first row and second column of the program angular velocity interpolation matrix; the yaw channel program angular velocity is the element in the first row and third column of the program angular velocity interpolation matrix; and the roll channel program angular velocity is the element in the first row and fourth column of the program angular velocity interpolation matrix. If the arrow movement time is longer than the attitude adjustment end time The pitch channel program angular velocity is the element in the last row and second column of the program angular velocity interpolation matrix; the yaw channel program angular velocity is the element in the last row and third column of the program angular velocity interpolation matrix; and the roll channel program angular velocity is the element in the last row and fourth column of the program angular velocity interpolation matrix. If the arrow time [Posture Adjustment Start Time] Posture adjustment end time Then, the current value is obtained by interpolation according to the following formula. time Channel program angular velocity , , respectively represent the roll, yaw and pitch channels, corresponding to the second, third and fourth columns in the interpolation matrix, and the interpolation period is the control period;

[0011] in: for aisle angular velocity at any given moment for aisle angular velocity at any given moment The element in the first column of the k-th row of the program angular velocity interpolation matrix. It is the element in the first column of the (k+1)th row of the program angular velocity interpolation matrix.

[0012] Preferably, the current program quaternion is obtained by calculating the program's angular velocity, as follows: (1) Using the formula Calculate the current time t Channel attitude deviation , Indicates the control cycle. For the present time The programmable angular velocity of the channel; (2) Based on the current time t Channel attitude deviation calculation transformation matrix D s ; (3) Calculate the program quaternion at the current time using the following formula. ,

[0013] This is the quaternion of the program in the previous operation cycle.

[0014] Preferably, based on the current time t Channel attitude deviation calculation transformation matrix D s The details are as follows:

[0015]

[0016] .

[0017] Preferably, the current quaternion deviation is calculated based on the current navigation quaternion calculated by the inertial navigation system and the program quaternion, as follows:

[0018] The quaternion of the program at the current moment, For the current quaternion, This is the quaternion deviation.

[0019] Preferably, the deviation of the current angular velocity is calculated based on the current angular velocity and the programmed angular velocity, as follows:

[0020] These represent the angular velocity deviations of the pitch, yaw, and roll channels at the current moment, respectively. These represent the navigation angular velocities of the pitch, yaw, and roll channels at the current moment, respectively. These represent the programmed angular velocities of the pitch, yaw, and roll channels at the current moment, respectively.

[0021] Preferably, the current RCS nozzle control signal for each channel is calculated as follows: (1) According to Channel attitude deviation Attitude angular rate deviation signal Establish the difference equation for the deviation signal and calculate Solution of channel difference equation; (2) According to The channel differential equation solution and the set switching threshold determine the RCS nozzle control signal for each channel.

[0022] Preferably, in step (1), the difference equation of the deviation signal is as follows:

[0023]

[0024]

[0025] in: , , , , , , For binding Channel difference equation coefficients, , , They are respectively , , The former Calculated value for each control cycle To control the cycle; , Let represent the intermediate variables in the difference equation operation. This represents the output of the difference equation at the current time. The solutions to the difference equations for each channel are synthesized as follows: .

[0026] Preferably, in step (2), the switching command signal for each channel is determined as follows: Channel current nonlinear switch control output signal satisfy:

[0027] in: , for Channel switch control threshold and lap coefficient, ; for A single-step switch on the channel controls the output signal; These represent the positive on, off, and negative on states of the nonlinear switch, respectively. This is the control cycle for the current stage, a constant value. for The channel switch controls the input signal, i.e. Solution of the channel difference equation.

[0028] The beneficial effects of this invention compared to the prior art are: (1) The present invention can design the path online using the navigation information of the rocket itself, without the need for an additional stand-alone machine, and the calculation is simple and the engineering feasibility is high; (2) Since the present invention introduces angular velocity information for attitude adjustment path planning, it has good adaptability to large initial angular velocities and constrains the maximum attitude adjustment angular velocity and the maximum attitude adjustment time, thus having high safety. (3) Compared with the single-channel attitude adjustment method, the present invention can simultaneously adjust the attitude of three channels, which can improve the attitude adjustment efficiency, reduce fuel consumption, and has certain economic benefits. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the attitude control nozzle installation; Figure 2 This is a flowchart of an attitude adjustment path planning method based on RCS composite control. Detailed Implementation

[0030] The invention will now be further described with reference to the accompanying drawings.

