Spacecraft attitude jet control method and system based on delta-sigma modulator

Abstract

The application provides a spacecraft attitude jet control method and system based on a delta-sigma modulator, which comprises the following steps: collecting the attitude angle and the attitude angular rate of a spacecraft, and feeding back the attitude angle and the attitude angular rate to an outer loop and an inner loop, respectively; in the outer loop, calculating an angular rate command according to the feedback attitude angle and an attitude angle command input into the outer loop, and inputting the angular rate command into the inner loop; in the inner loop, obtaining an angular rate deviation signal according to the angular rate command and the feedback attitude angular rate; in the inner loop, converting the angular rate deviation signal into a jet pipe relative thrust command, modulating the jet pipe relative thrust command into a jet pipe switch command with adjustable duty ratio, and converting the jet pipe switch command into an electromagnetic valve on-off signal of the jet pipe; and controlling the forward jet pipe and the reverse jet pipe to perform jet actions according to the electromagnetic valve on-off signal. The application realizes continuous control of the spacecraft attitude angle and the angular rate and improves the control precision of the spacecraft attitude under the premise of avoiding an increase in the number of jet pipe jet actions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of spacecraft attitude adjustment, and particularly relates to a spacecraft attitude jet control method and system based on a delta-sigma modulator. BACKGROUND

[0002] In spacecraft (for example, a carrier rocket, a spaceship), an attitude control system with fixed thrust nozzles (or called thrusters) as an actuator is widely used. The principle of the attitude control system is to use multiple fixed nozzles with different installation directions to spray working medium to generate thrust, and then generate a control torque, and then adjust the attitude of the spacecraft. Since the nozzle only has two states of opening and closing, the control torque is discontinuous, and the attitude angle and angular velocity of the spacecraft are continuous physical quantities, therefore, a certain algorithm needs to be used to control the opening and closing of the nozzle to simulate the continuously changing control torque to stabilize the continuous adjustment of the attitude angle and angular velocity of the spacecraft.

[0003] A commonly used method is to use a lead correction controller, as shown in the formula (1), which 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 gyroscope is commonly used instead of a differential action. This control scheme makes the attitude of the spacecraft converge from the initial state to a stable limit cycle. Figure 6

[0004] The mathematical expression of the Schmitt trigger is as follows:

[0005]

[0006] Wherein: U on is an opening limit; U off is a closing limit; u i is an input quantity; u c is a control instruction; u c [0] = 0; the mathematical expression of the Schmitt trigger when called is u c = Schmitt(u i , U on , U off ).

[0007] In the proportional differential controller, if the dynamic characteristics of the attitude measuring component and the delay of the jet actuator are not considered, the limit cycle angular velocity only depends on the hysteresis width hθ D of the Schmitt trigger and the gain k of the differential term (also called the rate gain). Reducing hθ D and increasing the gain k of the differential term can reduce the limit cycle speed, but increase the sensitivity of the system to the attitude angular velocity and angular velocity measurement noise, thereby increasing the number of jets. Therefore, under the premise of avoiding the increase in the number of jets, the hysteresis width hθ D ​And the differential term gain k cannot be too small, that is, it is difficult to adjust the limit ring speed to be very small by using a proportional differential controller (a controller with proportional and differential correction). Since a certain distance is required between the positive and negative switching thresholds (i.e. the opening threshold and the closing threshold) of the Schmidt trigger to reduce the jet frequency, it is difficult to achieve high precision in the spacecraft attitude control.

[0008] Therefore, how to continuously control the spacecraft attitude angle and angular rate without increasing the number of jet pipe jets and improve the control precision of the spacecraft attitude is a technical problem to be solved at present. SUMMARY

[0009] The purpose of the present application is to provide a spacecraft attitude jet control method and system based on a delta-sigma modulator, which continuously controls the spacecraft attitude angle and angular rate without increasing the number of jet pipe jets and improves the control precision of the spacecraft attitude.

[0010] To achieve the above-mentioned purpose, the present application provides a spacecraft attitude jet control method based on a delta-sigma modulator, which comprises the following steps: collecting the attitude angle and the attitude angular rate of the spacecraft and feeding them back to the outer loop and the inner loop respectively; in the outer loop, calculating the angular rate command according to the feedback attitude angle and the input attitude angle command of the outer loop, and inputting the angular rate command to the inner loop; in the inner loop, obtaining the angular rate deviation signal according to the angular rate command and the feedback attitude angular rate; in the inner loop, converting the angular rate deviation signal into the jet pipe relative thrust command by a proportional integral controller, modulating the jet pipe relative thrust command into the jet pipe on-off command with adjustable duty cycle by a delta-sigma modulator; converting the jet pipe on-off command into the electromagnetic valve on-off signal of the jet pipe, and controlling the forward jet pipe and the reverse jet pipe to execute the jet action according to the electromagnetic valve on-off signal.

[0011] The spacecraft attitude jet control method based on a delta-sigma modulator as described above, wherein in the outer loop, the method for calculating the angular rate command according to the feedback attitude angle and the input attitude angle command of the outer loop comprises the following steps: receiving the attitude angle command and the feedback attitude angle in the outer loop; calculating the difference between the attitude angle and the attitude angle in the input attitude angle command of the outer loop to obtain the attitude angle deviation value; calculating the product of the attitude angle deviation value and the outer loop gain as the angular rate command.

