Coil type electromagnetic emitter and projectile sensor thereof

Abstract

The invention discloses a coil type electromagnetic emitter and a projectile sensor thereof, relates to the field of electromagnetic emission, and is used for improving the reliability of a magnetoelectric sensor in the coil type electromagnetic emitter. The projectile sensor comprises a sensing circuit which comprises at least one level of sensing coil which is connected with each other, each level of sensing coil is wound on the same plane, and each level of sensing coil is coaxially arranged or arranged on the same plane; the measuring circuit is used for detecting at least one target characteristic of the magnetoelectric signal detected by the sensing circuit in frequency, amplitude or period; and the processing circuit is used for identifying the bullet state based on the target characteristics. The invention has the characteristics of low cost, reliable work, high practical value and wide application range.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic launch, and in particular to a coil-type electromagnetic launcher and its projectile sensor. Background Technology

[0002] An electromagnetic accelerator is a device that uses electromagnetic force to lift, propel, or accelerate an object. A coil-type electromagnetic transmitter is a subclass of an electromagnet, and its acceleration principle is divided into two types: induction and reluctance.

[0003] A typical structure of a coil-type electromagnetic transmitter is as follows: Figure 1 (For example only) As shown, it includes a magazine, a limiting tube, and multiple acceleration coils. The acceleration coils are hollow cylinders that wrap around the limiting tube (not necessarily in contact). Multiple acceleration coils are arranged in a straight line along the limiting tube. Under the action of the acceleration coils, the projectile is accelerated inside the limiting tube and finally exits from the limiting tube outlet.

[0004] To achieve automatic control of each stage of electromagnetic acceleration, it is necessary to collect the position information of the projectile and, when necessary, calculate the velocity information of the projectile based on the position information (which may require the size information of the projectile or the position information of the collection point, etc.).

[0005] Current common detection methods utilize photoelectric sensors to detect projectile position information. These sensors detect the projectile's current position based on the location and time of light signal obstruction. Examples include the multi-stage accelerating electromagnetic railgun experimental device based on STM32 control proposed in publication CN109737805A, and the two-stage accelerating electromagnetic coilgun driven by a disc coil and solenoid proposed in publication CN117889696A. However, photoelectric sensors, because they detect projectile status through light signals, are susceptible to obstruction by mud and sand, and interference from external light. Furthermore, they require openings in the limiting tube to arrange the optical path, resulting in complex manufacturing processes and affecting the structural strength of the limiting tube.

[0006] To overcome or mitigate the aforementioned shortcomings of photoelectric detectors, some scholars have proposed magnetoelectric sensors. These sensors operate based on the interaction of electromagnetic fields, detecting the projectile's state by sensing magnetoelectric signals. Since there is no optical path, there are no issues associated with optical paths. However, coil-type electromagnetic accelerators themselves utilize the strong magnetic field of accelerating coils to accelerate projectiles. Therefore, applying magnetoelectric sensors to coil-type electromagnetic accelerators would result in strong electromagnetic interference. Thus, how to reduce or avoid this electromagnetic interference is a crucial issue that must be considered to ensure the reliability of magnetoelectric sensor detection. Summary of the Invention

[0007] The application aims at providing a coil electromagnetic transmitter and a projectile sensor thereof to solve a series of problems existing in photoelectric sensors and improve the reliability of magneto electric sensors in coil electromagnetic transmitters.

[0008] The technical scheme adopted by the application is as follows: A projectile sensor for a coil electromagnetic transmitter comprises: A sensing circuit comprising at least one level of interconnected sensing coils, each level of sensing coils being wound on the same plane, and each level of sensing coils being arranged coaxially or on the same plane; A measurement circuit connected to the sensing circuit for detecting at least one target feature of a magnetic electric signal detected by the sensing circuit in frequency, amplitude or period; A processing circuit connected to the measurement circuit for identifying a projectile state based on the target feature, the projectile state comprising at least one of projectile position information or quantity information.

[0009] In another aspect, the application further provides a coil electromagnetic transmitter comprising a cartridge for accommodating projectiles to be launched, a limiting tube for guiding the direction of projectile launching, a plurality of acceleration coils for accelerating the projectiles, and at least one projectile sensor as described above; the projectile sensor is mounted on the limiting tube and / or the cartridge; when mounted on the limiting tube, the sensing coils are wrapped around the limiting tube perpendicularly to the axial direction of the limiting tube; when mounted on the cartridge, the plane of the sensing coils is parallel to the arrangement direction of the projectiles.

