Variable-recoil-length design method for artillery under different charges based on hybrid excitation control

Abstract

The invention discloses a variable-recoil-length design method for an artillery under different charges based on hybrid excitation control. The method comprises the following steps: establishing a hybrid excitation eddy current brake structure model; establishing a finite element model of the recoil machine in COMSOL, and performing steady-state and transient-state solving under different charges to obtain recoil displacement and eddy current damping force under different charges and different currents; an optimal Latin super method is adopted, simulation analysis is conducted in COMSOL, multiple sets of data of eddy current damping force and speed under different charges and different currents are obtained, the charges and the currents serve as input, the eddy current damping force and speed serve as output, and a BP neural network is trained; a control system based on a Comsol operation module and a neural network is established in Simulink, current optimization is carried out with the minimum difference between a resistance peak value and a resistance valley value as an optimization target, the optimized current is brought into Comsol, and finally an eddy current damping force curve with the saddle effect optimized is obtained. According to the method, a new reference direction can be provided for engineering application of changing the length of the artillery.

Description

Technical Field

[0001] The invention relates to a gun recoil displacement control technology, and in particular to a gun variable recoil length design method under different charges based on hybrid excitation control. Background Art

[0002] When the gun is charged with different propellants, the resultant force of the gun barrel varies greatly, so the recoil distance may be too long or too short, resulting in problems such as damage to the barrel and inability to eject the shell. This affects the stability of the overall structure of the gun. Variable recoil length guns can limit the recoil of guns with different charge numbers to a certain length, and have the advantages of optimizing the recoil structure, increasing the firing angle of large charges, and reducing the weight of the recoil device. At present, the variable charge number design of the hydraulic recoil device usually adjusts the relationship between the flow hole area and the recoil displacement, which has problems such as complex structure and difficult design and processing. The eddy current recoil brake is a new type of recoil brake that provides resistance based on the principle of electromagnetic induction. The hybrid excitation eddy current recoil brake can achieve resistance control by adjusting the external input current, and has great advantages in the design of variable recoil length.

[0003] For the problem of artillery recoil length, Li Huibin designed a general scheme of hydraulic recoil length variable recoil device, which controls the change of the flow hole area formed by the control cylinder and the control rod by changing the shooting angle to achieve the purpose of changing the recoil resistance; for the control problem of damping force, Arunesh Kumar Singh et al. developed a fuzzy logic controller, which can adaptively change the size of the excitation current according to the braking force required by the electromagnetic damper. At the same time, an artificial neural network controller was designed, which can give more reliable and accurate results in the same time compared with the fuzzy controller; He et al. designed a fuzzy controller based on matlab for the eddy current electro-hydraulic hybrid brake system, and verified and analyzed the performance of the eddy current electro-hydraulic hybrid brake system. At present, the method of controlling the recoil length of artillery is mainly hydraulic, but its structure is complex and prone to problems such as liquid leakage and sealing. The recoil length variable structure under hybrid excitation control is simpler and more reliable, and research in this area is still relatively lacking. Summary of the invention

[0004] The purpose of the present invention is to provide a method for designing variable recoil length of a gun under different charges based on hybrid excitation control, so as to provide a certain design direction for controlling the variable recoil length of the gun.

[0005] The technical solution for implementing the present invention is: a method for changing the recoil length of a gun under different charges based on hybrid excitation control, comprising the following steps:

[0006] Step 1: Establish a hybrid excitation eddy current brake structure model, analyze the magnetic flux lines and magnetic circuits, and perform constant current simulation analysis and verification to select the optimal solution structure;

[0007] Step 2: Establish a finite element model of the recoil machine in COMSOL, perform steady-state and transient solutions under different charges, and obtain the recoil displacement and eddy current damping force under different charges and currents;

[0008] Step 3. Use the optimal Latin hypercube method to perform simulation analysis in COMSOL to obtain multiple sets of data on eddy current damping force and velocity under different charges and currents. Take charge and current as input, and eddy current damping force and velocity as output to train the BP neural network. Establish a control system based on the Comsol operation module and neural network in Simulink, optimize the current with the minimum difference between the peak and valley values ​​of the resistance as the optimization goal, bring the optimized current into Comsol, and finally obtain the eddy current damping force curve with optimized "saddle" effect.