[0012] The spacecraft attitude jet control method based on a delta-sigma modulator as described above, wherein in the inner loop, the method for obtaining the angular rate deviation signal according to the angular rate command and the feedback attitude angular rate comprises the following steps: receiving the angular rate command and the attitude angular rate in the inner loop; calculating the difference between the angular rate in the angular rate command and the attitude angular rate to obtain the angular rate deviation signal.

[0013] The spacecraft attitude jet control method based on the delta-sigma modulator as described above, wherein the method for modulating the jet relative thrust command into the jet switch command with adjustable duty cycle based on the delta-sigma modulator is: limiting the jet relative thrust command as an input signal; subtracting the jet switch command output by the delta-sigma modulator in the last period from the limited input signal to obtain a difference signal; integrating the difference signal to calculate an integral result; comparing the integral result with a threshold to obtain a comparison result, and outputting the jet switch command according to the comparison result.

[0014] The spacecraft attitude jet control method based on the delta-sigma modulator as described above, wherein the limiting range of the limiter is set to 0-1, the threshold of the comparator is 0, when the input integral result is less than 0, the comparison result is 0, and the output jet switch command is 0, indicating that the jet is closed; when the input integral result of the comparator is greater than 0, the comparison result is 1, and the output jet switch command is 1, indicating that the jet is opened.

[0015] The spacecraft attitude jet control method based on the delta-sigma modulator as described above, wherein the limiting range of the limiter is set to -1-+1, when the integral result is less than 0, the output comparison result is -1, and the output jet switch command is -1, indicating that the reverse jet is opened and the forward jet is closed, when the input integral result of the comparator is greater than 0, the output comparison result is 1, and the output jet switch command is 1, indicating that the forward jet is opened and the reverse jet is closed.

[0016] The application also provides a spacecraft attitude jet control system based on a delta-sigma modulator, which comprises: an outer loop and an inner loop, the inner loop being connected inside the outer loop; the outer loop is used to calculate an angular rate command according to a feedback attitude angle and an attitude angle command input into the outer loop, and input the angular rate command into the inner loop; the inner loop is used to obtain an angular rate deviation signal according to the angular rate command and a feedback attitude angular rate; and convert the angular rate deviation signal into a jet relative thrust command by a proportional-integral controller, and modulate the jet relative thrust command into a jet switch command with adjustable duty cycle by a delta-sigma modulator; convert the jet switch command into an electromagnetic valve on-off signal of the jet; the output end of the inner loop is connected with the electromagnetic valves of the forward jet and the reverse jet; and control the electromagnetic valve on-off of the forward jet and the reverse jet according to the electromagnetic valve on-off signal to control the jet of the forward jet and the reverse jet.

[0017] The spacecraft attitude jet control system based on the delta-sigma modulator as described above, wherein the outer loop comprises: an inertial measurement unit and an outer loop controller; the inertial measurement unit is used to collect the attitude angle of the spacecraft and feed back to the outer loop; the outer loop controller is used to calculate the product of the attitude angle deviation value and the outer loop gain as the angular rate command; the output of the outer loop controller is connected with the input of the inner loop, and the outer loop controller inputs the angular rate command to the inner loop.

[0018] The spacecraft attitude jet control system based on the delta-sigma modulator as described above, wherein the inner loop comprises: a rate gyro or an inertial measurement unit, an inner loop controller, a filter, a delta-sigma modulator and a signal converter; the rate gyro or the inertial measurement unit is used to collect the attitude angular rate of the spacecraft and feed back to the inner loop; in the inner loop, the angular rate deviation signal is obtained according to the angular rate command and the feedback attitude angular rate; the inner loop controller is used to convert the angular rate deviation signal into the jet pipe relative thrust command; the filter is used to filter the jet pipe relative thrust command; the delta-sigma modulator is used to modulate the filtered jet pipe relative thrust command into the jet pipe switching command with adjustable duty cycle; and the signal converter is used to convert the jet pipe switching command into the electromagnetic valve on-off signal of the jet pipe.

[0019] The spacecraft attitude jet control system based on the delta-sigma modulator as described above, wherein the delta-sigma modulator comprises a first modulator and a second modulator, and the signal converter comprises a first signal converter and a second signal converter; the signal input ends of the first modulator and the second modulator are connected with the signal output end of the filter; the signal output end of the first modulator is connected with the electromagnetic valve of the forward jet pipe through the first signal converter; the first modulator modulates and converts the jet pipe relative thrust command output by the filter to output the jet pipe switching command with adjustable duty cycle, and the first signal converter converts the jet pipe switching command into the electromagnetic valve on-off signal to control the jet action of the forward jet pipe; the signal output end of the second modulator is connected with the electromagnetic valve of the reverse jet pipe through the second signal converter, the second modulator modulates and converts the jet pipe relative thrust command output by the filter to output the jet pipe switching command with adjustable duty cycle, and the second signal converter converts the jet pipe switching command into the electromagnetic valve on-off signal to control the jet action of the reverse jet pipe.