[0010] In summary, due to the adoption of the above technical scheme, the application has the following beneficial effects: The magneto electric projectile sensor designed in the application has the sensing coils designed on the same plane, which can be wound by PCB wiring and the like, facilitating wiring processing and insulation treatment, and ensuring the compactness and consistency of the coil structure, thereby ensuring the reliability of the work. In addition, the planar winding acceleration coil also facilitates the installation of the projectile sensor, and almost does not affect the layout design of the coil electromagnetic transmitter itself, and is applicable to inductive electromagnetic transmitters or magnetoresistive electromagnetic transmitters. The projectile sensor detects electromagnetic waves through the sensing circuit, and then detects the target feature of the detected magnetic electric signal (magnetic signal converted into electric signal) through the measurement circuit, thereby reducing or avoiding the influence of the electromagnetic field of the acceleration coil, and even using the electromagnetic field of the acceleration coil as the initial electromagnetic field for detection, and finally cooperating with the processing circuit to detect the projectile state through the corresponding processing method of the target feature. The application can greatly reduce the influence of the strong magnetic field on the work of the projectile sensor, and improve the working reliability of the projectile sensor. BRIEF DESCRIPTION OF DRAWINGS

[0011] The present application will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a typical structural diagram of a coil type electromagnetic transmitter.

[0012] Figure 2 is a configuration diagram of a projectile sensor provided by the present application.

[0013] Figure 3 is a configuration diagram of the projectile sensor of the present application operating in an inductive sensing mode in one embodiment.

[0014] Figure 4 is an application Figure 3 Target feature waveform diagram detected by the measurement circuit of the projectile sensor of the embodiment in one embodiment.

[0015] Figure 5 is a configuration diagram of the projectile sensor of the present application operating in a differential magnetic flux sensing mode in one embodiment, in which sub-diagram (a) is a front view of the PCB and sub-diagram (b) is a back view of the PCB.

[0016] Figure 6 is Figure 5 Equivalent circuit diagram of the sensing circuit and the measurement circuit of the projectile sensor of the embodiment.

[0017] Figure 7 is Figure 6 Workflow diagram of the projectile sensor of the embodiment in one application embodiment.

[0018] Figure 8 is a configuration diagram of the coil type electromagnetic transmitter of the present application in one embodiment.

[0019] In the figure, 1 is a limiting tube, 2 is an accelerating coil, 3 is a cartridge, 4 is a projectile, 5 is a projectile position sensor, 6 is a projectile number sensor, 50 is a PCB, 51 is a sensing circuit, 52 is a measurement circuit, 53 is a processing circuit, 54 is a magnetic shield, 51a is a first coil, and 51b is a second coil. DETAILED DESCRIPTION

[0020] All features disclosed in this specification, and / or all steps of any methods disclosed, may be combined in any combination, except combinations where at least some of the features and / or steps are mutually exclusive.

[0021] Any feature disclosed in this specification, unless stated otherwise, can be replaced by any equivalent or similar feature. That is, unless stated otherwise, each feature is one example only of a generic series of equivalent or similar features.

[0022] In view of the problems of the photoelectric sensor, such as being easily blocked by silt and disturbed by external light, and the problem of the limiting tube 1 being weakened in structure due to the need for opening, scholars have proposed the concept of a magneto-electric sensor. However, when the magneto-electric sensor is applied to a coil-type electromagnetic launcher, it is easily affected by the strong magnetic field of the accelerating coil 2, which greatly reduces the reliability of the detection result. The present application is directed to the problem of the current magneto-electric sensor being easily affected by electromagnetic interference, and proposes a coil-type electromagnetic launcher and a projectile sensor, which aims to use the design concept of the magneto-electric sensor to solve the problems of the photoelectric sensor, and through the cooperation of the sensing circuit 51, the measurement circuit 52 and the processing circuit 53, to solve or reduce the influence of the magnetic field on the projectile sensor and improve the working reliability.

[0023] The projectile sensor provided by the present application is used for a coil-type electromagnetic launcher and is designed according to a magneto-electric sensor, which can be applied to an inductive electromagnetic launcher and a magneto-resistive electromagnetic launcher.

[0024] As shown in Figure 2 The projectile sensor mainly includes three parts, namely a sensing circuit 51, a measurement circuit 52 and a processing circuit 53.

[0025] The sensing circuit 51 includes at least one level of interconnected (possibly in series, possibly in parallel, or both) sensing coils, each level of sensing coil is wound on the same plane, and the winding shape is a spiral, which can be a circular spiral or a square spiral, and can be designed flexibly according to needs. If multiple levels of sensing coils are included, the levels of sensing coils are coaxial (parallel) arranged or arranged on the same plane.

[0026] In the present application, the structure design of the sensing circuit 51 is different from the sensing coil of the known magneto-electric sensor. The known sensing coil spirals forward along the axial direction, which requires a long space in the axial direction, is not conducive to the sequential arrangement of the accelerating coil 2, is easy to interfere with the accelerating coil 2, and is usually wrapped in the inner layer, and the accelerating coil 2 is wrapped in the outer layer, and the two are arranged in the same three-dimensional space of the limiting tube 1. In this way, the inner diameter of the sensing coil and the accelerating coil 2 needs to meet a certain relationship, which increases the difficulty of design, manufacturing and assembly, at the same time, the size of the sensing coil is enlarged, the material cost is increased, the mutual inductance of the two layers of coils is strong, the force on the projectile 4 is reduced under the same current, and the acceleration performance of the projectile 4 is affected. In the present application, the sensing coils are wound on the same plane, which is convenient for installation, at the same time, only a very short distance is occupied in the axial direction of the limiting tube 1, which will not affect the normal arrangement of the accelerating coil 2, and will not interfere with the accelerating coil 2 in the axial direction. The accelerating coil 2 can be designed to be smaller, and the accelerating force on the projectile 4 is also greater.

