A dynamic joint simulation method for satellite electromagnetic docking process

Abstract

This invention discloses a dynamic co-simulation method for satellite electromagnetic docking processes, belonging to the field of spacecraft electromagnetic docking dynamics simulation. The simulation method includes the following steps: First, a 3D model of the spacecraft containing electromagnets is performed in Ansys Maxwell, and a spacecraft dynamics simulation model is established in Syslab. Then, simulation boundary conditions and initial conditions are set. Co-simulation is performed to establish a closed-loop dynamic information transmission process for electromagnetic and dynamic interaction. Subsequently, based on the simulation information from the previous step, the motion process of the current step is analyzed step by step in Syslab. At this time, the external control system is allowed to detect and control the electromagnet current. Finally, the co-simulation process is repeated, dynamically updating the spacecraft's motion state until it stops, realizing the electromagnetic docking dynamics simulation of electromagnetic field and motion coupling. This invention can overcome the shortcomings of traditional electromagnetic simulation in solving the dynamics simulation of electromagnetic field and motion coupling, and is more in line with the physical reality of spacecraft on-orbit docking.

Description

Technical Field

[0001] This invention relates to the field of spacecraft electromagnetic docking dynamics simulation. Background Technology

[0002] With the development of microsatellites and space stations, on-orbit interactions between spacecraft are becoming increasingly frequent. Traditional jet-propelled docking technology suffers from fuel consumption and plume impact, which have a significant impact on spacecraft lifespan. Electromagnetic docking, with its advantages of no fuel consumption and low docking impact, well meets the current requirements for high-frequency docking and small-amplitude on-orbit maneuvers. The main challenges of electromagnetic docking lie in the strong nonlinear characteristics of electromagnetics and the coupling characteristics between electromagnetics and kinematics. Furthermore, it requires designing the layout of onboard electromagnets to ensure multi-degree-of-freedom motion control for stable docking.

[0003] Designing a satellite electromagnetic docking flight procedure inevitably requires designing a spacecraft electromagnetic docking dynamics and control system. In terms of electromagnetic control, since the Biot-Savart law lacks an analytical solution in engineering, and most current simple magnetic dipole models used for theoretical analysis are only applicable at far-field scales and cannot meet the accuracy requirements of small-scale docking processes, it is necessary to establish a finite element analysis model to simulate the electromagnetic field and solve the interaction between electromagnets. This provides a theoretical basis for the spatial layout design, structural design, material selection, dynamic modeling, and the design and optimization of derived control systems for electromagnets.

[0004] Currently, simulation analysis in most related fields is mainly divided into two parts: first, finite element simulation of electromagnetics is performed to design electromagnets and their distribution; second, dynamics and control system simulation analysis is conducted. However, the former is mostly limited to static fields with simple motion, and cannot achieve dynamic closed-loop analysis of the influence between the electromagnetic field and the motion state; the latter mostly uses simple models obtained by linear approximation as the controlled object, resulting in insufficient correlation between electromagnetics and dynamics, and failing to achieve coupled dynamic analysis of electromagnetics and dynamics during electromagnetic docking. Therefore, joint simulation of electromagnetics and dynamics that combines the two is necessary. Summary of the Invention

[0005] To address the limitations of current electromagnetic docking dynamics simulation and analysis methods, this invention proposes a dynamic co-simulation method for satellite electromagnetic docking processes. Based on the principles of electromagnetic finite element analysis and Newton's laws of motion, dynamic closed-loop co-simulation is performed using AnsysMaxwell and Syslab software to improve the accuracy and reliability of the simulation model.

[0006] A dynamic co-simulation method for satellite electromagnetic docking process includes the following steps:

[0007] Step 1: Based on the design of the onboard electromagnets and their distribution, perform a 3D model of the spacecraft containing electromagnets in Maxwell.

[0008] Step 2: Establish a dynamic simulation model of the controlled object in Syslab.

[0009] Step 3: Set the simulation boundary conditions and initial conditions in Syslab.

[0010] Step 4: Perform co-simulation, establish information transmission process, input electromagnet pose data and current data from Syslab into Maxwell, use Maxwell to solve the interaction between electromagnets and feed it back to Syslab to form a signal closed loop.