[0020] The beneficial effects realized by the present application are as follows:

[0021] (1) The application adopts a double-loop attitude control system, feeds the measured attitude angle and attitude angular velocity back to the outer loop and the inner loop respectively, generates relative thrust control instructions through a proportional integral controller, modulates the relative thrust control instructions into a pulse duty ratio adjustable nozzle switch instruction through a delta-sigma modulator, converts the nozzle switch instruction into a solenoid valve on-off signal through a signal converter, controls the solenoid valve to be connected or disconnected according to the solenoid valve on-off signal, and then controls the nozzle to jet gas. On the premise of avoiding the increase of the number of times of jetting gas, the attitude angle and angular velocity of the spacecraft are continuously controlled, and the control precision of the spacecraft attitude is improved.

[0022] (2) The application modulates the nozzle relative thrust instruction into a pulse duty ratio adjustable nozzle switch instruction through a delta-sigma modulator, so that the fixed thrust nozzle achieves the control effect of continuously adjusting the control moment, the attitude angle deviation converges to the vicinity of the 0 axis, the low attitude angular velocity deviation and attitude angle deviation are realized, the number of times of jetting gas is greatly reduced, and the application realizes low working medium consumption in the case of improving the attitude control precision of the spacecraft. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments described in the application, and other drawings can also be obtained by those skilled in the art according to these drawings.

[0024] Figure 1 The flow chart of a spacecraft attitude jet control method based on a delta-sigma modulator according to an embodiment of the application.

[0025] Figure 2 The flow chart of a method for obtaining an angular velocity instruction according to an embodiment of the application.

[0026] Figure 3 The flow chart of a method for obtaining an angular velocity deviation signal according to an embodiment of the application.

[0027] Figure 4 The flow chart of a method for obtaining a pulse duty ratio adjustable nozzle switch instruction according to an embodiment of the application.

[0028] Figure 5 The flow chart of a method for modulating a nozzle relative thrust instruction into a pulse duty ratio adjustable solenoid valve on-off signal through a delta-sigma modulator according to an embodiment of the application.

[0029] Figure 6 The structural schematic diagram of a lead-lag controller in the prior art.

[0030] Figure 7A schematic diagram of a jet control loop for an embodiment of the application.

[0031] Figure 8 A schematic diagram of a jet control loop for another embodiment of the application.

[0032] Figure 9 An electromagnetic valve on-off signal for an embodiment of the application.

[0033] Reference numerals: 1 - inertial measurement unit; 2 - rate gyro; 3 - outer loop controller; 4 - inner loop controller; 5 - filter; 6 - delta-sigma modulator; 7 - forward jet electromagnetic valve; 8 - reverse jet electromagnetic valve; 9 - spacecraft; 11 - first path modulator; 12 - second path modulator; 13 - first path signal converter; 14 - second path signal converter; 61 - limiter; 62 - differentiator; 63 - integrator; 64 - comparator; 100 - outer loop; 200 - inner loop. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the application will be apparently and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are some embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all the other embodiments obtained by a person of ordinary skill in the art without any creative effort fall within the protection scope of the application.

[0035] Embodiment one

[0036] As shown in the figure, the application provides a spacecraft attitude jet control method based on a delta-sigma modulator, which comprises the following steps: Figure 1

[0037] Step S1, collect the attitude angle and the attitude angle rate of the spacecraft, and feed back to the outer loop and the inner loop respectively.

[0038] Specifically, the attitude angle θ of the spacecraft is collected by an inertial measurement unit. The attitude angle rate ω of the spacecraft is collected by a rate gyro. If there is no rate gyro, the attitude angle rate can also be obtained by using the angle increment data of the inertial measurement unit. The navigation of the spacecraft uses an inertial technology, and the specific sensitive device is called an inertial measurement unit, which is abbreviated as an inertial measurement unit.

[0039] Step S2, in the outer loop, according to the feedback attitude angle and the input attitude angle instruction of the outer loop, calculate the angle rate instruction, and input the angle rate instruction into the inner loop.

[0040] Specifically, the outer loop is an attitude loop, and the inner loop is an angle rate loop, which is used to realize angle rate stable control.

[0041] As shown in the figure, the application provides a spacecraft attitude jet control method based on a delta-sigma modulator, which comprises the following steps: Figure 2 ​As shown, step S2 includes the following sub-steps:

[0042] Step S210: In the external loop, receive attitude angle commands and attitude angles fed back by the inertial navigation system.

[0043] Step S220: Calculate the attitude angle and the attitude angle θ in the attitude angle command input from the external loop. r The difference is used to obtain the attitude angle deviation value Δθ.

[0044] Step S230: Calculate the product of the attitude angle deviation value and the outer loop gain kp, use it as the angular rate command, and input the angular rate command into the inner loop.

[0045] Step S3: In the inner loop, the angular rate deviation signal is obtained based on the angular rate command and the feedback attitude angular rate.

[0046] like Figure 3 As shown, step S3 includes the following sub-steps:

[0047] Step S310: In the inner loop, receive the angular rate command and attitude angular rate.

[0048] Step S320: Calculate the difference between the angular rate in the angular rate command and the attitude angular rate to obtain the angular rate deviation signal.