[0027] As an optional implementation, each stage of the sensing coil can be printed on the same layer or different layers of the PCB (Printed Circuit Board) board 50, and the interconnection can be realized through the metal via hole between the layers. The PCB board structure has the characteristics of low cost, good consistency, compact structure, convenient circuit connection, easy insulation treatment, etc. Moreover, the measurement circuit 52 and the processing circuit 53 can be arranged on the PCB board 50 together, and the projectile sensor on the same PCB board 50 can reduce the adverse effects of temperature drift on the detection results and improve the working reliability.

[0028] In the design results of the present application, the sensing circuit 51 of the projectile sensor has multiple working modes, different working modes collect different magneto-electric signals, and the reliable detection of the projectile state under the condition of reducing strong magnetic field interference is realized according to the different characteristics of the magneto-electric signals.

[0029] In different implementations, the sensing circuit 51 can work in the following modes respectively: (1) Inductive sensing mode (one) In this mode, the sensing circuit 51 includes at least one group of sensing coils, each group of sensing coils includes at least one stage of sensing coils, or multiple stages of sensing coils in the same direction are connected in series and equivalent to the winding of one stage of sensing coils, to generate an inductance signal after power-on, that is, to act as an inductive element after being connected to the circuit loop. After the sensing coil is sleeved on the limiting tube 1, the projectile 4 will pass through the sensing coil at a certain moment, temporarily acting as the core of the sensing coil, thereby affecting the inductance of the sensing coil and causing a sudden change.

[0030] For a magnetic resistance type electromagnetic launcher, the projectile 4 is a magnetic conductive material, so that when the projectile 4 enters the sensing coil, the inductance of the sensing coil increases, and when the projectile 4 leaves the sensing coil, the inductance of the sensing coil decreases. For an inductive type electromagnetic launcher, the projectile 4 is a conductive material, and the inductance of the sensing coil decreases due to eddy current when the projectile 4 enters the sensing coil.

[0031] Representatively, the acceleration circuit in the above working mode can be arranged at a position where the magnetic field is relatively weak (such as the end of the limiting tube 1), or in a scenario where the acceleration coil 2 works asynchronously, so as to reduce the influence of the strong magnetic field on the inductance signal measurement of the sensing coil (which can be completed by configuring the measurement circuit 52 as an inductance measurement circuit 52).

[0032] (2) Magnetic flux sensing mode In this working mode, the sensing circuit 51 includes at least one group of sensing coils, each group of sensing coils includes at least one stage of sensing coils or multiple stages of sensing coils wound in the same direction and connected in series, and the sensing coil generates an induced voltage signal due to the change of magnetic flux. When the projectile 4 passes through the sensing coil, the magnetic flux of the sensing coil changes, and the sensing coil generates an electric signal.

[0033] For the magnetic reluctance electromagnetic launcher, the projectile 4 is a magnetic conductive material, and the magnetic flux of the sensor coil rises after the projectile 4 enters the sensor coil; for the inductive electromagnetic launcher, the projectile 4 is a conductive material, and the eddy current causes the magnetic flux of the sensor coil to decrease after the projectile 4 enters the sensor coil.

[0034] Since the induced voltage signal is generated due to the change in the magnetic flux, the initial magnetic flux needs to be established for the sensor coil in this working mode. Since the projectile sensor is finally applied to the coil-type electromagnetic launcher, the acceleration coil 2 will generate a strong magnetic field, and therefore in some optional embodiments, the magnetic field of the acceleration coil 2 can be directly used to provide the initial magnetic flux for the sensor coil.

[0035] (3) Differential magnetic flux sensing mode This mode requires at least two sensor coils to generate a differential quantity. In some optional embodiments, the sensor circuit 51 includes at least one pair of sensor coils, each pair of sensor coils including two groups of sensor coils wound in opposite directions, and each group including at least one level of sensor coils. For each group of sensor coils, the structure can refer to the sensor coil structure in the working mode (1) and the working mode (2) described above. The two groups of sensor coils generate opposite induced currents due to the change in the magnetic flux.

[0036] Similarly to the working mode (2), the sensor coil needs to have an initial magnetic flux to subsequently generate an induced voltage signal due to the change in the magnetic flux. Therefore, an excitation coil can be designed in the sensor circuit 51 to emit an excitation signal to make the two groups of sensor coils have an initial magnetic flux. The excitation coil can be replaced by the acceleration coil 2.

