Spacecraft attitude jet control method and system

Abstract

The application discloses a spacecraft attitude jet control method and a system thereof, wherein the spacecraft attitude jet control method comprises the following steps: setting different control gears; after the design of the different control gears is completed, generating a continuous control signal according to an attitude angle deviation and an attitude angle rate; converting the continuous control signal into a discrete control signal by using a multi-binary Schmitt trigger; and after the conversion of the continuous control signal into the discrete control signal is completed, controlling corresponding nozzles according to the output of the Schmitt trigger to generate a control torque. The spacecraft attitude jet control method provided by the application can simultaneously operate different nozzles with different thrusts or different numbers of nozzles by using one strategy, and does not need to switch the control strategy; the attitude stability under large interference and high precision under small interference are simultaneously realized, and the propellant consumption is saved.

Description

Technical Field

[0001] This application relates to the field of rockets, and more specifically, to a spacecraft attitude jet control method and system thereof. Background Technology

[0002] Attitude control systems using jet engines as actuators are widely used in spacecraft (launch vehicles, artificial satellites, spacecraft). Their principle involves using multiple fixed nozzles with different installation orientations to eject working propellant and generate thrust, thereby controlling the spacecraft's attitude. A typical nozzle installation scheme is shown below. Figure 1 As shown. Since the nozzle only has two states, on and off, while the spacecraft's attitude and angular rate are continuously changing physical quantities, a certain algorithm is needed to control the nozzle's on / off state. A common method is to use a lead compensator, such as... Figure 2 The diagram shows the working principle of the lead compensator controller, which consists of a compensator and a Schmitt trigger connected in series. The compensator can be a proportional-derivative (1+ks) element; in engineering practice, a rate gyroscope is often used instead of a differential action. This control scheme allows the spacecraft's attitude motion to converge from the initial state to a stable limiting cycle. The mathematical expression for the Schmitt trigger process is: Among them: U on U off These are the open and close thresholds, respectively; u i u c These are input quantities and control commands, respectively; u c [0] = 0; when called, it is abbreviated as u. c =Schmitt(u i U on U off Using the above control scheme, the control output only has three states: +1, -1, and 0, corresponding to three control torque states: positive control torque, negative control torque, and no control torque. The control torque is a fixed value. During different flight phases of the spacecraft, due to changes in internal and external disturbances, changes in the center of mass position, changes in the magnitude of rotational inertia, and changes in control accuracy and speed, different thrusts or different numbers of nozzles are required to overcome disturbances and achieve control targets. Different nozzle configurations and corresponding control strategies need to be designed for different flight phases, resulting in low flexibility. Furthermore, when using small nozzles, if unexpected large disturbances occur, the small nozzles cannot effectively overcome the disturbances; while when using large nozzles, if there are no large disturbances, it will cause unnecessary propellant waste.

[0003] Therefore, how to provide an attitude jet control method that can simultaneously use nozzles with different thrusts or different numbers of nozzles, achieve attitude stability under large disturbances and high precision under small disturbances, and save propellant consumption has become an urgent problem to be solved in this field. SUMMARY

[0004] The application provides a spacecraft attitude jet control method, comprising the following steps: setting different control gears; after the design of different control gears is completed, generating a continuous control signal according to an attitude angle deviation and an attitude angle rate; converting the continuous control signal into a discrete control signal by using a multi-ary Schmitt trigger; and controlling corresponding nozzles according to the output of the Schmitt trigger to generate a control torque after the conversion of the continuous control signal into the discrete control signal is completed.

[0005] The spacecraft attitude jet control method as described above, wherein different control gears generate different sizes of thrust, and the number of different control gears is n.

[0006] The spacecraft attitude jet control method as described above, wherein the continuous control signal u i Specifically represented as: Wherein Δθ is an attitude angle deviation, is an attitude angle rate, a0 is a static gain coefficient, and a1 is a dynamic gain coefficient.

[0007] The spacecraft attitude jet control method as described above, wherein a 5-ary Schmitt trigger is used to convert the continuous control signal into a discrete control signal.

[0008] The spacecraft attitude jet control method as described above, wherein the expression of the 5-ary Schmitt trigger is: Wherein u0[k] represents the output signal of the 5-ary Schmitt trigger after the kth call, u i [k] represents the input signal of the 5-ary Schmitt trigger in the kth call, u0[k-1] represents the output signal of the 5-ary Schmitt trigger after the k-1th call, are respectively low control gear opening and closing thresholds, are respectively high control gear opening and closing thresholds.

[0009] A spacecraft attitude jet control system, specifically comprising: a setting unit, a continuous control signal generation unit, a discrete control signal conversion unit, and a control unit; the setting unit is used for setting different control gears; the continuous control signal generation unit is used for generating a continuous control signal according to an attitude angle deviation and an attitude angle rate; the discrete control signal conversion unit is used for converting the continuous control signal into a discrete control signal by using a multi-ary Schmitt trigger; and the control unit is used for controlling corresponding nozzles according to the output of the Schmitt trigger to generate a control torque.

