EA043355B1 - COMPREHENSIVE SERVICE IN ORBIT - Google Patents

Description

Field of technology

The invention relates generally to integrated on-orbit servicing, and in particular to orbital servicing spacecraft for on-orbit inspection and/or maintenance of spacecraft and for towing space vehicles or other space objects.

State of the art

As we know in outer space, on-orbit end-to-end services are completely changing space transportation and the way outer space is used.

Generally speaking, on-orbit end-to-end services can be classified into two broad categories: spacecraft inspection and/or maintenance services and towing services for towing space vehicles or other space objects, such as space debris.

Spacecraft inspection and/or maintenance services can, in turn, be divided into spacecraft inspection services, spacecraft service life extension services, including refueling, spacecraft relocation services; and spacecraft modernization services to adapt spacecraft missions throughout its service life.

Spacecraft towing services can, in turn, be subdivided into geostationary orbital towing services, which include the delivery of a spacecraft, and low-Earth orbit (LEO) towing services, which include the deployment of a constellation of satellites. They are provided, for example, to satellites that, due to launch errors, were unable to reach their operational orbits.

Towing services, or rather space object removal services, on the other hand, essentially consist of a cleaning service aimed at actively removing space debris.

In-orbit servicing services are provided by orbital servicing spacecraft, which are distinguished between inspection and/or maintenance spacecraft, when they are intended to provide inspection and/or maintenance services to space vehicles, and space tugs, when they are intended to provide space vehicle/object towing services.

The space object towing service may also be provided to space objects that are unable to cooperate in providing the service, and spacecraft inspection and/or maintenance services and spacecraft towing services are provided to space vehicles that are either able or unable to cooperate in providing the service. .

When used to provide spacecraft towing services, the spacecraft tugs may be attached to the spacecraft to be towed, prior to launch, directly to the launch vehicle so as to be launched together with the spacecraft to be towed, or they can be launched separately from the spacecraft to be towed into a so-called rendezvous orbit (LEO or NRHO - near rectilinear halo orbit) in anticipation of the spacecraft to be towed, which are launched into the rendezvous orbit after the space tugs.

When used to tow separately launched spacecraft, the spacecraft tugs are controlled to autonomously approach and dock with the spacecraft through appropriate docking systems, usually in the form of robotic arms, and are able to propel the docked spacecraft until they reach the desired orbit where spacecraft can operate, or maintenance/refueling, repairs or other operations can be performed.

When used to tow space objects, space tugs are controlled to autonomously approach and capture space objects through appropriate capture systems such as nets, harpoons or other systems, and lower or raise the orbit of captured space objects simply by changing their orbit to to bring them to where they can no longer pose a risk to operating satellites.

US 2018/148197 A1 discloses a service satellite having a main body, a controller and a docking unit. The docking unit contains at least two folding and adjustable gripping arms that are pivotally mounted on the main body of the satellite. Each gripping arm is rotatable relative to the main body of the satellite and includes a gripping end at each free end of the gripping arms. The gripping ends are adapted and configured to capture and hold a target fragment of an orbiting satellite. Each gripping arm is independently controlled by a controller that coordinates the movement of the gripping arms. The servicing satellite further comprises a propulsion system comprising a first thruster mounted near an end at the nadir point of the main body of the servicing satellite, and a counterbalance thruster spaced apart from the first thruster and facing in a different direction from with the first thruster, propellant for the thruster and counter thruster. The servicing satellite further comprises means for aligning the thrusters such that the thrust generation vector passes through the point of connection between the center of gravity of the servicing satellite and the satellite being serviced.

US 6,017,000 A discloses apparatus and methods for performing near-satellite operations such as inspecting, repairing, and extending the life of a target satellite through the operation of a Satellite Inspection, Repair, and Life Extension (SIRE) spacecraft that can operate in a remotely controlled manner. , automatic and autonomous modes. The SIRE concept further consists of those methods and techniques that are used to perform certain on-orbit operations, including, but not limited to, inspection, maintenance, repair and life extension of satellites, spacecraft, space systems, space platforms and others vehicles and objects in space, collectively called target satellites. The three main types of SIRE missions in spatial proximity are defined as Service Life Extension, Repair and Maintenance. A remote cabin system is provided to allow human control of the SIRE spacecraft during close proximity operations.

James Gillian: Adaptive control for post-dock manoeuvres with an unknown semi-cooperative object, 2016 IEEE Aerospace Conference, IEEE, March 5, 2016 (03/05/2016), pages 1-10, explores the maneuver space in which an adaptive controller can support the authority to control attitude when a spacecraft connects with an object with limited physical parameter information, for the purpose of generating a path map for confirmation by the controller through future spaceflight experiments. A comparison is made between a basic proportional-integral-derivative (PID) attitude and position control system and an adaptive PID approach. The coupled spacecraft inertia, mass, and center of mass location are varied to evaluate the constraint, performance, and robustness of these controllers.

