CN111650402B - Trajectory vertex identification method based on triaxial accelerometer - Google Patents

Abstract

The invention belongs to the field of fuze control, in particular to a ballistic vertex identification method based on a three-axis accelerometer. The scheme includes a projectile body and a fuze, and the fuze is fixedly installed inside the projectile body; the axis of the fuze coincides with the axis of the projectile body; a PCB board is fixed on the fuze, and the PCB board is provided with a power module, a three-axis accelerometer, CPLD and Peripheral circuits. In this scheme, two triaxial accelerometers installed inside the fuze of a certain type of mortar projectile are used to measure the xy plane and z axis acceleration values of the projectile during the ballistic flight, and the projectile is judged by the algorithm of "threshold + sequence + time window" Whether it is in the launch state and reaches the apex of the ballistic trajectory, thereby providing an environmental stimulus signal for the fuze long-distance disarming. The invention adopts the accelerometer installed inside the fuze to judge the ballistic apex signal, so as to control the safety switch state, and has the advantages of not destroying the aerodynamic shape of the projectile body, requiring no additional power-electricity conversion structure, being extremely easy to engineer, and having high reliability.

Description

A ballistic vertex recognition method based on three-axis accelerometer

technical field

The invention belongs to the field of fuze control, in particular to a ballistic vertex identification method based on a three-axis accelerometer.

Background technique

According to the requirements of the national military standard GJB373A-97 and GJB6456-2008 for fuze design, the fuze electronic safety and release safety device requires two static switches and one dynamic switch as the detonation energy spacer, and the environmental excitation signals to activate the safety switch must be independent of each other and Taken from different environments. Fuze electronic safety and defuse devices are currently only used in high-value weapon systems such as missiles and torpedoes, and conventional ammunition such as mortar shells has yet to be popularized.

Since the projectile launched by the mortar is a micro-spin, its fuze release environmental force is not only the recoil force, but the current design usually uses aerodynamics, electrical insurance, etc. as the second environmental information. Insufficient distance, etc.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a ballistic vertex identification method based on a three-axis accelerometer, by measuring the xy plane and the The z-axis acceleration value is used to judge whether the projectile is in the launch state and reaches the ballistic vertex through the "threshold + sequence + time window" algorithm, thereby providing an environmental excitation signal for the fuse release.

The technical solution for realizing the purpose of the present invention is: a ballistic vertex identification method based on a three-axis accelerometer, measuring the xy plane and the The z-axis acceleration value is used to judge whether the projectile is in the launch state and reaches the ballistic vertex through the "threshold + sequence + time window" algorithm.

Further, the two three-axis accelerometers are symmetrically arranged on both sides of the center of mass of the projectile, and the three sensitive axes of the three-axis accelerometer are: the x-axis points to the direction of the center of mass of the projectile, the y-axis points to the forward direction of the longitudinal axis of the projectile, The z-axis points in the tangential direction of the projectile.

Further, the axis of the fuze coincides with the axis of the projectile body, the fuze is fixedly provided with a PCB board, and the installation position of the PCB board is perpendicular to the axis; the PCB board has a power module, a CPLD, a three-axis accelerometer and a peripheral circuit. .

Further, determining whether the projectile is in the launch state and reaching the ballistic vertex through the "threshold + sequence + time window" algorithm is specifically:

According to the measurement error of the three-axis accelerometer, the threshold value A of the resultant acceleration of the projectile on the xy plane of the projectile axis is set, and a larger time window T is set according to the time range of reaching the ballistic vertex. The frequency f is sampled and compared with the threshold value A, and the safety switch is released in accordance with the logic of the CPLD module.

Further, determining whether the projectile is in the launch state and reaching the ballistic vertex through the "threshold + sequence + time window" algorithm is specifically:

Step (1): After the forced launch, the CPLD collects the x-axis, y-axis, and z-axis accelerations of the two three-axis accelerometers every 1ms in the time window T, which are respectively recorded as a _x1 , a _x2 , a _y1 , a _y2 , a _z1 , a _z2 , and calculate the resultant acceleration a _xy of the xy plane;

Step (2): set the initial combined acceleration maximum value a _xymax =0, compare the calculated resultant acceleration a _xy with the maximum value, if a _xy is greater than the maximum value, update and cover a _xymax with the current value;

Step (3): Set the initial z-axis acceleration of the two accelerometers a _z0 = 0, compare the collected a _z1 and a _z2 with a _z0 respectively, if both a _z1 and a _z2 are smaller than T/1ms times a _z0 , it means that the projectile has been fired and has been off the plane; if a _z1 and a _z2 are greater than or equal to a _z0 once in T/1ms times, it means that the projectile is not in a normal firing state, and the fuze cannot release the safety switch state. T is the preset time window;

Step (4): Monitor the change trend of a _xymax in real time. When a _xymax is not updated for 3 consecutive samplings, compare it with the threshold value A. If a _xymax is greater than or equal to the threshold value, it indicates that the projectile has reached the ballistic vertex or just passed the ballistic vertex. The CPLD sends out the corresponding release signal of the safety switch.

