Spacecraft attitude jet control method and system

Abstract

The invention discloses a spacecraft attitude jet control method and system. The spacecraft attitude jet control method comprises the following steps: setting different control gears; after different control gears are designed, a continuous control signal is generated according to the attitude angle deviation and the attitude angle rate; a multi-system Schmitt trigger is adopted to convert a continuous control signal into a discrete control signal; and after continuous control signals are converted into discrete control signals, corresponding nozzles are controlled according to the output of the Schmitt trigger, and control torque is generated. According to the spacecraft attitude jet control method provided by the invention, nozzles with different large and small thrust or different numbers of nozzles can be operated at the same time by using one strategy, and control strategy switching does not need to be carried out; meanwhile, attitude stability under large interference and high precision under small interference are achieved, and propellant consumption is reduced.

Description

Technical Field

[0001] The present application relates to the field of rockets, and in particular, to a spacecraft attitude jet control method and system thereof. Background Art

[0002] The attitude control system with jet engines as actuators is widely used in spacecraft (launch vehicles, satellites, and spacecraft). Its principle is to use multiple fixed nozzles with different installation directions to eject working fluid to generate thrust, thereby controlling the attitude of the spacecraft. Typical nozzle installation schemes are as follows: Figure 1 As shown in Figure 2. Since the nozzle has only two states, on and off, and the spacecraft attitude and angular velocity are continuously changing physical quantities, a certain algorithm is needed to control the nozzle on and off. A common method is to use an advance correction controller, such as Figure 2 As shown in the figure, the working principle diagram of the advance correction controller is composed of a correction link and a Schmitt trigger in series. The correction link can be a proportional differential link (1+ks). In engineering practice, a rate gyro is often used to replace the differential action. This control scheme can make the attitude motion of the spacecraft converge from the initial state to a stable limit cycle. The mathematical expression of the Schmitt trigger process is: Among them: U on , U off are the opening and closing thresholds respectively; u i ,u c are input quantity and control instruction respectively; u c [0] = 0; abbreviated as u when calling c =Schmitt(u i , U on , U off ). With the above control scheme, the control output only has three states: +1, -1 and 0, corresponding to the three control torque states of positive control torque, negative control torque and no control torque, and the control torque is a fixed value. In different flight phases of the spacecraft, due to changes in internal and external interference, changes in the center of mass position, changes in the size of the moment of inertia, and changes in indicators such as control accuracy and control speed, different thrusts or different numbers of nozzles are required at different stages to overcome interference and achieve control indicators. Different nozzle configurations need to be selected at different flight phases, and corresponding control strategies need to be designed, which has low flexibility. In addition, when using a small nozzle, if there is an unexpected large interference, the small nozzle cannot effectively overcome the interference; when using a large nozzle, if there is no large interference at this time, it will cause unnecessary waste of propellant.

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

[0004] The present application proposes a spacecraft attitude jet control method, comprising the following steps: setting different control gears; after completing the design of different control gears, generating a continuous control signal according to the attitude angle deviation and the attitude angle rate; using a multi-binary Schmitt trigger to convert the continuous control signal into a discrete control signal; after completing the conversion of the continuous control signal into a discrete control signal, controlling the corresponding nozzle according to the output of the Schmitt trigger to generate a control torque.

[0005] In the spacecraft attitude jet control method as described above, different control gears generate thrusts of different magnitudes, and the number of different control gears is n.

[0006] As described above, the spacecraft attitude jet control method, wherein the continuous control signal u i Specifically expressed as: Where Δθ is the attitude angle deviation, is the attitude angular rate, a0 is the static gain coefficient, and a1 is the dynamic gain coefficient.

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

[0008] In the above-mentioned spacecraft attitude jet control method, the expression of the 5-ary Schmitt trigger is: Where 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 k-th call of the 5-ary Schmitt trigger, u0[k-1] represents the output signal after the k-1-th call of the 5-ary Schmitt trigger, They are the opening and closing thresholds of the low control gear respectively. They are respectively the opening and closing thresholds of the high control gear.

[0009] A spacecraft attitude jet control system specifically comprises: a setting unit, a continuous control signal generating 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 generating 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 a continuous control signal into a discrete control signal by using a multi-binary Schmitt trigger; and the control unit is used for controlling a corresponding nozzle according to the output of the Schmitt trigger to generate a control torque.

[0010] In the spacecraft attitude jet control system as described above, different control gears generate thrusts of different magnitudes, and the number of different control gears is n.

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

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

[0013] In the above-mentioned spacecraft attitude jet control system, the expression of the 5-ary Schmitt trigger is: Where 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 k-th call of the 5-ary Schmitt trigger, u0[k-1] represents the output signal after the k-1-th call of the 5-ary Schmitt trigger, They are the opening and closing thresholds of the low control gear respectively. They are respectively the opening and closing thresholds of the high control gear.