US 9,115,662 B1 discloses methods and equipment for controlling a plurality of thrusters in a platform, comprising driving a plurality of thrusters in a platform using a thruster control system, estimating the vehicle response resulting from the operation of the plurality of thrusters, so as to formulate the calculated response of the device, and compare the calculated response of the device with the desired response of the device in order to clarify objective functional errors.

CN 110 110 342 A discloses a combined method for controlling the movement of spacecraft data based on a proximity algorithm. The method contains the following steps: creating a combined model of the spacecraft motion; design of a data controller for spatial position control based on a proximity algorithm; initializing controller parameters and creating a database; calculating the predicted value of the system using a formula and calculating the predicted output value of the system using the formula; calculation controller; updating data in the database; and performing an iteration to adjust the output value of the controller.

CN 109 625 333 A discloses a method for acquiring a non-cooperative target in space based on deep learning with enhancement. The method contains two stages. The interaction may be accomplished through a method. The method comprises steps in which, a first, three-dimensional visualized environment for the serving spacecraft and the target spacecraft is created using three-dimensional visualization software, the input data for the visualized environment is the control force and control torque of the serving spacecraft, and the output data are the states of the serving spacecraft apparatus and target spacecraft; second, a convolutional neural network model is created, and intelligent acquisition training of an autonomous space non-interacting target is carried out on the serving spacecraft in a three-dimensional visualized environment. The states of the servicing spacecraft and the target spacecraft are taken as input to the convolutional neural network model, the weight parameters of the convolutional neural network model are used to output the control forces and torques required to control the servicing spacecraft, the control forces and moments are sent to the visualized environment, and the states two spacecraft are fed into the neural network continuously to perform continuous deep learning with improvement.

Purpose and essence of the invention

The Applicant has learned from experience that one of the key technology challenges that spacecraft servicing vehicles must address in providing servicing services to client spacecraft, particularly satellites, is optimization, i.e. reduction of fuel consumption,

- 2 043355 to ensure proper attitude control, especially when docked with client satellites, a situation in which the center of mass of the aggregate satellite is placed at an intermediate position (usually unknown a priori) between the two spacecraft.

Based on its best knowledge, the Applicant has discovered that technologies, either currently in use or proposed to overcome the above technological problem, are essentially based on the provision of thrusters for attitude control, moved, by means of suitable mechanisms, in two or more advances. certain discrete positions, usually the stowed or collapsed position and the deployed position, in which, to the best knowledge of the Applicant, the deployed positions are calculated on the ground based on an estimate of the positions that can be assumed from the center of mass of the aggregate spacecraft in all possible missions predicted a priori, which the servicing spacecraft and the aggregate spacecraft must perform.

As a result, the Applicant confirmed that the above technologies, while satisfactory in many aspects, have significant areas for improvement both in terms of efficiency in optimizing the fuel consumption of servicing spacecraft throughout their service life, especially when it is difficult to interact with the servicing spacecraft from the ground due to its distance from the Earth, and in terms of the number and therefore total mass of attitude control thrusters required to control the attitude of the servicing spacecraft and the aggregate spacecraft throughout the life of the servicing spacecraft.

Therefore, the present invention has the object of providing technology that allows improvements to be made both in terms of efficiency in optimizing fuel consumption and in terms of the number of attitude control thrusters required for attitude control of the service spacecraft and the overall spacecraft, also taking into account the necessary reservations.

According to the present invention, an orbital servicing spacecraft is provided as claimed in the appended claims.

Brief description of drawings

Fig. 1 shows an orbital service spacecraft, FIG. 2 shows a space system formed by the orbital service spacecraft of FIG. 1, docked to a spacecraft that is to be serviced or towed;

fig. 3 shows a thruster positioning and orientation system for controlling the spatial position of the orbital service spacecraft in FIG. 1;

fig. 4 shows a block diagram of the electronic response control system for the orbital servicing spacecraft of FIG. 1; and figs. 5 shows a flowchart of operations performed by a computer to control the attitude of the electronic response control system of FIG. 4.

Detailed description of possible embodiments of the invention

The present invention will now be described in detail with reference to the accompanying drawings to enable one skilled in the art to make and use it. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the general principles described may be applied to other embodiments and applications without thereby departing from the scope of the present invention as defined in the appended claims. Therefore, the present invention should not be considered limited to the embodiments described and illustrated, but should be within the broadest possible scope of protection consistent with the features described and claimed.

Until otherwise defined, all technical and scientific terms used herein have the same meaning as commonly used by those skilled in the art pertaining to the present invention. In the event of any conflict, this description, including the definitions provided, shall be binding. Moreover, the examples are provided for illustrative purposes only and, as such, should not be construed as limiting.

