A method for long-term autonomous low-fuel consumption companion flight of spacecraft
An autonomous open-loop control method for spacecraft companion flights addresses high fuel consumption issues by setting boundary values and control parameters, ensuring low-fuel operations and extended service life.
Patent Information
- Application Number
- CN202211678412.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-26
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2042-12-26
AI Technical Summary
Existing methods for spacecraft companion flights are either non-autonomous or not suitable for long-term flights due to high fuel consumption, limiting the service life of spacecraft.
An on-board autonomous open-loop control method that sets companion flight boundary values and control parameters to enable low-fuel companion flights, using initial adjustment modes and controls along the x, y, and z axes to maintain a spacecraft within a defined area.
Enables long-term low-fuel companion flights, improving spacecraft service life and autonomy with reduced fuel consumption and adaptability across various flight conditions.
Smart Images
Figure CN115783310B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of space on-orbit service technology, and in particular to a method for realizing long-term autonomous low-fuel consumption accompanying flight of a spacecraft to a target. Background Art
[0002] With the rapid expansion of aerospace technology application fields, space on-orbit services have received more and more attention, and long-term autonomous escort missions for targets have gradually become a necessary function of service vehicles, i.e., space vehicles. During long-term escort flights, the fuel consumed by the service vehicle determines the cost of the service vehicle's on-orbit services.
[0003] At present, there are roughly two ways of accompanying a spacecraft: the first is the ground guidance method, in which the ground supports the measurement and control of the relative motion state of the spacecraft relative to the target star, and then calculates the long-term free drift situation, and transmits the strategy to the satellite for orbit adjustment; the second is the on-satellite closed-loop accompanying flight control, which uses the LQG control algorithm to convert the relative motion state of the on-satellite relative navigation input into a control output after algorithm processing. However, the former method cannot achieve on-satellite autonomy, and the latter method is not suitable for long-term accompanying flight due to continuous jetting and huge consumption. Therefore, it is necessary to improve the existing accompanying flight methods.
[0004] It should be understood that the above statements merely provide background technology related to the present invention and do not necessarily constitute prior art. Summary of the invention
[0005] The purpose of the present invention is to provide a method for long-term autonomous low-fuel companion flight of a spacecraft. The method adopts an on-board autonomous open-loop control method and can set companion flight boundary values and related control parameters to enable the spacecraft to perform long-term low-fuel companion flight with a target vehicle, i.e., a target satellite, within a given companion flight area, thereby greatly improving the service life of the spacecraft.
[0006] In order to achieve the above object, the present invention is implemented by the following technical solutions:
[0007] A method for long-term autonomous low-fuel consumption companion flight of a space vehicle, comprising:
[0008] S1. Setting the companion flight parameters, setting the initial far-away mode, initial close-in mode and free-drifting control mode of the spacecraft. When the spacecraft initially enters the companion flight state, if it is not close to the companion flight boundary, it enters the free-drifting control mode. If it is close to the companion flight boundary, it enters the initial far-away mode or the initial close-in mode. Then, when the conditions for entering the free-drifting control mode are met, it switches to the free-drifting control mode.
[0009] S2, accompanying flight tangential control, which includes adjusting the relative speed of the orbital system on the x-axis;
[0010] S3. Flying - along radial control, which includes adjusting the relative velocity of the orbital system along the z - axis;
[0011] S4. Flying - along normal control, which includes adjusting the relative velocity of the orbital system along the y - axis.
[0012] Optionally, the flying - along parameters include: boundary values related to the flying - along area, an orbit drift threshold, and an out - of - plane control threshold.
[0013] Optionally, in S2, the flying - along tangential control includes a return - drift control when touching the flying - along boundary value and an adjustment control when not touching the flying - along boundary value. The return - drift control is to trigger a condition and apply control to make the space vehicle return to the flying - along area after the service vehicle touches the flying - along boundary. The adjustment control is to perform a semi - major axis increase control after free - flying for one orbit to reduce the one - orbit drift distance.
[0014] Optionally, if |x| < X_near, the space vehicle enters the initial drifting - away mode, and the space vehicle jets away from the target star with a velocity increment of k p Δv p -v x ;
[0015] If X_near ≤ |x| ≤ X_far, the space vehicle enters the initial maintaining state, and the space vehicle maintains its orbit with a velocity increment of -v x ;
[0016] If |x| > X_far, the space vehicle enters the initial drifting - closer mode, and the space vehicle jets closer to the target star with a velocity increment of -k p Δv p -v x ;
[0017] Where x is the real - time coordinate of the space vehicle relative to the target star on the x - axis, X_near and X_far are the near - boundary and far - boundary of the defined flying - along area respectively, Δv p is a set fixed value, v x represents the relative velocity of the current relative navigation output on the x - axis, and k p is a calibration coefficient.
