Modular magnetic reconfigurable parallel robot joint system for spacecraft on-orbit autonomous assembly

Abstract

The application relates to a modular magnetic reconfiguration parallel robot joint system for on-orbit autonomous assembly of a spacecraft, and belongs to the technical field of space equipment. The system is aimed at solving the problems of poor flexibility, low reconfiguration efficiency, difficulty in balancing high precision and high stiffness, and low reliability of existing space parallel robots. The technical scheme comprises a Halbach array magnetic ball and an electromagnetic locking ring of a magnetic joint module, a carbon fiber telescopic connecting rod micro servo motor and a harmonic reducer of a distributed drive branch chain, a multi-sensor data fusion unit configuration optimization algorithm module and a real-time control unit of an intelligent control system. The system can realize rapid joint mode switching, improve task response and execution efficiency, autonomously switch between precision mode and high stiffness mode to meet different operation scene requirements, adopt non-contact magnetic transmission to avoid friction and wear and pollution, improve system service life and reliability, and realize modular design for convenient maintenance and upgrading.

Description

Technical Field

[0001] This invention relates to the field of aerospace equipment technology, specifically to a modular magnetic reconfiguration parallel robot joint system for autonomous on-orbit assembly of spacecraft, which is particularly suitable for the precision manufacturing, assembly and maintenance of spacecraft such as launch vehicles and sounding rockets and their ground equipment. Background Technology

[0002] As space exploration missions become increasingly complex, on-orbit assembly and maintenance of spacecraft have become key technologies for ensuring mission success and extending spacecraft lifespan. Robotic systems performing these tasks must possess extremely high precision, rigidity, and adaptability to the variable space environment.

[0003] Currently, parallel robots applied in the aerospace field mainly fall into the following technical categories: First, fixed-configuration robot systems. These systems are typically pre-designed for specific missions. While highly reliable, they lack flexibility and struggle to adapt to unexpected situations or changes in mission objectives during on-orbit operations. Second, mechanically reconfigurable robot systems. This method adjusts the robot's configuration by mechanically disassembling, replacing, or reassembling components to meet different mission requirements. However, this process is complex, time-consuming, and usually requires astronaut intervention, failing to meet the high efficiency and autonomy requirements of on-orbit missions. Third, robots using traditional ball joints control movement through mechanical contact and transmission. However, they generally suffer from large clearance errors, friction and wear, lubrication difficulties, and limited stiffness adjustment range. These drawbacks directly affect the robot's assembly accuracy and long-term on-orbit reliability.

[0004] In summary, existing technical solutions are insufficient to simultaneously meet the comprehensive requirements of high precision, high rigidity, high efficiency, and high reliability for spacecraft on-orbit missions. In particular, there are significant technical bottlenecks in achieving rapid and autonomous configuration reconfiguration, which severely restricts the development of spacecraft on-orbit servicing technology. Summary of the Invention

[0005] This invention aims to solve the technical problems of poor flexibility, low reconfiguration efficiency, difficulty in balancing high precision and high rigidity, and low reliability in the on-orbit application of existing aerospace parallel robots.

[0006] To achieve the above objectives, this invention provides a modular magnetic reconfiguration parallel robot joint system for autonomous on-orbit assembly of spacecraft. The system includes a magnetic joint module, a distributed drive chain, and an intelligent control system. The magnetic joint module includes a Halbach array magnetic sphere for generating a magnetic field and an electromagnetic locking ring for controlling the magnetic field changes by switching power on and off. The distributed drive chain is connected to the magnetic joint module and is used to adjust the robot's configuration. The intelligent control system is communicatively connected to the magnetic joint module and the distributed drive chain, and can autonomously decide and control the electromagnetic locking ring to unlock or lock the Halbach array magnetic sphere based on mission instructions and multi-sensor fusion data, while simultaneously driving the distributed drive chain to perform precise parameter adjustments, thereby enabling rapid and autonomous reconfiguration of the robot joint system between different operating modes.