In particular, the block diagrams included in the accompanying drawings and described below are not intended to represent structural features, i.e. design constraints, but they must be interpreted as representing functional attributes, i.e. inherent properties of devices, determined by the resulting effects, which are functional limitations and which can be implemented in various ways, therefore, in order to protect their functionality (ability to function).

To facilitate understanding of the embodiments described herein, reference will be made to certain specific embodiments and specific language will be used to describe them. The terminology used herein is for the purpose of describing selected embodiments only and is not intended to limit the scope of the present invention.

Additionally, for convenience of description, the following description will refer, without thereby losing generality, to a mission in which an orbital servicing spacecraft in the form of a space tug is to dock with a spacecraft in the form of a satellite (not necessarily a cooperative one), thus , forming a rigid space system consisting of a space tug and a satellite, rigidly coupled to each other.

Generally speaking, the idea behind the present invention is the practical provision of artificial intelligence (AI)-based attitude control adapted to infer, based on information provided by the space tug's sensor system, the best decision regarding the positioning, orientation and operation of small spacecraft engines. thrust to control the attitude of the space tug when it is engaged with the satellite, or when it is still separated from the satellite.

Artificial intelligence-based attitude control is also designed to adapt to changes over time, such as a shift in the position of the space system's center of mass due to the gradual consumption of fuel in the space system.

Thus, it is possible, on the one hand, to reduce fuel consumption and, on the other hand, it is possible to reduce the total number (including redundancies) of the required thrusters for attitude control, consistently reducing the weight of the attitude control system, at the same time also providing greater capacity to absorb any failure of the attitude control thrusters and increasing the maneuverability of the space system.

Fig. 1, 2 and 3 show a space tug according to the present invention, generally designated by reference numeral 1.

Space Tug 1 contains:

main body or structure or platform 2; and avionics supported by main part 2 and containing, among other things:

solar panels 3 to supply electricity to on-board electrical systems;

an electronically controlled engagement system 4 of a known type and therefore not described in detail or illustrated by way of example in the form of a ring on which the engagement mechanisms according to the prior art (not illustrated) are secured to dock/grab the towed satellite 5, thereby forming space system 6 with him; and an electronic response control system (RCS) 7 (FIG. 4) to instruct the spacecraft 1 to rotate about the longitudinal, vertical and lateral axes to adjust the attitude and its displacement along predetermined trajectories to instruct the spacecraft 1 to perform predetermined maneuvers such as such as rendezvous and docking maneuvers between spacecraft (using offset control to adjust speed of approach to the target and alignment with the docking point) and orbital change maneuvers.

As shown in the block diagram in FIG. 4, the electronic response control system 7 contains:

a sensor system 8 of a known type and therefore not described in detail, to enable direct detection of physical quantities or their indirect calculation based on detected physical quantities, such as position, attitude, angular velocities, available fuel, geometric features and the state of the on-board system;

electronically controlled actuators/motors in the form of thrusters 9 for controlling spatial position, mounted in such a way as to allow adjustment of their positions and orientations; and an attitude control computer 10 in communication with the sensor system 8 and the attitude control thrusters 9, programmed to receive data from the sensor system 8 and control, based on the received data, the positions, orientations and operating states of the thrusters 9 for attitude control so as to control the attitude and position of the space tug 1.

Referring again to FIG. 1, 2 and 3, in order to enable adjustment of their position and orientation, attitude control thrusters 9 are mounted on the main body 2 of the space tug 1 by means of an electronically controlled deployable motion system 11 designed to enable position adjustment and orientation of the thrusters 9 for attitude control in response to electrical commands from the attitude control computer 10.

As shown in more detail in FIG. 2, by way of non-limiting example, the movement system 11 comprises, for each individual attitude control thruster 9 whose orientation is to be individually adjusted, or each group of attitude control thrusters 9 whose orientation is to be individually adjusted, hereinafter document referred to as the RCS cluster 9 for the sake of brevity, an electronically controlled orientation structure 12 designed to support the RCS cluster 9 to enable it to rotate about at least two orthogonal axes of rotation A, B in response to electrical commands from an attitude control computer 10 so as to enable the orientation of the RCS cluster 9 on the space tug 1 to be adjusted if desired.

The movement system 11 further comprises, for each individual orientation structure 12 whose position is desirably to be individually adjustable, or group of orientation structures 12 whose position is desirably to be collectively adjustable, an electronically controlled positioning structure 13 configured to support the structure 12 for orientation, or a group of structures 12 for orientation, so as to allow them to move in a rectilinear or curved displacement direction, so as to allow their positions on the space tug 1 to be adjusted.