[0037] (4) Inductive sensing mode (two) Similarly to the working mode (1), in this working mode, the sensor coil also needs to generate an inductance signal. The difference is that the working mode (4) may differ from the working mode (1) in the shape and layout of the sensor coil due to the difference in the application scenarios. For example, the working mode (1) is applied to the exploration of the position information of the projectile 4, while the working mode (4) is applied to the exploration of the quantity information of the projectile 4, so the sensor coil in the working mode (1) is designed in a circular shape and can be stacked in multiple layers, while the sensor coil in the working mode (4) is designed in a square shape and can be arranged in the same plane.

[0038] (5) Differential transformer mode In this working mode, the sensing circuit 51 includes at least one group of sensing coils, each group of sensing coils including at least one level of sensing coils or multiple levels of sensing coils wound in the same direction and connected in series, and at least one excitation coil corresponding to each group of sensing coils. The excitation coil radiates an electromagnetic field of a predetermined frequency, and the sensing coil is used to detect the electromagnetic field in the space and generate an induced voltage. The larger the induced voltage, the greater the mutual inductance, and when applied to the detection of the number of projectiles, the greater the number of projectiles. The target of the sensing coil is to detect the electromagnetic field of the predetermined frequency, but only through the coil cannot only detect the electromagnetic wave of the specific frequency, so the sensing coil usually transmits the entire signal detected to the subsequent circuit for processing.

[0039] From the above, in some working modes, the sensing circuit 51 should be avoided as much as possible in a strong magnetic field environment, but due to the limitations of the use environment, the sensing circuit 51 has to be set in a strong magnetic field environment. In view of this, in some optional embodiments, the sensing circuit 51 is provided with a magnetic shielding cover 54, which surrounds the sensing circuit 51. The magnetic shielding cover 54 is made of magnetic conductive material, which can reduce the interference of the external magnetic field on the internal circuit. In addition, the magnetic conductive material of the magnetic shielding cover 54 cannot be filled into the sensing coil, otherwise it will cause the magnetic circuit near the projectile 4 to be bypassed, reducing the sensitivity of the projectile sensor. Since it is to reduce the influence of the external magnetic field, therefore, the sensing circuit 51 in the above working mode (1), working mode (4) and working mode (5) can be considered to be provided with a magnetic shielding cover 54.

[0040] The measurement circuit 52 is connected to the sensing circuit and is used to detect at least one target feature of the magnetic and electric signals detected by the sensing circuit in frequency, amplitude or period.

[0041] The magnetic and electric signals detected by the sensing circuit 51 in different working modes are different, and correspondingly, the target features detected by the measurement circuit 52 also have certain differences. That is, the target circuit corresponds to the working mode of the sensing circuit 51.

[0042] Specifically, the optional configuration of the measurement circuit 52 includes: (1) corresponding to the working mode (1) of the sensing circuit 51 In this working mode, the measurement circuit 52 detects the frequency characteristics of the inductance signal.

[0043] The frequency characteristics can have various forms, and in an optional embodiment, the frequency characteristics of the inductance signal are represented by the length of the PWM wave period, which can greatly reduce the false detection caused by the influence of the strong magnetic field.

[0044] In this embodiment, the measurement circuit 52 comprises a capacitance circuit and a comparison circuit, the capacitance circuit and the sensing circuit 51 form an oscillation circuit, i.e. the sensing circuit 51 forms part of the oscillation circuit, and the capacitance circuit forms an LC oscillator, which generates an oscillation signal whose frequency changes with the inductance of the sensing circuit 51. The comparison circuit is connected to the oscillation circuit, and converts the oscillation signal output by the oscillation circuit into a PWM wave, and uses the period of the PWM wave (with a constant duty ratio) as the frequency characteristic to be detected.

[0045] (2) Corresponding to the working mode (2) and the working mode (3) of the sensing circuit 51 In this working mode, the measurement circuit 52 detects the amplitude characteristic of the induced voltage signal. For the working mode (2), it directly detects the amplitude characteristic of the induced voltage signal of the sensing coil, and for the working mode (3), it respectively connects the two groups of sensing coils of each pair, and detects the amplitude characteristic of the induced voltage signal at the connection point. The amplitude characteristic includes the size characteristic of the amplitude, the direction characteristic of the amplitude, and the change degree characteristic of the amplitude, etc. In this embodiment, the detected amplitude characteristic is the change degree characteristic of the amplitude, specifically, it is the characteristic of the amplitude mutation, which is represented by the rising edge or the falling edge of the induced voltage signal.

[0046] In an alternative embodiment, the measurement circuit 52 comprises a differentiator and a comparator, the differentiator is connected to the induced voltage signal, and is used to detect the voltage change rate of the induced voltage signal at every two adjacent time points. The comparator is connected to the voltage change rate, and compares it with a preset change rate threshold (used to determine whether a mutation occurs), and outputs the amplitude characteristic of the judgment of whether the voltage change rate reaches the change rate threshold. The rising edge and the falling edge of the output signal of the comparator represent that the induced voltage signal has undergone a mutation.

[0047] In another alternative embodiment, the measurement circuit 52 comprises an ADC sampler, which samples the induced voltage signal, converts the analog level signal into a digital signal, and uses the digital signal amplitude to represent the amplitude characteristic of the induced voltage signal.