[0009] Further, in step 1, a hybrid excitation eddy current brake structure model is established, magnetic flux lines and magnetic circuits are analyzed, constant current simulation analysis and verification are performed, and the optimal solution structure is selected, wherein:

[0010] Three hybrid excitation eddy current recoil brake structural models are constructed. The hybrid excitation eddy current recoil brake structural models are divided into two parts, the primary and the secondary. The barrel, permanent magnets, magnetic shoes and coils constitute the primary part, and the secondary part consists of inner and outer cylinders. However, the permanent magnets and coils are arranged in different ways, namely, the permanent magnets and coils are arranged crosswise, the coils are arranged outside and the permanent magnets are arranged inside, and the coils are arranged inside and the permanent magnets are arranged outside. When the gun is fired, the primary part moves backward due to the recoil force and moves relative to the secondary part. The magnetic flux in the inner cylinder changes to generate induced electromotive force to form eddy currents. The eddy currents generate electromagnetic damping force under the action of the magnetic field to achieve the recoil effect.

[0011] When the number of winding turns and the current are consistent, the barrel is simulated at a speed of 5m / s. The electromagnetic damping force generated under the three schemes can be compared, and the structure that can generate the maximum eddy current damping force under the same conditions can be obtained, and the optimal structure can be selected.

[0012] Further, in step 1, a hybrid excitation eddy current brake structure model is established, magnetic flux lines and magnetic circuits are analyzed, constant current simulation analysis and verification are performed, and the optimal solution structure is selected, wherein:

[0013] When the number of winding turns and the current are consistent, the barrel is simulated at a speed of 5m / s. The electromagnetic damping force generated under the three schemes is compared, and the structure that can generate the maximum eddy current damping force under the same conditions is obtained, and this is selected as the optimal structure.

[0014] Furthermore, in step 2, a finite element model of the recoil machine is established in COMSOL, and steady-state and transient solutions are performed under different charges to obtain the recoil displacement and eddy current damping force under different charges and currents. The specific method is as follows:

[0015] A finite element model of the recoil machine is established in COMSOL. The finite element model of the recoil machine adopts a two-dimensional axisymmetric model of a hybrid excitation eddy current recoil machine, including a barrel, permanent magnets, coil windings, inner barrel, outer barrel, and air domain.

[0016] Set material parameters, including barrel material, permanent magnet material, coil winding material, inner tube material, outer tube material and air domain;

[0017] Set initial and boundary conditions, including barrel force, recoil mechanism force, coil turns, and current;

[0018] Determine the constitutive relations of the moving rod, permanent magnet, coil winding, inner cylinder, outer cylinder and air domain;

[0019] Set up the recoil total differential equation while constraining the unknowns;

[0020] The overall grid is divided, and each partial area is discretized. Different grid units are used for different parts. Dynamic grids are set for the moving rod, permanent magnet, and coil winding, and the remaining parts are set as fixed grids. The movement of the dynamic grid is realized by the recoil total differential equation.