[0007] In a further embodiment, the distributed drive chain includes a carbon fiber telescopic link, a micro servo motor, and a harmonic reducer. The intelligent control system includes a multi-sensor data fusion unit, a configuration optimization algorithm module, and a real-time control unit. The system may also include a mechanical locking mechanism, such as a mechanical latch and a spring, which works in conjunction with an electromagnetic locking ring to form a dual magnetic and mechanical locking system with a tensile strength exceeding 500N. To adapt to the extreme environment of space, the system adopts a sealed protective structure consisting of an upper shell and a lower shell, and integrates heat dissipation fins and a temperature compensation system.

[0008] The beneficial effects of this invention are as follows:

[0009] (1) Through the magnetic coupling control of the electromagnetic locking ring and the Halbach array magnetic ball, millisecond-level joint mode switching was achieved. The entire configuration reconfiguration process can be completed within 3 minutes, which significantly improves the response speed and execution efficiency of on-orbit missions.

[0010] (2) The system can autonomously switch between a six-degree-of-freedom precision mode and a three-degree-of-freedom high-stiffness mode according to task requirements. Combined with an optimization algorithm based on Grassmann line geometry, active control of joint stiffness is achieved, meeting the stringent requirements of precision and stiffness in different operating scenarios.

[0011] (3) The magnetic coupling non-contact transmission fundamentally avoids the friction, wear and particulate matter pollution problems caused by traditional mechanical transmission, making it particularly suitable for long-term reliable operation in extreme space environments and significantly improving system lifespan.

[0012] (4) The modular design makes the system structure compact and the layout reasonable, which facilitates maintenance and upgrades. The non-contact magnetic transmission design reduces mechanical connection parts, which is conducive to the lightweighting of the system.

[0013] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0014] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0015] Figure 1 This is an exploded view of a single joint component in one embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of the operation of a magnetic reconfiguration joint system in one embodiment of the present invention;

[0017] Figure 3 This is a schematic diagram of the control flow for dynamic reconfiguration in one embodiment of the present invention;

[0018] Figure 4 This is a schematic diagram illustrating the complete workflow of an on-orbit autonomous assembly system for spacecraft in one embodiment of the present invention.

[0019] Reference numerals: 1. Upper half of the outer casing; 2. Heat sink fins; 3. Electromagnetic locking ring; 4. Wire; 5. Halbach array magnetic ball N-pole unit; 6. Halbach array magnetic ball S-pole unit; 7. DLC plating; 8. Mechanical buckle; 9. Spring; 10. Lower half of the outer casing; 11. Base mounting flange; 12. Cable interface. Detailed Implementation

[0020] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0021] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0022] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0023] This invention provides an active control device for axial attitude stabilization of a sounding rocket based on momentum wheel assemblies. Structurally, it employs a modular design, with clearly defined functions for each module. First-order and second-order momentum wheel systems serve as backups for each other, allowing for independent or parallel collaborative operation to ensure high reliability. In principle, the system utilizes data collected by sensors and employs a fusion control algorithm to control the first-order and second-order momentum wheels, thereby achieving axial attitude regulation. Structurally, it adopts a symmetrical layout with a coaxial center of mass, reducing system interference and enhancing control performance. Software-wise, the system utilizes a fusion control algorithm, PID closed-loop control, and a long-range wireless monitoring system to achieve axial attitude regulation.

[0024] Please see Figure 1 This invention provides a modular magnetic reconfiguration parallel robot joint system for autonomous on-orbit assembly of spacecraft. Its core is a modular joint unit. The structure of this unit mainly includes:

[0025] Structural support module: Consists of an upper shell 1 and a lower shell 10. Both are made of high-strength aluminum alloy and are joined together by precision interfaces to form a sealed protective shell, protecting internal components from environmental factors such as space radiation and micrometeoroids.

[0026] Magnetic Joint Module: Located inside the housing, its core consists of Halbach array magnetic spheres and an electromagnetic locking ring 3. The Halbach array magnetic spheres are composed of precisely arranged Halbach array magnetic sphere N-pole units 5 and Halbach array magnetic sphere S-pole units 6. This array design allows the magnetic field to be significantly enhanced on one side of the sphere and weakened on the other, thus providing a powerful and controllable magnetic force. The surface of the magnetic spheres is covered with a diamond-like carbon (DLC) coating 7, which has extremely high hardness and an extremely low coefficient of friction, effectively preventing cold welding in a vacuum environment and improving wear resistance. The electromagnetic locking ring 3 contains a coil wound with multiple layers of high-temperature insulating material, connected to an external intelligent control system via wires 4.