[0010] The spacecraft attitude jet control system as described above, wherein different control gears generate different sizes of thrust, and the number of different control gears is n.

[0011] The spacecraft attitude jet control system as described above, wherein the continuous control signal u i Specifically expressed as: Wherein Δθ is the attitude angle deviation, is the attitude angle rate, a0 is the static gain coefficient, and a1 is the dynamic gain coefficient.

[0012] The spacecraft attitude jet control system as described above, wherein a 5-bit Schmitt trigger is used to convert the continuous control signal into a discrete control signal.

[0013] The spacecraft attitude jet control system as described above, wherein the expression of the 5-bit Schmitt trigger is: Wherein u0[k] represents the output signal of the 5-bit Schmitt trigger after the kth call, u i [k] represents the input signal of the 5-bit Schmitt trigger at the kth call, u0[k-1] represents the output signal of the 5-bit Schmitt trigger after the k-1th call, are the low control gear opening and closing thresholds, respectively, are the high control gear opening and closing thresholds, respectively.

[0014] The present application has the following beneficial effects:

[0015] The spacecraft attitude jet control method provided by the present application can simultaneously operate different nozzles with large and small thrusts or different numbers of nozzles using one strategy, without the need for control strategy switching; simultaneously realizes attitude stability under large disturbance and high precision under small disturbance, and saves propellant consumption. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0017] Figure 1 is a typical installation scheme of the nozzle proposed in the prior art;

[0018] Figure 2 is a working principle diagram of the prior art lead-lag controller;

[0019] Figure 3 is a flowchart of the spacecraft attitude jet control method according to the embodiments of the present application;

[0020] Figure 4 is a conversion mode of the output signal of the multi-bit Schmitt trigger according to the embodiments of the present application;

[0021] Figure 5 This is a schematic diagram of the internal structure of a spacecraft attitude jet control system provided according to an embodiment of this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Based on the thrust magnitude and number of nozzles, this application designs several control levels for thrust from small to large, and automatically switches between different control levels according to the magnitude of attitude deviation and attitude angular rate to output corresponding control force.

[0024] Example 1

[0025] like Figure 3 As shown, the spacecraft attitude jet control method provided in this application embodiment specifically includes the following steps:

[0026] Step S310: Set different control levels.

[0027] Different control gears produce different amounts of thrust, and the number of different gears is n (2≦n≦N).

[0028] Specifically, in this embodiment, multiple nozzles in the same direction are divided into several gears. Different gears activate different nozzles and provide different control torques. The higher the gear, the greater the control torque provided.

[0029] For example, the first control setting provides relatively low thrust and is therefore considered a low control setting. The second control setting provides relatively high thrust compared to the first control setting and is therefore considered a high control setting.

[0030] Step S320: After completing the design of different control gears, generate continuous control signals based on attitude angle deviation and attitude angle rate.

[0031] Among them, the continuous control signal u i Specifically, it is expressed as follows:

[0032]

[0033] Where Δθ is the attitude angle deviation. denoted as attitude angular rate, a0 as static gain coefficient, and a1 as dynamic gain coefficient.

[0034] Step S330: converting the continuous control signal into a discrete control signal by using a multi-valued Schmitt trigger.

[0035] For example, taking two control gears (such as a low control gear and a high control gear) as an example, a Schmitt 5 trigger is used for the case of two gears, the input signal of the Schmitt 5 trigger is u i , and the output signal is u o , where the input signal is a continuous control signal, and the output signal is a discrete control signal. The expression of the Schmitt 5 trigger is as follows.

[0036]

[0037] Where u0[k] represents the output signal of the Schmitt 5 trigger after the kth call, u i [k] represents the input signal of the Schmitt 5 trigger after the kth call, u0[k-1] represents the output signal of the Schmitt 5 trigger after the (k-1) th call, are the opening and closing thresholds of the low control gear, respectively, are the opening and closing thresholds of the high control gear, respectively.

[0038] It is worth noting that the opening threshold of the higher control gear (for example, the "high control gear" described above) should be greater than the opening threshold of the lower control gear (for example, the "low control gear" described above), and the closing threshold of the higher control gear should also be greater than the closing threshold of the lower control gear.

[0039] Where the Schmitt 5 trigger initializes the output signal in the following way when it is called for the first time, u0[1] represents the output signal of the Schmitt 5 trigger after the first call, and u i [1] represents the input signal of the Schmitt 5 trigger after the first call.

[0040]

[0041] Where the conversion method of the output signal of the Schmitt 5 when it is called for the first time is as shown in the following formula. Figure 4 Where u i represents the input signal when it is called for the first time, and u o represents the output signal after the first call.

