Electromagnetic track launching system and method for friction coefficient full-period measurement

Abstract

The invention belongs to the field of electromagnetic emission, and discloses an electromagnetic track emission system and method for friction coefficient full-period measurement. The electromagnetic track launching system comprises an electromagnetic track launching device, a pulse power system, a diagnosis system and a control system. According to the electromagnetic track launching system, full-launching-period measurement of the friction coefficient in an extreme electromagnetic environment can be achieved, and the system is used for monitoring the contact state between central tracks in each launching process and predicting the service life of a device; the full-emission period measurement of the local temperature of the guide rail can be realized; and full emission period measurement of contact pressure and contact resistance between the pivot rails is realized. According to the contact state between the guide rails in the launching process, the pretightening force of the guide rails or the size of the armature is adjusted, so that the service life of the guide rails is prolonged. The local temperature of the guide rail and the contact pressure between the pivot rails are monitored by utilizing the intrinsic physical characteristics of the Bragg grating, the reliability is high, the wavelength self-reference characteristic is realized, the absolute measurement can be realized, the temporal-spatial resolution is high, and the structure is compact.

Description

Technical Field

[0001] The invention belongs to the field of electromagnetic launch, and relates to an electromagnetic track launch system and method for full-cycle measurement of friction coefficient. Background Art

[0002] Compared to traditional mechanical and chemical launches, electromagnetic launch technology surpasses the energy and speed limits of traditional launch methods, accelerating payloads to ultra-high speeds of several thousand meters per second, offering broad application prospects. Electromagnetic launchers can be categorized by launch principle as electromagnetic rail launchers, coil-type electromagnetic launchers, and reconnection-type electromagnetic launchers. The electromagnetic rail launcher utilizes the principle of a linear motor, capable of accelerating the armature to speeds of 2 km / s or even higher.

[0003] Electromagnetic rail launchers, with their simple structure, high speed, and excellent controllability, have broad application prospects. However, research on their failure mechanisms in high-speed, strong electromagnetic environments requires extensive experimental data verification. This is primarily because the extreme electromagnetic environment during electromagnetic launch prevents many diagnostic devices from being used in electromagnetic launchers, resulting in the inability to accurately measure many parameters during the electromagnetic launch process. However, these parameters, such as speed, contact force between the pivot rail, and friction coefficient, are essential for studying damage mechanisms during electromagnetic launch, establishing failure models, and predicting and improving lifespan.

[0004] Therefore, the present invention proposes a device and method for full-cycle measurement of the friction coefficient of an electromagnetic launch system. Summary of the Invention

[0005] The present invention aims to provide an electromagnetic rail launch system and method for full-cycle friction coefficient measurement, addressing the following technical issues: 1. During each launch, material may melt and adhere between the armature and rail, or even transition, which can seriously affect the contact state between the armature and rail. This patent enables full-cycle measurement of the friction coefficient in extreme electromagnetic environments, used to monitor the contact state between the armature and rail during each launch and predict the device lifespan. 2. Research on rail temperature during electromagnetic launch generally assumes ideal contact between the armature and rail. However, in actual electromagnetic launches, the local temperature of the rail during electromagnetic launch is affected by the actual contact state between the armature and rail. This patent enables full-cycle measurement of the local temperature of the rail. 3. As the number of launches increases, the contact state between the armature and rail deteriorates due to friction and wear between the armature and rail. However, it is inconvenient to determine the contact state between the armature and rail by observing the rail surface morphology after each disassembly of the launch device. Therefore, full-cycle measurement of the contact pressure between the armature and rail is essential. Adjusting the rail preload or armature size based on the contact state between the armature and rail during launch can help extend the rail's service life.