[0027] Connection and Interface Module: Includes base mounting flange 11 and cable interface 12. Base mounting flange 11 uses a standardized interface, facilitating quick and precise installation of the joint unit onto the distributed drive chain or spacecraft robotic arm. Cable interface 12 uses a multi-pin high-reliability connector with anti-misfit and locking mechanisms to ensure stable power and signal transmission in space vibration environments.

[0028] Dual locking mechanism: In addition to the electromagnetic lock, the system also features a mechanical locking mechanism consisting of a mechanical latch 8 and a spring 9. In the locked state, the mechanical latch 8 provides physical locking, forming a double safety net with the magnetic lock to ensure absolute reliability of the connection.

[0029] Thermal management system: The outer surface of the upper shell 1 is integrated with heat dissipation fins 2, which adopt a wing-shaped structure to maximize the heat dissipation area and effectively radiate the heat generated inside to space, ensuring that the joints work stably in extreme temperature environments.

[0030] Please see Figure 2 The diagram illustrates the workflow of magnetic reconfiguration in this system. The entire process is led by an intelligent control system and based on a multi-sensor monitoring and feedback network.

[0031] (1) Status perception: The system monitors its own and the environment status in real time through an integrated sensor network, which includes a temperature sensor for monitoring the temperature of the magnetic ball, an optical fiber strain gauge for monitoring the load deformation of the carbon fiber telescopic link, and a vision sensor for sensing the external assembly environment and target pose.

[0032] (2) Reconstruction trigger: When the vision sensor detects a deviation in the pose of the target part, or when the main control system receives a new task instruction that requires a change in the robot configuration, the reconstruction sequence is triggered.

[0033] (3) Unlocking process: The main control system first sends a power-off command to the electromagnetic locking ring 3, which eliminates its internal magnetic field and releases the magnetic constraint on the Halbach array magnetic ball. Almost simultaneously, the mechanical latch 8 automatically retracts and releases under the action of the spring 9, and the joint enters a reconfigurable state where it can rotate freely.

[0034] (4) Configuration Adjustment: After entering the reconfiguration state, the intelligent control system drives the distributed drive chain to adjust according to the calculation results of the configuration optimization algorithm. The micro servo motor and harmonic reducer precisely control the length (adjustable within the range of 50-150mm) and orientation of the carbon fiber telescopic link, thereby changing the pose of the robot end effector and forming a new working configuration.

[0035] (5) Relocking process: After the configuration is adjusted to the correct position, the main control system re-energizes the electromagnetic locking ring 3, generating a strong directional magnetic field that firmly attracts and precisely positions the Halbach array magnetic balls, with an attraction force exceeding 200N. Simultaneously, the mechanical latch 8 engages synchronously, forming a double mechanical safety. At this point, the system operates stably with the new configuration.

[0036] This magnetic reconfiguration mechanism demonstrates significant advantages in spacecraft on-orbit assembly. Through non-contact magnetic coupling, it achieves millisecond-level mode switching, avoiding the particulate contamination problems associated with traditional mechanical reconfiguration. The entire reconfiguration process is completed within 3 minutes, supporting autonomous switching between a six-degree-of-freedom precision mode and a three-degree-of-freedom high-stiffness mode. This perfectly adapts to the varying precision and stiffness requirements in spacecraft component assembly, providing reliable technical support for on-orbit servicing missions.

[0037] Please see Figure 3 This diagram illustrates the intelligent control process of dynamic reconfiguration. The core of this process is an advanced control algorithm.

[0038] (1) Task input and decision: After receiving the task instruction, the system first matches in the configuration database to find the optimal initial configuration scheme and makes a reconstruction decision.

[0039] (2) Parameter Optimization and Control: After the decision is made, the control system performs multi-parameter optimization calculations. This invention adopts a dynamic reconfiguration control algorithm based on Grassmann linear geometry theory. The algorithm uses the Lie group SE(3) and the Lie algebra se(3) to mathematically describe the motion of the mechanism, where the end pose of the mechanism can be expressed as:

[0040]

[0041] Where R∈SO(3) is the rotation matrix, p∈R 3 This is a position vector.