[0014] This application has the following beneficial effects:

[0015] The spacecraft attitude jet control method proposed in this application can use one strategy to simultaneously operate nozzles with different large and small thrusts or different numbers of nozzles without the need to switch control strategies; at the same time, it can achieve attitude stability under large disturbances and high precision under small disturbances, and save propellant consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

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

[0018] Figure 2 It is a working principle diagram of the advance correction controller in the prior art;

[0019] Figure 3 is a flow chart of a spacecraft attitude jet control method provided according to an embodiment of the present application;

[0020] Figure 4 This is a conversion method of the output signal of the multi-base Schmitt trigger provided in an embodiment of the present application;

[0021] Figure 5 It is a schematic diagram of the internal structure of a spacecraft attitude jet control system provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0023] The present application designs several control gears of thrust from small to large according to the thrust size and number of the nozzles, automatically switches different control gears according to the size of the attitude deviation and the attitude angular velocity, and outputs the corresponding control force.

[0024] Embodiment 1

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

[0026] Step S310: Setting different control gears.

[0027] Different control gears generate thrusts of different magnitudes, 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 open different nozzles and provide different control torques. The higher the gear, the greater the control torque provided.

[0029] For example, the first control gear can output a smaller thrust, which is used as a low control gear. The second control gear can output a larger thrust than the first control gear, which is used as a high control gear.

[0030] Step S320: After completing the design of different control gears, a continuous control signal is generated according to the attitude angle deviation and the attitude angle rate.

[0031] The continuous control signal u i Specifically expressed as:

[0032]

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

[0034] Step S330: using a multi-level Schmitt trigger to convert the continuous control signal into a discrete control signal.

[0035] Taking two control gears (such as low control gear and high control gear) as an example, a 5-bit Schmitt trigger (Schmitt5) is used for the two gears. The input signal of the 5-bit Schmitt trigger is u i , 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 5-bit Schmitt trigger is shown below.

[0036]

[0037] Where u0[k] represents the output signal after the Schmitt5 trigger is called for the kth time, u i [k] represents the input signal of the kth call of the Schmitt5 trigger, u0[k-1] represents the output signal after the k-1th call of the Schmitt5 trigger, They are the opening and closing thresholds of the low control gear respectively. They are respectively the opening and closing thresholds of the high control gear.

[0038] It is worth noting that the opening limit of a higher control gear (such as the above-mentioned "high control gear") should be greater than the opening limit of a lower control gear (such as the above-mentioned "low control gear"), and the closing limit of a higher control gear should also be greater than the closing limit of a lower control gear.

[0039] The Schmitt5 trigger uses the following method to initialize the output signal when it is called for the first time. u0[1] represents the output signal after the Schmitt5 trigger is called for the first time. i [1] indicates the input signal for the first call of the Schmitt5 trigger.

[0040]

[0041] When Schmitt5 is not called for the first time, the output signal conversion method is as follows Figure 4 As shown below. i That is, the input signal when it is not the first call, u o Indicates the output signal after a non-first call.

[0042] Specifically, when u i Passing from left to right Threshold time, u o From 0 to 1; from right to left Threshold time, u o From 1 to 0; from left to right Threshold time, u o Changes from 1 to 2; passes from right to left Threshold time, u o From 2 to 1. Cross from right to left Threshold time, u o From 0 to -1; from left to right Threshold time, u o From -1 to 0; from left to right Threshold time, u o Changes from -1 to -2; passes from right to left Threshold time, u o Changed from -2 to -1.

[0043] Based on the above, then:

[0044]

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

[0046] The corresponding nozzle is controlled according to the corresponding value of the output signal after the Schmitt5 trigger is called for the kth time, thereby generating the corresponding control torque.

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

[0048] The positions of the positive small nozzle, positive large nozzle, negative small nozzle and negative large nozzle are arranged as reference Figure 1 Typical installation scheme of existing nozzles, where #1 to #8 are large nozzles and #9 to #16 are small nozzles.

[0049] Positive and negative directions can be understood as the positive and negative directions of the X-axis and Y-axis directions. 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] Embodiment 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 generating unit 520, a discrete control signal converting unit 530 and a control unit 540.

[0052] The setting unit 510 is used to set different control gears.

[0053] Different control gears generate thrusts of different magnitudes, 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 open different nozzles and provide different control torques. The higher the gear, the greater the control torque provided.

[0055] For example, the first control gear can output a smaller thrust, which is used as a low control gear. The second control gear can output a larger thrust than the first control gear, which is used as a high control gear.

[0056] The continuous control signal generating unit 520 is used to generate a continuous control signal according to the attitude angle deviation and the attitude angle rate.

[0057] The continuous control signal u i Specifically expressed as:

[0058]

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

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

[0061] Taking two control gears (such as low control gear and high control gear) as an example, a 5-bit Schmitt trigger (Schmitt5) is used for the two gears. The input signal of the 5-bit Schmitt trigger is u i , 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 5-bit Schmitt trigger is shown below.