[0006] The technical solution of the present invention:

[0007] An electromagnetic track launch system for full-cycle measurement of friction coefficient, comprising an electromagnetic track launch device, a pulse power system, a diagnostic system, and a control system;

[0008] The electromagnetic rail launcher comprises an armature, two rails, an insulating support structure and a fastening structure, and is used to convert electrical energy into kinetic energy to achieve high exit velocity launch of the armature;

[0009] in,

[0010] The armature is installed between the two rails and is installed in the electromagnetic rail launcher according to the caliber of the electromagnetic rail launcher and the "four times caliber rule";

[0011] The rail is installed in the groove of the insulating support structure. With the restraining force of the insulating support structure, the lateral displacement of the armature is restrained and the contact between the armature and the rail is maintained. One of the two rails receives the pulse output from the pulse power system. The current flows through the armature and then is transferred to the other rail. The other rail guides the current back to the pulse power system to form a loop.

[0012] The insulating support structure serves to electrically isolate the high-voltage end from the low-voltage end and also provides support, and includes an insulating support structure wrapped around the armature and track, and an insulating support structure supporting the electromagnetic track launcher. The insulating support structure wrapped around the armature and track, with the aid of fastening bolts, maintains structural stability when subjected to pressure from the armature during launch, and serves to constrain lateral displacement of the armature, preventing the armature from laterally separating from the electromagnetic track launcher. The insulating support structure supporting the electromagnetic track launcher is used to insulate the electromagnetic track launcher from the ground and elevate it to a certain height, facilitating its coordinated use with the diagnostic system and armature collection device, and the installation of a pulse power system.

[0013] The armature collecting device is used to recover the armature fired out of the muzzle and is filled with a stainless steel iron box containing a wet rag;

[0014] The fastening structure is tightened into the insulating support structure around the armature and the track by means of a screw and a nut, or is directly pressed against the surface of the insulating support structure around the armature and the track by means of a screw and a nut in combination with a steel plate, thereby constraining the structural stability of the electromagnetic track launch device.

[0015] The pulse power system is used to compress electrical energy on a time scale to achieve high-power and high-frequency output of electrical energy;

[0016] The diagnostic system includes equipment and an oscilloscope for detecting various physical quantities during the electromagnetic launch process; wherein the physical quantities include current, voltage, local temperature of the track, contact pressure between the armature and the track, speed of the armature in the electromagnetic track launcher, exit speed of the armature, and friction coefficient between the armature and the track;

[0017] The control system shown realizes the control of the charging and discharging of the electromagnetic rail launch system. The controller can be a PLC or other MCU equipped with a strong electromagnetic shielding device as the control core, and the strong current end and the weak current end are controlled and coupled through the optoelectronic coupling module.

[0018] A method for using an electromagnetic emission system for full-cycle measurement of friction coefficient, comprising the following steps:

[0019] Step 1: Install and debug the pulse power system, control system, electromagnetic rail launch device and diagnostic system;

[0020] Step 2: The control system controls the pulse power system to charge to the required voltage;

[0021] Step 3: The control system sends a start signal to the diagnostic system to start the high-speed camera, demodulator, and oscilloscope;

[0022] Step 4: The control system sends a discharge signal to the pulse power system. The pulse power system applies the expected excitation current to the electromagnetic rail launcher according to the timing given by the control system. Under the action of the excitation current, the armature gradually accelerates and eventually leaves the barrel.

[0023] Step 5: Observe the voltage and current signals displayed by the oscilloscope, use the host computer to analyze and calculate the armature-rail contact pressure and local rail temperature information stored in the demodulator, fit the armature's velocity and acceleration information in the electromagnetic rail launcher, and calculate the resultant force acting on the armature along the electromagnetic launch direction at each time point;

[0024] Step 6: Input the structural parameters of the electromagnetic rail launcher, the excitation current of the armature, and the position information into the deep learning model to calculate the electromagnetic thrust acting on the armature at each time point. Based on the net force acting on the armature along the electromagnetic launch direction at each time point, the friction acting on the armature is calculated.

[0025] Step 7: Calculate the friction coefficient between the armature and the rail based on the friction force on the armature at a certain time and the contact pressure between the armature and the rail.

