Space debris cleaning mechanism based on electromagnetic catapult and debris cleaning method

Abstract

The application discloses a space debris cleaning mechanism based on electromagnetic ejection and a debris cleaning method, and relates to the technical field of spacecraft control research.The application is characterized in that flexible grippers are symmetrically arranged on the two sides of a service spacecraft, the flexible grippers are connected to corresponding spinning wheels arranged on brushless motors through ropes, and electromagnetic coils are arranged on the side walls of the flexible grippers and the inner side walls of the service spacecraft corresponding to the flexible grippers.In use, the two electromagnetic coils are oppositely arranged, and the current of the two electromagnetic coils is in the same direction, so that the flexible grippers are ejected to the space debris; meanwhile, the brushless motors generate different resistances according to the orientation of the debris, so that the spinning wheels rotate the ropes to stretch the flexible grippers to the space debris, and then the rudders and electromagnets arranged on the flexible grippers are used to adsorb and capture the space debris, thereby avoiding the problem that the spring is not easy to control and unstable in use, and the efficiency of capturing the debris in space is high, and the high-quality cleaning of the debris in the space can be ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of spacecraft control research, and particularly relates to a space debris cleaning mechanism based on electromagnetic ejection and a debris cleaning method. BACKGROUND

[0002] With the development of space technology, the number of spacecraft launched increases year by year, and the number of malfunctioning spacecraft or space debris caused thereby increases day by day, which seriously endangers the safety of space assets. In order to reduce the collision probability of on-orbit spacecraft and other space assets, maintain limited orbital resources, and solve the problem of global cleaning of multi-directional space debris, each space power is establishing its own space debris environment model to detect and warn space debris. The existing space debris cleaning methods focus on space manipulator capture, flying net capture, harpoon capture, tethered robot capture, electric power tether capture, and electrostatic force capture. These capture methods mostly use approximation capture, and most capture mechanisms can only capture a single target at a time, with limited capture range, long capture time, high risk, difficulty in capturing high-maneuvering non-cooperative targets, and difficulty in stabilizing the attitude after capture.

[0003] Currently, some researchers have proposed a space tethered robot that approaches the space debris capture position near the space debris and captures the debris by closing the operation gripper. The capture mechanism of this research has one capture gripper, which approaches the space debris and demonstrates the capture of the debris by the capture gripper. This research has an operation gripper installed on the side, which cannot capture multiple debris in parallel, can only capture one piece of debris at a time, has a long capture time and high energy consumption, and cannot capture multiple large debris in series, making single gripper operation difficult and causing problems such as debris spinning and orbit change during capture. This research cannot cover all aspects, has a small capture range, and requires constant adjustment of the attitude of the service spacecraft to keep the debris within the target range of the operation gripper when the relative angle and position of the debris to the service spacecraft are large, requiring high attitude adjustment capability and attitude stability of the tracker. This research uses a spring and a motor as the power mechanism. Because the spring has a large stiffness coefficient, it is difficult to compress the spring during recovery of the operation gripper, which has a long capture time, high delay, and large error. The operation gripper of this research is a mechanical gripper, which is prone to rigid collision with the debris and relative motion with the debris during recovery, causing problems such as attitude instability and loss of control of the service spacecraft, debris falling off, and the like.

[0004] Therefore, the existing research mainly uses a spring to eject a single gripper to capture debris. Because the spring has a large stiffness coefficient and is difficult to control when compressed, it is difficult to control the gripper and capture multiple debris in series, resulting in low efficiency when capturing debris in space and difficulty in ensuring high-quality cleaning of debris in space. SUMMARY

[0005] The embodiment of the present application provides a space debris cleaning mechanism based on electromagnetic ejection and a debris cleaning method, which can solve the problem of low efficiency in capturing space debris and difficulty in ensuring high-quality cleaning of the debris in the space.

[0006] The embodiment of the present application provides a space debris cleaning mechanism based on electromagnetic ejection, which comprises a service spacecraft for space debris cleaning, and further comprises two brushless motors arranged side by side in the interior of the service spacecraft, and a spinning wheel is arranged on the output shaft of each brushless motor.

[0007] Flexible claws are symmetrically arranged on the two sides of the service spacecraft, and each flexible claw is connected with the corresponding spinning wheel through a rope.