[0048] (3) Corresponding to the working mode (4) of the sensing circuit 51 In this working mode, the measurement circuit 52 detects the amplitude characteristic of the inductance signal.

[0049] The more the bullets 4 in the magazine 3, the more full the space of the sensing coil core, and the greater the inductance of the sensing coil, i.e. the number of bullets is positively correlated with the size of the inductance. For this, the measurement circuit 52 uses the inductance detection circuit to detect the inductance of the sensing circuit 51, and then the processing circuit 53 obtains the bullet number information according to the matching relationship (which can be calibrated in advance) between the inductance and the bullet number.

[0050] (4) Corresponding to the working mode of the sensing circuit 51 (5) In this working mode, the measurement circuit 52 detects the amplitude feature of the mutual inductance voltage / current signal of the sensing circuit 51 at a predetermined frequency.

[0051] In this working mode, the excitation coil is injected with an analog signal (for example, a sine signal) of a predetermined frequency, and the sensing coil collects electromagnetic waves containing the predetermined frequency and converts them into a mutual inductance signal in the form of voltage. The strength of the mutual inductance signal reflects the number of the projectiles 4. The more the projectiles 4, the stronger the mutual inductance signal. For this reason, the measurement circuit 52 detects the amplitude feature of the mutual inductance signal, and the processing circuit 53 obtains the projectile 4 quantity information according to the matching relationship (which can be calibrated in advance) between the mutual inductance and the projectile quantity.

[0052] The processing circuit 53 is connected to the measurement circuit 52 and is used to identify the projectile state based on the detected target feature. The projectile state includes at least one of the projectile 4 position information or the quantity information. Obviously, the projectile state can also include speed information, acceleration information, etc. However, these state information can be further calculated according to the requirements on the basis of identifying the position information of the projectile 4. Therefore, the most basic projectile state is still the position information and the quantity information of the projectile 4.

[0053] The target feature detected by the measurement circuit 52 is different, and the processing flow / circuit structure corresponding to the identification of the projectile state can be different. Therefore, the configuration of the processing circuit 53 is introduced according to the different configurations of the measurement circuit 52 in the foregoing.

[0054] The processing circuit 53 can consider zeroing the target feature in advance for any configured measurement circuit 52, so as to reduce the cumulative error caused by external magnetic fields, etc.

[0055] (1) Corresponding to the configuration (1) of the measurement circuit 52 In this configuration, the processing circuit 53 locates the mutation time of the inductance signal according to the frequency feature, and identifies the position information of the projectile 4 according to the mutation direction of the mutation time.

[0056] Specifically, for a magnetoresistive electromagnetic transmitter, when the projectile 4, made of magnetically conductive material, enters the sensing coil, the inductance increases, the oscillation frequency of the oscillation signal decreases, and each cycle of the PWM wave becomes longer (duty cycle remains unchanged). Conversely, when the projectile 4 leaves the sensing coil, each cycle of the PWM wave becomes shorter. In an inductive electromagnetic reflector, when the projectile 4, made of conductive material, enters the sensing coil, the inductance decreases, the oscillation frequency of the oscillation signal increases, and each cycle of the PWM wave becomes shorter. Conversely, when the projectile 4 leaves the sensing coil, each cycle of the PWM wave becomes longer. Therefore, for the frequency characteristics detected by the measurement circuit 52, the processing circuit 53 extracts the rising / falling edge time of the inductance. For the magnetoresistive electromagnetic transmitter, the rising / falling edge time is determined as the moment when the head of the projectile enters the projectile sensor / the tail of the projectile leaves the projectile sensor, that is, at the corresponding moment, the projectile 4 enters / leaves the position of the projectile sensor. For the inductive electromagnetic transmitter, the opposite is true: the falling / rising edge time is determined as the moment when the head of the projectile enters the projectile sensor / the tail of the projectile leaves the projectile sensor, that is, at the corresponding moment, the projectile 4 enters / leaves the position of the projectile sensor.

[0057] For example, such as Figure 3 As shown, the sensing coil is mounted on a PCB board, coiled around a circular hole for the limiting tube 1 to pass through, allowing the projectile sensor to be mounted onto the limiting tube 1. A magnetic shield 54 is mounted on the sensing circuit 51. The measurement circuit 52 uses a capacitor circuit combined with a comparator circuit structure to convert the inductance signal detected by the sensing circuit 51 into a PWM wave with consistent amplitude. When the inductance of the sensing circuit 51 changes, the frequency change of the oscillation signal output by the oscillation circuit connected to it is ultimately represented by the change in each cycle of the PWM wave. Figure 4 The figure shows the statistical relationship between the period duration of the PWM wave output by the comparator of a magnetoresistive electromagnetic transmitter, which is converted from the inductance signal output by a set of sensing coils, and the number of cycles.