[0031] This invention considers attitude adjustment path planning based on the initial angular velocity of the rocket body, thereby ensuring that fuel consumption is minimized while meeting attitude adjustment requirements.

[0032] The concept of this invention is as follows: The unpowered phase requires attitude adjustment of the rocket body via the RCS nozzle, with the goal of reaching the target attitude within a specified time. To quickly meet this requirement, a typical approach is to plan the attitude adjustment along the shortest path based on the current and target attitudes, while ensuring nozzle capacity is met. However, this approach does not consider the current angular velocity of the rocket body. If the rocket body has an angular velocity before the attitude adjustment, it will result in additional fuel consumption.

[0033] To optimize fuel consumption during attitude adjustment, this invention provides a method for attitude adjustment path planning using initial angular velocity, such as... Figure 2 As shown, the specific steps include the following: Step 1: Obtain the program angular velocity interpolation matrix based on the initial pitch angular velocity magnitude. First, the initial pitch angular velocity of the rocket body is obtained based on the inertial navigation system (INS) calculation results. Different planning methods are selected according to the magnitude of the initial pitch angular velocity to obtain the program angular velocity interpolation matrix.

[0034] Determine the initial pitch angular velocity With angular velocity threshold Relationship: like Then the angular velocity is planned to be 0, and the program angular velocity interpolation matrix is ​​used. as follows

[0035] Otherwise, the angular velocity interpolation matrix for the planning program is as follows:

[0036] in: This is the start time for posture adjustment. For maximum posture adjustment time, The time required for posture adjustment Angular velocity is designed for attitude adjustment. For the maximum permissible angular acceleration, It is a symbolic function.

[0037] Step 2: Generate program quaternions based on the program angular velocity. The program angular velocity at the current moment is obtained by interpolating the program angular velocity matrix, and the current program quaternion is obtained by solving the program angular velocity.

[0038] If the arrow timing is less than the attitude adjustment start time The pitch channel program angular velocity is the element in the first row and second column of the program angular velocity interpolation matrix; the yaw channel program angular velocity is the element in the first row and third column of the program angular velocity interpolation matrix; and the roll channel program angular velocity is the element in the first row and fourth column of the program angular velocity interpolation matrix. If the arrow movement time is longer than the attitude adjustment end time The pitch channel program angular velocity is the element in the last row and second column of the program angular velocity interpolation matrix; the yaw channel program angular velocity is the element in the last row and third column of the program angular velocity interpolation matrix; and the roll channel program angular velocity is the element in the last row and fourth column of the program angular velocity interpolation matrix. If the arrow time [Posture Adjustment Start Time] Posture adjustment end time Then, the current value is obtained by interpolation according to the following formula. time Channel program angular velocity , , respectively represent the roll, yaw and pitch channels, corresponding to the second, third and fourth columns in the interpolation matrix, and the interpolation period is the control period;

[0039] in: for aisle angular velocity at any given moment for aisle angular velocity at any given moment The element in the first column of the k-th row of the program angular velocity interpolation matrix. It is the element in the first column of the (k+1)th row of the program angular velocity interpolation matrix.

[0040] The current quaternion of the program is obtained based on the angular velocity calculation, as follows:

[0041]

[0042]

[0043]

[0044]

[0045] in: Indicates the control cycle. express Channel attitude deviation, Represents the quaternion of the program at the current moment; This is the quaternion of the program in the previous operation cycle.

[0046] Step 3: Calculate attitude deviation Calculate the quaternion deviation based on the current navigation quaternion calculated by the inertial navigation system and the programmed quaternion; calculate the angular velocity deviation based on the current angular velocity and the programmed angular velocity.

[0047] The deviation quaternion of the rocket body navigation attitude quaternion from the programmed angle quaternion is:

[0048] The quaternion of the program at the current moment, For the current quaternion, This is the quaternion deviation.