[0026] Beneficial effects of the invention: This work aims to provide an electromagnetic guide rail launch system and method for full-cycle measurement of the friction coefficient, which can solve the following technical problems: First, during each launch process, there will be material melting and adhesion between the armature and the guide rail, and even transition will occur, which will seriously affect the contact state between the armature and the rail. This work can realize the full-launch cycle measurement of the friction coefficient in extreme electromagnetic environments, which is used to monitor the contact state between the armature and the rail during each launch process and predict the life of the device; Second, the research on the guide rail temperature during electromagnetic launch generally assumes ideal contact between the armature and the rail, but in actual electromagnetic launch, the local temperature of the guide rail during electromagnetic launch will be affected by the actual contact state between the armature and the rail, and this work can realize the full-launch cycle measurement of the local temperature of the guide rail; Third, as the number of device launches increases, the contact state between the armature and the rail deteriorates due to friction and wear between the armature and the guide rail, but it is very inconvenient to judge the contact state between the armature and the rail by observing the morphology of the guide rail surface each time the launch device is disassembled, so it is very necessary to realize the full-launch cycle measurement of the contact pressure and contact resistance between the armature and the rail. Adjusting the rail preload or armature size based on the contact state between the rail and the pivot during launch can help extend the rail's service life. Fourth, this work utilizes the intrinsic physical properties of Bragg gratings to monitor the rail's local temperature and the contact pressure between the rail and the pivot. These features offer high reliability, wavelength self-referencing, absolute measurement capabilities, immunity to background light interference, high temporal and spatial resolution, and a compact design. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of an electromagnetic track transmitting system for full-cycle measurement of friction coefficient according to an embodiment of the present invention;

[0028] Figure 2 This is a diagram of the overall structure of the electromagnetic rail launcher according to an embodiment of the present invention and a partial enlarged diagram thereof;

[0029] Figure 3 1. It is a bottom view of the electromagnetic rail launcher according to an embodiment of the present invention and a partially enlarged view thereof;

[0030] Figure 4 1 is a schematic diagram of the end structure of the electromagnetic rail launch device of an example of the present invention;

[0031] Figure 5 This is a schematic diagram of the installation position of the fiber Bragg grating of the upper track of the embodiment of the present invention and a partial enlarged view thereof;

[0032] Figure 6 1 is a side view of the upper track of an embodiment of the present invention and a partial enlarged view thereof;

[0033] Figure 7 It is an end view of the upper rail of an example of the present invention.

[0034] In the figure: 1 upper rail; 2 lower rail; 3 pivot rail contact force fiber Bragg grating groove; 4 support fixing structure; 5 lower support fixing structure; 6 fastening bolt; 7 fastening nut; 8 pre-tightening screw; 9 temperature fiber Bragg grating groove; 10 pre-tightening screw hole. DETAILED DESCRIPTION

[0035] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0036] An electromagnetic track launch system for full-cycle measurement of friction coefficient, comprising an electromagnetic track launch device, a pulse power system, a diagnostic system, and a control system;

[0037] The electromagnetic rail launcher comprises an armature, two rails, an insulating support structure and a fastening structure, and is used to convert electrical energy into kinetic energy to achieve high exit velocity launch of the armature;

[0038] in,

[0039] The armature is installed between the two rails and is installed in the electromagnetic rail launcher according to the caliber of the electromagnetic rail launcher and the "four times caliber rule";

[0040] The rail is installed in the groove of the insulating support structure. With the restraining force of the insulating support structure, the lateral displacement of the armature is restrained and the contact between the armature and the rail is maintained. One of the two rails receives the pulse output from the pulse power system. The current flows through the armature and then is transferred to the other rail. The other rail guides the current back to the pulse power system to form a loop.