[0058] Before launching the projectile 4, the processing circuit 53 measures the PWM wave period duration and performs a zeroing (i.e., sets the PWM wave period duration as the starting cycle number). Additionally, the processing circuit 53 pre-sets a threshold for the PWM wave period duration, such as 105% of the zeroing point PWM wave period duration (other thresholds are also possible). When the PWM wave period duration in the waveform rises to this threshold, it is determined that the projectile 4 (head) has reached the sensing coil position; conversely, when the PWM wave period duration in the waveform falls to this threshold, it is determined that the projectile 4 (tail) has left the sensing coil position. The reverse is true for inductive electromagnetic launchers.

[0059] In addition, in an alternative embodiment, the processing circuit 53 also records the time when the projectile 4 reaches and leaves the position of the sensing coil, calculates the time difference between the two times, and according to the length of the projectile 4, calculates the speed information of the projectile 4 at this position.

[0060] In another alternative embodiment, two or more groups of sensing coils can be provided, and the measurement circuit 52 converts the inductance signal of each group of sensing coils into Figure 4 The processing circuit 53 identifies the time when the projectile 4 reaches / leaves each group of sensing coils in each group of frequency characteristics, respectively, calculates the time difference when the projectile 4 reaches any two groups of sensing coils, and according to the distance between the two groups of sensing coils, calculates the average speed information of the projectile 4 during this period. In addition, according to the design of the above-mentioned structure, the processing circuit 53 can also calculate the speed of the projectile 4 at the two groups of sensing coils, and calculate the acceleration information of the projectile 4 according to the time difference when the projectile 4 reaches / leaves the two groups of sensing coils.

[0061] The above-mentioned embodiments correspond to the working mode (1) of the sensing circuit 51, and the sensing coils in this working mode can be provided at the end position of the limiting tube 1 and can work asynchronously with the acceleration coil 2.

[0062] (2) Corresponding to the configuration (2) of the measurement circuit 52 In this configuration, the processing circuit 53 locates the mutation time of the inductive voltage signal according to the amplitude characteristics, and identifies the position information of the projectile 4 according to the mutation direction of the mutation time. The design of calculating speed information, acceleration information, etc. based on position information can refer to the design in the configuration (1) of the processing circuit 53 in the foregoing, that is, designing multiple groups of sensing coils to calculate the speed information or acceleration information of the projectile 4.

[0063] For the embodiment of the measurement circuit 52 using a differentiator and a comparator, the processing circuit 53 locates the rising edge / falling edge time in the output waveform of the comparator, determines the time when the projectile 4 reaches / leaves the sensing coil, and determines the position of the projectile 4 at the corresponding time. For the embodiment of the measurement circuit 52 using an ADC sampler, the processing circuit 53 identifies the time when the amplitude characteristics occur mutation (rise / fall) by using digital filtering, slope extraction, zero-crossing comparison, extreme value calculation, etc., and determines the time when the projectile 4 reaches / leaves the sensing coil.

[0064] (3) Corresponding to the configuration (3) and configuration (4) of the measurement circuit 52 The processing circuit 53 obtains the number information of the projectile 4 according to the matching relationship between the mutual inductance and the number of projectiles (previously calibrated).

[0065] (4) Based on the configuration (1) or configuration (2) of the processing circuit 53, the processing circuit 53 calculates the speed of the projectile 4 according to the time difference of the projectile 4 entering / leaving the sensor coil, or comprehensively analyzes the signal characteristics in the process of the projectile 4 passing through the sensor, and combines the known length of the projectile 4.

[0066] (5) Based on the configuration (1) or configuration (2) of the processing circuit 53, two or more sets of sensor coils are used to calculate the time difference of the projectile 4 passing through any two sets of sensor coils, and the distance between the sensor coils is known. The interval velocity measurement method can be used to calculate the speed of the projectile. When the speed of the projectile 4 in the interval is basically constant, and the interval length is not less than the length of the projectile, this configuration method is usually more accurate than the configuration (4).

[0067] The following describes the implementation of the projectile sensor in some embodiments of the application.

[0068] As shown in Figure 5 , a structure design is adopted in the working mode (3) of the sensing circuit 51. Two sensor coils with opposite spiral directions are printed on the same PCB board 50 on both sides: the first coil 51a is printed on the front side, and the second coil 51b is printed on the back side. One end of each of the two sensor coils is connected through an impedance element, and the other end of each of the two sensor coils is grounded. The connection point is grounded through a test element. The voltage signal at the test element is the induced voltage signal. This embodiment is equivalent to the circuit structure shown in Figure 6 , where L1 and L2 represent the first sensor coil and the second sensor coil respectively, L1 and L2 are opposite in the direction of electrical connection, and therefore will generate opposite direction currents under the action of the same electromagnetic field. L1 is connected to the test element RL through the resistor R1, L2 is also connected to RL through the resistor R2, the other end of RL is grounded, and the non-grounded end of RL is the connection point, and the voltage at this point is the induced voltage signal.

[0069] The projectile sensor is used to detect when the projectile 4 reaches the predetermined position, as shown in Figure 7 , the process is as follows: S1, install the projectile sensor (sensing coil) to the predetermined position of the limiting tube 1, assuming between the second stage acceleration coil and the third stage acceleration coil (the same for other adjacent acceleration coils 2), and the second stage acceleration coil provides the initial magnetic flux for the sensing coil.