[0021] Further, in step 3, the optimal Latin hypercube method is used to perform simulation analysis in COMSOL to obtain multiple sets of data on eddy current damping force and velocity under different charges and currents, and the charge and current are used as inputs, and the eddy current damping force and velocity are used as outputs to train the BP neural network; a control system based on the Comsol operation module and the neural network is established in Simulink, and the current is optimized with the minimum difference between the peak value and the valley value of the resistance as the optimization goal, and the optimized current is brought into Comsol, and finally the eddy current damping force curve with the optimized "saddle" effect is obtained, wherein:

[0022] A control system based on Comsol running module and neural network is established in Simulink. Starting with speed of 0, the expected damping force is input for BP neural network calculation to obtain the expected current. Due to environmental problems, the maximum expected current does not exceed 300A. The Simulink comparison module is used to compare the expected current with 300A. The smaller value is taken before 12mm through the Simulink timing module and passed into the COMSOL module. After 12mm, a stable current of 280A is passed into the COMSOL module to calculate the electromagnetic damping force, recoil displacement, acceleration and velocity. The calculated speed is returned to the BP neural network for calculation at the next time. Finally, the calculation is completed, and the expected damping force is adjusted according to the calculation results. The cycle is repeated until the current reaches the expected effect. The calculation is completed and the calculation results are saved. The calculated current is brought into Comsol to obtain the eddy current damping force curve that optimizes the "saddle" effect.

[0023] A system for changing the recoil length of a gun under different charges based on hybrid excitation control is implemented, and the design method for changing the recoil length of a gun under different charges based on hybrid excitation control is implemented to realize the electromagnetic resistance control of a hybrid excitation eddy current recoil brake based on COMSOL-Simulink joint simulation under BP neural network.

[0024] Compared with the prior art, the present invention has the following significant advantages: (1) It adopts a hybrid excitation recoil mechanism to control the variable recoil length of the gun, which has a simple and reliable structure and does not need to consider issues such as liquid leakage and sealing; (2) By further optimizing the control model parameters, the resistance stability is effectively improved, and the engineering value is stronger. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The structures and magnetic circuit distributions of three types of hybrid excitation eddy current brakes are shown.

[0026] Figure 2 The damping force of three hybrid excitation eddy current brakes under constant current and speed is compared.

[0027] Figure 3 This is the structure and mesh division of the hybrid excitation eddy current brake.

[0028] Figure 4 The figure is a comparison of the recoil displacement of different charges and different currents under the control of the hybrid excitation eddy current recoil machine of the present invention.

[0029] Figure 5 To optimize the electromagnetic damping force curve under the first 0 and 1 charges

[0030] Figure 6 This is the COMSOL-Simulink joint simulation flow chart of the hybrid excitation eddy current brake.

[0031] Figure 7 It is a Simulink flow chart.

[0032] Figure 8 This is the damping force curve of the hybrid excitation electromagnetic damper under No. 0 charge obtained by the COMSOL-Simulink joint simulation optimization of the present invention.

[0033] Fig. 9 This is the damping force curve of the hybrid excitation electromagnetic damper under No. 1 charge obtained by the COMSOL-Simulink joint simulation optimization of the present invention. DETAILED DESCRIPTION

[0034] In order to make the intention, technical implementation means and advantages of this application clearer, the following will be further explained through drawings and specific examples. It should be clear that the specific implementation cases shown here are only used to illustrate the core idea of ​​this application, and are not intended to limit it in any form.

[0035] The design method of variable recoil length of gun under different charges based on hybrid excitation control includes the following steps:

[0036] Step 1: Propose three different hybrid excitation eddy current brake structures, analyze the magnetic flux lines and magnetic circuits of the three structures respectively, and perform constant current simulation analysis and verification.

[0037] Figure 1 The three structural schemes of hybrid excitation eddy current recoil brake and the corresponding magnetic circuit distribution are shown in the figure. The hybrid excitation eddy current recoil brake in the first three schemes can be divided into two parts: primary and secondary. The barrel, permanent magnet, magnetic shoe and coil constitute the primary part, and the secondary part consists of inner and outer cylinders. The main difference between the three schemes is that the permanent magnet and coil are arranged in different ways, which are arranged crosswise, coil outside and permanent magnet inside, and coil inside and permanent magnet outside. When the gun is fired, the primary part moves backward due to the recoil force and moves relative to the secondary part. The magnetic flux in the inner cylinder changes to generate induced electromotive force to form eddy current. The eddy current generates electromagnetic damping force under the action of the magnetic field to achieve the recoil effect.