Fig. 1, 2 and 3 show as an example a guide bar type positioning structure 13 in which the orientation structure 12 is secured to a slider slidably mounted on a straight guide so as to move in the straight direction C in response to electrical commands from a computer. 10 for attitude control, thereby allowing the position of the RCS cluster 9 to be adjusted by the orientation structure 12.

Finally, the movement system 11 further comprises, for each positioning structure 13, an electronically controlled deployment structure 14 that connects the positioning structure 13 to the main body 2 of the space tug 1 and is designed to receive, in response to electrical commands from the computer 10, for spatial control. position, a collapsed configuration in which the positioning structure 13 is held adjacent to the main body 2, and an expanded configuration relative to the main body 2 in which the positioning structure 13 is moved away from the main body 2 and brought into position adjacent to the satellite 5.

Fig. 1, 2 and 3 show as an example the deployment structure 14 having a type with arms pivotally connected between the main body 2 and the straight guide of the positioning structure 13.

In the example shown in FIG. 1, 2 and 3, the motion system 11 is formed by two motion subsystems with identical architectures, each formed by an orientation structure 12 carrying an RCS cluster 9 with two attitude control thrusters 9, a positioning structure 13 supporting a single structure 12 for orientation, and a structure 14 for deployment between the positioning structure 13 and the main body 2 of the space tug 1.

The two motion subsystems are symmetrically radially positioned on the main body 2 so as to maintain a neutral operating mode relative to the center of mass of the space system and to provide full control of the position and direction of the thrusters 9 for attitude control in order to maximize the efficiency of the resulting thrust.

Fig. 5 shows a flowchart of operations implemented by the attitude control computer 8 to control the position, orientation and operating state of the attitude control thrusters 9 to adjust and maintain the attitude of the space tug 1 and change its orbit.

To this end, the mission of space tug 1, which is known a priori, is conceptually divisible into operational phases comprising a preliminary step of docking with satellite 5 to be towed, followed by one or more operational phases to achieve the mission objective, such as maintenance pre-assigned guidance of satellite 5, possibly with inserted, depending on the specific mission, stages of orbit transfer and attitude stabilization.

The attitude control computer 10 is programmed to carry out the mission intended for space tug 1 and to optimize mid- to long-term operational steps, assuming that the orbit transfer steps are optimized based on criteria established a priori, depending on the specific mission, or during the mission , for example, using one or different specialized neural networks suitably trained on the ground.

Since expansion to more complex scenarios is straightforward, for the sake of brevity the description below is based on the assumption that the Space Tug 1 mission consists solely of the preliminary docking/capture phase of Satellite 5 and a single operational phase subsequent to the preliminary phase. It is also assumed that once the space tug 1 has docked or captured the satellite 5, the space system 6 that is thus formed behaves in a manner similar to a rigid body, thus allowing a coordinate system known a priori to be considered integral to the space system 6 , to control the space system 6.

- 5 043355

The operating stage comprises, firstly, stabilizing the spatial position of the space system 6 in accordance with mission requirements, for example, guidance, and with a selected optimization criterion, for example, minimizing fuel consumption, guidance errors, etc. For convenience of description, hereinafter the acronym FS will be used to refer to the attitude stabilization sub-step, and the acronym FR will be used to refer to the steady operation sub-step, which begins when the attitude stabilization sub-step ends, i.e., when stabilization space system 6 has been achieved and which is supported by the computer 10 for attitude control throughout the FR sub-step by performing attitude control steps of a known type and therefore not described in detail.

According to an aspect of the present invention, the implementation of the FS sub-step is controlled by the attitude control computer 10 based on a neural network previously trained on the ground. For this purpose, it is possible to use already available technology, for example that described in CN 109625333 A, which concerns the stabilization of a space system 6, however, without considering additional objectives such as minimizing fuel consumption. In sub-stage FS, the attitude control thrusters 9 are positioned and oriented according to a default configuration set a priori.

In the scenario under consideration, the use of a neural network can be especially useful as an alternative to traditional control methods, since both the center of mass of the space system 6 and the relative moments of inertia are not known a priori.

During the FS sub-stage, the neural network is designed to efficiently solve a standard control problem, which can be described mathematically as follows:

min\ f[/ ₀ ,х(/ ₀ ),/,,*(/,)]+ [£[x(/),«(/),/]Л [

LJ (i) x(t) = f(x(t), ₍₂₎ #(*(/), «(/),/)<0 φ^,χαρ,ί^χα^/ο ₍₄₎ where expression (1) is the goal of optimization, for example, minimizing fuel consumption, pointing errors, etc.; vector equation (2) is a representation of the dynamic state of ^{the X} O of the considered space system 6 (position and angular velocity relative to the assigned coordinate systems), at each moment time ¹ as a function of its time derivative ^(0 (angular velocity and acceleration of the space system 6), as well as the control vector formed by the forces and torques exerted as a whole on the space system 6 at any time ¹ .