[0049] Step S4: In the inner loop, the angular rate deviation signal is converted into a nozzle relative thrust command by a proportional-integral controller, the nozzle relative thrust command is modulated into a nozzle switching command with an adjustable duty cycle by a Δ-Σ modulator, and the nozzle switching command is converted into a solenoid valve on / off signal of the nozzle.

[0050] like Figure 9 The diagram shows the on / off signal of a solenoid valve. A high level signal turns the solenoid valve on, and a low level signal turns it off. The on / off signal controls the opening or closing of the solenoid valve.

[0051] like Figure 4 As shown, step S4 includes the following sub-steps:

[0052] In step S410, the angular rate deviation signal is input to the proportional-integral controller, which converts the angular rate deviation signal into a nozzle relative thrust command.

[0053] Specifically, the inner loop includes an inner loop controller, with the angular rate deviation signal serving as the input to the inner loop controller, which is a proportional-integral controller.

[0054] Specifically, the transfer function expression of the proportional-integral controller is: Among them, K d K represents the gain of the proportional term; iKp represents integral term gain; s represents complex variable. The role of proportional regulation is to react to the deviation of the system in proportion, which is used to reduce the deviation, and the larger the proportional action is, the faster the regulation can be; the role of integral regulation is to make the system eliminate steady-state error, and the integral regulation is performed until there is no error, and the integral regulation stops. Among them, the function of the proportional term is to realize fast response, so that the inner loop has a certain bandwidth; the main function of the integral term is to eliminate static error.

[0055] The angular rate deviation signal is input into a proportional-integral controller for processing, and the control instruction output by the proportional-integral controller is a nozzle relative thrust instruction.

[0056] In step S420, the nozzle relative thrust instruction is input into a filter for filtering processing.

[0057] Specifically, the filter is connected to the output end of the proportional-integral controller, receives the nozzle relative thrust instruction output by the proportional-integral controller, and performs filtering processing on the nozzle relative thrust instruction. Preferably, the filter is a low-pass filter.

[0058] In step S430, the filtered nozzle relative thrust instruction is input into a delta-sigma modulator, and based on the delta-sigma modulator, the nozzle relative thrust instruction is modulated into a nozzle switch instruction with adjustable duty cycle, and the nozzle switch instruction is converted into an electromagnetic valve on-off signal of the nozzle.

[0059] As a specific embodiment of the present application, the delta-sigma modulator is connected to the output end of the filter, the delta-sigma modulator includes a first modulator and a second modulator, the first modulator and the second modulator are connected in parallel, the signal input ends of the first modulator and the second modulator are connected with the signal output end of the filter, the signal output end of the first modulator is connected with the electromagnetic valve of the forward nozzle through a first signal converter, the first modulator is used to control the forward nozzle switch, the signal output end of the second modulator is connected with the electromagnetic valve of the reverse nozzle through a second signal converter, the second modulator is used to control the reverse nozzle switch, the first modulator and the second modulator modulate and convert the nozzle relative thrust instruction output by the filter, output a nozzle switch instruction with adjustable duty cycle, and convert the nozzle switch instruction into an electromagnetic valve on-off signal of the nozzle through the first signal converter and the second signal converter respectively.

[0060] As shown in Figure 5 , step S430 includes the following sub-steps:

[0061] In step S431, the input signal of the delta-sigma modulator is input into a limiter, and the input signal is limited in the limiter. The limited input signal is input into a differentiator.

[0062] Specifically, the nozzle relative thrust command is input as an input signal into the delta-sigma modulator, and since the nozzle state only has two states of 0 and 1, 0 represents closing the nozzle, and 1 represents opening the nozzle. Therefore, the input signal of the delta-sigma modulator needs to be amplitude-limited, and the amplitude-limited range of the amplitude limiter is set to 0-1.

[0063] The application adopts the amplitude limiter to amplitude-limit the nozzle relative thrust command, limits the nozzle relative thrust command to the range that the delta-sigma modulator can respond to, improves the rate and accuracy of the nozzle switching command generated by the delta-sigma modulator, and further improves the control accuracy of the spacecraft attitude.

[0064] The second path modulator has the same structure as the first path modulator. The difference lies in that the input signal of the second path modulator needs to be inverted, and the input signal of the first path modulator does not need to be inverted.

[0065] In step S432, the input signal after amplitude limiting is subtracted from the nozzle switching command output by the delta-sigma modulator in the last period in the differentiator to obtain a difference signal, and the difference signal is input into the integrator.

[0066] In step S433, the difference signal is integrated in the integrator to calculate an integration result, and the integration result is input into the comparator.

[0067] Specifically, the output signal of the integrator is the integral of the input signal with respect to time. The transfer function expression of the integrator is: wherein T s represents the sampling period of the discrete system; and Z is a z-transform operator.

[0068] In step S434, the integration result is compared with the threshold in the comparator to obtain a comparison result, and the nozzle switching command is output according to the comparison result.

[0069] Specifically, the integration result is compared with the threshold in the comparator to obtain a comparison result of the comparator.

[0070] As a specific embodiment of the application, the threshold of the comparator is set to 0, when the integration result input into the comparator is less than 0, the comparison result output by the comparator is 0, that is, the nozzle switching command output is 0, indicating that the nozzle is closed; when the integration result input into the comparator is greater than 0, the comparison result output by the comparator is 1, that is, the nozzle switching command output is 1, indicating that the nozzle is opened.