[0038] Depend on Figure 1 By comparison, it can be found that among the three schemes, the magnetic flux line strength of scheme 1 is the weakest. The main difference between schemes 2 and 3 is that the positions of the coil and the permanent magnet are different. The magnetic flux flow directions of schemes 2 and 3 are basically the same, but during the movement, the magnetic field strength generated inside the coil is much smaller than the magnetic field generated inside the permanent magnet. Compared with scheme 2, the permanent magnet is on the outside of scheme 3, and the permanent magnet has a greater impact on the magnetic field strength at the air gap than the coil, so the magnetic flux line strength of scheme 3 is the largest.

[0039] When the number of winding turns and the current are consistent, the barrel is simulated at a speed of 5m / s. The electromagnetic damping force generated under the three schemes can be compared, and the structure that can generate the maximum eddy current damping force under the same conditions can be obtained, and the optimal structure can be selected.

[0040] Step 2: Establish a finite element model of the recoil machine in COMSOL, assign the structural dimensions, materials, meshes and differential relationships between various parameters, and then solve the steady-state and transient conditions under different charges to obtain the eddy current damping force and velocity under different charges and currents. The mesh division is as follows: Figure 3 shown.

[0041] Step 3: Make multiple attempts to determine the initial value range of the current parameters, use the optimal Latin hypercube to generate sample points, perform a large number of simulation analyses, and obtain multiple sets of data on eddy current damping force and velocity under different charges and currents. Train and generate a BP neural network, and then substitute the BP neural network into the COMSOL-Simulink joint simulation for current optimization. The minimum difference between the peak and valley values ​​of the resistance is selected as the optimization target.

[0042] The present invention proposes to use a hybrid excitation recoil brake to achieve the purpose of variable recoil length, which is achieved by adjusting the input current to change the damping force. At the same time, the damping force fluctuation is optimized through joint simulation, which can provide a new reference direction for the engineering application of variable recoil length of artillery.

[0043] Example

[0044] In order to verify the effectiveness of the scheme of the present invention, the commercial software COMSOL and MATLAB Simulink modules are used to control the recoil displacement of different charges of the hybrid excitation eddy current recoil machine. The specific method is as follows:

[0045] Step 1: Propose three different hybrid excitation eddy current brake structures, analyze the magnetic flux lines and magnetic circuits of the three structures respectively, and perform constant current simulation analysis and verification to select the optimal solution structure.

[0046] Figure 1 The three structural schemes of hybrid excitation eddy current recoil brake and the corresponding magnetic circuit distribution are shown in the figure. The hybrid excitation eddy current recoil brake in the three schemes can be divided into two parts: primary and secondary. The barrel, permanent magnet, magnetic shoe and coil constitute the primary part, and the secondary part consists of inner and outer cylinders. The main difference between the three schemes is that the permanent magnet and coil are arranged in different ways, which are arranged crosswise, coil outside and permanent magnet inside, and coil inside and permanent magnet outside. When the gun is fired, the primary part moves backward due to the recoil force and moves relative to the secondary part. The magnetic flux in the inner cylinder changes to generate induced electromotive force to form eddy current. The eddy current generates electromagnetic damping force under the action of the magnetic field to achieve the recoil effect.

[0047] When the number of winding turns and the current are consistent, the barrel is simulated at a speed of 5m / s. The electromagnetic damping force generated under the three schemes can be compared. Figure 2 As shown, the second scheme is the optimal structure.

[0048] Step 2. Based on the optimal structure of the hybrid excitation eddy current recoil brake selected in step 1, a finite element model of the recoil brake is established. After assigning the differential relationship between each structural size, material, grid and each parameter, the steady-state and transient solutions are performed under different charges to obtain the recoil displacement and eddy current damping force under different charges and currents.