Expressions (3) and (4) respectively define restrictions on the state/control variables, as well as on the initial and final states (if necessary) of the space system 6, at times and /

The solution to the problem defined by equations (1)-(4), derived by the neural network, is optimized relative to the intended (default) configuration of thrusters 9 for attitude control. However, since, according to the present invention, the configuration of the attitude control thrusters 9 is adjustable, the parameters of the space system 6, namely the position and orientation of the attitude control thrusters 9, in turn, are considered from the point of view of additional (although and time-independent) control variables. Thus, the range of solutions expands, leading to a new optimization problem, which follows:

min J f[/ ₀ ,x(/ ₀ ),/,,l:(/,)] + fz[x(/), u(t),P,y,t\dt\ ^LJ (5) x( f) = f(x(f),u(f),P,y,t) ₍₆₎ g(x(f),u(f),P,y,f)<0 (7) <p[ t _o ,x(t _o ),t _f ,x(t _f )/o ₍₈₎

- 6 043355 where vectors P and 7 (implicitly implied in formulas (1)-(4)) represent, respectively, the positions and orientations of the thrusters 9 for attitude control (no longer considered constants, but structural parameters of the space system 6, which can be defined in the context of the relevant areas expressed by the conditions (7)). The optimization problem defined by (1)-(4) will be referred to hereinafter as a reduced optimization problem (PR), while the optimization problem defined by (5)-(8) will be referred to as an extended optimization problem (PE ).

Optimal solutions to the extended PE optimization problem are generally, regardless of the specific objective function chosen, superior to optimal solutions to the reduced PR optimization problem. In formulas:

Since the spacecraft 1 is equipped with a motion system 11 to determine the operating mode of the attitude control thrusters 9, the attitude control computer 10 is programmed to calculate, for each attitude control thruster 9, after docking, the permissible positions and orientations. (regions P and 7 in the extended PE optimization problem).

It is also worth noting that the short solution to the extended PE optimization problem is much more complex compared to the solution to the reduced PR optimization problem. Simultaneous optimization of the stabilization of the space system 6 and the configuration of the thrusters 9 for attitude control will therefore be unrealistic, and for this reason the reconfiguration (RC) sub-step of the thrusters 9 for attitude control is introduced, and an iterative process of optimizing the configuration of the thrusters 9 for attitude control shown in the flowchart of FIG. 4 is proposed and described below.

As shown in FIG. 4, the process of optimizing the configuration of thrusters 9 for attitude control practically contains the following operations, which will be described in detail below:

1. receiving/updating input data for the work step; (block 100),

2. stabilization of space system 6 (block 110),

3. receiving/updating input data to optimize the layout of low-thrust engines 9 for attitude control (block 120),

4. optimization of the position and orientation of the low thrust motors 9 for attitude control (block 130), and

5. (physically) adjusting the position and orientation of the low thrust motors 9 to control the spatial position (block 140).

Operations 1-5 are performed only in the operational stage of the space system 6, therefore, as shown in the dashed line flowchart, the exit of the space system 6 from the operational stage instructs the immediate emergency termination of the execution of the stage at this implemented moment (general stopping rule).

Operation 1.

Receive/update input data for a work step.

Operation 1 aims to obtain or, during the optimization process, update the operating scenario of the space system 6 in the operational phase.

Operation 1 contains the following steps:

1.1 obtaining/updating requirements for operational steps, for example, maintaining a given pointing angle of the on-board optical system of satellite 5, and optimization criteria, for example, minimizing fuel consumption;

1.2 obtaining/updating (available) data on the initial/current state of the space system 6, such as the position, orientation and angular velocities of the space system 6 in a coordinate system integrated with the space system 6;

1.3 determining the position and orientation of the satellite 5 relative to the space tug 1, so as to enable the geometric configuration of the space system 6 to be determined;

1.4 obtaining the current positions and orientations of the thrusters 7 for attitude control (at the initial stage of the optimization process, design nominal values/default values).

As for step 1.1, the requirements for the work step and the optimization criterion are known when the optimization process is initiated. They may change later if a need for updating is identified, for example due to changes in conditions detected by the sensor system 8, or due to the occurrence of other unpredictable conditions.

- 7 043355

Determining updates for the operational step, i.e., obtaining updated data to execute (or execute again, if necessary) operations 2 and 3, is conveniently performed through a specialized neural network previously trained on the ground.

Step 1.3 is carried out through a sensor system, for example in the form of optical sensors, image capture and recognition sensors, etc., after docking, if necessary. For example, in a case in which the pointing function of an optical instrument on board a captured satellite must be restored.

Operation 1 is performed at the beginning of the optimization process and thereafter only if condition 1 described below occurs. Steps 1.1), 1.2), 1.3) and 1.4) have the purpose of initializing (or reinitializing, if necessary) operation 2 and/or passing input data to operation 3.