[0041] The insulating support structure serves to electrically isolate the high-voltage end from the low-voltage end and also provides support, and includes an insulating support structure wrapped around the armature and track, and an insulating support structure supporting the electromagnetic track launcher. The insulating support structure wrapped around the armature and track, with the aid of fastening bolts, maintains structural stability when subjected to pressure from the armature during launch, and serves to constrain lateral displacement of the armature, preventing the armature from laterally separating from the electromagnetic track launcher. The insulating support structure supporting the electromagnetic track launcher is used to insulate the electromagnetic track launcher from the ground and elevate it to a certain height, facilitating its coordinated use with the diagnostic system and armature collection device, and the installation of a pulse power system.

[0042] The armature collecting device is used to recover the armature fired out of the muzzle and is filled with a stainless steel iron box containing a wet rag;

[0043] The fastening structure is tightened into the insulating support structure around the armature and the track by means of a screw and a nut, or is directly pressed against the surface of the insulating support structure around the armature and the track by means of a screw and a nut in combination with a steel plate, thereby constraining the structural stability of the electromagnetic track launch device.

[0044] The pulse power system is used to compress electrical energy on a time scale to achieve high-power and high-frequency output of electrical energy;

[0045] The diagnostic system includes equipment and an oscilloscope for detecting various physical quantities during the electromagnetic launch process; wherein the physical quantities include current, voltage, local temperature of the track, contact pressure between the armature and the track, speed of the armature in the electromagnetic track launcher, exit speed of the armature, and friction coefficient between the armature and the track;

[0046] The control system shown realizes the control of the charging and discharging of the electromagnetic rail launch system. The controller can be a PLC or other MCU equipped with a strong electromagnetic shielding device as the control core, and the strong current end and the weak current end are controlled and coupled through the optoelectronic coupling module.

[0047] Furthermore, in the electromagnetic rail launcher, during the electromagnetic launch process, the armature connects the two rails to form a closed loop, and then the magnetic induction intensity B is generated in the electromagnetic rail launcher, and its distribution is:

[0048]

[0049] Where l′ is the magnetic field source area; R is the vector from the source point where Idl′ points to the solution field point, and R is its magnitude; e R is its unit vector; μ1 is the magnetic permeability of the medium; the Ampere force on the armature is:

[0050]

[0051] Where J is the current density vector in the armature, V is the armature area; the electromagnetic thrust F on the armature is the Ampere force F A The component along the axial direction of the electromagnetic rail launch device is:

[0052]

[0053] Among them, J y and J z are the y-direction and z-direction components of the current density vector, B z and B y are the z-direction and y-direction components of the magnetic induction intensity B respectively.

[0054] Furthermore, the electromagnetic rail launcher also includes a pre-tightening screw for adjusting the contact pressure between the armature and the rail; the pre-tightening screw is used to set the initial pre-tightening force, set different pre-tightening forces for rails at different positions, and adjust the depth of the pre-tightening screw embedded in the insulating support structure after the rail and armature are worn, thereby increasing the contact force between the armature and the rail.

[0055] Furthermore, the oscilloscope has multiple input channels for receiving detection signals from a device for detecting current and a device for detecting voltage, directly displays the curves of current and voltage changes over time during the electromagnetic emission process, and performs data processing;

[0056] The device used for detecting current is used to detect the excitation current during electromagnetic emission. It is a Rogowski coil installed on the outlet lead of the electromagnetic track launch device. The detection data is input into the oscilloscope;

[0057] The device used for detecting voltage is used to detect the muzzle voltage and the tail voltage during electromagnetic launch. It is a differential voltage probe, and the detection data is input into the oscilloscope;

[0058] The equipment used to detect the local temperature of the track is a temperature detection fiber Bragg grating installed on the side of the track and a demodulator for demodulating the Bragg wavelength shift of the grating, which is used to monitor the local temperature of the track during electromagnetic emission;

[0059] The equipment used to detect the contact pressure between the armature and the rail is a pressure fiber Bragg grating and demodulator installed in the grooves on the upper and lower sides of the rail, which is used to monitor the contact pressure between the armature and the rail during electromagnetic transmission;

[0060] The speed v of the armature in the electromagnetic rail launch device is obtained by fitting the relationship between the contact pressure between the armature and the rail, the installation position of the pressure fiber Bragg grating and time by the host computer;

[0061] The device used to detect the exit velocity of the armature is a high-speed camera, which is mounted at the muzzle and synchronously triggered by an oscilloscope. The high-speed camera measures the exit velocity of the armature and also records the arcing at the muzzle.