[0049] The process of establishing the finite element model of the recoil machine in COMSOL is as follows:

[0050] (1) According to the structure in the scheme, a two-dimensional axisymmetric model of the hybrid excitation eddy current recoil machine was established in the finite element simulation software. The main components include the barrel, permanent magnets, coil windings, inner tube, outer tube, and air domain.

[0051] (2) The specific parameters of the materials are set: the barrel material is iron, the permanent magnet material is sintered NdFeB, the coil winding material is copper, the inner tube material is aluminum, the outer tube material is magnetic steel, and the air space is air.

[0052] (3) Setting the initial and boundary conditions, such as barrel force, recoil mechanism force, number of coil turns, and current.

[0053] (4) Determine the constitutive relations of the moving rod, permanent magnet, coil winding, inner cylinder, outer cylinder and air domain.

[0054] (5) Set up the recoil total differential equation to link the various parameters together and constrain the unknown quantities.

[0055] (6) Perform overall grid division and discretize each partial area. Different grid units are used for different parts, and different grid types are used accordingly. The moving rod, permanent magnet, and coil winding are set as dynamic grids, and the rest are set as fixed grids. The movement of the dynamic grid is realized by the recoil total differential equation buffered motion differential equation in process (5).

[0056] (7) After adding the differential relationship between the size, material, grid and various parameters of each part, the entire model forms a tight whole, and the steady-state and transient solutions are performed under different charges and currents.

[0057] (8) After the solution is completed, the calculation results are extracted and processed to obtain the required speed and eddy current damping force information.

[0058] The recoil displacement of the No. 2 charge without current is 538 mm. Based on this, the simulation of mixed excitation eddy current braking under different currents is carried out on different charges, and the recoil displacement under different conditions is obtained as follows: Figure 4 As shown, in the case of charge No. 0, the corresponding recoil displacements when 150A, 200A and 250A currents are passed are 851mm, 725mm and 611mm respectively. In the case of charge No. 1, the corresponding recoil displacements when 150A, 180A and 250A currents are passed are 632mm, 582mm and 464mm respectively. Based on the recoil displacement of charge No. 2 and the difficulty of passing current in practical applications, the scheme of passing 250A current to charge No. 0 and 180A current to charge No. 1 is adopted, and no current is passed to charge No. 2. After the current is passed, the corresponding recoil displacements of charges No. 0, No. 1 and No. 2 are 611mm, 582mm and 538mm respectively. The recoil displacements under different charges are greatly reduced, and the difference in recoil displacement between charge No. 0 and charge No. 2 is only 64mm.

[0059] Step 3: Make multiple attempts to determine the initial value range of the current parameters, use the optimal Latin hypercube to generate sample points, perform a large number of simulation analyses, and obtain multiple sets of data on eddy current damping force and velocity under different charges and currents. Train and generate a BP neural network, and then substitute the BP neural network into the COMSOL-Simulink joint simulation for current optimization. The minimum difference between the peak and valley values ​​of the resistance is selected as the optimization target.

[0060] Under the initial parameter design conditions of the hybrid excitation eddy current brake, after the eddy current damping force reaches the peak value under the No. 0 and No. 1 charges, the damping force curve drops rapidly due to the demagnetization effect, resulting in a common "saddle" curve, such as Figure 5 As shown in Figure 1, the damping force fluctuates greatly, affecting the stability of the entire recoil process. The block diagram of the Simlink and Comsol joint simulation design is shown in Figure 1. Figure 6In Comsol, the calculation of different charges and currents is first performed to generate the running module of Comsol. At the same time, the eddy current damping force and speed generated by the calculation are summarized. The Neural Net Fitting module of Matlab is used to train a large amount of calculation data to form a BP neural network corresponding to the current under different charges. In Simulink, a control system based on Comsol operation module and neural network is established. Starting with speed of 0, the expected damping force is input for BP neural network calculation to obtain the expected current. Due to environmental and other issues, the maximum expected current does not exceed 300A. The Simulink comparison module is used to compare the expected current with 300A. The Simulink timing module takes a smaller value before 12mm and passes it into the COMSOL module. After 12mm, a stable 280A current is passed into the COMSOL module to calculate the electromagnetic damping force, recoil displacement, acceleration and speed, and the calculated speed is returned to the BP neural network for the next calculation. Finally, the calculation is completed, and the expected damping force is adjusted according to the calculation results. Repeat the cycle until the current reaches the expected effect. The calculation is completed and the calculation results are saved. The calculated current is brought into Comsol to obtain the eddy current damping force curve that optimizes the "saddle" effect. The flow chart in Simulink is as follows: Figure 7 shown.