[0071] As a specific embodiment of the present application, if the nozzle has a maximum (or minimum) opening nozzle (or closing nozzle) time constraint, state switching needs to be performed, when the opening nozzle time reaches the maximum continuous opening time, no matter the size of the input value, the closing nozzle action is performed; if the opening or closing nozzle time is less than the continuous opening or closing nozzle time, no matter the size of the input value, the opening nozzle or closing nozzle action is not performed. It can be understood that the opening nozzle or closing nozzle action is realized by the on or off action of the electromagnetic valve, and the on or off action of the electromagnetic valve meets the requirements of the maximum continuous working time, the minimum continuous working time, the minimum continuous closing time and the like.

[0072] Step S435, the continuously output nozzle switch instruction is converted into the electromagnetic valve on-off signal of the nozzle through the signal converter.

[0073] Specifically, the output end of the modulator is connected with the signal converter, when the nozzle switch instruction is 1, the output electromagnetic valve on-off signal is high, that is, the electromagnetic valve is opened; when the nozzle switch instruction is 0 or -1, the output electromagnetic valve on-off signal is low, that is, the electromagnetic valve is closed.

[0074] As a specific embodiment of the present application, the signal converter includes a first signal converter and a second signal converter.

[0075] As a specific embodiment of the present application, the first signal converter converts the nozzle switch instruction output by the first modulator into the first electromagnetic valve on-off signal, and the first electromagnetic valve on-off signal is used to control the on-off of the electromagnetic valve of the first nozzle (that is, the forward nozzle); the second signal converter converts the nozzle switch instruction output by the second modulator into the second electromagnetic valve on-off signal, and the second electromagnetic valve on-off signal is used to control the on-off of the electromagnetic valve of the second nozzle (that is, the reverse nozzle).

[0076] As another specific embodiment of the present application, the Δ-Σ modulator only includes one modulator, the first signal converter and the second signal converter both use the nozzle switch instruction output by the modulator, except that the second signal converter needs to perform the inverse operation when using the instruction, that is, when the nozzle switch instruction input into the second signal converter is 0 and 1, the second signal converter outputs the electromagnetic valve on-off signal as low, and when the nozzle switch instruction input into the second signal converter is -1, the second signal converter outputs the electromagnetic valve on-off signal as high.

[0077] Step S5, according to the electromagnetic valve on-off signal, the forward nozzle and the reverse nozzle are controlled to perform the jet action.

[0078] Specifically, the electromagnetic valve on-off signal is converted from the nozzle switch signal. According to the electromagnetic valve on-off signal, the electromagnetic valves of the forward nozzle and the reverse nozzle are controlled to be on or off, thereby controlling the forward nozzle and the reverse nozzle to perform the jet action.

[0079] As a specific embodiment of the present application, the electromagnetic valve on-off signal includes the electromagnetic valve on-off signal output by the first signal converter and the electromagnetic valve on-off signal output by the second signal converter.

[0080] As a specific embodiment of the present application, the electromagnetic valve of the forward nozzle performs the jet action according to the electromagnetic valve on-off signal output by the first signal converter. If the electromagnetic valve on-off signal (or the nozzle switch instruction is 1) is high, the forward nozzle opens the jet action to generate a positive control torque. If the electromagnetic valve on-off signal (or the nozzle switch instruction is 0) is low, the forward nozzle closes the jet action and does not generate a control torque.

[0081] As a specific embodiment of the present application, the electromagnetic valve of the reverse nozzle performs the jet action according to the electromagnetic valve on-off signal output by the second signal converter. If the electromagnetic valve on-off signal (or the nozzle switch instruction is 1) is high, the reverse nozzle opens the jet action to generate a positive control torque. If the electromagnetic valve on-off signal (or the nozzle switch instruction is 0) is low, the reverse nozzle closes the jet action and does not generate a control torque.

[0082] As a specific embodiment of the present application, the jet action of the forward nozzle and the reverse nozzle generates a control torque, thereby controlling the attitude angle and the angular rate of the spacecraft body. Since the duty cycle of the nozzle switch instruction generated by the present application can be continuously adjusted, a continuous small thrust can be simulated, thereby realizing accurate control of the attitude angle and the angular rate.

[0083] As another specific embodiment of the present application, the delta-sigma modulator only includes one modulator. The clipping range of the clipper is set to -1 to +1, and the output of the comparator only has -1 and +1 two states. When the integral result input into the comparator is less than 0, the comparison result output by the comparator is -1, the nozzle switch instruction output is -1, the electromagnetic valve on-off signal output by the first signal converter is low, and the electromagnetic valve on-off signal output by the second signal converter is high, that is, the reverse nozzle is opened and the forward nozzle is closed. When the integral result input into the comparator is greater than 0, the comparison result output by the comparator is 1, the nozzle switch instruction output is 1, the electromagnetic valve on-off signal output by the first signal converter is high, and the electromagnetic valve on-off signal output by the second signal converter is low, that is, the forward nozzle is opened and the reverse nozzle is closed. In the scheme with only one modulator, one electromagnetic valve is opened (that is, turned on) at each moment, so that one of the nozzles jets, which is suitable for the normally open type gas distribution device.