[0062] The friction coefficient μ between the armature and the track is the friction force F on the armature when air resistance is ignored. f Contact pressure F between the pivot rail C The ratio of:

[0063]

[0064] Among them, the friction force F on the armature is fThe following method is used for calculation: First, the acceleration a of the armature is calculated based on the curve of the change of the armature speed v with time, so as to obtain the resultant force F along the launch direction of the armature s :

[0065] F s =ma (5)

[0066] Where m is the armature mass.

[0067] Furthermore, a deep learning model is used to learn the complex relationship between the excitation current waveform, armature position, structural parameters of the electromagnetic rail launcher and the transient electromagnetic field during the launch of the electromagnetic rail launcher from a large amount of simulation data to complete the high-precision electromagnetic thrust F prediction within milliseconds; the electromagnetic thrust F predicted by the deep learning model is the actual resultant force F along the electromagnetic launch direction on the armature. s The difference is the friction force on the armature:

[0068] F f =FF s (6)

[0069] The deep learning model is designed to rapidly and accurately predict the electromagnetic thrust F exerted on the armature during electromagnetic launch based on the excitation current waveform, armature position, and structural parameters of the electromagnetic rail launcher within milliseconds. Training data for the deep learning model can come from finite element simulation software, such as COMSOL Multiphysics, using the magnetic field interface and symmetry conditions to calculate the electromagnetic thrust exerted on the armature during electromagnetic launch.

[0070] Furthermore, the temperature detection fiber Bragg grating is used to convert the local temperature signal of the track into an optical signal. The grating period gradually changes along the electromagnetic emission direction; the Bragg wavelength of the grating shifts Δλ B It is linearly related to the temperature change ΔT:

[0071]

[0072] In, λ B is the Bragg wavelength of the grating, T is the temperature of the monitoring point of the track, K T is the temperature sensitivity of the fiber Bragg grating, n eff is the effective refractive index of the optical fiber material, and Λ is the grating period. The local temperature of each monitoring point on the orbit is inverted by real-time monitoring of the Bragg wavelength during the transmission process.

[0073] Furthermore, the pressure fiber Bragg grating is used to convert the contact pressure signal between the armature and the track into an optical signal; when the temperature remains unchanged, the Bragg wavelength shifts Δλ B Change in contact pressure ΔF between the pivot rail and theC The linear relationship is:

[0074]

[0075] Among them, K F is the contact pressure sensitivity coefficient of the optical fiber, P e is the effective elastic-optical coefficient of the optical fiber, S C is the contact area between the armature and the rail, υ is the Poisson's ratio of the optical fiber, υ′ is the Poisson's ratio of the adhesive, k is the ratio of the cross-sectional area of ​​the optical fiber to the cross-sectional area of ​​the adhesive, E is the elastic modulus of the optical fiber, E′ is the elastic modulus of the adhesive, and C is the ratio of the axial deformation of the optical fiber to the average axial deformation of the adhesive; after the Brad wavelength shift is decoupled from the temperature, the linear relationship between the wavelength and the contact pressure between the armature and the rail is used to utilize the contact pressure between the armature and the rail during the inversion electromagnetic launch process.

