Design method for end trajectory planning of autonomous rendezvous and docking under target moment balance attitude

Abstract

The application discloses a kind of target torque balance posture under autonomous rendezvous and docking end trajectory planning method, for realizing the docking of the active end of the docking mechanism of tracking spacecraft with the passive end of the docking mechanism of target spacecraft.It includes steps: S1, the passive end coordinate system of docking mechanism is selected as docking system, and the nominal position and nominal speed of docking end in docking system are designed;S2, the nominal position and nominal speed in docking system are converted into the position and speed of target spacecraft orbit system, for orbit control.The application realizes the rendezvous and docking of target non-earth orientation posture, and reduces the constraint on target posture.

Description

Technical Field

[0001] This invention relates to the field of trajectory planning, and specifically to a method for planning and designing the end-point trajectory of autonomous rendezvous and docking under target torque balance attitude. Background Technology

[0002] Currently, most autonomous rendezvous and docking terminal trajectory planning for aircraft is designed under a stable ground-to-target attitude, and is carried out within the target's orbital system. Since the target is in zero attitude, the trajectory changes of the orbital system are consistent with those of the target's own system. However, existing technologies have not yet adequately researched methods for autonomous rendezvous and docking terminal trajectory planning under a target moment equilibrium attitude. Summary of the Invention

[0003] The purpose of this invention is to provide a method for planning and designing the end trajectory of autonomous rendezvous and docking under target torque balance attitude, so as to realize rendezvous and docking of target non-ground-oriented attitude and reduce the constraints on target attitude.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for autonomous rendezvous and docking end-stage trajectory planning under target moment balance attitude is used to achieve docking between the active end of the docking mechanism of the tracking spacecraft and the passive end of the docking mechanism of the target spacecraft, including the following steps:

[0006] S1. Select the passive end coordinate system of the docking mechanism as the docking system, and design the nominal position and nominal speed of the docking end under the docking system.

[0007] S2. Convert the nominal position and nominal velocity of the docking system into the position and velocity of the target spacecraft's orbital system for orbital control.

[0008] Preferably, in step S1, the docking end is divided into a short-range segment and an ultra-short-range segment with 2m as the dividing point. The short-range segment is 2 to 200m long, and the ultra-short-range segment is 0 to 2m long. The nominal position and nominal speed design of the docking system of the docking end includes the nominal position and nominal speed design of the short-range segment and the nominal position and nominal speed design of the ultra-short-range segment.

[0009] Preferably, step S1 includes:

[0010] S11. The nominal position and nominal velocity of the short segment are designed using a polynomial fitting method, with the following formula:

[0011]

[0012]

[0013] Among them, l D (t) represents the nominal position; iD (t) represents the nominal speed; The initial velocity of the short-range segment; t f To approximate the total duration; t is the current approximation time; l f For the desired position at the end of the short-range segment, l f =-2m; The expected speed at the end of the short-range segment;

[0014] Approximation direction calculation:

[0015]

[0016] Where l0 is the initial position, which is the relative position from the relative navigation output;

[0017] Finally, the nominal position and speed for the short-range segment are:

[0018] P t =l D (t)·d bj +l0

[0019]

[0020] Preferably, step S1 further includes:

[0021] S12. Design the nominal position and nominal speed for the ultra-short range segment, using the following formula:

[0022]

[0023]

[0024] Among them, l D (t) represents the nominal position; i D (t) represents the nominal velocity; l0 represents the initial position of the ultra-short segment, l0 = -2m.

[0025] Preferably, step S2 includes:

[0026]

[0027]

[0028]

[0029] Among them, l To This represents the converted position within the target spacecraft's orbital system. The converted velocity in the target spacecraft's orbital system; The transformation matrix from the target aircraft's own system to the docking system; This is the transformation matrix from the target spacecraft's orbital system to its own system. To track the transformation matrix from the aircraft's own frame to its inertial frame; ω is the transformation matrix from the inertial frame to the target spacecraft's orbital frame; r1 is the coordinate of the active end of the docking mechanism in the tracking spacecraft's own frame; r2 is the coordinate of the passive end of the docking mechanism in the target spacecraft's own frame; ω is the angular velocity of the target spacecraft's own frame relative to the target spacecraft's orbital frame; ω Toi ω is the orbital angular velocity of the target spacecraft. Tbi Let ω be the inertial angular velocity of the target aircraft; [ω×] is the antisymmetric matrix of ω.