[0008] The side wall of each flexible claw and the inner side wall of the corresponding service spacecraft are both provided with an electromagnetic coil; when the currents in the pair of electromagnetic coils arranged oppositely are set to be in the same direction, the electromagnetic force repelling each other is generated to eject the flexible claw, and the flexible claw is simultaneously pulled through the rope; when the currents in the pair of electromagnetic coils arranged oppositely are set to be in the opposite direction, the electromagnetic force attracting each other is generated to recover the flexible claw, and the flexible claw is simultaneously pulled through the rope to be recovered.

[0009] A steering engine is arranged on each flexible claw, which is used to control the opening and closing of the flexible claw during the ejection of the flexible claw, so as to capture the debris within a specific direction and distance.

[0010] Preferably, the two inner side walls of the service spacecraft are symmetrically provided with circular ring grooves, and the rope wound on each spinning wheel passes through the corresponding circular ring groove and is connected with the corresponding flexible claw.

[0011] Preferably, the two sides of the service spacecraft are symmetrically provided with mechanical buckles, which are used to fix the corresponding flexible claws.

[0012] Preferably, an electromagnet is arranged in the interior of the flexible claw.

[0013] Preferably, an infrared sensor is arranged on the flexible claw.

[0014] Preferably, a flywheel is arranged in the interior of the flexible claw, which is used to adjust the posture of the flexible claw when the flexible claw captures the debris.

[0015] Preferably, a plurality of debris detectors are arranged on the service spacecraft.

[0016] The embodiment of the present application also provides a space debris cleaning method of the space debris cleaning mechanism based on electromagnetic ejection.

[0017] After the service spacecraft detects the plurality of debris, the relative directions and positions of the two most easily captured debris are determined, and the attitude of the service spacecraft is adjusted so that the two debris are located in the capture domains of the two flexible claws;

[0018] The controller obtains the resistance generated by the brushless motor according to the average power, action time and distance of the electromagnetic force during the electromagnetic ejection process; and the debris detector obtains the electromagnetic force and electromagnetic torque required by the oppositely arranged electromagnetic coils during the electromagnetic ejection according to the position of the debris.

[0019] The currents in the oppositely arranged pair of electromagnetic coils are set to be in the same direction to generate repulsive electromagnetic force to eject the flexible claws; the rudders driving the flexible claws to grip the debris and the electromagnets to adsorb the debris are controlled.

[0020] The brushless motor drives the flyer wheel to pull back the rope, and the currents in the oppositely arranged pair of electromagnetic coils are set to be in opposite directions to generate attractive electromagnetic force, which cooperates with the rotation of the flyer wheel to recover the flexible claws, thereby completing the cleaning of the space debris.

[0021] The embodiment of the present application provides a space debris cleaning mechanism and a debris cleaning method based on electromagnetic ejection, which has the following advantages compared with the prior art.

[0022] The flexible claws are symmetrically installed on the two sides of the service spacecraft, and the flexible claws are connected to the corresponding flyer wheels arranged on the brushless motor through ropes; meanwhile, the electromagnetic coils are oppositely arranged on the side walls of the flexible claws and the inner side walls of the service spacecraft corresponding to the flexible claws. In use, the oppositely arranged electromagnetic coils eject the flexible claws to the space debris with the same direction of the current, and the brushless motor generates different resistance according to the position of the debris to make the flyer wheel rotate and stretch the rope to the space debris. Unlike the spring ejection of a single claw to capture the space debris, the present application uses two electromagnetic coils oppositely arranged on the side walls of the flexible claws and the inner side walls of the service spacecraft corresponding to the flexible claws to eject and recover the two claws by electromagnetic ejection, and simultaneously cooperates with the brushless motor and the flyer wheel. Then, the rudders and electromagnets arranged on the flexible claws adsorb and capture the space debris, thereby avoiding the unstable problem of the spring in use, improving the efficiency of capturing the space debris, and ensuring the high-quality cleaning of the debris in the space.

[0023] Moreover, the circular hole slot is arranged on the inner side of the service spacecraft, the flexible claws are connected to the flyer wheels through the ropes passing through the circular hole slot, and the flexible claws can serially capture the debris in the whole domain, thereby greatly improving the capture range. BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1 A schematic diagram of the overall structure of a space debris cleaning mechanism and debris cleaning method based on electromagnetic ejection provided by an embodiment of the present application is shown in the figure.