[0076] Furthermore, the demodulator operates at a frequency of MHz and is used to provide a wide spectrum light beam to the fiber Bragg grating, and receives the reflected light and the transmitted light of the fiber Bragg grating, from which the Bragg wavelength λ is analyzed. B The information collected is used by the host computer to invert the changes in temperature and contact pressure during the entire emission cycle based on the offset wavelength.

[0077] A method for using an electromagnetic emission system for full-cycle measurement of friction coefficient, comprising the following steps:

[0078] Step 1: Install and debug the pulse power system, control system, electromagnetic rail launch device and diagnostic system;

[0079] Step 2: The control system controls the pulse power system to charge to the required voltage;

[0080] Step 3: The control system sends a start signal to the diagnostic system to start the high-speed camera, demodulator, and oscilloscope;

[0081] Step 4: The control system sends a discharge signal to the pulse power system. The pulse power system applies the expected excitation current to the electromagnetic rail launcher according to the timing given by the control system. Under the action of the excitation current, the armature gradually accelerates and eventually leaves the barrel.

[0082] Step 5: Observe the voltage and current signals displayed by the oscilloscope, use the host computer to analyze and calculate the armature-rail contact pressure and local rail temperature information stored in the demodulator, fit the armature's velocity and acceleration information in the electromagnetic rail launcher, and calculate the resultant force acting on the armature along the electromagnetic launch direction at each time point;

[0083] Step 6: Input the structural parameters of the electromagnetic rail launcher, the excitation current of the armature, and the position information into the deep learning model to calculate the electromagnetic thrust acting on the armature at each time point. Based on the net force acting on the armature along the electromagnetic launch direction at each time point, the friction acting on the armature is calculated.

[0084] Step 7: Calculate the friction coefficient between the armature and the rail based on the friction force on the armature at a certain time and the contact pressure between the armature and the rail.

Claims

1. An electromagnetic track transmission system for full-cycle measurement of friction coefficient, characterized in that: The electromagnetic rail launch system includes an electromagnetic rail launch device, a pulse power system, a diagnostic system and a control system; The electromagnetic rail launcher comprises an armature, two rails, an insulating support structure and a fastening structure, and is used to convert electrical energy into kinetic energy to achieve high exit velocity launch of the armature; in, The armature is installed between the two rails and is installed in the electromagnetic rail launcher according to the caliber of the electromagnetic rail launcher and the "four times caliber rule"; The rail is installed in the groove of the insulating support structure. With the restraining force of the insulating support structure, the lateral displacement of the armature is restrained and the contact between the armature and the rail is maintained. One of the two rails receives the pulse output from the pulse power system. The current flows through the armature and then is transferred to the other rail. The other rail guides the current back to the pulse power system to form a loop. The insulating support structure serves to electrically isolate the high-voltage end from the low-voltage end and also provides support, and includes an insulating support structure wrapped around the armature and track, and an insulating support structure supporting the electromagnetic track launcher. The insulating support structure wrapped around the armature and track, with the aid of fastening bolts, maintains structural stability when subjected to pressure from the armature during launch, and serves to constrain lateral displacement of the armature, preventing the armature from laterally separating from the electromagnetic track launcher. The insulating support structure supporting the electromagnetic track launcher is used to insulate the electromagnetic track launcher from the ground and elevate it to a certain height, facilitating its coordinated use with the diagnostic system and armature collection device, and the installation of a pulse power system. The armature collecting device is used to recover the armature fired out of the muzzle and is filled with a stainless steel iron box containing a wet rag; The fastening structure is tightened into the insulating support structure around the armature and the track by means of a screw and a nut, or is directly pressed against the surface of the insulating support structure around the armature and the track by means of a screw and a nut in combination with a steel plate, thereby constraining the structural stability of the electromagnetic track launch device. The pulse power system is used to compress electrical energy on a time scale to achieve high-power and high-frequency output of electrical energy; The diagnostic system includes equipment and an oscilloscope for detecting various physical quantities during the electromagnetic launch process; wherein the physical quantities include current, voltage, local temperature of the track, contact pressure between the armature and the track, speed of the armature in the electromagnetic track launcher, exit speed of the armature, and friction coefficient between the armature and the track; The control system shown realizes the control of the charging and discharging of the electromagnetic rail launch system. The controller can be a PLC or other MCU equipped with a strong electromagnetic shielding device as the control core, and the strong current end and the weak current end are controlled and coupled through the optoelectronic coupling module.