[0011] Step 5: Perform dynamic step analysis of the motion process in Syslab.

[0012] Step 6: Allow the external control system to detect and control the current of the electromagnet to achieve the designed control objective.

[0013] Step 7: Repeat steps 4, 5, and 6 according to the simulation step size to achieve coupled simulation of electromagnetic field and pose, and realize dynamic updating of electromagnetic and dynamic information.

[0014] In step 1, the simplified mechanism model established in Maxwell includes an electromagnet core, a coil, and the spatial distribution of multiple electromagnets. This requires defining the electromagnet core material, core dimensions, spatial orientation of the electromagnets, number of turns in the energized coil, magnitude of the current flowing through the coil, the number of electromagnets, their relative positions and orientations, and the spatial mesh generation. This electromagnetic model allows for co-simulation analysis with Syslab's dynamic model, representing different information about the simulated object in electromagnetics and dynamics, respectively.

[0015] In step 2, the controlled object is a spacecraft containing electromagnets and capable of electromagnetic docking. Based on the spacecraft's mass, moment of inertia, and other dynamic properties, the dynamic equations of the controlled object are established according to Newton's laws of motion.

[0016] In step 3, the simulation initial conditions refer to the dynamic information such as the initial position and attitude of the controlled object and the electromagnetic parameters such as the initial current of the electromagnet; the simulation boundary conditions refer to the geometric constraints such as the motion region and the simulation stopping conditions.

[0017] In steps 4 and 5, the co-simulation and dynamic stepping process involves establishing a data interaction model between the rigid body kinematics simulation model and the Ansys Maxwell electromagnetics simulation in Syslab. This includes two parts: Syslab transmitting the simulated pose information of the rigid body and electromagnets to Maxwell, and Maxwell transmitting the simulated interaction information between the electromagnets to Syslab. During this process, the pose output by Syslab in the previous step is used as the electromagnet pose information for the current Maxwell electromagnetics simulation. The Maxwell simulation results are used as the external forces and torques in the current dynamics model to update the spacecraft pose information for the current step, thus forming a dynamic closed-loop structure of step-iteration. In the co-simulation process, the above closed-loop information transmission is performed at each iteration until the simulation ends.

[0018] In step 5, the motion analysis section, based on the forces on each electromagnet output by Maxwell, combined with the on-board electromagnet distribution set during the initial modeling, can calculate the torque vector of the spacecraft in Syslab. Then, the acceleration and angular acceleration of the spacecraft can be solved using the dynamic model established in step 2. By performing double inertial integration, the attitude change of the spacecraft can be obtained, thereby realizing the simulation of the spacecraft's motion process.

[0019] In step 6, allowing the external control system to control the current means changing the electromagnet current value in each simulation step according to a preset control law.

[0020] In step 7, the coupling between the electromagnetic field and the pose refers to the fact that the electromagnetic force at each step is affected by the change in current, and the change in current is determined by a preset control law based on the pose. At the same time, the pose will affect the magnitude of the electromagnetic force (torque) of the electromagnet.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] This invention proposes a dynamic co-simulation method for satellite electromagnetic docking processes. Using Ansys Maxwell and Syslab software, it achieves closed-loop dynamic simulation of electromagnetics and dynamics. Unlike traditional static electromagnetic simulation and isolated dynamic analysis, this invention strengthens the correlation between electromagnetics and dynamics, more closely resembling the electromagnetic field and attitude coupling in actual physical processes, making the simulation more realistic.

[0023] This invention proposes a dynamic co-simulation method for satellite electromagnetic docking processes, which solves the problem that traditional linearized dynamic analysis and magnetic dipole models are only applicable to far-field analysis. The closed-loop iterative simulation of electromagnetics and dynamics improves the accuracy and reliability of the model, and provides a feasible simulation scheme for the problem that the accurate Biot-Savart law model has no analytical solution in engineering. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating a dynamic co-simulation method for satellite electromagnetic docking.

[0025] Figure 2 This is a schematic diagram of a binary satellite electromagnetic docking operation according to a specific embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of binary star electromagnetic modeling calculation based on Maxwell software, according to a specific embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the dynamic coordinate system for binary star docking according to a specific embodiment of the present invention; Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings.