[0018] Optionally, in S2, record the initial system time when the space vehicle enters the floating - flying state with control stopped and the current relative position of the two satellites along the x - axis: [t0, x0]. After one orbital period, record the relative position of the two satellites along the x - axis as x1, and calculate the drift amount of one orbit: delt_x = x1 - x0;
[0019] If |2·x1 - x0| ≥ X_far, the space vehicle jets closer to the target star, and the velocity increment Δv is
[0020]
[0021] If |2·x1-x0|<X_near, the spacecraft will jet away from the target star, and the velocity increment Δv is
[0022]
[0023] Among them, a M is the semi-major axis of the spacecraft, μ is the gravitational constant, k p is the calibration coefficient, Δv p is a fixed value.
[0024] Optional, Δv p =0.05m / s;
[0025] and / or, when the spacecraft is initially behind the target star, k p =1; when the spacecraft is initially in front of the target star, k p =-1.
[0026] Optionally, in S3, the relative speed of the z-axis of the orbital system is adjusted, thereby adjusting the configuration size of the companion ellipse, and calculating the minor semi-axis BF_Tyb of the companion ellipse in real time:
[0027]
[0028] Among them, R MT (3) and V MT (3) are the z-axis relative position and relative velocity output by relative navigation, respectively, and ω is the angular velocity of the spacecraft;
[0029] When BF_Tyb>z max When the jet is executed along the x-axis, the spacecraft performs jet control to approach the target star, and the speed increment is Δv z =-v z , where z max The maximum drift distance in the z direction is set.
[0030] Optional, z max =50m.
[0031] Optionally, in S4, the drift outside the orbital plane is reduced by adjusting the relative speed of the orbital system on the y-axis;
[0032] If | R MT (2)|>y max , remember y max =|R MT (2)|, to update y max ,
[0033] When | R MT (2)|≤y-direction preset threshold, the spacecraft performs jet control to move away from the target star, and the velocity increment Δv y for
[0034]
[0035] Among them, R MT (2) is the relative position of the y-axis output of the relative navigation, y max is the maximum drift distance in the y direction, a M is the semi-major axis of the spacecraft, and μ is the gravitational constant.
[0036] Optional, y max =50m;
[0037] and / or, |R MT (2)|≤2m.
[0038] Compared with the prior art, the present invention has the following advantages:
[0039] In a method for long-term autonomous low-fuel escort flight of a spacecraft of the present invention, the method adopts an on-board autonomous open-loop control method and can set escort flight boundary values and related control parameters to enable the spacecraft to perform long-term low-fuel escort flight with a target vehicle, i.e., a target satellite, within a given escort flight area, thereby greatly improving the service life of the spacecraft.
[0040] Furthermore, the method is clearly defined and has universal adaptability: by setting the escort boundary value and a few control parameters, the method can achieve escort in any area of the target star, and has a certain degree of universal adaptability.
[0041] Furthermore, the method is simple to operate and can be implemented autonomously on board: the method is simple to calculate, has a clear process, and can be implemented autonomously on board, thereby improving the level of satellite autonomy.
[0042] Furthermore, this method adopts open-loop control and has low fuel consumption: Different from the traditional LQG closed-loop escort control, the low-fuel escort method proposed in the present invention only applies control after the escort boundary conditions are triggered. The number of controls is small, the fuel consumption is low, and the service life of the aircraft can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0043] Figure 1 A schematic diagram of a method for long-term autonomous low-fuel consumption companion flight of a space vehicle according to the present invention;
[0044] Figure 2 The present invention is a schematic diagram of a low-fuel consumption companion flight of a space vehicle. DETAILED DESCRIPTION
[0045] The present invention will be further described below by describing a preferred specific embodiment in detail in conjunction with the accompanying drawings.