[0025] Fig. 2 A multi-debris parallel capture method schematic diagram of a space debris cleaning mechanism and debris cleaning method based on electromagnetic ejection provided by an embodiment of the present application is shown in the figure.

[0026] Fig. 3 A debris serial capture method schematic diagram of a space debris cleaning mechanism and debris cleaning method based on electromagnetic ejection provided by an embodiment of the present application is shown in the figure.

[0027] Wherein: 1, infrared sensor, 2, flywheel, 3, electromagnet, 4, electromagnetic coil, 5, steering engine, 6, circular ring hole groove, 7, service spacecraft, 8, debris detector, 9, flexible paw, 10, rope, 11, spinning wheel, 12, brushless motor, 13, space debris, 14, mechanical buckle. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0029] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0030] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0031] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0033] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0034] See Figs. 1-3 This invention provides a space debris removal mechanism based on electromagnetic ejection, including a service spacecraft 7, a debris detector 8, a flexible gripper 9, a rope 10, a spinning wheel 11, an electromagnetic coil 4, a brushless motor 12, an infrared sensor 1, a flywheel 2, a servo motor 5, an electromagnet 3, a circular slot 6, and a mechanical buckle 14. The spinning wheel 11 is installed inside the service spacecraft 7 and is driven by the brushless motor 12 installed at the bottom of the service spacecraft 7. The rope wound on the spinning wheel 11 passes through the circular slot 6 and is connected to the flexible gripper 9. The electromagnetic coil 4 is installed on the inner wall of the service spacecraft 7 and the side wall of the flexible gripper 9. By controlling the current in the electromagnetic coil 4, the magnitude and direction of the electromagnetic force are changed, thereby performing electromagnetic ejection and electromagnetic adsorption on the flexible gripper 9. The electromagnet 3 is installed at the center of the flexible gripper 9 and adsorbs debris after being energized. The flexible gripper 9 is connected to the servo motor 5, which drives the opening and closing of the flexible gripper 9.

[0035] The global debris removal method of the space debris removal mechanism based on the electromagnetic ejection provided by the present application, taking parallel capture as an example, comprises the following steps:

[0036] S1: The debris detector 8 located on the service spacecraft 7 detects a plurality of debris, and determines the relative direction and relative position of the two most easily captured debris.

[0037] S2: The controller gives instructions according to the positions of the two debris, and the flywheel inside the service spacecraft 7 adjusts the attitude of the service spacecraft 7 to a suitable position, so that the two debris are located in the capture domain of the two flexible claws 9.

[0038] S3: The controller calculates the resistance size required by the brushless motor 12 according to the average power of the electromagnetic force, the action time and the distance from the relative debris during the electromagnetic ejection process.

[0039] S4: The flexible claw 9 capture dynamics equation is established according to the debris position obtained by the debris detector 8, the correction amount e of the expected pose of the electromagnetic ejection mechanism is estimated, and the system model uncertainty Further, the electromagnetic force and electromagnetic torque Q required for the electromagnetic ejection mechanism to be stable are calculated.

[0040] S5: The mechanical buckle inside the flexible claw 9 is opened, the flexible claw 9 is released, and the currents of the electromagnetic coils 4 located inside the flexible claw 9 and the inner wall of the service spacecraft 7 are in the same direction, generating repulsive electromagnetic force to eject the flexible claw 9.

[0041] S6: When the debris is located in the capture domain of the flexible claw 9, the attitude of the flexible claw 9 is adjusted through the infrared sensor 1 and the flywheel 2 inside the flexible claw 9, so that the contact point of the flexible claw 9 and the debris is optimal.

[0042] S7: The flexible claw 9 is driven and controlled by the rudder 5, the flexible claw 9 grips the debris, and the electromagnet 3 at the center of the flexible claw 9 is energized to adsorb the debris.

[0043] S8: When the two flexible claws 9 on both sides grip the debris, the force between the debris and the flexible claw 9 causes the attitude of the service spacecraft 7 system to change, at which time the attitudes of the flywheels 2 inside the two flexible claws 9 on the front and back sides are adjusted respectively to keep the overall attitude of the service spacecraft 7 system stable.