[0084] The application measures the spacecraft attitude angle and attitude angle rate through the inertial measurement unit and the rate gyro, feeds the measured attitude angle and attitude angle rate into the outer loop and the inner loop respectively, generates analog control instructions through the proportional integral controller, and modulates the analog control instructions into the pulse width continuous change jet pipe switch instruction through the delta-sigma modulator, so that the fixed thrust jet pipe is controlled by the electromagnetic valve to realize the continuous control of the attitude angle and the angle rate.

[0085] As a specific embodiment of the application, if there is external force interference, the attitude of the spacecraft is deviated under the action of the external moment, the non-0 attitude angle and the angle rate are controlled to generate relative thrust instructions, the analog control instructions are modulated into the pulse width continuous change jet pipe switch instruction through the delta-sigma modulator, and then the jet pipe generates the pulse width adjustable jet pulse. When the control moment generated by the minimum pulse width jet pulse cannot overcome the influence of the interference moment, the single-sided limit cycle is formed.

[0086] Embodiment two

[0087] As Figure 7 shown, the application provides a spacecraft attitude jet control system based on a delta-sigma modulator, which comprises:

[0088] The outer loop 100 is an attitude loop, and the inner loop 200 is an angle rate loop; the inner loop 200 is connected inside the outer loop 100. The attitude angle deviation of the spacecraft 9 is eliminated and the stability of the system is controlled through the outer loop 100. The attitude angle speed deviation of the spacecraft 9 is eliminated through the inner loop.

[0089] The outer loop 100 comprises an inertial measurement unit 1 and an outer loop controller 3.

[0090] The inertial measurement unit 1 is used to collect the attitude angle θ of the spacecraft 9 and feed back to the input end of the differentiator of the outer loop 100.

[0091] In the outer loop 100, according to the attitude angle fed back by the inertial measurement unit 1 and the attitude angle instruction input into the outer loop 100, the angle rate instruction is calculated and input into the inner loop 200. The outer loop gain of the outer loop controller 3 is kp, and the outer loop controller 3 is used to calculate the product of the attitude angle deviation value and the outer loop gain kp as the angle rate instruction.

[0092] Specifically, the differentiator of the outer loop 100 is used to calculate the deviation of the attitude angle fed back by the inertial measurement unit 1 and the attitude angle instruction input into the outer loop 100, so as to obtain the attitude angle deviation value.

[0093] The output end of the outer loop controller 3 is connected with the input end of the inner loop 200, and the outer loop controller 3 inputs the angle rate instruction into the inner loop 200.

[0094] The inner loop 200 comprises a rate gyro 2 (or an inertial measurement unit), an inner loop controller 4, a filter 5, a delta-sigma modulator 6 and a signal converter.

[0095] The output of the rate gyro 2 (or the inertial measurement unit) is connected to the input of the inner loop 200 for collecting the attitude angular rate of the spacecraft 9. The attitude angular rate is fed back to the inner loop 200. Specifically, the attitude angular rate collected by the rate gyro 2 is input into the differentiator of the inner loop 200, and the angular rate command is input into the differentiator of the inner loop 200.

[0096] In the inner loop 200, the differentiator of the inner loop 200 obtains an angular rate deviation signal according to the angular rate command and the feedback attitude angular rate.

[0097] The inner loop controller 4, the filter 5 and the delta-sigma modulator 6 are connected in sequence.

[0098] The inner loop controller 4 is configured to receive the angular rate deviation signal and convert the angular rate deviation signal into a thruster relative thrust command.

[0099] The inner loop controller 4 is a proportional-integral controller.

[0100] The filter 5 is configured to receive the thruster relative thrust command output by the inner loop controller 4 and perform filtering processing on the thruster relative thrust command.

[0101] The delta-sigma modulator 6 is configured to modulate the thruster relative thrust command after the filtering processing to obtain a thruster switching command with adjustable duty cycle.

[0102] The signal converter is configured to convert the thruster switching command into an electromagnetic valve on-off signal. The electromagnetic valve on-off signal is configured to control the jet action of the thruster. When the thruster switching command is 1, the electromagnetic valve on-off signal is output as a high level, and the high level signal is configured to control the electromagnetic valve of the thruster to open, thereby controlling the jet of the thruster. When the thruster switching command is 0 or -1, the electromagnetic valve on-off signal is output as a low level, and the low level signal is configured to control the electromagnetic valve of the thruster to close, thereby controlling the jet of the thruster to stop.

[0103] As shown in FIG. 1, the inner loop 200 is connected to the outer loop 100. Figure 7The diagram shows a control circuit suitable for normally closed nozzles. The Δ-Σ modulator 6 includes a first modulator 11 and a second modulator 12, connected in parallel. The inputs of both modulators 11 and 12 are connected to the output of filter 5. The output of the first modulator 11 is connected to the input of a first signal converter 13, and the output of the first signal converter 13 is connected to the forward nozzle solenoid valve 7. The first modulator 11 controls the on / off state of the forward nozzle solenoid valve 7, thereby controlling the jet propulsion from the forward nozzle. The output of the second modulator 12 is connected to the input of the second signal converter 14. The input terminal is connected, and the output terminal of the second signal converter 14 is connected to the reverse nozzle solenoid valve 8. The second modulator 12 is used to control the on / off state of the reverse nozzle solenoid valve 8, thereby controlling the reverse nozzle's airflow. The first modulator 11 and the second modulator 12 modulate and convert the nozzle relative thrust command output from the filter 5, outputting a nozzle switching command with an adjustable duty cycle. The first signal converter 13 and the second signal converter 14 convert the nozzle switching command into a solenoid valve on / off signal for the nozzle. The solenoid valve on / off signal is used to control the on / off state of the nozzle's solenoid valve. If the solenoid valve is on, the nozzle will spray air. If the solenoid valve is off, the nozzle will stop spraying air.