[0049] definition:

[0050] Angular velocity deviation calculation:

[0051] These represent the angular velocity deviations of the pitch, yaw, and roll channels at the current moment, respectively. These represent the navigation angular velocities of the pitch, yaw, and roll channels at the current moment, respectively. These represent the programmed angular velocities of the pitch, yaw, and roll channels at the current moment, respectively.

[0052] Step 4: Calculate and output the RCS nozzle control signal for each channel. Based on the comparison results between the deviation of each channel and the nozzle switching threshold, the switching signal is obtained and output.

[0053] (1) According to Channel attitude deviation Attitude angular rate deviation signal Establish the difference equation for the deviation signal and calculate Solution of the channel difference equation.

[0054] Input to the differential equation for the deviation signal: Channel attitude deviation Attitude angular rate deviation signal input quantity Output: Channel difference equation solution

[0055]

[0056]

[0057] in: , , , , , , For binding Channel difference equation coefficients, , , They are respectively , , The former Calculated value for each control cycle To control the cycle; , Let represent the intermediate variables in the difference equation operation. This represents the output of the difference equation at the current time. The solutions to the difference equations for each channel are synthesized as follows: .

[0058] (2) According to The channel differential equation solution determines the RCS nozzle control signal for each channel.

[0059] Channel current nonlinear switch control output signal satisfy:

[0060] in: , for Channel switch control threshold and lap coefficient, ; for A single-step switch on the channel controls the output signal; These represent the positive on, off, and negative on states of the nonlinear switch, respectively. This is the control cycle for the current stage, a constant value. for The channel switch controls the input signal, i.e. Solution of channel difference equation; RCS nozzle command allocation for each channel: Figure 1 This is a schematic diagram of the attitude control nozzle installation. The command assignment for each nozzle is as follows:

[0061]

[0062] in: This indicates the on / off command for extension i, where 1 means on and 0 means off.

[0063] This invention provides a method for attitude adjustment path planning based on RCS composite control for the unpowered phase of a launch vehicle, mainly including power configuration, control scheme, attitude adjustment implementation methods and steps. An RCS nozzle is used for attitude control during the unpowered phase of the launch vehicle, where the pitch channel uses independent control, and the yaw and roll channels use composite control. This invention requires the onboard computer to perform attitude adjustment path planning based on the target attitude requirements using the current attitude angle and angular velocity information, calculate the control signals of each channel in real time, and perform RCS nozzle switching control to bring the rocket to the target attitude. This invention aims to utilize initial angular velocity for attitude adjustment planning during the unpowered reentry phase of a launch vehicle, where RCS nozzles are used for composite attitude control of the channels. This method can meet the requirements for attitude adjustment accuracy, reduce fuel consumption, and has high engineering practicality.

[0064] The parts of this invention not described in detail are common knowledge to those skilled in the art.

Claims

1. A posture adjustment path planning method based on RCS composite control, characterized in that, include: The initial pitch angular velocity of the rocket body is obtained based on the inertial navigation system calculation results, and the program angular velocity interpolation matrix is ​​planned based on the magnitude of the initial pitch angular velocity. The current program angular velocity is obtained by interpolating the program angular velocity matrix, and the current program quaternion is calculated based on the program angular velocity. Calculate the current quaternion deviation based on the current navigation quaternion calculated by the inertial navigation system and the programmed quaternion; calculate the current angular velocity deviation based on the current angular velocity and the programmed angular velocity. Based on the deviation calculation results of each channel and the set switching threshold, the switching command signal of each channel is calculated and output to the RCS nozzle.

2. The attitude adjustment path planning method based on RCS composite control according to claim 1, characterized in that, The program angular velocity interpolation matrix is ​​planned based on the initial pitch angular velocity magnitude, as follows: Determine the initial pitch angular velocity With angular velocity threshold Relationship: like Then the angular velocity is planned to be 0, and the program angular velocity interpolation matrix is ​​used. as follows Otherwise, the angular velocity interpolation matrix for the planning program is as follows: in: This is the start time for posture adjustment. For maximum posture adjustment time, The time required for posture adjustment Angular velocity is designed for attitude adjustment. For the maximum permissible angular acceleration, It is a symbolic function.