[0030] In summary, compared with existing technologies, the present invention provides an autonomous rendezvous and docking end-of-course trajectory planning and design method under target moment balance attitude. First, a suitable coordinate system is selected for docking trajectory design based on the target attitude and orbital changes, and the nominal trajectory and nominal velocity are designed in combination with end-of-course docking condition constraints. Second, the nominal trajectory and nominal velocity are converted to the target orbital system according to orbital control requirements. Combined with the position and velocity of the target satellite orbital system relative to the navigation output, the corresponding control law is used to calculate the orbital jet volume, realizing rendezvous and docking with a non-ground-oriented attitude of the target and reducing constraints on the target attitude. Attached Figure Description

[0031] Figure 1 This is a geometric diagram showing the relationship between the active and passive ends of the docking mechanism of the present invention and the target aircraft and the tracking aircraft;

[0032] Figure 2 This is a flowchart of the autonomous rendezvous and docking end trajectory planning and design method under the target torque balance attitude of the present invention. Detailed Implementation

[0033] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a more detailed explanation of the autonomous rendezvous and docking end-point trajectory planning and design method proposed in this invention under a target moment balance attitude. The advantages and features of this invention will become clearer from the following description. It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions, intended only to facilitate and clarify the illustration of the embodiments of this invention, and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0034] It should be noted that, in this invention, relational terms such as "and" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0035] Combined with appendix Figure 1 , 2 This invention provides an autonomous rendezvous and docking end-of-course trajectory planning method under a target moment balance attitude, used to achieve docking between a tracking spacecraft and a target spacecraft in a moment balance attitude. The tracking spacecraft includes an active docking mechanism, and the target spacecraft includes a passive docking mechanism. The docking between the tracking spacecraft and the target spacecraft refers to the docking of the active docking mechanism of the tracking spacecraft with the passive docking mechanism of the target spacecraft. Its working principle is as follows:

[0036] Based on the characteristics of the docking mechanism, at the docking end (the distance between the active and passive ends of the docking mechanism is within 200m), it is required that the lateral position of the active and passive ends of the docking mechanism be controlled within a small deviation range and the axial speed reach the rated value (wherein, the direction of the line connecting the center points of the active and passive ends of the docking mechanism is the axial direction, and the direction perpendicular to the axial direction is the lateral direction). After the track control stops, under the action of the axial speed, the active end of the docking mechanism gradually approaches the passive end of the docking mechanism until the docking is completed.

[0037] Because the target aircraft is a non-ground-oriented aircraft, there is a significant deviation between its intrinsic system and orbital system. The passive end of the docking mechanism is fixedly connected to the intrinsic system of the target aircraft. The orbital system of the target aircraft changes with its attitude, with components on all three axes, and this changes in real time, which is not conducive to the design of the nominal trajectory. Therefore, this invention selects the coordinate system of the passive end of the docking mechanism as the docking system for designing the formation vector at the docking end, and calculates the nominal position and nominal velocity under the docking system. The active end of the docking mechanism approaches the passive end of the docking mechanism along the axial direction in a straight-line approximation manner. It reaches the nominal position at the docking end and simultaneously reaches the nominal velocity. Under the action of the nominal velocity, the active end of the docking mechanism gradually approaches the passive end of the docking mechanism until it grasps and holds firmly. Considering that the accuracy of the ultra-short-range relative navigation sensor is consistent within 2m of the docking end, the active end of the docking mechanism approaches the passive end of the docking mechanism in a uniform straight-line manner within 2m of the docking end. Within this range, the control accuracy of the lateral position of the active and passive ends of the docking mechanism is judged, and an emergency evacuation is carried out if an anomaly is detected.

[0038] Since the orbital control rate is designed in the target spacecraft's orbital system, the nominal position and velocity under the planned docking system need to be converted to the target spacecraft's orbital system. Based on the relative position and relative velocity of the two spacecraft in the target spacecraft's orbital system at the current moment given by relative navigation, the deviation is calculated and orbital control is implemented.

[0039] Specifically, as shown in the attached document Figure 2 As shown, the steps include:

[0040] S1. Select the passive end coordinate system of the docking mechanism as the docking system, and design the nominal position and nominal speed of the docking end under the docking system.

[0041] The docking end is divided into a short-range section and an ultra-short-range section, with 2m as the dividing point. The short-range section is 2 to 200m long, and the ultra-short-range section is 0 to 2m long. The nominal position and nominal speed design of the docking system of the docking end includes the nominal position and nominal speed design of the short-range section and the nominal position and nominal speed design of the ultra-short-range section.

[0042] S11. The nominal position and nominal velocity of the short segment are designed using a polynomial fitting method, with the following formula:

[0043]

[0044]

[0045] Among them, l D (t) represents the nominal position; i D (t) represents the nominal speed; The initial velocity of the short-range segment; t f To approximate the total duration; t is the current approximation time; l f For the desired position at the end of the short-range segment, l f =-2m; This refers to the expected speed at the end of the short-range segment, which is the nominal speed expected at 2m from the docking end.