[0042] For parallel mechanisms, their kinematic constraints can be expressed as:

[0043] f i (q,T)=0,i=1,2,...,n

[0044] Where q is the joint variable vector and n is the number of branches.

[0045] (3) Temperature Compensation: Considering the severe temperature differences in the space environment, the algorithm integrates a temperature compensation model. By monitoring the temperature T in real time, the excitation current I of the electromagnetic locking ring is dynamically adjusted. comp This is to compensate for changes in the material's magnetic properties and electrical resistance caused by temperature variations. The compensation formula is:

[0046] I comp=I0·[1+α(T-T0)+β(T-T0)] 2 ]

[0047] Among them, I comp The excitation current after compensation is I0, the reference current is T, the real-time temperature is T0, the reference temperature is α and β, and the temperature coefficients are obtained through experimental calibration.

[0048] (4) Status Verification and Task Execution: During the branch adjustment process, the system monitors the system status in real time through sensors such as fiber optic strain gauges to form closed-loop control and ensure the accuracy of the adjustment. After the status verification is successful, the system enters the task execution phase.

[0049] Strain data processing employs a wavelet transform-based signal processing method:

[0050]

[0051] Where ε(t) is the strain signal, ψ is the wavelet basis function, and a and b are the scale parameter and translation parameter, respectively.

[0052] During the trajectory planning phase, the algorithm uses a B-spline-based interpolation method to generate a smooth motion trajectory:

[0053]

[0054] Among them B i,k (u) is a k-th degree B-spline basis function, Q i For control points.

[0055] The adaptive controller is designed based on Lyapunov stability theory, and the control law can be expressed as:

[0056]

[0057] Where M(q) is the inertia matrix, Here is the Coriolis force matrix, G(q) is the gravity term, and K... d and K p Let e ​​be the gain matrix, and e = qq d This is for tracking error.

[0058] In terms of parameter learning, the algorithm uses recursive least squares to update the model parameters in real time:

[0059] θ(k)=θ(k-1)+K(k)[y(k)-φ T (k)θ(k-1)]

[0060] Where θ is the vector of parameters to be estimated, K(k) is the gain matrix, and φ(k) is the regression vector.

[0061] The stability of the reconstruction process is guaranteed by Lyapunov functions:

[0062]

[0063] By proof Ensure the system remains stable throughout the entire refactoring process.

[0064] (5) Optimal Configuration Decision: In order to achieve a balance among multiple performance indicators, the algorithm determines the optimal configuration by optimizing a comprehensive objective function J:

[0065] J = w1·t reconfig +w2·E consumption +w3·P accuracy

[0066] Where J is the value of the objective function, t reconfig For reconstruction time, E consumption For energy consumption, P accuracy For accuracy, w1, w2, and w3 are preset weighting coefficients, representing the relative importance of reconstruction time, energy consumption, and accuracy, respectively.

[0067] Please see Figure 4 The figure illustrates the complete workflow of this system during autonomous on-orbit assembly missions on spacecraft.

[0068] Environmental perception and positioning: After the system is started, it first uses a visual environment perception system to perform a three-dimensional scan of the work area, and then uses deep learning algorithms to identify key structural features such as target components and installation interfaces to complete precise spatial positioning.

[0069] Autonomous Decision-Making and Reconfiguration: After outputting environmental data to the autonomous assembly system, the system makes reconfiguration decisions. For example, if a large-scale transfer and docking is required, it switches to a high-rigidity, high-stability three-degree-of-freedom mode; if a precise insertion and removal operation is required, it switches to a flexible, high-precision six-degree-of-freedom mode. The reconfiguration process, as described above, includes unlocking, joint parameter adjustment, and relocking.

[0070] On-orbit assembly execution: In the selected working mode, the robot performs assembly tasks. During precision assembly, the electromagnetic locking ring can remain in a semi-excited state, providing controllable compliance; when handling heavy components, it switches to a high-rigidity state with full magnetic attraction force and mechanical locking.