Operation 2.

Stabilization of the space system.

Operation 2 is aimed at performing sub-stage FS, i.e., stabilizing the spatial position of the space system 6 in accordance with the requirements of the operating stage and with the selected optimization criterion, i.e., solving the abbreviated PR optimization problem when the current orientation and positions of the engines 9 low thrust for spatial position control are considered constant.

Operation 2 is easily performed by a neural network pre-trained on the ground.

The neural network is enabled by importing the information obtained from operation 1 through steps 1.1, 1.2, 1.3 and 1.4.

Operation 3 is then performed when the space system 6 is able to satisfy the operational phase requirements and the selected optimization criterion, for example, minimizing fuel consumption.

Operation 3.

Receiving/updating input data to optimize the layout of thrusters for attitude control.

Operation 3 aims to prepare input data that can be updated during the optimization process required to perform the RC sub-step, i.e., optimizing the position and orientation of the thrusters 9 for attitude control.

Operation 3 contains the following steps:

3.1. extracting a subset of the attitude control forces and torques applied to the space system 6 during the control stages of the FR steady-state operating stage; And

3.2 determination of acceptable areas of position and orientation of low thrust engines 9 for attitude control and any updates.

The subset of attitude control forces and torques required to execute step 3.1 is obtained by following an appropriate statistical sampling of the attitude control forces and torques applied to the space system 6 during a sufficiently long sampling period during sub-step FR, i.e., stable operation of the space system 6.

To this end, the attitude control computer 10 is programmed to extract a predetermined size subset of the resulting forces and torques acting on the space system during attitude control over a sufficiently long sampling period during the FR sub-step.

For convenience, the attitude control computer 10 may be programmed to extract the attitude control forces and torques acting on the space system 6 during the most critical attitude control stages of the FR sub-stage, and which correspond to, for example, the maximum and minimum the values of the modules of the attitude control forces and torques, the maximum required flow rate, etc., as well as the attitude control forces and torques acting most frequently on the space system 6 during sub-step FR.

To ensure that the subset of the extracted attitude control forces and torques is as representative as possible of the forces and moments actually acting on the space system 6 during the attitude control steps that occur during the FR substep, the attitude control computer 10 position control can be conveniently programmed to select attitude control steps that maximize the total difference in attitude control forces and, likewise, torques. For this purpose, various formulations can be applied, for example, by maximizing, using selected weighting factors, the standard deviation of forces and moments, the sums of the corresponding distances expressed by L1, L2 norms, etc. Useful methods and algorithms are available for this purpose, such as K-means clustering.

Step 3.2 primarily aims to identify the valid positions and orientations of each thruster 9 for attitude control, which define the areas

- 8 043355 vectors P and in the extended PE optimization problem. Since this information is not known a priori, since it is unpredictable what exact position and orientation the satellite 5 will be in relative to the space tug 1, the valid positions and orientations for each thruster 9 for attitude control are conveniently determined by image recognition methods.

Step 3.2 has the additional purpose of identifying any updates on the availability of the attitude control thrusters 9, this information being necessary for the execution of step 4. In fact, it may happen, for example, that the attitude control thruster 9 signals a possible malfunction, in which case it should be suitably replaced by one or different attitude control thrusters 9 that operate under more reliable conditions. A further example may relate to the need to redistribute the use of thrusters 9 for attitude control to avoid overloading some of them. Step 3.2 is also, for convenience, carried out using a neural network pre-trained on the ground.

The attitude control forces and torques selected in step 3.1, the identification of serviceable attitude control thrusters 9, and the determination of the corresponding position and orientation regions calculated in step 3.2 are the basic elements for the discretized (small-sized) formulation of the extended the PE optimization problem used in the RC substep described later in Step 4.

At the end of operation 3, the attitude control computer 10 is programmed to check for the occurrence of the operating condition specified in the flowchart by condition expression 1 (block 150), which is determined by execution of operation 3, resulting or failing to result. resulting in a modified operating scenario of the space system 6, in particular identifying a different subset of attitude control forces and torques, or the elimination of one or more thrusters 9 for attitude control, compared to those existing before step 3 in the optimization process .

If condition 1 is determined to occur, then the attitude control computer 10 is programmed to perform step 4 described below, otherwise step 1 is expected to be repeated after a predetermined period of time has passed (block 160).

During the first execution of operation 3, condition 1 is always determined to have occurred, while in subsequent iterations condition 1 may not occur, in which case there is no reason to re-execute operation 4, since it will fall into the operation scenarios already discussed, thus, creating a possible loop. Therefore, operation 4 is activated only if condition 1 occurs.

Operation 4.

Optimization of thruster positions and orientations for attitude control.

