Non-cooperative target full-autonomous rendezvous method

Abstract

The application discloses a non-cooperative target full-autonomous rendezvous method, which comprises the following steps: 1, a Hohmann transfer algorithm is used to perform autonomous long-distance guidance on a main star; 2, a semi-major axis correction and closed-loop orbit control algorithm is used to perform long-distance guidance end correction; 3, a follow-sighting single machine on the main star is started, a target star is captured and tracked, relative position and speed information of the main star and the target star is solved, and far and near range handover control is performed and completed; and 4, autonomous near-range guidance accompanying control on the main star is started. The application reduces the dependence of satellite on-the-orbit task execution on the ground, and improves the efficiency of real-time task execution.

Description

TECHNICAL FIELD

[0001] The present application relates to satellite guidance, navigation and control technology, in particular to a non-cooperative target autonomous rendezvous method of high, medium and low orbit satellites. BACKGROUND

[0002] With the increasing number of on-orbit spacecraft, the demand for a service spacecraft as a primary star to autonomously rendezvous with a non-cooperative target spacecraft within a specified time and perform on-orbit service is increasingly strong. Therefore, in the non-telemetric remote control arc segment (without ground support), how to complete high-precision autonomous rendezvous with a non-cooperative target spacecraft and ensure the safety of the two stars is the primary problem to be solved. SUMMARY

[0003] The present application is based on on-board autonomous navigation and target orbit prediction information, solves the technical difficulties of long time consumption by ground strategy and poor real-time performance due to the limitation of the telemetry and remote control arc segment, and realizes the autonomous rendezvous process with optimal fuel and strong timeliness.

[0004] To solve the above technical problems, the present application is realized by the following technical scheme, a non-cooperative target autonomous rendezvous method, comprising the following steps:

[0005] Step one, using Hohmann transfer algorithm for autonomous long-range guidance on the primary star;

[0006] Step two, using semi-major axis correction and closed-loop orbit control algorithm for long-range guidance end correction;

[0007] Step three, starting the follow-up single machine on the primary star, capturing and tracking the target star, calculating the relative position and velocity information of the primary star and the target star, and performing and completing the long-range handover control;

[0008] Step four, starting autonomous short-range guidance companion control on the primary star.

[0009] Further, the step one further comprises:

[0010] According to the total rendezvous time of the primary star and the target star, the long-range guidance time, the long-range handover time and the short-range guidance time are allocated;

[0011] According to the orbit phase difference and the height difference of the primary star and the target star, the long-range guidance time, the height of the drift orbit and the orbit control strategy are calculated.

[0012] Further, the step two further comprises: using closed-loop orbit control to eliminate the position and velocity error at the end of long-range guidance.

[0013] Further, the step four further comprises: after the far and near range handover is completed, a multi-pulse optimal control strategy is adopted to realize the transfer of the relative position of the main star and the target star according to the rendezvous task requirement, when the main star is transferred to the vicinity of the target star position, a closed-loop orbit control algorithm is adopted to realize high-precision fixed-point companion flying until the task is completed.

[0014] Further, the calculation formula of the Hohmann transfer in the step one is:

[0015]

[0016]

[0017] Wherein, Δv1 and Δv2 respectively refer to the first and second jet speed pulses of the Hohmann transfer, a1 is the transfer orbit height, and ac is the orbit height of the main star.

[0018] Further, in the step two, the formula for calculating the closed-loop orbit control strategy is U=KKΔX; wherein, KK is a constant gain matrix, and ΔX is the difference between the expected relative position and speed value and the real relative position and speed.

[0019] Further, in the step three, the handover control, the calculation formula of the control pulse in the Z (Y axis similar) axis direction is established as:

[0020] Δv z =v z期望 -v z

[0021] Wherein, A is the expected companion flying ellipse major axis;

[0022] z0 is the current relative position Z, and n is the average orbit angular velocity.

[0023] The present application has the following beneficial effects:

[0024] The method proposed in the present application realizes the guidance control of the long-range, medium-range and near-range through three stages of on-board self-realization, truly realizes the "one-key start" of the autonomous rendezvous task, that is, only the relevant parameters need to be input when starting the task, and the subsequent on-board self-realization is performed, thereby reducing the dependence of the satellite on the ground during the on-orbit task execution and improving the efficiency of the real-time task execution. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a schematic diagram of the long-range guidance segment task process of the present application. DETAILED DESCRIPTION

[0026] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed explanation of the non-cooperative fully autonomous rendezvous method for targets proposed in this invention. The advantages and features of this invention will become clearer from the following description.

[0027] like Figure 1 The diagram shows the mission flow for the remote guidance phase. The primary satellite operates in a drift orbit behind the target satellite. Upon receiving the activation command from the ground, the primary satellite obtains the total rendezvous time, closest distance, and the target satellite's orbit. It then calculates the remote guidance control strategy for a specified time, including drift time calculation, drift orbit altitude calculation, and control timing calculation. Specifically, the following implementation steps achieve high-precision, fully autonomous rendezvous with a non-cooperative target.