[0070] S2, adjust the ratio of L1 and L2, or adjust the ratio of R1 and R2, so that there is no current through RL when the second stage accelerating coil switches between on / off state. Thus, the anti-electromagnetic interference effect is achieved. This is because the electromagnetic interference on the sensing coil is the strongest when the second stage accelerating coil is started, and the third stage accelerating coil is working when the projectile sensor has completed the sensing task, at this time the sensing coil is no longer disturbed by the third stage accelerating coil. This design mainly aims at the anti-interference design of the first working accelerating coil 2, that is, for the accelerating coil 2, when the current of the accelerating coil 2 changes, the current flowing from L1 and L2 to RL is equivalent to reverse, so that there is no current on RL.

[0071] S3, during the process that the projectile 4 gradually enters the sensing coil, it is assumed that L1 is entered first, then the induced current is generated on L1, and the positive induced voltage signal is generated on RL, then the projectile 4 enters L2, and the induced current is generated on L2, and the reverse induced voltage signal is generated on RL. The direction of the current generated when the projectile 4 leaves L1 and L2 is opposite to that when the projectile 4 enters L1 and L2. Therefore, the amplitude characteristics of the induced voltage signal on RL can reflect the time when the projectile 4 enters / leaves L1 and L2. Therefore, after the projectile 4 is launched, the amplitude characteristics of the induced voltage signal on RL are detected by the measuring circuit 52 during the movement of the projectile 4.

[0072] S4, the rising edge / falling edge of the induced voltage signal is located according to the amplitude characteristics by using the processing circuit 53, and the rising edge is taken as the time when the projectile 4 enters the sensing circuit 51, and the falling edge is taken as the time when the projectile 4 leaves the sensing circuit 51.

[0073] Further, S5, the time difference between the time when the projectile 4 enters and leaves the sensing circuit 51 is calculated by using the processor, and the projectile speed is calculated according to the length of the projectile.

[0074] According to the idea of the present application, the present application further provides a coil electromagnetic transmitter, which comprises a cartridge 3 for containing a projectile 4 to be launched, a limiting tube 1 for guiding the launching direction of the projectile 4, a plurality of acceleration coils 2 for accelerating the projectile 4, and at least one projectile sensor of the above-mentioned embodiments. According to the detection purpose (detecting position information or quantity information), the projectile sensor of different embodiments is selected. For example, the projectile sensor under the working mode (4) and (5) of the sensing circuit 51 can be used to detect the quantity information of the projectile 4, and this projectile sensor is called a projectile quantity sensor 6; and the projectile sensor under the working mode (1), (2) and (3) of the sensing circuit 51 can be used to detect the position information of the projectile, and this projectile sensor is called a projectile position sensor 5. The sensing circuit 51 of the projectile sensor is mounted on the limiting tube 1 (for detecting position information) and / or the cartridge 3 (for detecting quantity information). When mounted on the limiting tube 1, the sensing coil is wrapped around the limiting tube 1 perpendicular to the axial direction of the limiting tube 1; when mounted on the cartridge 3, the plane of the sensing coil is parallel to the arrangement direction of the projectile 4, for example, on the left / right side surface of the cartridge 3.

[0075] As shown in Figure 8 The schematic diagram of the projectile sensor that can be installed at different positions on the coil electromagnetic transmitter is shown. Among them, at both ends of the limiting tube 1, the projectile sensor under the working mode (1) of the sensing circuit 51 can be installed respectively, at the middle position of the limiting tube 1 (between any two acceleration coils 2), the projectile sensor under the working mode (3) of the sensing circuit 51 can be installed, and on the side surface of the cartridge 3, the projectile sensor under the working mode (4) or (5) of the sensing circuit 51 can be installed.

[0076] Taking the projectile sensor installed between the second acceleration coil and the third acceleration coil as an example, the working process can be referred to the corresponding embodiment shown in Figure 7 .

[0077] Compared with the currently known magnetic electric type sensor, the projectile sensor provided by the present application provides a plurality of working modes, can detect a plurality of state information of the projectile 4 in a plurality of ways, and has a wide application range. Moreover, the projectile sensor can reduce or eliminate the interference of external magnetic field, improve the reliability of the detection result, and has high industrial application value.

[0078] The present application is not limited to the foregoing specific embodiments. The present application extends to any new feature or any new combination disclosed in the present specification, and any new method or process steps or any new combination disclosed.

Claims

1. A projectile sensor for a coil electromagnetic emitter, characterized in that, Comprise: a sensing circuit comprising at least one level of sensing coils, each level of sensing coils is wound on the same plane respectively, and each level of sensing coils is arranged coaxially or on the same plane; a measuring circuit connected to the sensing circuit, for detecting at least one target feature of the magnetic and electric signals detected by the sensing circuit in frequency, amplitude or period; a processing circuit connected to the measuring circuit, for identifying the projectile state based on the target feature, the projectile state comprising at least one of the projectile position information or the quantity information.