Operation 4 aims to optimize the positions and orientations of the available attitude control thrusters 9 identified in operation 3, i.e., the computational aspects of the RC sub-step, during exit from the RC sub-step, i.e., the movement of the thrusters 9 for attitude control are put into practice in step 5 described later in this document.

In operation 4, the extended PE optimization problem is solved, where the vectors P and ?, indicating the position and orientation of each thruster 9 for attitude control, are no longer considered constants, but system parameters (independent of time) that can change in related areas, identified in operation 3.

The adopted optimization model/algorithm is entered (from step 3) with a representative subset of attitude control forces and torques, available attitude control thrusters 9, thrust constraints for each of the available attitude control thrusters 9, as well as any restrictions on the time of use, or the traction provided, and/or additional conditions.

It is worth noting that a representative subset of the attitude control forces and torques is used for convenience, rather than a subset including the attitude control forces and torques of all actually selected control stages, in order to significantly reduce the size (and therefore difficulty) of the extended PE optimization problem.

An extended PE optimization problem (discretized according to a subset of selected forces and torques) can be formulated in a mathematical programming language, with

- 9 043355 using a nonlinear or partial integer programming (MIP) model, and solved using global optimizers (GO) or MIP. Alternatively, an advanced PE optimization problem can be solved by a specialized neural network pre-trained on the ground (using specialized models, algorithms and optimizers). In this case, operations 3 and 4 can be combined into a single operation performed by a specialized neural network previously trained on the ground.

When step 4 has been completed, the attitude control computer 10 is programmed to check whether the operating condition indicated in the flowchart by condition expression 2 (block 170) determined by the decision identified in step 4 is or is not considered to be the best. compared to the solutions identified in the same operation 4 in previous iterations of the process of optimizing the configuration of thrusters 9 for attitude control, based on the considered optimization criterion.

If, for example, the optimization criterion is the minimization of fuel consumption, condition 2 is determined by the configuration of the attitude control engines 9 identified in step 4, providing the opportunity to obtain fuel savings compared to the configurations of the attitude control engines 9 identified in the same operation 4 in previous iterations of the process of optimizing the configuration of thrusters 9 for attitude control.

If condition 1 is determined to occur, then the attitude control computer 10 is programmed to perform step 5 described below, otherwise step 1 is expected to be repeated after a predetermined period of time has passed (block 160).

Operation 5.

(Physical) modification of thruster positions and orientations for attitude control.

Operation 5 aims to modify the positions and orientations of thrusters 9 for attitude control based on the output of operation 4.

To this end, the attitude control computer 10 is programmed to control the motion system 11 to instruct the attitude control thrusters 9 to assume the positions and orientations calculated in step 4.

Based on what has been described above, it is possible to evaluate the advantages that the present invention can achieve.

In particular, the present invention provides the ability to provide an electronic response control system that allows improvements to be made both in terms of the efficiency of optimizing the fuel consumption of the orbital servicing spacecraft and in terms of the number of attitude control thrusters required for attitude control an orbital servicing spacecraft, and a space system formed by an orbiting servicing spacecraft and a docked or captured space vehicle or object.

An electronic response control system may also be used, for example, on a single spacecraft such as a satellite, in order to optimize fuel consumption during various phases of use, or in order to optimally reconfigure thrusters for attitude control in the event of failure of one or more of them.

In addition, the neural network used can be designed to learn itself, improving its responsiveness over time. With the current state of technology, it is envisaged that it can be trained again from the ground using data detected during use on board and re-updated via the uplink.

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Claims (8)