[0028] Step 1: Achieve autonomous long-range guidance on the primary satellite using the most fuel-efficient Hohmann orbit transfer algorithm. In orbital transfers between two coplanar circular orbits sharing a common focus, the Hohmann transfer is the most energy-efficient double-pulse maneuver. Therefore, this invention employs the Hohmann transfer maneuver to ensure minimal fuel consumption throughout the entire process. The Hohmann transfer transition orbit is an elliptical orbit tangent to both circles on their camber lines. The transfer can be from the inner circle to the outer circle, or vice versa. The time for one transfer is half the transfer orbit period.

[0029] During the transfer orbit, the long-range guidance time, the long-range handover time, and the short-range guidance time are allocated based on the total rendezvous time between the primary and target stars; the drift orbit altitude and orbit control strategy are calculated based on the orbital phase difference, altitude difference, and long-range guidance time between the primary and target stars.

[0030] The energy requirement for the Hohmann transfer is calculated by the following formula:

[0031]

[0032]

[0033] Where Δv1 and Δv2 refer to the first and second jet velocity pulses of the Hohmann maneuver, respectively, and a1 is the transfer trajectory altitude. c The orbital altitude of the primary star.

[0034] Calculation of the drift track height a1:

[0035] 1. Calculate the difference in orbital elements between the two stars: Δu = u t -u c +δu, where u t δu represents the current latitude argument of the target satellite, and δu represents the difference in latitude argument between the two satellites during the final rendezvous phase (ground-based note). c The current latitude and angle of the main star;

[0036] 2. Where a1 = ac a1 as the initial value c the orbital radius of the primary star;

[0037] 3. First and second Hohmann transfer interval time estimation:

[0038] 4. Third and fourth Hohmann transfer interval time estimation:

[0039] 5. Target orbital angular velocity of the primary star transfer control:

[0040] 6. Downward drifting orbital angular velocity: n1 = (Δu + n t (Tsum-0.5(T1+T3))-π) / (Tsum-T1-T3)

[0041] 7. Downward drifting orbital altitude:

[0042] 8. Iteration of a1 calculated by 7 once:

[0043] First and second Hohmann transfer interval time:

[0044] Third and fourth Hohmann transfer interval time estimation:

[0045] Target orbital angular velocity of the primary star transfer control:

[0046] Downward drifting orbital angular velocity: n1 = (Δu + n t (Tsum-0.5(T1+T3))-π) / (Tsum-T1-T3);

[0047] Downward drifting orbital altitude:

[0048] Downward drifting orbital duration calculation:

[0049] △θ = u t -u c +δu.

[0050] Wherein, a2 is the orbital radius of the target star, T3 is the third and fourth Hohmann transfer interval time, n is the average orbital angular velocity, a1 is the orbital radius of the primary star, u t is the current target star latitude amplitude angle, u c is the current primary star latitude amplitude angle, and δu is the latitude amplitude angle difference between the two stars in the final companion state (ground note).

[0051] Hohmann transfer is used to adjust the orbit height of the circular orbit, and a Hohmann transfer is implemented by two times of jet in half of the orbit period, and the in-place accuracy is improved by updating the length of the drift orbit multiple times. After the four times of jet implementation of the two Hohmann transfers, step two is entered;

[0052] Step two, remote guidance end correction is implemented, and a semi-major axis correction and a closed-loop orbit control algorithm are adopted;

[0053] Due to the long distance between the two stars, the remote guidance time is long, there is a certain error in the target orbit prediction, the perturbation influence is not considered in the strategy calculation, and there is a certain error in the strategy implementation, and there is a certain deviation in the position and speed at the end of the remote guidance. In order to ensure that the target can be searched by the follow-up sighting, the relative position between the two stars at the end of the remote guidance is required to be less than the ranging range of the follow-up sighting, and the relative speed is also small. Therefore, the closed-loop orbit control is adopted to eliminate the position and speed errors at the end of the remote guidance, and the subsequent handover is ensured to be successful. 1, judge the relative position state of the two stars (main star and target star): the relative position X f If the relative position X f If the condition is met, if the relative position X f If the condition is still not met, semi-major axis correction is performed; otherwise, the relative position X f If the relative position X

[0054] 2, semi-major axis correction control: make the main star drift into a specified range in front of the target star;

[0055] Calculate the current semi-major axis difference Δa of the two stars: (Xqw is the expected handover position);

[0056] If the absolute value of Δa is greater than 10 km, it is considered that the autonomous orbit rendezvous control error is too large, the control amount Δa is sign(Δa)×5000, and the drift is 50 km; if the absolute value is greater than 500 m and less than 10 km, the correction jet is executed; if the absolute value is less than 500 m, the correction jet is executed according to 500 m;

[0057] The correction speed increment is

[0058] 3, closed-loop orbit control process:

[0059] Control speed increment calculation:

[0060] U=KK·ΔX·T

[0061] Wherein, KK is a constant gain matrix, ΔX is the expected relative position and velocity value and the real relative position and velocity difference, T is the control period;

[0062] After the LQG real-time closed-loop orbit control is completed, step three is entered.

