Drift-based rendezvous control

Patent metadata

Field	Value
Publication number	US-11834203-B2
Application number	US-202017011360-A
Country	US
Kind code	B2
Filing date	Sep 3, 2020
Priority date	Sep 3, 2020
Publication date	Dec 5, 2023
Grant date	Dec 5, 2023

Abstract

Drift-based rendezvous control system for controlling an operation of a spacecraft to rendezvous the spacecraft to a goal region over a finite time (FT) horizon. The system including accepting data including values of spacecraft states at a specified time period within the FT horizon. A processor at the specified time period selects a set of drift regions corresponding to a desired goal region at a location on an orbit where the target is located at the specified time period. Update a controller having a model of dynamics of the spacecraft with the accepted data. Formulate the set of drift regions as a penalty in a cost function of the updated controller. Generate control commands resulting in a real-time drift-based control policy where upon entering the drift region, the thrusters are turned off in order to minimize an amount of operation of the thrusters while rendezvousing with the desired goal region.

First claim

What is claimed is:

1. A drift-based rendezvous control system for controlling an operation of a chaser spacecraft to rendezvous the chaser spacecraft to a goal region over a finite time horizon, comprising:
a transceiver configured to accept data including values of chaser spacecraft states at a specified time period within the finite time horizon;
a processor at the specified time period configured to:
access a memory having stored data including a goal region database;
select a set of drift regions corresponding to a desired goal region at a location on an orbit where a target is located at the specified time period, wherein the set of drift regions represents regions of state space around the desired goal region that guarantee thruster free operation to reach the desired goal region, wherein each of the regions of state space comprise a position and a velocity of the chaser spacecraft;
update a controller having a model of dynamics of the chaser spacecraft with the accepted data;
formulate the set of drift regions as a penalty in a cost function of the updated controller;
generate control commands that result in a real-time drift-based control policy where upon entering the drift regions, the thrusters are turned off in order to minimize an amount of operation of the thrusters while rendezvousing with the desired goal region; and
output the control commands to activate or not activate one or more thrusters of the chaser spacecraft for the specified time period based on the control commands.

2. The drift-based rendezvous control system of claim 1 , wherein the chaser spacecraft states and target states of the target further comprise one or combination of orientations, and translational and angular velocities of the chaser spacecraft and the target, and perturbations acting on a system of multiple celestial objects including the chaser spacecraft and the target.

3. The drift-based rendezvous control system of claim 2 , wherein the perturbations are natural orbital forces including one or more of solar gravitational perturbations, lunar gravitational perturbations, anisotropic gravitational perturbations, solar radiation pressure, and air drag.

4. The drift-based rendezvous control system of claim 3 , wherein the celestial objects include a primary body around which the target orbits, and a secondary body, so that the target is in a halo orbit.

5. The drift-based rendezvous control system of claim 1 , wherein the processor is a guidance and control computer (GCC) in communication with the transceiver and the memory, such that a target orbit is determined from the accepted data, the data includes uploaded ephemeris from a ground station, ground data obtained in satellite tracking databases, or estimated from onboard sensor measurements on the chaser spacecraft.

6. The drift-based rendezvous control system of claim 1 , wherein the target is one of a spacecraft, a space station, a celestial body or orbital debris, and wherein a region around the target is one of an approach ellipsoid (AE) region, a keep-out sphere (KOS) region, an approach polytope (AP) region or a keep-out polytope (KOP) region.

7. The drift-based rendezvous control system of claim 1 , wherein a target orbit is one of circular orbits, elliptic orbits, halo orbits, near rectilinear halo orbits or a quasi-satellite orbit.

8. A drift-based rendezvous control system for controlling an operation of a spacecraft to rendezvous the spacecraft with a target over a finite time horizon, comprising:
a transceiver configured to accept data including values of spacecraft states and target states of the target in a multi-object celestial system at a specified time period within the finite time horizon;
a processor at the specified time period configured to:
access a memory having stored a target region database and a goal region database, where a goal region is outside a target region;
select a set of avoidance regions corresponding to a desired target region at a location on an orbit where the target is located at the specified time period, wherein the set of avoidance regions represents regions of space around the desired target region guaranteeing intersection trajectories with the desired target region, in an event of total or partial spacecraft thruster failure;
select a set of drift regions corresponding to a desired goal region in proximity to a location on an orbit where the target is located at the specified time period, wherein the set of drift regions represents regions of state space around the desired goal region that guarantee spacecraft thruster free operation to reach the desired goal region, wherein each of the regions of state space around the desired goal region comprise a position and a velocity of the spacecraft;
formulate the set of avoidance regions as constraints;
update a controller having a model of dynamics of the spacecraft with the accepted data;
formulate the set of drift regions as a penalty in a cost function of the updated controller;
generate control commands by subjecting the updated controller to the constraints to generate control commands that result in a real-time drift-based control policy producing a collision free rendezvous trajectory which avoids the set of avoidance regions, guaranteeing an intersection-free trajectory with respect to the desired target region in the event of the total or partial spacecraft thruster failure and upon the spacecraft entering the set of drift regions the thrusters are turned off in order to minimize an amount of operation of the thrusters while rendezvousing with the target; and
output the control commands to activate or not activate one or more thrusters of the spacecraft for the specified time period based on the control commands.

9. The drift-based rendezvous control system of claim 8 , wherein the spacecraft states and target states in the multi-object celestial system further comprise one or combination of orientations, and translational and angular velocities of the spacecraft and the target, and perturbations acting on the multi-object celestial system, wherein the spacecraft and the target form the multi-object celestial system, wherein the perturbations acting on the multi-object celestial system are natural orbital forces including one or more of solar gravitational perturbations, lunar gravitational perturbations, anisotropic gravitational perturbations, solar radiation pressure, and air drag.

10. The drift-based rendezvous control system of claim 8 , wherein the multi-object celestial system includes a celestial reference system or celestial coordinate system, that includes positions of the spacecraft, the target and celestial objects, in a three-dimensional space, or a plot of a direction on a celestial sphere, if an object's distance is unknown, wherein the celestial objects include a primary body around which the target orbits and a secondary body, so that the target is in a halo orbit.

11. The drift-based rendezvous control system of claim 8 , wherein the processor is a guidance and control computer (GCC) in communication with the transceiver and the memory, such that a target orbit is determined based on uploaded ephemeris from a ground station, based on ground data obtained in satellite tracking databases, or estimated from onboard sensor measurements on the spacecraft obtained from the accepted data.

12. The drift-based rendezvous control system of claim 8 , wherein the target is one of a spacecraft, a space station, a celestial body or orbital debris, and wherein a region around the target is one of an approach ellipsoid (AE) region, a keep-out sphere (KOS) region, an approach polytope (AP) region or a keep-out polytope (KOP

Assignees

• Mitsubishi Electric Res Laboratories Inc

Inventors

• Weiss Avishai
• Marsillach Daniel Aguilar
• Di Cairano Stefano

Classifications

• B64G1/368 Primary

  using gravimeters · CPC title

• B64G1/2422

  using Lagrange points, e.g. halo orbits · CPC title

• B64G1/646 Primary

  Docking or rendezvous systems (refuelling in space B64G1/4024) · CPC title

• B64G1/242 Primary

  Orbits and trajectories · CPC title

• B64G2001/247

  Operations & Transport · mapped topic