[0046] As can be seen from the foregoing, for some aircraft designed for on-orbit service missions, it is often necessary to conduct long-term escort flights near the target aircraft in order to wait for a time window suitable for completing the service mission. During the long-term escort flight, reducing the fuel consumed by the aircraft can significantly increase the life of the aircraft. Based on the above and the foregoing problems, in order to enable the on-orbit service aircraft, i.e., the spacecraft, to achieve long-term low-fuel escort flights with the target satellite and increase its service life, the present invention proposes a long-term autonomous low-fuel escort flight method for spacecraft. The method uses an autonomous open-loop control method on the satellite, and can set the escort boundary value and related control parameters to enable the service aircraft to perform long-term low-fuel escort flights with the target aircraft, i.e., the target satellite, within a given escort flight area.
[0047] like Figure 1 As shown, a method for long-term autonomous low-fuel consumption companion flight of a spacecraft according to the present invention comprises:
[0048] S1. Setting the accompanying flight parameters. In this embodiment, the accompanying flight parameters include: the accompanying flight area related boundary value, the one-track drift threshold, the out-of-plane control threshold and other parameters, which can be set according to the needs.
[0049] In order to adapt to the different flight conditions of the spacecraft when initially entering the low-fuel escort flight, the present invention sets three initial adjustment modes for the spacecraft, namely, the initial far-away mode, the initial close-in mode and the free-flying control mode. Under normal circumstances, the set escort flight area will be near the spacecraft or the spacecraft is in it. When the spacecraft initially enters the escort flight state, if it is not close to the escort flight boundary of the set escort flight area, it enters the free-flying control mode; if it is close to the escort flight boundary, it enters the initial far-away mode or the initial close-in mode to adjust the spacecraft, so that it meets the conditions for entering the free-flying control mode, and then switches to the free-flying control mode. That is, if the spacecraft is not in the escort flight area or is near the boundary of the escort flight area, the spacecraft is adjusted to be located inside the escort flight area so as to enter the free-flying control mode and realize natural flying in a low-fuel state.
[0050] like Figure 2 The figure shows a schematic diagram of a low-fuel companion flight of a spacecraft according to the present invention. In this embodiment, the target star is taken as the origin of the orbital coordinate system, and the spacecraft, i.e., the service aircraft, performs companion flight on the target star. After the initial companion flight adjustment is completed, in-plane drift control and out-of-plane drift control can be further performed. The in-plane drift control is mainly for xoz plane control, and the out-of-plane drift control is mainly for y direction control.
[0051] In the initial drifting-away / drifting-towards / freely-floating control of the present invention, three different initial adjustment situations are designed to ensure that when the space vehicle initially enters the low-fuel-consumption accompanying flight, it can form an accompanying flight with a small drift rate within the specified accompanying flight area.
[0052] Optionally, if |x| < X_near, the space vehicle enters the initial drifting-away mode, and the space vehicle jets away from the target star with a velocity increment of k p Δv p -v x ;
[0053] If X_near ≤ |x| ≤ X_far, the space vehicle enters the initial maintaining state, i.e., the freely-floating state, and the space vehicle maintains its orbit with a velocity increment of -v x ;
[0054] If |x| > X_far, the space vehicle enters the initial drifting-towards mode, and the space vehicle jets towards the target star with a velocity increment of -k p Δv p -v x ;
[0055] where x is the real-time coordinate of the space vehicle relative to the target star on the x-axis, X_near and X_far are respectively the near boundary and the far boundary of the defined accompanying flight area, Δv p is a set fixed value, v x represents the relative velocity of the current relative navigation output on the x-axis, and k p is a calibration coefficient.
[0056] In this embodiment, Δv p = 0.05 m / s. Further, when the space vehicle is initially behind the target star, k p = 1; when the space vehicle is initially in front of the target star, k p = -1. It can be understood that, however, Δv p and k p are not limited to the above. In other embodiments, they can also be set to other values or other ways, and the present invention does not limit this.
[0057] Further, the method further includes: S2. Accompanying flight tangential control.
[0058] In this embodiment, the tangential flight control mainly adjusts the relative speed of the x-axis of the orbital coordinate system, and reduces the drift of each track by adjusting the relative semi-major axis. This step has two layers of parallel control, which are the return drift control when the accompanying flight boundary value is touched and the adjustment control when the accompanying flight boundary value is not touched. The former triggers the conditions (such as the tangential accompanying flight boundary value) and applies control to make the service aircraft return to the accompanying flight area after the service aircraft touches the accompanying flight boundary. The latter is to perform the semi-major axis adjustment control after free flying for one track, which can effectively reduce the drift distance of one track.