[0061] The designed control model is applied to the hybrid excitation eddy current brake model for control simulation. By continuously adjusting the expected electromagnetic damping force, the control results of the brake under different expectations are obtained. Figures 8-9 As shown. Under charge No. 0, after optimization, the eddy current damping force has a peak value reduced from 629kN to 623kN, while the trough value increased from 574kN to 595kN, and its fluctuation range decreased from 55kN to 28kN, reducing the damping force fluctuation by 49%. Under charge No. 1, the peak value decreased from 466kN to 439kN, while the trough value increased from 414kN to 420kN, and its fluctuation range decreased from 52kN to 19kN, reducing the damping force fluctuation by 63.4%.

[0062] In summary, the present invention adopts a method for changing the recoil length of a gun under different charges under hybrid excitation control, so that a hybrid excitation eddy current recoil brake can control the current under different charges to achieve the effect of controlling the displacement. It can effectively control the variable recoil length from the source, and further optimize the control parameters to improve the resistance stability, which can provide a reference and direction for controlling the variable recoil length of the gun.

[0063] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for designing variable recoil length of artillery under different charges based on hybrid excitation control, characterized in that: The steps include: Step 1: Establish a hybrid excitation eddy current brake structure model, analyze the magnetic flux lines and magnetic circuits, and perform constant current simulation analysis and verification to select the optimal solution structure; Step 2: Establish a finite element model of the recoil machine in COMSOL, perform steady-state and transient solutions under different charges, and obtain the recoil displacement and eddy current damping force under different charges and currents; Step 3. Use the optimal Latin hypercube method to perform simulation analysis in COMSOL to obtain multiple sets of data on eddy current damping force and velocity under different charges and currents. Take charge and current as input, and eddy current damping force and velocity as output to train the BP neural network. Establish a control system based on the Comsol operation module and neural network in Simulink, take the minimum difference between the peak and valley values ​​of resistance as the optimization goal, perform current optimization, bring the optimized current into Comsol, and finally obtain the eddy current damping force curve with optimized "saddle" effect.

2. The method for designing variable recoil length of artillery under different charges based on hybrid excitation control according to claim 1 is characterized in that: Step 1: Establish a hybrid excitation eddy current brake structure model, analyze the magnetic flux lines and magnetic circuits, and perform constant current simulation analysis and verification to select the optimal solution structure, where: Three hybrid excitation eddy current recoil brake structural models are constructed. The hybrid excitation eddy current recoil brake structural models are divided into two parts, the primary and the secondary. The barrel, permanent magnets, magnetic shoes and coils constitute the primary part, and the secondary part consists of inner and outer cylinders. However, the permanent magnets and coils are arranged in different ways, namely, the permanent magnets and coils are arranged crosswise, the coils are arranged outside and the permanent magnets are arranged inside, and the coils are arranged inside and the permanent magnets are arranged outside. When the gun is fired, the primary part moves backward due to the recoil force and moves relative to the secondary part. The magnetic flux in the inner cylinder changes to generate induced electromotive force to form eddy currents. The eddy currents generate electromagnetic damping force under the action of the magnetic field to achieve the recoil effect. When the number of winding turns and the current are consistent, the barrel is simulated at a speed of 5m / s. The electromagnetic damping force generated under the three schemes can be compared, and the structure that can generate the maximum eddy current damping force under the same conditions can be obtained, and the optimal structure can be selected.