[0029] like Figure 2 As shown in the figure, as a specific embodiment of the present invention, the dynamic joint simulation process of on-orbit electromagnetic docking of two CubeSats is described below.

[0030] The preprocessing steps for co-simulation, specifically the modeling process corresponding to steps 1 and 2, are as follows:

[0031] (1) Electromagnetic modeling of spacecraft in Maxwell:

[0032] Add two relative coordinate systems, RelativeCS1 and RelativeCS2, in Ansys Maxwell to serve as the fixed coordinate systems for the two spacecraft.

[0033] In Ansys Maxwell, add design variables for the relative position, relative attitude, and current excitation value of two spacecraft in three-dimensional space.

[0034] The RelativeCS1 coordinate system is established with reference to the initial Global coordinate system of Ansys Maxwell. To simplify the modeling process, the origin position and orientation of each axis of the two coordinate systems can be set to be the same. The RelativeCS2 coordinate system is established with reference to the RelativeCS1 coordinate system. Based on the relative position and attitude of the two spacecraft, the origin position and orientation of each axis of the RelativeCS2 are input by the pose transformation.

[0035] Based on the spacecraft's structural design and geometric relationships, the spatial distribution and material parameters of the onboard electromagnets were determined, and three-dimensional models of the respective fixed spacecraft were drawn in RelativeCS1 and RelativeCS2.

[0036] To facilitate the modeling process, the 3D model needs to be appropriately simplified, retaining only the electromagnet part and its necessary connections; this will be referred to as the simplified model. Electromagnetic simulation boundary conditions are set according to the spacecraft's operating environment. Finite element mesh parameters are set according to the required computational accuracy and speed.

[0037] Add the current excitation from the design variables to the corresponding electromagnet.

[0038] Establish a solution method and set the allowable error range. Select the simplified electromagnets in RelativeCS2 and set the virtual work force calculation parameters for each.

[0039] like Figure 3 As shown in this embodiment, for a cube star with four electromagnets located at the four corners of the docking surface, the docking surface baffle and the four electromagnets are retained as a three-dimensional model for simulation, hereinafter referred to as the "simplified mechanism". The docking surface baffle serves as a geometric connection and can be used to initially simulate the influence of the front baffle material on the electromagnetic simulation results.

[0040] In existing electromagnetic docking mechanisms, electromagnets typically use energized solenoids with iron cores. In Maxwell's geometric modeling, a cylinder can represent the iron core, and a circular tube can represent the tightly wound solenoid. The inner diameter of the tube should be slightly larger than the diameter of the cylinder, and the two should not touch. The cylinder is set to electrical pure iron, and the tube to copper. The connecting baffle is simplified to a cuboid with a thickness minimal compared to its length and width; its material is not additionally specified to avoid affecting the simulation results. The excitation on the tightly wound solenoid is set to current excitation; the desired simulation current value and direction are selected, and the winding type is adjusted.

[0041] (2) Perform rigid body dynamics modeling of the spacecraft in Syslab:

[0042] Rigid body dynamics modeling is performed in Syslab, including parameters such as given spacecraft mass, moment of inertia, principal axis of inertia, center of mass position, and size information.

[0043] like Figure 4 As shown, the motion reference coordinate system S1 and the target spacecraft fixed coordinate system S are defined. t Tracking spacecraft fixed coordinate system S c Define the relative motion and relative attitude between the two spacecraft in S1 and initialize the pose information, respectively in S... t S c The spatial distribution of onboard electromagnets is defined as the installation position vector; the attitude transformation matrix between the three coordinate systems is calculated, and the dynamic equations of the three-axis position vector and three-axis attitude with respect to external forces and torques are derived.

[0044] After completing the preprocessing, corresponding to steps 3-7, the specific process of co-simulation begins:

[0045] A. Set the joint simulation boundary conditions and simulation step size.

[0046] B. Initialize the three-dimensional position and attitude of the tracking spacecraft and the target spacecraft, i.e., the initial conditions of the double inertial integral, and set the initial current for electromagnetic simulation.