[0044] S9: The brushless motor 12 drives the spinning wheel 11 to pull back the rope 10, and reverses the current in the electromagnetic coils 4 located inside the flexible claw 9 and the inner wall of the service spacecraft 7, generating attractive electromagnetic force, cooperating with the spinning wheel 11 to rotate to recover the flexible claw 9.

[0045] In step S4, the resistance F generated by the brushless motor 12 can be calculated d is:

[0046]

[0047] Wherein: L is the relative distance between the debris and the flexible gripper 9, which is calculated by the debris detector 8; P is the average acting power during the electromagnetic ejection process; t is the average acting time.

[0048] The debris capture dynamics equation of the flexible gripper 9 is:

[0049]

[0050] Wherein: l is the length of the rope 10; α is the in-plane angle of the rope 10; β is the out-of-plane angle of the rope 10; θ and ψ are the attitude angles of the space electromagnetic ejection mechanism; M is the system inertia matrix of the service spacecraft 7; N is the nonlinear velocity related term; G is the gravity related term; Q is the control force and control torque of the space electromagnetic ejection mechanism; τ is the interference term of the rope 10.

[0051] The method for calculating the correction amount e of the desired pose of the space electromagnetic ejection mechanism is:

[0052]

[0053] Wherein: n is the number of contact points between the space electromagnetic ejection mechanism and the debris.

[0054]

[0055] Wherein: s is the Laplace operator; F ei is the ith contact impact force; M d , B d and K d are the inertia matrix, damping matrix and stiffness matrix of the debris capture part.

[0056] The specific method for estimating the uncertainty of the space electromagnetic ejection mechanism system model is:

[0057]

[0058] Wherein: is the RBF neural network output weight, and its update law is F ρ is any positive definite matrix, k p > 0 is a design parameter, ξ d is the desired system state, Λ is any positive definite matrix, Φ d ​Radial basis function (RBF) output value.

[0059] The formula for calculating the stable electromagnetic force and electromagnetic moment Q of the space electromagnetic ejection mechanism is:

[0060]

[0061] Wherein, K is a positive definite matrix, M0, N0 and G0 are the nominal values of the matrices M, N and G in the system dynamics equation respectively, η=(η δ +η τ )·sgn(r) is a robust term, sgn(·) is a sign function, η δ is an upper bound of the RBF neural network estimation error, and η τ is an upper limit of the rope disturbance.

[0062] The space debris cleaning mechanism based on electromagnetic ejection provided in the application utilizes electromagnetic force as driving force, ejects the flexible gripper 9 through the action of electromagnetic force, cooperates with the flyer wheel 11 and the brushless motor 12 to capture and recycle multiple / single debris in parallel / series, adjusts the posture by the flywheel 2 and the infrared sensor 1 at each place in the mechanism, and keeps the mechanism posture stable; the debris cleaning method utilizes the characteristics of high controllability and strong stability of electromagnetic force, breaks through the problems of long time consumption, high energy consumption, low efficiency and poor posture stability in the traditional debris removal mode, can efficiently recycle multiple debris or large mass debris, reduces the recycling time and cost, and improves the stability of the system and the reliability of debris removal; can be applied to the field of future satellite orbit debris cleaning, and has important significance for the operation of China's space spacecraft.

[0063] The two flexible grippers are installed on the front and rear sides of the service spacecraft, two debris around the tracker can be ejected and captured in parallel at the same time, the capture time is short, the cleaning efficiency is high, and fuel is saved.

[0064] The two flexible grippers are installed on the front and rear sides of the service spacecraft, and the two flexible grippers can capture large mass debris in series through the controller, the operation precision is high, and the capture capacity is strong.

[0065] The two flexible grippers are installed on the front and rear sides of the service spacecraft, and the two flexible grippers can capture large mass debris in series through the controller, the operation precision is high, and the capture capacity is strong.

[0066] The present application can preliminarily adjust the ejection direction of the flexible hand claw through electromagnetic torque, and install infrared sensors and flywheels inside the service spacecraft and the two flexible hand claws, so that the attitude of the spacecraft can be adjusted quickly after the flexible hand claw captures the debris, and the stability of the service spacecraft can be maintained.