2. The electromagnetic rail launch system according to claim 1, characterized in that: In the electromagnetic rail launcher, during the electromagnetic launch process, the armature connects the two rails to form a closed loop, and then the magnetic induction intensity B is generated in the electromagnetic rail launcher, and its distribution is: Where l′ is the magnetic field source area; R is the vector from the source point where Idl′ points to the solution field point, and R is its magnitude; e R is its unit vector; μ1 is the magnetic permeability of the medium; the Ampere force on the armature is: Where J is the current density vector in the armature, V is the armature area; the electromagnetic thrust F on the armature is the Ampere force F A The component along the axial direction of the electromagnetic rail launch device is: Among them, J y and J z are the y-direction and z-direction components of the current density vector, B z and B y are the z-direction and y-direction components of the magnetic induction intensity B respectively.

3. The electromagnetic rail launch system according to claim 1, characterized in that: The electromagnetic rail launcher also includes a pre-tightening screw for adjusting the contact pressure between the armature and the rail; the pre-tightening screw is used to set the initial pre-tightening force, set different pre-tightening forces for rails at different positions, and adjust the depth of the pre-tightening screw embedded in the insulating support structure after the rail and armature wear, thereby increasing the contact force between the armature and the rail.

4. The electromagnetic rail launch system according to claim 1, characterized in that: The oscilloscope has multiple input channels for receiving detection signals from devices used to detect current and voltage, directly displays the curves of current and voltage changes over time during electromagnetic emission, and performs data processing. The device used for detecting current is used to detect the excitation current during electromagnetic emission. It is a Rogowski coil installed on the outlet lead of the electromagnetic track launch device. The detection data is input into the oscilloscope; The device used for detecting voltage is used to detect the muzzle voltage and the tail voltage during electromagnetic launch. It is a differential voltage probe, and the detection data is input into the oscilloscope; The equipment used to detect the local temperature of the track is a temperature detection fiber Bragg grating installed on the side of the track and a demodulator for demodulating the Bragg wavelength shift of the grating, which is used to monitor the local temperature of the track during electromagnetic emission; The equipment used to detect the contact pressure between the armature and the rail is a pressure fiber Bragg grating and demodulator installed in the grooves on the upper and lower sides of the rail, which is used to monitor the contact pressure between the armature and the rail during electromagnetic transmission; The speed v of the armature in the electromagnetic rail launch device is obtained by fitting the relationship between the contact pressure between the armature and the rail, the installation position of the pressure fiber Bragg grating and time by the host computer; The device used to detect the exit velocity of the armature is a high-speed camera, which is mounted at the muzzle and synchronously triggered by an oscilloscope. The high-speed camera measures the exit velocity of the armature and also records the arcing at the muzzle. The friction coefficient μ between the armature and the track is the friction force F on the armature when air resistance is ignored. f Contact pressure F between the pivot rail C The ratio of: Among them, the friction force F on the armature is f The following method is used for calculation: First, the acceleration a of the armature is calculated based on the curve of the change of the armature speed v with time, so as to obtain the resultant force F along the launch direction of the armature s : F s =in (5) Where m is the armature mass.

5. The electromagnetic rail launch system according to claim 4, characterized in that: A deep learning model is used to learn the complex relationship between the excitation current waveform, armature position, structural parameters of the electromagnetic rail launcher, and the transient electromagnetic field during the launch of the electromagnetic rail launcher from a large amount of simulation data. The electromagnetic thrust F is predicted by the deep learning model, and the actual resultant force F along the electromagnetic launch direction on the armature is s The difference is the friction force on the armature: F f =F-F s (6) The deep learning model is used to quickly predict the electromagnetic thrust F exerted on the armature during electromagnetic launch based on the excitation current waveform, armature position and structural parameters of the electromagnetic rail launch device within milliseconds with high accuracy.