[0059] Specifically, in S2 of this embodiment, the system time at the initial moment when the spacecraft enters the controlled flight and the current relative position of the two satellites (spacecraft and target satellite) along the x-axis are recorded as [t0, x0], and the relative position of the two satellites along the x-axis after one orbital cycle is recorded as x1, and the drift of one orbit is calculated: delt_x = x1-x0. And judge:
[0060] If |2·x1-x0|≥X_far, the spacecraft jets towards the target star, and the velocity increment Δv is
[0061]
[0062] If |2·x1-x0|<X_near, the spacecraft will jet away from the target star, and the velocity increment Δv is
[0063]
[0064] Among them, a M is the semi-major axis of the spacecraft, μ is the gravitational constant, k p is the calibration coefficient, Δv p is a fixed value.
[0065] S3, escort radial control.
[0066] In this embodiment, the companion flight radial control mainly adjusts the relative speed of the orbital system z-axis, thereby adjusting the size of the companion flight ellipse. Since both the x-axis and the z-axis belong to the control within the orbital plane and are coupled together, when the z-axis relative distance exceeds the threshold to trigger the control, the x-axis and the z-axis need to be adjusted at the same time.
[0067] Specifically, in S3 of this embodiment, the companion flight radial control is to adjust the relative speed of the z-axis of the orbital system, thereby adjusting the configuration size of the companion flight ellipse, and calculating the short semi-axis BF_Tyb of the companion flight ellipse in real time:
[0068]
[0069] Among them, R MT (3) and V MT(3) are the z-axis relative position and relative velocity output by relative navigation, respectively, and ω is the angular velocity of the spacecraft;
[0070] When BF_Tyb>z max When the jet is executed along the x-axis, the spacecraft performs jet control to approach the target star, and the speed increment is Δv z =-v z , where z max is the maximum drift distance in the z direction. max =50m, it can be understood that in other embodiments, z max For other values.
[0071] S4. Companion flight normal control.
[0072] In this embodiment, the normal control of the accompanying flight mainly adjusts the relative speed of the y-axis of the orbital system. Since the y-axis is decoupled from the xoz plane, the y-direction control can be independent of the control in the orbital plane. The maximum distance y of the y-direction drift is obtained by real-time calculation. max , control is applied when the relative position in the y direction passes through the 0 point, i.e. the origin, to reduce the amplitude out of the plane.
[0073] Specifically, in S4 of this embodiment, the companion flight normal control is to reduce the drift outside the orbital plane by adjusting the relative speed of the orbital system on the y-axis.
[0074] If | R MT (2)|>y max , remember y max =|R MT (2)|, to update y max .
[0075] When | R MT )2)|≤y-direction preset threshold, the spacecraft performs jet control to move away from the target star, and the speed increment Δv y for
[0076]
[0077] Among them, R MT (2) is the relative position of the y-axis output of the relative navigation, y max is the maximum drift distance in the y direction, a M is the semi-major axis of the spacecraft, and μ is the gravitational constant. In this embodiment, V MT (2) is the relative velocity on the y-axis output by the relative navigation, and the jet direction of the spacecraft is -V MT (2), that is, -V MT (2) > 0, it is the orbital +y direction, otherwise it is the orbital -y direction.
[0078] In this embodiment, the initial value sets the maximum drift distance y in the y direction. max =50m; further, |R MT (2)|≤2m, that is, the preset threshold in the y direction is 2. Of course, the preset threshold in the y direction may also be other values. Since it is expected to apply control when the relative position in the y direction passes through 0 to reduce the amplitude outside the plane, this value does not need to be too large.
[0079] In summary, in a method for long-term autonomous low-fuel escort flight of a spacecraft of the present invention, the method adopts an on-board autonomous open-loop control method and can set the escort flight boundary value and related control parameters to enable the spacecraft to perform long-term low-fuel escort flight with a target star within a given escort flight area, thereby greatly improving the service life of the spacecraft.
[0080] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.