[0104] like Figure 8 The diagram shows a control loop suitable for normally open nozzles. The Δ-Σ modulator 6 consists of only one modulator, making it a single-channel modulator. The input of the single-channel modulator is connected to the output of the filter 5, and its output is connected to the input of the first signal converter 13. After inversion, the output is connected to the input of the second signal converter 14. The output of the first signal converter 13 is connected to the forward nozzle solenoid valve 7, and the output of the second signal converter 14 is connected to the reverse nozzle solenoid valve 8. The single-channel modulator modulates and converts the nozzle relative thrust command output from the filter 5, outputting a nozzle switching command with an adjustable duty cycle. This nozzle switching command is converted into a nozzle solenoid valve on / off signal. Based on the solenoid valve on / off signal, the forward nozzle solenoid valve 7 and the reverse nozzle solenoid valve 8 are controlled to open and close, thereby controlling the jet propulsion of the forward and reverse nozzles.

[0105] As a specific embodiment of the present invention, the first modulator 11 and the second modulator 12 have the same structure. The structure of the first modulator 11 includes: a limiter 61, a differential 62, an integrator 63 and a comparator 64.

[0106] Limiter 61 is used to limit the input signal of the first modulator 11.

[0107] Differential converter 62 is used to subtract the input signal after the amplitude limiting process from the nozzle switching command output by the Δ-Σ modulator 6 in the previous cycle to obtain the difference signal.

[0108] An integrator 63 is configured to integrate the difference signal to obtain an integral result.

[0109] A comparator 64 is configured to compare the integral result with a threshold to obtain a comparison result, and output a nozzle switch instruction according to the comparison result.

[0110] The application has the following beneficial effects:

[0111] (1) The application adopts a double-loop attitude control system, feeds the measured attitude angle and attitude angular velocity back to the outer loop and the inner loop respectively, generates a relative thrust control instruction through a proportional-integral controller, modulates the relative thrust control instruction into a nozzle switch instruction with adjustable duty ratio through a delta-sigma modulator, converts the nozzle switch instruction into an electromagnetic valve on-off signal to control the electromagnetic valve of the nozzle to be on or off, and further controls the nozzle to jet gas. On the premise of avoiding the increase of the number of times of jetting gas, the attitude angle and angular velocity of the spacecraft are continuously controlled, and the control precision of the spacecraft attitude is improved.

[0112] (2) The application modulates the nozzle relative thrust instruction into a nozzle switch instruction with adjustable duty ratio through a delta-sigma modulator, so that the fixed-thrust nozzle achieves the control effect of continuously adjusting the control moment, the attitude angle deviation converges to the vicinity of the 0 axis, the low attitude angular velocity deviation and attitude angle deviation are achieved, the number of times of jetting gas is greatly reduced, and the application realizes low working medium consumption in the case of improving the attitude control precision of the spacecraft.

[0113] The above only describes the embodiments of the application and is not used to limit the application. The application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application should be included in the scope of the claims of the application.

Claims

1. A spacecraft attitude jet control method based on a delta-sigma modulator, characterized by, The method comprises the following steps: Collecting the attitude angle and the attitude angular rate of the spacecraft, and feeding back to the outer loop and the inner loop respectively; In the outer loop, according to the feedback attitude angle and the input attitude angle command of the outer loop, the angular rate command is calculated and input into the inner loop; In the inner loop, the angular rate deviation signal is obtained according to the angular rate command and the feedback attitude angular rate; In the inner loop, the angular rate deviation signal is converted into the relative thrust command of the nozzle by the proportional integral controller, the relative thrust command of the nozzle is modulated into the on-off command of the nozzle with adjustable duty cycle by the delta-sigma modulator, and the on-off command of the nozzle is converted into the on-off signal of the electromagnetic valve of the nozzle; wherein the transfer function expression of the proportional-integral controller is wherein K d represents the gain of the proportional term; K i represents the gain of the integral term; and s represents a complex variable. According to the on-off signal of the electromagnetic valve, the forward nozzle and the reverse nozzle are controlled to execute the jet action; The method for modulating the relative thrust command of the nozzle into the on-off command of the nozzle with adjustable duty cycle based on the delta-sigma modulator comprises the following steps: The relative thrust command of the nozzle is limited as an input signal; The difference signal is obtained by subtracting the limited input signal from the on-off command of the nozzle output by the delta-sigma modulator in the last period; The integral result is calculated by integrating the difference signal; The comparison result is obtained by comparing the integral result with the threshold, and the on-off command of the nozzle is output according to the comparison result.