[0046] Approximation direction calculation:

[0047]

[0048] Where l0 is the initial position, which is the relative position from the relative navigation output.

[0049] Finally, the nominal position and speed for the short-range segment are:

[0050] P t =l D (t)·d bj +l0

[0051]

[0052] S12. Design the nominal position and nominal speed for the ultra-short range segment, using the following formula:

[0053]

[0054]

[0055] Among them, l D (t) represents the nominal position; i D (t) represents the nominal velocity; l0 represents the initial position of the ultra-short segment, l0 = -2m.

[0056] S2. Convert the nominal position and nominal velocity under the docking system into the relative position and relative velocity of the target spacecraft's orbital system for orbital control; the calculation formula is:

[0057]

[0058]

[0059]

[0060] Among them, l To This represents the converted position within the target spacecraft's orbital system. The converted velocity in the target spacecraft's orbital system; The transformation matrix from the target aircraft's own system to the docking system; This is the transformation matrix from the target spacecraft's orbital system to its own system. To track the transformation matrix from the aircraft's own frame to its inertial frame; ω is the transformation matrix from the inertial frame to the target spacecraft's orbital frame; r1 is the coordinate of the active end of the docking mechanism in the tracking spacecraft's own frame; r2 is the coordinate of the passive end of the docking mechanism in the target spacecraft's own frame; ω is the angular velocity of the target spacecraft's own frame relative to the target spacecraft's orbital frame; ω Toi ω is the orbital angular velocity of the target spacecraft. Tbi Let ω be the inertial angular velocity of the target aircraft; [ω×] is the antisymmetric matrix of ω.

[0061] In summary, the present invention provides an autonomous rendezvous and docking end-of-course trajectory planning and design method under target moment balance attitude. First, a suitable coordinate system is selected based on the target spacecraft's attitude and orbital changes to design the docking trajectory. The nominal trajectory and nominal velocity are designed in conjunction with the docking end-of-course docking condition constraints. Second, the nominal trajectory and nominal velocity are converted to the target orbital system according to the orbital control requirements. Combined with the position and velocity of the target satellite orbital system relative to the navigation output, the orbital jet volume is calculated using the corresponding control law. This achieves rendezvous and docking of the target spacecraft in a non-ground-oriented attitude, reducing constraints on the target attitude.

[0062] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for autonomous rendezvous and docking end-stage trajectory planning under target moment balance attitude, used to realize the docking of the active end of the docking mechanism of the tracking spacecraft and the passive end of the docking mechanism of the target spacecraft, characterized in that, Including the following steps: S1. Select the passive end coordinate system of the docking mechanism as the docking system, and design the nominal position and nominal speed of the docking end under the docking system. S2. Convert the nominal position and nominal velocity of the docking system into the position and velocity of the target spacecraft's orbital system for orbital control. In step S1, the docking end is divided into a short-range segment and an ultra-short-range segment with 2m as the dividing point. The short-range segment is 2~200m and the ultra-short-range segment is 0~2m. The nominal position and nominal speed design of the docking system of the docking end includes the nominal position and nominal speed design of the short-range segment and the nominal position and nominal speed design of the ultra-short-range segment. Step S1 includes: S11. The nominal position and nominal velocity of the short segment are designed using a polynomial fitting method, with the following formula: in, lD (t) represents the nominal position; iD (t) represents the nominal speed; The initial velocity for the short-range segment; To approximate the total duration; For the current approximation time; This represents the desired position at the end of the short-range segment. =-2m; The expected speed at the end of the short-range segment; Approximation direction calculation: in, The initial position is the relative position derived from the relative navigation output; Finally, the nominal position and speed for the short-range segment are: 。 2. The trajectory planning method as described in claim 1, characterized in that, Step S1 also includes: S12, Design of nominal position and nominal speed for ultra-short range, the formula is: in, lD (t) represents the nominal position; iD (t) represents the nominal speed; This is the initial position for the ultra-short segment. .

3. The trajectory planning method as described in claim 2, characterized in that, Step S2 includes: in, This represents the converted position within the target spacecraft's orbital system. The converted velocity in the target spacecraft's orbital system; The transformation matrix from the target aircraft's own system to the docking system; This is the transformation matrix from the target spacecraft's orbital system to its own system. To track the transformation matrix from the aircraft's own frame to its inertial frame; r1 is the transformation matrix from the inertial frame to the target spacecraft's orbital frame; r2 is the coordinates of the active end of the docking mechanism in the tracking spacecraft's own frame; r2 is the coordinates of the passive end of the docking mechanism in the target spacecraft's own frame. The angular velocity of the target spacecraft's own system relative to the target spacecraft's orbital system; The orbital angular velocity of the target spacecraft; The inertial angular velocity of the target aircraft; for An antisymmetric matrix.

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