[0063] Step three, the self-starting of the follow-up and sighting single machine on the main star is realized, the target star is self-captured and tracked, the relative position and velocity information of the two stars is self-solved, and the far and near range shift control is self-completed;

[0064] The "follow-up and sighting self-closed-loop" instruction is self-sent (the follow-up and sighting search and capture target is enabled), the near range relative navigation is self-started after the follow-up and sighting is effective, and the shift control is performed after the navigation data is effective.

[0065] Shift control: the in-plane and out-of-plane relative motion amplitude is adjusted to form a preliminary stable companion flying, wherein the in-plane refers to the XZ plane of the main star orbit system, and the out-of-plane refers to the relative motion trajectory normal to the XZ plane of the main star orbit system.

[0066] X-direction velocity pulse calculation: dx = -(6nz-3v x )·orbit_time; Δv1 x is the X-direction velocity pulse;

[0067] The calculation formula of the Z-axis direction control pulse is:

[0068] Δv z =v z期望 -v z

[0069] Wherein, the expected Z-direction relative velocity is A is the expected companion flying ellipse major axis, v z is the current relative velocity Z;

[0070] Z is the current relative position Z, v x is the current X-direction velocity, orbit_time is one orbit period, unit: second, and n is the average orbit angular velocity.

[0071] After the shift control is completed, step four is entered;

[0072] Step four, the star self-near range guidance companion flying control is realized; after the far and near range shift is completed, the multi-pulse optimal control strategy is adopted, the relative position of the main star and the target star is shifted according to the rendezvous task requirement, when the main star is shifted to the vicinity of the target star position, the closed-loop orbit control algorithm is adopted to realize the high-precision fixed-point companion flying until the task is completed.

[0073] Through the X / Y / Z-direction control, a small-scale companion flying ellipse is finally formed;

[0074] X direction coarse control: first calculate the coarse drift dx = -(6nz-3v x )·orbit_time; Then calculate the fine drift dx = the difference of relative position X between two adjacent orbits; velocity increment calculation

[0075] The calculation formula of the control pulse in Z (Y axis similar) direction is:

[0076] Δv z = v z期望 -v z

[0077] Wherein, A is the expected long semi-axis of the flyby ellipse.

[0078] The present application has the following beneficial effects:

[0079] The method proposed in the present application realizes the long-range, medium-range and short-range guidance control through three stages on the satellite, and truly realizes the "one-key start" of the autonomous rendezvous mission, that is, only the relevant parameters need to be input when starting the mission, and the subsequent satellite is fully autonomous, which reduces the dependence of the satellite on the ground during the on-orbit mission execution, and improves the efficiency of real-time mission execution.

[0080] Although the content of the present application has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present application. After reading the above content, various modifications and alternatives of the present application will be obvious to those skilled in the art. Therefore, the protection scope of the present application should be defined by the appended claims.

Claims

1. A fully autonomous rendezvous method for non-cooperative targets, characterized in that, Includes the following steps: Step 1: Use the Hohmann orbit change algorithm for autonomous long-range guidance on the primary satellite; Step 2: Use semi-major axis correction and closed-loop orbit control algorithms for remote guidance end correction; Step 3: Activate the main star tracking and aiming single-machine, capture and track the target star, calculate the relative position and velocity information of the main star and the target star, and perform and complete the long-range and short-range handover control. Step 4: Activate autonomous close-range guidance and escort control on the primary satellite; Step one also includes: The long-range guidance time, long-range handover time, and short-range guidance time are allocated according to the total rendezvous time between the primary star and the target star. The drift trajectory altitude and orbit control strategy are calculated based on the orbital phase difference, altitude difference, and remote guidance time between the primary and target stars. Step two also includes: Closed-loop orbit control is used to eliminate position and velocity errors at the end of remote guidance; Step four also includes: After completing the long-range and short-range handover, a multi-pulse optimal control strategy is adopted to realize the transfer of the relative positions of the primary star and the target star according to the rendezvous mission requirements. When the primary star moves to the vicinity of the target star's position, a closed-loop orbit control algorithm is adopted to achieve fixed-point rendezvous flight until the mission ends. In step two, the formula for calculating the closed-loop track control algorithm is: U = KKΔX Where KK is a constant gain matrix, and ΔX is the difference between the desired relative position velocity and the actual relative position velocity; In step three, the calculation formula for establishing the Z-axis direction control pulse during shift handover control is as follows: Δv z =v z期望 -v z in, A is the semi-major axis of the desired ellipse for flight companions; z0 is the current relative position Z, and n is the average orbital angular velocity.

2. The non-cooperative target fully autonomous rendezvous method as described in claim 1, characterized in that, The formula for calculating the Hohmann transfer in step one is as follows: Where Δv1 and Δv2 refer to the first and second jet velocity pulses of the Hohmann maneuver, respectively, and a1 is the transfer trajectory altitude. c The orbital altitude of the primary star.

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