3. The attitude adjustment path planning method based on RCS composite control according to claim 1, characterized in that, The current program angular velocity can be obtained by interpolating the program angular velocity matrix as follows: If the arrow timing is less than the attitude adjustment start time The pitch channel program angular velocity is the element in the first row and second column of the program angular velocity interpolation matrix; the yaw channel program angular velocity is the element in the first row and third column of the program angular velocity interpolation matrix; and the roll channel program angular velocity is the element in the first row and fourth column of the program angular velocity interpolation matrix. If the arrow movement time is longer than the attitude adjustment end time The pitch channel program angular velocity is the element in the last row and second column of the program angular velocity interpolation matrix; the yaw channel program angular velocity is the element in the last row and third column of the program angular velocity interpolation matrix; and the roll channel program angular velocity is the element in the last row and fourth column of the program angular velocity interpolation matrix. If the arrow time [Posture Adjustment Start Time] Posture adjustment end time Then, the current value is obtained by interpolation according to the following formula. time Channel program angular velocity , , respectively represent the roll, yaw and pitch channels, corresponding to the second, third and fourth columns in the interpolation matrix, and the interpolation period is the control period; in: for aisle angular velocity at any given moment for aisle angular velocity at any given moment The element in the first column of the k-th row of the program angular velocity interpolation matrix. It is the element in the first column of the (k+1)th row of the program angular velocity interpolation matrix.

4. The attitude adjustment path planning method based on RCS composite control according to claim 1, characterized in that, The current program quaternion is obtained by calculating the program's angular velocity, as follows: (1) Using the formula Calculate the current time t Channel attitude deviation , Indicates the control cycle. For the present time The programmable angular velocity of the channel; (2) Based on the current time t Channel attitude deviation calculation transformation matrix D s ; (3) Calculate the program quaternion at the current time using the following formula. , This is the quaternion of the program in the previous operation cycle.

5. The attitude adjustment path planning method based on RCS composite control according to claim 4, characterized in that, Based on the current time t Channel attitude deviation calculation transformation matrix D s The details are as follows: 。 6. The attitude adjustment path planning method based on RCS composite control according to claim 1, characterized in that, Based on the current navigation quaternions calculated by the inertial navigation system and the program quaternions, the current quaternion deviation is calculated as follows: The quaternion of the program at the current moment, For the current quaternion, This is the quaternion deviation.

7. The attitude adjustment path planning method based on RCS composite control according to claim 1, characterized in that, The deviation of the current angular velocity is calculated based on the current angular velocity and the programmed angular velocity, as follows: These represent the angular velocity deviations of the pitch, yaw, and roll channels at the current moment, respectively. These represent the navigation angular velocities of the pitch, yaw, and roll channels at the current moment, respectively. These represent the programmed angular velocities of the pitch, yaw, and roll channels at the current moment, respectively.

8. The attitude adjustment path planning method based on RCS composite control according to claim 1, characterized in that, The current RCS nozzle control signals for each channel are calculated as follows: (1) According to Channel attitude deviation Attitude angular rate deviation signal Establish the difference equation for the deviation signal and calculate Solution of channel difference equation; (2) According to The channel differential equation solution and the set switching threshold determine the RCS nozzle control signal for each channel.

9. The attitude adjustment path planning method based on RCS composite control according to claim 8, characterized in that, In step (1), the difference equation for the deviation signal is as follows: in: , , , , , , For binding Channel difference equation coefficients, , , They are respectively , , The former Calculated value for each control cycle To control the cycle; , Let represent the intermediate variables in the difference equation operation. This represents the output of the difference equation at the current time. The solutions to the difference equations for each channel are synthesized as follows: 。 10. The attitude adjustment path planning method based on RCS composite control according to claim 8, characterized in that, In step (2), the switch command signals for each channel are determined, as follows: Channel current nonlinear switch control output signal satisfy: in: , for Channel switch control threshold and lap coefficient, ; for A single-step switch on the channel controls the output signal; These represent the positive on, off, and negative on states of the nonlinear switch, respectively. This is the control cycle for the current stage, a constant value. for The channel switch controls the input signal, i.e. Solution of the channel difference equation.

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