3. The method for designing variable recoil length of artillery under different charges based on hybrid excitation control according to claim 2 is characterized in that: Step 1: Establish a hybrid excitation eddy current brake structure model, analyze the magnetic flux lines and magnetic circuits, and perform constant current simulation analysis and verification to select the optimal solution structure, where: When the number of winding turns and the current are consistent, the barrel is simulated at a speed of 5m / s. The electromagnetic damping force generated under the three schemes is compared, and the structure that can generate the maximum eddy current damping force under the same conditions is obtained, and this is selected as the optimal structure.

4. The method for designing variable recoil length of a gun under different charges based on hybrid excitation control according to claim 1 is characterized in that: Step 2: Establish a finite element model of the recoil machine in COMSOL, perform steady-state and transient solutions under different charges, and obtain the recoil displacement and eddy current damping force under different charges and currents. The specific method is as follows: A finite element model of the recoil machine is established in COMSOL. The finite element model of the recoil machine adopts a two-dimensional axisymmetric model of a hybrid excitation eddy current recoil machine, including a barrel, permanent magnets, coil windings, inner barrel, outer barrel, and air domain. Set material parameters, including barrel material, permanent magnet material, coil winding material, inner tube material, outer tube material and air domain; Set initial and boundary conditions, including barrel force, recoil mechanism force, coil turns, and current; Determine the constitutive relations of the moving rod, permanent magnet, coil winding, inner cylinder, outer cylinder and air domain; Set up the recoil total differential equation while constraining the unknowns; The overall grid is divided, and each partial area is discretized. Different grid units are used for different parts. Dynamic grids are set for the moving rod, permanent magnet, and coil winding, and the remaining parts are set as fixed grids. The movement of the dynamic grid is realized by the recoil total differential equation.

5. The method for designing variable recoil length of artillery under different charges based on hybrid excitation control according to claim 1 is characterized in that: In step 3, the optimal Latin hypercube method is used to perform simulation analysis in COMSOL to obtain multiple sets of data on eddy current damping force and velocity under different charges and currents, and the charge and current are used as inputs, and the eddy current damping force and velocity are used as outputs to train the BP neural network; a control system based on the Comsol operation module and the neural network is established in Simulink, and the current is optimized with the minimum difference between the peak value and the valley value of the resistance as the optimization goal, and the optimized current is brought into Comsol, and finally the eddy current damping force curve with the "saddle" effect optimized is obtained, where: A control system based on Comsol operation module and neural network is established in Simulink. Starting with speed of 0, the expected damping force is input for BP neural network calculation to obtain the expected current. Due to environmental problems, the maximum expected current does not exceed 300A. The Simulink comparison module is used to compare the expected current with 300A. The smaller value is taken before 12mm through the Simulink timing module and passed into the COMSOL module. After 12mm, a stable current of 280A is passed into the COMSOL module to calculate the electromagnetic damping force, recoil displacement, acceleration and velocity. The calculated speed is returned to the BP neural network for calculation at the next time. Finally, the calculation is completed, and the expected damping force is adjusted according to the calculation results. The cycle is repeated until the current reaches the expected effect. The calculation is completed and the calculation results are saved. The calculated current is brought into Comsol to obtain the eddy current damping force curve that optimizes the "saddle" effect.

6. A variable recoil length design system for guns under different charges based on hybrid excitation control, characterized in that: Implement the variable recoil length design method for artillery under different charges based on hybrid excitation control as described in any one of claims 1-5, and realize the electromagnetic resistance control of the hybrid excitation eddy current recoil machine based on COMSOL-Simulink joint simulation under BP neural network.

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