2. The projectile sensor for the coil electromagnetic transmitter according to claim 1, wherein: the sensing circuit comprises at least one group of sensing coils, each group of sensing coils comprises at least one level of sensing coils or multiple levels of sensing coils wound in the same direction in series, for generating an inductance signal after power-on; the measuring circuit detects the frequency feature of the inductance signal; the processing circuit locates the mutation time of the inductance signal according to the frequency feature, and identifies the position information of the projectile according to the mutation direction of the mutation time.

3. A projectile sensor for a coil electromagnetic launcher as defined in claim 2, wherein, the measuring circuit comprises a capacitor circuit and a comparison circuit, the capacitor circuit and the sensing circuit form an oscillation circuit, the comparison circuit is connected to the oscillation circuit, converts the oscillation signal output by the oscillation circuit into a PWM wave, and takes the period of the PWM wave as the frequency feature; the processing circuit measures the period of the PWM wave, and locates the mutation time of the inductance signal according to the period.

4. The projectile sensor for the coil electromagnetic transmitter according to claim 1, wherein: the sensing circuit comprises at least one group of sensing coils, each group of sensing coils comprises at least one level of sensing coils or multiple levels of sensing coils wound in the same direction in series, and the sensing coils generate an induced voltage signal due to the change of magnetic flux; the measuring circuit detects the amplitude feature of the induced voltage signal; the processing circuit locates the mutation time of the induced voltage signal according to the amplitude feature, and identifies the position information of the projectile according to the mutation direction of the mutation time.

5. The projectile sensor for the coil electromagnetic transmitter according to claim 1, wherein: the sensing circuit comprises at least one pair of sensing coils, each pair of sensing coils comprises two groups of sensing coils wound in opposite directions respectively, and each group comprises at least one level of sensing coils; the two groups of sensing coils of each pair generate opposite induced currents due to the change of magnetic flux respectively; the measuring circuit connects the two groups of sensing coils of each pair respectively, and detects the amplitude feature of the induced voltage signal at the connection point; the processing circuit locates the mutation time of the induced voltage signal according to the amplitude feature, and identifies the position information of the projectile according to the mutation direction of the mutation time.

6. Projectile sensor for a coil electromagnetic emitter according to claim 4 or 5, characterized in that, The measurement circuit includes a differentiator and a comparator, the differentiator is connected to the induced voltage signal for detecting the voltage rate of change of every adjacent two time points of the induced voltage signal; the comparator is connected to the voltage rate of change, compares it with a preset rate of change threshold, and outputs a magnitude feature of judging whether the voltage rate of change reaches the rate of change threshold; the processing circuit locates the rising edge or falling edge of the output signal of the comparator as the mutation time point of the induced voltage signal.

7. The projectile sensor for the coil electromagnetic transmitter according to claim 1, characterized in that, The sensing circuit includes at least one group of sensing coils, each group of sensing coils includes at least one level of sensing coil or multiple levels of sensing coils wound in the same direction and connected in series, and at least one excitation coil, the excitation coil corresponds to the sensing coil group one by one, the excitation coil radiates electromagnetic field of a predetermined frequency, and the sensing coil is used for detecting electromagnetic field in the space and generating mutual inductance current; The measurement circuit detects the amplitude feature of the mutual inductance voltage / current signal of the sensing circuit at the predetermined frequency; The processing circuit identifies the quantity information of the projectile according to the amplitude feature.

8. A projectile sensor for a coil electromagnetic launcher as claimed in any one of claims 2, 3 or 7, characterised in that, The sensing circuit is provided with a magnetic shield.

9. A coil electromagnetic transmitter, characterized by The cartridge includes a cartridge for accommodating the projectile to be launched, a limiting tube for guiding the direction of launching the projectile, multiple acceleration coils for accelerating the projectile, and at least one projectile sensor according to claim 1; the sensing circuit of the projectile sensor is mounted on the limiting tube and / or the cartridge; when mounted on the limiting tube, the sensing coil is wrapped around the limiting tube perpendicular to the axial direction of the limiting tube; when mounted on the cartridge, the sensing coil plane is parallel to the arrangement direction of the projectile.

10. A coil electromagnetic transmitter as claimed in claim 9, characterised in that, A projectile sensor is arranged between two acceleration coils at a predetermined position on the limiting tube; The sensing circuit of the projectile sensor includes at least one pair of sensing coils, each pair of sensing coils includes two groups of sensing coils wound in opposite directions, and each group includes at least one level of sensing coil; the two groups of sensing coils generate opposite induced currents due to the change of magnetic flux; The measurement circuit connects the two groups of sensing coils of each pair respectively, detects the amplitude feature of the induced voltage signal at the connection point; the two groups of sensing coils generate equal and opposite induced currents at the connection point when the preceding start acceleration coil starts; The processing circuit locates the mutation time point of the induced voltage signal according to the amplitude feature, and identifies the position information of the projectile according to the mutation direction of the mutation time point.

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