Claims
1. A method for long-term autonomous low-fuel consumption escort flight of a spacecraft, characterized in that: The method for long-term autonomous low-fuel-consumption companion flight of a spacecraft adopts an on-board autonomous open-loop control method, and the method for long-term autonomous low-fuel-consumption companion flight of a spacecraft comprises: S1. Setting the companion flight parameters, setting the initial far-away mode, initial close-in mode and free-drifting control mode of the spacecraft. When the spacecraft initially enters the companion flight state, if it is not close to the companion flight boundary, it enters the free-drifting control mode. If it is close to the companion flight boundary, it enters the initial far-away mode or the initial close-in mode. Then, when the conditions for entering the free-drifting control mode are met, it switches to the free-drifting control mode. S2, accompanying flight tangential control, which includes adjusting the relative speed of the orbital system on the x-axis; S3, accompanying flight radial control, which includes adjusting the relative speed of the orbital system on the z axis; S4, companion flight normal control, which includes adjusting the relative speed of the orbital system on the y-axis; In S2, the system time at the initial moment when the spacecraft enters the controlled flight and the current relative position of the two satellites along the x-axis are recorded: [t0, x0], and the relative position of the two satellites along the x-axis after one orbital cycle is recorded as x1, and the drift of one orbit is calculated: delt_x = x1-x0; If |2·x1-x0|≥X_far, the spacecraft jets towards the target star, and the velocity increment Δv is If |2·x1-x0|<X_near, the spacecraft will jet away from the target star, and the velocity increment Δv is Among them, a M is the semi-major axis of the spacecraft, μ is the gravitational constant, k p is the calibration coefficient, Δv p is a fixed value set; In S4, the drift outside the orbital plane is reduced by adjusting the relative velocity of the orbital system on the y-axis; If | R MT (2)|>y max , remember y max =|R MT (2)|, to update y max , When | R MT (2)|≤y-direction preset threshold, the spacecraft performs jet control to move away from the target star, and the velocity increment Δv y for Among them, R MT (2) is the relative position of the y-axis output of the relative navigation, y max is the maximum drift distance in the y direction, a M is the semi-major axis of the spacecraft, and μ is the gravitational constant.
2. The method for long-term autonomous low-fuel-consumption escort flight of a spacecraft as claimed in claim 1, characterized in that: The accompanying flight parameters include: accompanying flight area related boundary values, one track drift threshold, and out-of-plane control threshold.
3. The method for long-term autonomous low-fuel-consumption escort flight of a spacecraft as claimed in claim 1, characterized in that: In S2, the accompanying flight tangential control includes the back-drifting control when the accompanying flight boundary value is touched and the adjustment control when the accompanying flight boundary value is not touched. The back-drifting control is to trigger the conditions and apply control to make the spacecraft float back to the accompanying flight area after the spacecraft touches the accompanying flight boundary. The adjustment control is to perform semi-major axis increase control after free flying for one orbit to reduce the drift distance of one orbit.
4. The method for long-term autonomous low-fuel escort flight of a spacecraft as claimed in claim 1, characterized in that: If |x|<X_near, the spacecraft enters the initial drifting mode, the spacecraft jets away from the target star, and the speed increment is k p Δv p -v x ; If X_near≤|x|≤X_far, the spacecraft enters the initial maintenance state, the spacecraft maintains the orbit, and the speed increment is -v x ; If |x|>X_far, the spacecraft enters the initial approach mode, and the spacecraft jets towards the target star, with a velocity increment of -k p Δv p -v x ; Among them, x is the real-time coordinate of the spacecraft relative to the target star on the x-axis, X_near and X_far are the near boundary and far boundary of the defined accompanying flight area respectively, Δv p is a fixed value, v x Indicates the relative speed of the current relative navigation output x-axis, k p is the calibration factor.
5. The method for long-term autonomous low-fuel escort flight of a spacecraft as claimed in claim 1, characterized in that: Δv p =0.05m / s; and / or, when the spacecraft is initially behind the target star, k p =1; when the spacecraft is initially in front of the target star, k p =-1.
6. The method for long-term autonomous low-fuel escort flight of a spacecraft as claimed in claim 1, characterized in that: In S3, the relative speed of the z-axis of the orbital system is adjusted, thereby adjusting the configuration size of the companion ellipse, and calculating the minor semi-axis BF_Tyb of the companion ellipse in real time: Among them, R MT (3) and V MT (3) are the z-axis relative position and relative velocity output by relative navigation, respectively, and ω is the angular velocity of the spacecraft; When BF_Tyb>z max When the jet is executed along the x-axis, the spacecraft performs jet control to approach the target star, and the speed increment is Δv z =-v z , where z max The maximum drift distance in the z direction is set.
7. The method for long-term autonomous low-fuel-consumption escort flight of a spacecraft as claimed in claim 6, characterized in that: z max =50m。 8. The method for long-term autonomous low-fuel escort flight of a spacecraft as claimed in claim 1, characterized in that: y max =50m; and / or, |R MT (2)|≤2m.