[0042] Specifically, when u i crosses the threshold from left to right, u o changes from 0 to 1; when it crosses the threshold from right to left, u o changes from 1 to 0; when it crosses the threshold from left to right, At threshold, u o Change from 1 to 2; pass through from right to left At threshold, u o Change from 2 to 1. Pass through from right to left. At threshold, u o Changes from 0 to -1; passes through from left to right At threshold, u o Changes from -1 to 0; passes through from left to right At threshold, u o Change from -1 to -2; pass through from right to left At threshold, u o It changes from -2 to -1.

[0043] Based on the above, then:

[0044]

[0045] Step S340: After converting the continuous control signal into a discrete control signal, the corresponding nozzle is controlled according to the output of the Schmitt trigger to generate control torque.

[0046] The corresponding nozzle is controlled based on the output signal value after the kth call of the Schmitt5 trigger, thereby generating the corresponding control torque.

[0047] Specifically, when the output u0[k] is 0, no nozzle is turned on; when the output u0[k] is 1, the positive small nozzle is turned on; when the output u0[k] is 2, the positive large nozzle is turned on; when the output u0[k] is -1, the negative small nozzle is turned on; when the output u0[k] is -2, the negative large nozzle is turned on.

[0048] The positional arrangement of the positive small nozzle, positive large nozzle, negative small nozzle, and negative large nozzle is as follows: Figure 1 The existing typical nozzle installation scheme is as follows: #1 to #8 are large nozzles, and #9 to #16 are small nozzles.

[0049] Positive and negative can be understood as the positive and negative directions of the X-axis and Y-axis. The positive large nozzles are #4 to #7. The positive small nozzles are #12 to #15. The negative large nozzles are #1 to #3 and #8. The negative small nozzles are #9 to #11 and #16.

[0050] Example 2

[0051] like Figure 5 As shown, this embodiment provides a spacecraft attitude jet control system, which specifically includes: a setting unit 510, a continuous control signal generation unit 520, a discrete control signal conversion unit 530, and a control unit 540.

[0052] Setting unit 510 is used to set different control levels.

[0053] Different control gears produce different amounts of thrust, and the number of different gears is n (2≦n≦N).

[0054] Specifically, in this embodiment, multiple nozzles in the same direction are divided into several gears. Different gears activate different nozzles and provide different control torques. The higher the gear, the greater the control torque provided.

[0055] For example, the first control setting provides relatively low thrust and is therefore considered a low control setting. The second control setting provides relatively high thrust compared to the first control setting and is therefore considered a high control setting.

[0056] The continuous control signal generation unit 520 is used to generate continuous control signals based on attitude angle deviation and attitude angle rate.

[0057] Among them, the continuous control signal u i Specifically, it is expressed as follows:

[0058]

[0059] Where Δθ is the attitude angle deviation. denoted as attitude angular rate, a0 as static gain coefficient, and a1 as dynamic gain coefficient.

[0060] The discrete control signal conversion unit 530 is used to convert continuous control signals into discrete control signals using a multi-level Schmitt trigger.

[0061] Taking a two-gear configuration (e.g., low and high control gears) as an example, a 5-ary Schmitt trigger (Schmitt5) is used for this configuration. The input signal of the 5-ary Schmitt trigger is u. i The output signal is u o The input signal is a continuous control signal, and the output signal is a discrete control signal. The expression for a 5-ary Schmitt trigger is shown below.

[0062]

[0063] Where u0[k] represents the output signal after the k-th call of the Schmitt5 flip-flop, u i [k] represents the input signal of the Schmitt5 flip-flop during the k-th call, and u0[k-1] represents the output signal of the Schmitt5 flip-flop after the (k-1)-th call. These are the opening and closing thresholds for the low control level, respectively. These are the opening and closing thresholds for the high control gear, respectively.

[0064] It is worth noting that the opening limit of a higher control gear (such as the "high control gear" mentioned above) should be greater than the opening limit of a lower control gear (such as the "low control gear" mentioned above), and the closing limit of a higher control gear should also be greater than the closing limit of a lower control gear.

[0065] The Schmitt5 trigger is initialized with its output signal on its first call in the following manner: u0[1] represents the output signal after the first call of the Schmitt5 trigger, u i [1] indicates the input signal for the first call of the Schmitt5 trigger.

[0066]

[0067] When Schmitt5 is called multiple times, the output signal conversion method is as follows: Figure 4 As shown. The following u i This refers to the input signal during non-first-time calls, u o This indicates the output signal after a non-first call.