[0047] C. Start the Maxwell and Syslab co-simulation platform and wait for the two simulation platforms to complete the communication handshake.

[0048] D. After the two platforms successfully handshake, the electromagnet current value and the spacecraft's attitude information at that moment are transmitted from Syslab to Maxwell. Based on this, Maxwell updates the position and attitude of the simplified mechanism in the preset electromagnetic field and the current value in the energized solenoid in the 3D model, resets the calculation force parameters, and calculates the electromagnetic force vector between the electromagnets at that moment.

[0049] E. The electromagnetic force vector simulated by Maxwell is returned to Syslab. Syslab calculates the net external force and net external torque on the spacecraft based on the spacecraft's attitude at that moment and the initially set spatial distribution of electromagnets, and calculates the motion process step by step according to the established dynamic equations.

[0050] F. Syslab updates the spacecraft's attitude information for the next simulation step based on the inertial integral.

[0051] G. The external control system detects and controls the current, and changes the electromagnet current value for the next simulation according to the preset control law.

[0052] H. Proceed to the next simulation step and re-enter step C to iterate until the simulation ends.

Claims

1. A dynamic co-simulation method for satellite electromagnetic docking process, characterized in that: The method includes the following steps: Step 1: Based on the design of the onboard electromagnets and their distribution, perform a 3D model of the spacecraft containing electromagnets in Ansys Maxwell; Step 2: Establish a dynamic simulation model of the controlled object in Syslab; Step 3: Set the simulation boundary conditions and initial conditions in Syslab; Step 4: Establish a data interaction model between Syslab and Ansys Maxwell electromagnetic simulation software, establish an information flow, and input the pose information of the central rigid body and electromagnet obtained from the simulation in Syslab into Maxwell. Maxwell then solves the interaction between the electromagnets and feeds it back to Syslab, forming a signal closed loop. Step 5: Perform co-simulation and dynamically step-by-step analyze the motion process in Syslab. In this process, the pose output by the Syslab simulation in the previous step is used as the electromagnet pose information of the Maxwell electromagnetic simulation in the current step. The electromagnetic interaction results of the Maxwell simulation in the previous step are used as the external forces and external torques of the dynamic model of the Syslab simulation in the current step to update the spacecraft pose information of the current step simulation. The dynamic flow of the signal is realized in the signal closed loop described in Step 4. Step 6: Allow the external control system to detect and control the current of the electromagnet in order to achieve the preset control target; Step 7: Repeat steps 4, 5, and 6 according to the simulation step size until the simulation boundary conditions are reached, so as to realize the coupled simulation of electromagnetic field and pose, and realize the dynamic update of electromagnetic and dynamic information.

2. The dynamic co-simulation method for satellite electromagnetic docking process as described in claim 1, characterized in that, In step 5, the motion analysis section, based on the forces on each electromagnet output by Maxwell, calculates the torque vector of the spacecraft in Syslab by combining the on-board electromagnet distribution set during the initial modeling. Then, it uses the dynamic model established in step 2 to solve for the acceleration and angular acceleration of the spacecraft, performs double inertial integration to obtain the attitude change of the spacecraft, and then realizes the simulation of the motion process of the spacecraft.

3. The dynamic co-simulation method for satellite electromagnetic docking process as described in claim 1, characterized in that, The docking dynamics simulation method under the coupling of electromagnetic field and attitude refers to the fact that the electromagnetic force on the spacecraft in each step of the simulation is affected by the change of current. The change of current is determined by a preset control law based on the attitude. At the same time, the attitude will affect the magnitude of the electromagnetic force and electromagnetic torque of the electromagnet.

4. The dynamic co-simulation method for satellite electromagnetic docking process as described in claim 1, characterized in that, In step 1, the 3D modeling of the spacecraft containing electromagnets in Maxwell software is a static modeling of the electromagnetic actuators of the spacecraft, i.e., the electromagnetic simulation of the electromagnets, and is independent of the dynamic characteristics of the spacecraft.

5. The dynamic co-simulation method for satellite electromagnetic docking process as described in claim 1, characterized in that, In step 6, the external control system is allowed to control the current by changing the electromagnet current value in each simulation step according to a preset control law. This control law is a control method used for simulation of specific working conditions.

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