[0067] The present application adopts electromagnetic coils and brushless motors as power mechanisms, changes the current direction of the flexible hand claw and the electromagnetic coil in the service spacecraft when the flexible hand claw is launched, so that the two repel each other to perform ejection operation, changes the current direction of the flexible hand claw and the electromagnetic coil in the service spacecraft when the flexible hand claw is recovered, so that the two attract each other to perform recovery operation, and the recovery difficulty is small, the energy consumption is small, and the efficiency is high.

[0068] The operation hand claw used in the present application is a flexible hand claw, which is not easy to collide rigidly with the debris, and an electromagnet is installed in the center of the flexible hand claw, which has an adsorption effect on the captured debris, so that the relative motion between the debris and the flexible hand claw is not easy to occur, the attitude of the spacecraft is stable, and the reliability of the capture is improved.

[0069] The above-mentioned embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. An electromagnetic catapult based space debris removal mechanism comprising a servicing spacecraft (7) for space debris removal, characterized in that, Also include: Two brushless motors (12) are arranged in parallel inside the service spacecraft (7), and a spinning wheel (11) is arranged on the output shaft of each brushless motor (12); A flexible gripper (9) is symmetrically installed on each side of the service spacecraft (7), and each flexible gripper (9) is connected to the corresponding spinning wheel (11) through a rope (10); The side wall of each flexible gripper (9) and the inner side wall of the corresponding service spacecraft (7) are oppositely provided with an electromagnetic coil (4); when the currents in the oppositely arranged pair of electromagnetic coils (4) are set in the same direction, an electromagnetic force that repels each other is generated to eject the flexible gripper (9), and at the same time, the flexible gripper (9) is pulled through the rope (10); when the currents in the oppositely arranged pair of electromagnetic coils (4) are set in opposite directions, an electromagnetic force that attracts each other is generated to recover the flexible gripper (9), and at the same time, the flexible gripper (9) is pulled through the rope (10) to recover it; An actuator (5) is arranged on each flexible gripper (9) to control the opening and closing of the flexible gripper (9) during the ejection process of the flexible gripper (9) to capture debris within a specific direction and distance; The two inner side walls of the service spacecraft (7) are symmetrically provided with a circular hole slot (6), and the rope (10) wound on each spinning wheel (11) passes through the corresponding circular hole slot (6) and is connected to the corresponding flexible gripper (9); An electromagnet (3) is installed inside the flexible gripper (9); A flywheel (2) is installed inside the flexible gripper (9) to adjust the attitude of the flexible gripper (9) when the flexible gripper (9) captures debris.

2. The electromagnetic catapult-based space debris cleaning mechanism of claim 1, wherein, Mechanical buckles (14) are symmetrically arranged on the two sides of the service spacecraft (7) to fix the corresponding flexible grippers (9).

3. The electromagnetic catapult based space debris cleaning mechanism of claim 1, wherein, An infrared sensor (1) is arranged on the flexible gripper (9).

4. The electromagnetic catapult based space debris cleaning mechanism of claim 1, wherein, A plurality of debris detectors (8) are arranged on the service spacecraft (7).

5. A method of space debris removal according to any one of claims 1 to 4, wherein, The steps include: After the service spacecraft (7) detects a plurality of debris, it determines the relative direction and relative position of the two most easily captured debris, and adjusts the attitude of the service spacecraft (7) so that the two debris are located within the capture domain of the two flexible grippers (9); The controller obtains the resistance size that the brushless motor (12) needs to generate according to the average power of the electromagnetic force, the action time and the distance from the relative debris during the electromagnetic ejection process; at the same time, the debris detector (8) obtains the electromagnetic force and electromagnetic torque required by the oppositely arranged electromagnetic coils (4) during electromagnetic ejection according to the orientation of the debris; The currents in the oppositely arranged pair of electromagnetic coils (4) are set in the same direction, and an electromagnetic force that repels each other is generated to eject the flexible gripper (9); the actuator (5) is driven to control the flexible gripper (9) to grip the debris and power the electromagnet (3) to adsorb the debris; The brushless motor (12) drives the pulley (11) to pull back the rope (10), and at the same time, the current in the oppositely arranged pair of electromagnetic coils (4) is set to be opposite, so as to generate electromagnetic force attracting each other, and the flexible gripper (9) is recovered by cooperation of the pulley (11) rotation, so as to complete the cleaning of the space debris.

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