[0068] Specifically, when u i Cross from left to right At threshold, u o Change from 0 to 1; pass through from right to left At threshold, u o Change from 1 to 0; pass through from left to right At threshold, u o Change from 1 to 2; pass through from right to left At threshold, u o Change from 2 to 1. Pass through from right to left. At threshold, u o Changes from 0 to -1; passes through from left to right At threshold, u o Changes from -1 to 0; passes through from left to right At threshold, u o Change from -1 to -2; pass through from right to left At threshold, u o It changes from -2 to -1.

[0069] Based on the above, then:

[0070]

[0071] The control unit 540 is used to control the corresponding nozzle according to the output of the Schmitt trigger to generate control torque.

[0072] The corresponding nozzle is controlled based on the output signal value after the kth call of the Schmitt5 trigger, thereby generating the corresponding control torque.

[0073] Specifically, when the output u0[k] is 0, no nozzle is turned on; when the output u0[k] is 1, the positive small nozzle is turned on; when the output u0[k] is 2, the positive large nozzle is turned on; when the output u0[k] is -1, the negative small nozzle is turned on; when the output u0[k] is -2, the negative large nozzle is turned on.

[0074] The positional arrangement of the positive small nozzle, positive large nozzle, negative small nozzle, and negative large nozzle is as follows: Figure 1 The existing typical nozzle installation scheme is as follows: #1 to #8 are large nozzles, and #9 to #16 are small nozzles.

[0075] Positive and negative can be understood as the positive and negative directions of the X-axis and Y-axis. The positive large nozzles are #4 to #7. The positive small nozzles are #12 to #15. The negative large nozzles are #1 to #3 and #8. The negative small nozzles are #9 to #11 and #16.

[0076] This application has the following beneficial effects:

[0077] The spacecraft attitude jet control method proposed in this application can operate nozzles with different thrust levels or different numbers of nozzles simultaneously using a single strategy without switching control strategies; it can simultaneously achieve attitude stability under large disturbances and high precision under small disturbances, while saving propellant consumption.

[0078] Although the examples referenced in this application are described for illustrative purposes only and not for limiting the scope of this application, changes, additions and / or deletions to the implementation may be made without departing from the scope of this application.

[0079] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A spacecraft attitude jet control method, characterized in that, Includes the following steps: Set different control levels; After setting different control levels, a continuous control signal is generated based on the attitude angle deviation and attitude angle rate. A multi-level Schmitt trigger is used to convert continuous control signals into discrete control signals; After converting the continuous control signal into a discrete control signal, the corresponding nozzle is controlled according to the output of the Schmitt trigger to generate control torque. The continuous control signal is converted into a discrete control signal using a 5-ary Schmitt trigger. The expression for a 5-ary Schmitt trigger is: Where u0[k] represents the output signal of the 5-ary Schmitt trigger after the k-th call, u i [k] represents the input signal of the 5-ary Schmitt trigger in its k-th invocation, and u0[k-1] represents the output signal of the 5-ary Schmitt trigger after its (k-1)-th invocation. These are the opening and closing thresholds for the low control level, respectively. These are the opening and closing thresholds for the high control gear, respectively.

2. The spacecraft attitude jet control method as described in claim 1, characterized in that, Different control gears produce different amounts of thrust, and there are n different control gears.

3. The spacecraft attitude jet control method as described in claim 1, characterized in that, Continuous control signal u i Specifically, it is expressed as follows: Where Δθ is the attitude angle deviation. denoted as attitude angular rate, a0 as static gain coefficient, and a1 as dynamic gain coefficient.

4. A spacecraft attitude jet control system, characterized in that, Specifically, it includes: The system includes a setting unit, a continuous control signal generation unit, a discrete control signal conversion unit, and a control unit. The setting unit is used to set different control levels; A continuous control signal generation unit is used to generate continuous control signals based on attitude angle deviation and attitude angle rate. Discrete control signal conversion unit, used to convert continuous control signals into discrete control signals using a multi-level Schmitt trigger; The control unit is used to control the corresponding nozzle based on the output of the Schmitt trigger, thereby generating a control torque. The continuous control signal is converted into a discrete control signal using a 5-ary Schmitt trigger. The expression for a 5-ary Schmitt trigger is: Where u0[k] represents the output signal of the 5-ary Schmitt trigger after the k-th call, u i [k] represents the input signal of the 5-ary Schmitt trigger in its k-th invocation, and u0[k-1] represents the output signal of the 5-ary Schmitt trigger after its (k-1)-th invocation. These are the opening and closing thresholds for the low control level, respectively. These are the opening and closing thresholds for the high control gear, respectively.

5. The spacecraft attitude jet control system as described in claim 4, characterized in that, Different control gears produce different amounts of thrust, and there are n different control gears.

6. The spacecraft attitude jet control system as described in claim 4, characterized in that, Continuous control signal u i Specifically, it is expressed as follows: Where Δθ is the attitude angle deviation. denoted as attitude angular rate, a0 as static gain coefficient, and a1 as dynamic gain coefficient.

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