[0071] Quality Verification and Learning: During and after assembly, the system verifies assembly quality using data collected by force sensors (fiber optic strain gauges) and temperature sensors, such as determining whether the joint force is within a preset threshold. All data is recorded and the control parameters are iteratively optimized using machine learning algorithms, thereby continuously improving the system's autonomous decision-making ability and assembly accuracy for future tasks, achieving self-learning and evolution.

[0072] This invention creatively proposes a robotic joint system suitable for autonomous on-orbit assembly of spacecraft by combining modular design, magnetic reconfiguration technology, and intelligent control algorithms. It effectively solves many problems faced by existing technologies and provides reliable and efficient technical support for future on-orbit space servicing missions.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A modular magnetic reconfiguration parallel robot joint system for autonomous on-orbit assembly of spacecraft, characterized in that: include: A magnetic joint module, the magnetic joint module including a Halbach array of magnetic spheres for generating a magnetic field and an electromagnetic locking ring for controlling the on and off of the magnetic field; A distributed drive branch, connected to the magnetic joint module, is used to adjust the configuration of the robot joints; and The intelligent control system is connected to the magnetic joint module and the distributed drive chain respectively. It is used to control the electromagnetic locking ring to de-energize or energize according to the task instructions to unlock or lock the Halbach array magnetic ball, and drive the distributed drive chain to adjust the configuration to achieve autonomous reconfiguration of the robot joint system. The distributed drive chain includes a carbon fiber telescopic link, a micro servo motor and a harmonic reducer. The length of the carbon fiber telescopic link is adjustable. It also includes a mechanical locking mechanism, which includes a mechanical latch and a spring. The mechanical locking mechanism works in conjunction with the electromagnetic locking ring. When the electromagnetic locking ring is energized to lock the Halbach array magnetic ball, the mechanical latch simultaneously completes the mechanical locking, forming a dual locking mechanism of magnetic force and mechanical force.

2. The modular magnetic reconfiguration parallel robot joint system for on-orbit autonomous assembly of spacecraft according to claim 1, characterized in that: The Halbach array magnetic spheres include N-pole and S-pole units arranged according to a specific pattern; the electromagnetic locking ring includes a coil winding, and the intelligent control system controls the magnetic field of the electromagnetic locking ring by controlling the current flowing into the coil winding.

3. The modular magnetic reconfiguration parallel robot joint system for on-orbit autonomous assembly of spacecraft according to claim 1, characterized in that: The intelligent control system includes: A multi-sensor data fusion unit is used to fuse monitoring data from temperature sensors, fiber optic strain gauges, and vision sensors. Configuration optimization algorithm module, used to perform configuration optimization calculations based on the monitoring data; and The real-time control unit is used to execute the calculation results of the configuration optimization algorithm module and generate control commands for the magnetic joint module and the distributed drive branch.

4. The modular magnetic reconfiguration parallel robot joint system for on-orbit autonomous assembly of spacecraft according to claim 1, characterized in that: It also includes an upper shell and a lower shell, which together form a sealed protective structure; the outer surface of the sealed protective structure is integrated with heat dissipation fins.

5. The modular magnetic reconfiguration parallel robot joint system for on-orbit autonomous assembly of spacecraft according to claim 1, characterized in that: The surface of the Halbach array magnetic spheres is covered with a DLC coating.

6. The modular magnetic reconfiguration parallel robot joint system for on-orbit autonomous assembly of spacecraft according to claim 3, characterized in that: The configuration optimization algorithm module is built based on Grassmann line geometry theory and employs Lie groups. The motion of the mechanism is mathematically described, where the end effector pose is represented as: in, For rotation matrix, p ∈ R 3 This is a position vector.

7. The modular magnetic reconfiguration parallel robot joint system for on-orbit autonomous assembly of spacecraft according to claim 3, characterized in that: The intelligent control system is also used for temperature compensation, which is achieved by establishing a functional relationship between the electromagnetic locking loop excitation current and temperature change: in, The excitation current after compensation, As the reference current, For real-time temperature, For reference temperature, and This is the temperature coefficient.

8. The modular magnetic reconfiguration parallel robot joint system for on-orbit autonomous assembly of spacecraft according to claim 3, characterized in that: The configuration optimization algorithm module determines the optimal configuration by optimizing the objective function: in, To optimize the objective function value, For reconstruction time, For energy consumption, For accuracy, These are the preset weighting coefficients.

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