6. The electromagnetic rail launch system according to claim 4, characterized in that: The temperature detection fiber Bragg grating is used to convert the local temperature signal of the track into an optical signal. The grating period gradually changes along the electromagnetic emission direction; the Bragg wavelength of the grating shifts by Δλ. B It is linearly related to the temperature change ΔT: In, λ B is the Bragg wavelength of the grating, T is the temperature of the monitoring point of the track, K T is the temperature sensitivity of the fiber Bragg grating, n eff is the effective refractive index of the optical fiber material, and Λ is the grating period. The local temperature of each monitoring point on the orbit is inverted by real-time monitoring of the Bragg wavelength during the transmission process.

7. The electromagnetic rail launch system according to claim 4, characterized in that: The pressure fiber Bragg grating is used to convert the contact pressure signal between the armature and the track into an optical signal; when the temperature remains unchanged, the Bragg wavelength shifts Δλ B Change in contact pressure ΔF between the pivot rail and the C The linear relationship is: Among them, K F is the contact pressure sensitivity coefficient of the optical fiber, P e is the effective elastic-optical coefficient of the optical fiber, S C is the contact area between the armature and the rail, υ is the Poisson's ratio of the optical fiber, υ′ is the Poisson's ratio of the adhesive, k is the ratio of the cross-sectional area of ​​the optical fiber to the cross-sectional area of ​​the adhesive, E is the elastic modulus of the optical fiber, E′ is the elastic modulus of the adhesive, and C is the ratio of the axial deformation of the optical fiber to the average axial deformation of the adhesive; after the Brad wavelength shift is decoupled from the temperature, the linear relationship between the wavelength and the contact pressure between the armature and the rail is used to utilize the contact pressure between the armature and the rail during the inversion electromagnetic launch process.

8. The electromagnetic rail launch system according to claim 6 or 7, characterized in that: The demodulator operates at a frequency of MHz and is used to provide a wide spectrum light beam to the fiber Bragg grating, and receives the reflected light and transmitted light of the fiber Bragg grating, from which the Bragg wavelength λ is analyzed. B The information collected is used by the host computer to invert the changes in temperature and contact pressure during the entire emission cycle based on the offset wavelength.

9. A method for using an electromagnetic emission system for full-cycle measurement of friction coefficient, characterized in that: Here are the steps: Step 1: Install and debug the pulse power system, control system, electromagnetic rail launch device and diagnostic system; Step 2: The control system controls the pulse power system to charge to the required voltage; Step 3: The control system sends a start signal to the diagnostic system to start the high-speed camera, demodulator, and oscilloscope; Step 4: The control system sends a discharge signal to the pulse power system. The pulse power system applies the expected excitation current to the electromagnetic rail launcher according to the timing given by the control system. Under the action of the excitation current, the armature gradually accelerates and eventually leaves the barrel. Step 5: Observe the voltage and current signals displayed by the oscilloscope, use the host computer to analyze and calculate the armature-rail contact pressure and local rail temperature information stored in the demodulator, fit the armature's velocity and acceleration information in the electromagnetic rail launcher, and calculate the resultant force acting on the armature along the electromagnetic launch direction at each time point; Step 6: Input the structural parameters of the electromagnetic rail launcher, the excitation current of the armature, and the position information into the deep learning model to calculate the electromagnetic thrust acting on the armature at each time point. Based on the net force acting on the armature along the electromagnetic launch direction at each time point, the friction acting on the armature is calculated. Step 7: Calculate the friction coefficient between the armature and the rail based on the friction force on the armature at a certain time and the contact pressure between the armature and the rail.

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