[0062]

[0063] Where u0[k] represents the output signal after the Schmitt5 trigger is called for the kth time, u i [k] represents the input signal of the kth call of the Schmitt5 trigger, u0[k-1] represents the output signal after the k-1th call of the Schmitt5 trigger, They are the opening and closing thresholds of the low control gear respectively. They are respectively the opening and closing thresholds of the high control gear.

[0064] It is worth noting that the opening limit of a higher control gear (such as the above-mentioned "high control gear") should be greater than the opening limit of a lower control gear (such as the above-mentioned "low control gear"), 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 uses the following method to initialize the output signal when it is called for the first time. u0[1] represents the output signal after the Schmitt5 trigger is called for the first time. i [1] indicates the input signal for the first call of the Schmitt5 trigger.

[0066]

[0067] When Schmitt5 is not called for the first time, the output signal conversion method is as follows Figure 4 As shown below. i That is, the input signal when it is not the first call, u o Indicates the output signal after a non-first call.

[0068] Specifically, when u i Passing from left to right Threshold time, u o From 0 to 1; from right to left Threshold time, u o From 1 to 0; from left to right Threshold time, u o Changes from 1 to 2; passes from right to left Threshold time, u o From 2 to 1. Cross from right to left Threshold time, u o From 0 to -1; from left to right Threshold time, u o From -1 to 0; from left to right Threshold time, u o Changes from -1 to -2; passes from right to left Threshold time, u o Changed 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 Schmidt trigger to generate a control torque.

[0072] The corresponding nozzle is controlled according to the corresponding value of the output signal after the Schmitt5 trigger is called for the kth time, thereby generating the corresponding control torque.

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

[0074] The positions of the positive small nozzle, positive large nozzle, negative small nozzle and negative large nozzle are arranged as reference Figure 1 Typical installation scheme of existing nozzles, where #1 to #8 are large nozzles and #9 to #16 are small nozzles.

[0075] Positive and negative directions can be understood as the positive and negative directions of the X-axis and Y-axis directions. 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 use one strategy to simultaneously operate nozzles with different large and small thrusts or different numbers of nozzles without the need to switch control strategies; at the same time, it can achieve attitude stability under large disturbances and high precision under small disturbances, and save propellant consumption.

[0078] Although the present application is described with reference to examples, this is for illustrative purposes only and is not intended to limit the present application, and changes, additions and / or deletions to the embodiments may be made without departing from the scope of the present application.

[0079] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A spacecraft attitude jet control method, characterized in that: The following steps are involved: Set different control gears; After completing the design of different control gears, a continuous control signal is generated according to the attitude angle deviation and attitude angle rate; A multi-level Schmitt trigger is used to convert the continuous control signal into a discrete control signal; After the continuous control signal is converted into a discrete control signal, the corresponding nozzle is controlled according to the output of the Schmitt trigger to generate a control torque.

2. The spacecraft attitude jet control method according to claim 1, characterized in that: Different control gears generate thrusts of different magnitudes, and the number of different control gears is n.

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

4. The spacecraft attitude jet control method according to claim 1, characterized in that: A quinary Schmitt trigger is used to convert the continuous control signal into a discrete control signal.

5. The spacecraft attitude jet control method according to claim 4, characterized in that: The expression of the 5-bit Schmitt trigger is: Where 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 k-th call of the 5-ary Schmitt trigger, u0[k-1] represents the output signal after the k-1-th call of the 5-ary Schmitt trigger, They are the opening and closing thresholds of the low control gear respectively. They are respectively the opening and closing thresholds of the high control gear.

6. A spacecraft attitude jet control system, characterized in that: Specifically include: A setting unit, a continuous control signal generating unit, a discrete control signal converting unit and a control unit; A setting unit, used for setting different control gears; A continuous control signal generating unit, used for generating a continuous control signal according to an attitude angle deviation and an attitude angle rate; A discrete control signal conversion unit, used for converting a continuous control signal into a discrete control signal by using a multi-level Schmitt trigger; The control unit is used to control the corresponding nozzle according to the output of the Schmidt trigger to generate a control torque.

7. The spacecraft attitude jet control system according to claim 6, characterized in that: Different control gears generate thrusts of different magnitudes, and the number of different control gears is n.

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

9. The spacecraft attitude jet control system according to claim 6, characterized in that: A quinary Schmitt trigger is used to convert the continuous control signal into a discrete control signal.

10. The spacecraft attitude jet control system according to claim 9, characterized in that: The expression of the 5-bit Schmitt trigger is: Where 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 k-th call of the 5-ary Schmitt trigger, u0[k-1] represents the output signal after the k-1-th call of the 5-ary Schmitt trigger, They are the opening and closing thresholds of the low control gear respectively. They are respectively the opening and closing thresholds of the high control gear.

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