2. The Δ-Σ modulator-based spacecraft attitude jet control method according to claim 1, wherein, In the outer loop, the angular rate command is calculated according to the feedback attitude angle and the input attitude angle command of the outer loop, which comprises the following steps: In the outer loop, the attitude angle command and the feedback attitude angle are received; The difference between the attitude angle and the attitude angle in the input attitude angle command of the outer loop is calculated to obtain the attitude angle deviation value; The product of the attitude angle deviation value and the gain of the outer loop is calculated as the angular rate command.

3. The Δ-Σ modulator-based spacecraft attitude jet control method according to claim 1, wherein, In the inner loop, the angular rate deviation signal is obtained according to the angular rate command and the feedback attitude angular rate, which comprises the following steps: In the inner loop, the angular rate command and the attitude angular rate are received; The difference between the angular rate in the angular rate command and the attitude angular rate is calculated to obtain the angular rate deviation signal.

4. The delta-sigma modulator based spacecraft attitude jet control method of claim 1, wherein, The amplitude limiting range of the amplitude limiter is set to 0-1, the threshold of the comparator is 0, when the integral result is less than 0, the comparison result is 0, and the on-off command of the nozzle is 0, indicating that the nozzle is closed; when the integral result is greater than 0, the comparison result is 1, and the on-off command of the nozzle is 1, indicating that the nozzle is opened.

5. The delta-sigma modulator based spacecraft attitude jet control method of claim 1, wherein, The amplitude limiting range of the amplitude limiter is set to-1-+1, when the integral result is less than 0, the output comparison result is-1, and the on-off command of the nozzle is-1, indicating that the reverse nozzle is opened and the forward nozzle is closed; when the integral result is greater than 0, the output comparison result is 1, and the on-off command of the nozzle is 1, indicating that the forward nozzle is opened and the reverse nozzle is closed.

6. A spacecraft attitude jet control system based on a delta-sigma modulator, performing the method of one of claims 1 to 5, characterized in that The system comprises: An outer loop and an inner loop, the inner loop being connected inside the outer loop; The outer loop is used to calculate the angular rate command according to the feedback attitude angle and the input attitude angle command of the outer loop, and input the angular rate command into the inner loop; The inner loop is used to obtain an angular rate deviation signal according to an angular rate command and a feedback attitude angular rate, and convert the angular rate deviation signal into a nozzle relative thrust command through a proportional integral controller, modulate the nozzle relative thrust command into a nozzle on-off command with adjustable duty cycle through a delta-sigma modulator, and convert the nozzle on-off command into an electromagnetic valve on-off signal of the nozzle. An output end of the inner loop is connected with electromagnetic valves of the forward nozzle and the reverse nozzle, and is used to control the electromagnetic valve on-off of the forward nozzle and the reverse nozzle according to the electromagnetic valve on-off signal of the nozzle, so as to control the forward nozzle and the reverse nozzle to jet air.

7. The Δ-Σ modulator-based spacecraft attitude jet control system of claim 6, wherein, The outer loop comprises an inertial measurement unit and an outer loop controller. The inertial measurement unit is used to collect an attitude angle of the spacecraft and feed back to the outer loop. The outer loop controller is used to calculate a product of an attitude angle deviation value and an outer loop gain as an angular rate command. An output end of the outer loop controller is connected with an input end of the inner loop, and the outer loop controller inputs the angular rate command into the inner loop.

8. The delta-sigma modulator-based spacecraft attitude jet control system of claim 6, wherein, The inner loop comprises a rate gyro or an inertial measurement unit, an inner loop controller, a filter, a delta-sigma modulator and a signal converter. The rate gyro or the inertial measurement unit is used to collect an attitude angular rate of the spacecraft and feed back to the inner loop. In the inner loop, an angular rate deviation signal is obtained according to an angular rate command and a feedback attitude angular rate. The inner loop controller is used to convert the angular rate deviation signal into a nozzle relative thrust command. The filter is used to filter the nozzle relative thrust command. The delta-sigma modulator is used to modulate the filtered nozzle relative thrust command into a nozzle on-off command with adjustable duty cycle. The signal converter is used to convert the nozzle on-off command into an electromagnetic valve on-off signal of the nozzle.

9. The Δ-Σ modulator-based spacecraft attitude jet control system of claim 8, wherein, The delta-sigma modulator comprises a first modulator and a second modulator, and the signal converter comprises a first signal converter and a second signal converter. Signal input ends of the first modulator and the second modulator are connected with a signal output end of the filter. A signal output end of the first modulator is connected with an electromagnetic valve of the forward nozzle through the first signal converter, the first modulator modulates and converts the nozzle relative thrust command output by the filter, outputs a nozzle on-off command with adjustable duty cycle, and the first signal converter converts the nozzle on-off command into an electromagnetic valve on-off signal, and is used to control the forward nozzle to jet air. A signal output end of the second modulator is connected with an electromagnetic valve of the reverse nozzle through the second signal converter, the second modulator modulates and converts the nozzle relative thrust command output by the filter, outputs a nozzle on-off command with adjustable duty cycle, and the second signal converter converts the nozzle on-off command into an electromagnetic valve on-off signal, and is used to control the reverse nozzle to jet air.

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