CLAIM 1. Orbital service spacecraft (1), containing: an engagement system (4) to engage a space vehicle or object (5) that is to be serviced or towed so as to form a space system (6); and an electronic response control system (7) to instruct the spacecraft (1) to rotate about the longitudinal, vertical and transverse axes to control the attitude and displacement of the spacecraft (1) along specified trajectories, to instruct the spacecraft (1) to perform specified maneuvers; The electronic response control system (7) contains: a sensor system (8) to enable direct detection of physical quantities or indirect calculation thereof based on the detected physical quantities comprising one or more of position, attitude, angular velocities, available fuel, geometric features and on-board system state; low-thrust engines (9) for controlling spatial position, installed in such a way as to provide the ability to regulate their positions and orientations; and an attitude control computer (10) in communication with the sensor system (8) and the attitude control thrusters (9), programmed to receive data from the sensor system (8) and control, based on the received data, positions, orientations and operating states of thrusters (9) for attitude control so as to control the attitude and position of the spacecraft (1); The attitude control computer (10) is programmed to instruct the spacecraft (1) to perform a predetermined mission comprising an engagement step in which the engagement system (4) and attitude control thrusters (9) are controlled by the computer (10) to attitude control to engage the space vehicle or object (5) to be serviced or towed, and one or more operating stages, each of which has thrusters (9) for attitude control the position is controlled by a computer (10) to control the spatial position to satisfy one or more requirements set for the operating step; each working stage may contain at least one stabilization sub-stage (FS), during which the spatial position of the space system (6) is stabilized in accordance with the requirements of the working stage and with a given optimization criterion, characterized in that each stabilization sub-stage (FS) is followed by sub-stage (FR) of stable operation, which begins when the sub-stage (FS) of stabilizing the spatial position of the space system (6) ends; and at each operating step, the attitude control computer (10) is further programmed to optimize the configuration of the attitude control motors (9) in accordance with the requirements of the operating step, implementing an iterative process of optimizing the configuration of the attitude control motors (9), containing: operation 1 containing: 1.1 obtaining/updating requirements for the work step and optimization criterion; 1.2 obtaining/updating the current state of the space system (6), determined by the position, orientation and angular velocities of the space system (6) in the coordinate system of the space system (6); 1.3 determining the position and orientation of the engaged space vehicle or object (5) relative to the spacecraft (1) so as to enable the geometric configuration of the space system (6) to be determined; And 1.4 determination of the current positions and orientations of the low thrust engines (9) to control the spatial position; operation 2 containing: stabilization of the spatial position of the space system (6) in accordance with the requirements for the operating stage and with the optimization criterion based on the current state and geometric configuration of the space system (6) and the current positions and orientations of the thrusters (9) for attitude control determined at the stage 1.4; operation 3 containing: 3.1 determination of forces for controlling spatial position and torques, acting - 11 043355 operating on the space system (6) during a sufficiently long period of sampling phase (FR) of stable operation; And 3.2 determination of permissible areas of positions and orientations of low-thrust engines (9) for attitude control and availability of low-thrust engines (9) for attitude control; operation 4 containing: optimizing the positions and orientations of the available attitude control thrusters (9), based on the optimization criterion and considering the positions and orientations of the attitude control thrusters (9) as system variables that can vary in the associated allowable regions defined by stage 3.2; operation 5 containing: modifying the positions and orientations of the attitude control thrusters (9) to cause the attitude control thrusters (9) to adopt the optimized positions and orientations calculated in step 4.1. 2. Orbital service spacecraft (1) according to claim 1, wherein the computer (10) for controlling the spatial position is additionally programmed so that: when step 3 has been completed, check (150) for the occurrence of the first operating condition determined by performing step 3 that does or does not result in a change in the operating scenario of the space system (6) determined through a plurality of attitude control forces and torques, applied to the space system (6), and/or through the availability, or lack thereof, of one or more thrusters (9) for attitude control, compared to the operating scenario before performing step 3 in the iterative process of optimizing the configuration of the engines (9) low thrust for spatial position control; if the first operating condition is determined to have occurred, perform step 4 (130); and if the first operating condition is determined to have not occurred, repeat step 1 after the predetermined period of time (160) has elapsed. 3. Orbital service spacecraft (1) according to claim 1 or 2, wherein the computer (10) for controlling the spatial position is additionally configured to: when step 4 has been completed, check (170) for the occurrence of a second operating condition determined by execution of step 4 that has or has not resulted in an improvement determined based on the optimization criterion compared to previous executions of steps 4 in the iterative engine configuration optimization process (9) low thrust for attitude control; if the second operating condition is determined to have occurred, perform step 5 (140); and if the second operating condition is determined to have not occurred, repeat step 1 after the predetermined period of time (160) has elapsed. 4. The orbital servicing spacecraft (1) according to any of the preceding claims, wherein the attitude control computer (10) is further programmed to implement one or more of the stabilization sub-step (FS), determining the need for updating according to step 1.1 in operation 1, operation 2 and step 3.2 in operation 3 through the same or different neural networks pre-trained on the ground. 5. An orbital servicing spacecraft (1) according to any of the preceding paragraphs, wherein the attitude control computer (10) is further programmed to determine the position and orientation of the space vehicle or object (5) that is/is to be serviced /o or towed/o, relative to the spacecraft (1) and the geometric configuration of the space system (6) according to step 1.3 in operation 1 based on data output by the sensor system (8). 6. The orbital service spacecraft (1) as claimed in any one of the preceding claims, wherein the attitude control computer (10) is further programmed to perform step 3 when the space system (6) satisfies the operational step requirements and optimization criterion. 7. The orbital service spacecraft (1) as claimed in any one of the preceding claims, wherein the attitude control computer (10) is further programmed to perform step 3.1 in step 3, retrieving a subset of the attitude control forces and torques applied to the spacecraft system (6) and representing the attitude control forces and torques applied to the space system (6) during the control steps that occurred during steady operation (FR). 8. Orbital servicing spacecraft (1) according to claim 7, wherein the computer (10) for attitude control is additionally programmed to retrieve subsets -