Compared with the prior art, the present invention has the following significant advantages:

(1) The present invention adopts the accelerometer installed inside the fuze to judge the ballistic apex signal, thereby controlling the safety switch state, and has the advantages of not destroying the aerodynamic shape of the projectile body, without additional power-to-electricity conversion structure, being extremely easy to engineer, and having high reliability; Applications in electronic security and defuse devices enable small, low-cost designs.

(2) Due to the launch environment of the forced bomb, there are not many deprotection environment excitation signals that can be used. The present invention adopts the method of identifying the ballistic vertex signal to provide the deprotection excitation signal, which provides the electronic safety and the application of the safety release device in the forced bomb. A new solution.

(3) The generation distance of the release signal used in the present invention is more than half the range of the forced ejection, which can realize the release of the insurance control at a long distance and ensure the high safety of the design.

(4) The present invention adopts a double accelerometer measurement method to offset the system error of the accelerometer.

Description of drawings

FIG. 1 is a schematic diagram of the installation of the safety release device of the forced bomb fuze all-electronic safety system of the present invention.

FIG. 2 is a schematic structural diagram of a three-axis accelerometer in a forced bomb fuze full electronic safety system release device of the present invention.

Description of reference numbers:

1-Forcing projectile, 2-Forcing fuze, 3-Triaxial accelerometer I, 4-Triaxial accelerometer II.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings.

As shown in Figures 1-2, the present invention includes a projectile body and a fuze 2, the fuze 2 is fixedly installed inside the projectile body, and the axis of the fuze 2 coincides with the axis of the projectile body; a PCB board is fixed on the fuze, and the PCB The installation position of the board is perpendicular to the axis; there are power modules, CPLDs, triaxial accelerometers and peripheral circuits on the PCB; two triaxial accelerometers are symmetrically arranged on both sides of the center of mass of the projectile, and the three sensitive axes are: the x-axis points to The direction of the center of mass of the projectile, the y-axis points to the forward direction of the longitudinal axis of the projectile, and the z-axis points to the tangential direction of the projectile; the fuze includes a fuze casing and a hardware circuit; the hardware circuit is potted and fixed inside the fuze casing.

The ballistic vertex identification method of the present application is as follows:

Two triaxial accelerometers are installed inside a mortar shell fuze to measure the xy plane and z axis acceleration values of the projectile under the launch environment, and the "threshold + sequence + time window" algorithm is used to determine whether the projectile is in the launching state and reaches the Ballistic apex, thereby providing environmental information incentives for fuze de-assurance.

First, set the threshold value A of the resultant acceleration of the projectile on the xy plane of the projectile axis according to the measurement error of the accelerometer, and set a larger time window T according to the time range of reaching the ballistic vertex, and sample at the frequency f within this time window. And compared with the threshold value A, the safety switch is released in accordance with the logic of the CPLD module.

The specific implementation process is as follows:

(1) After the forced bomb is launched, the CPLD collects the x-axis, y-axis, and z-axis accelerations of the two three-axis accelerometers every 1ms in the time window T, which are respectively recorded as a _x1 , a _x2 , a _y1 , a _y2 , a _z1 , a _z2 , and calculate the resultant acceleration a _xy in the xy plane;

(2) Set the initial resultant acceleration maximum value a _xymax =0, compare the calculated resultant acceleration a _xy with the maximum value, if a _xy is greater than the maximum value, update and cover a _xymax with the current value,;

(3) Set the initial z-axis acceleration of the two accelerometers a _z0 = 0, and compare the collected a _z1 and a _z2 with a _z0 respectively. If both a _z1 and a _z2 are smaller than a _z0 in T/1ms times , it means that the projectile has been fired, that is, it has left the aircraft; if a _z1 and a _z2 are greater than or equal to a _z0 once in T/1ms times, it means that the projectile is not in a normal firing state, and the fuze cannot release the safety switch state. T is the preset duration.

(4) Monitor the change trend of a _xymax in real time. When a _xymax is not updated for 3 consecutive samplings, compare it with the threshold A. If a _xymax is greater than or equal to the threshold, it means that the projectile has reached the ballistic vertex or just passed the ballistic vertex, and the CPLD sends out The safety switch correspondingly releases the safety signal.

The embodiments are only examples and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (1)

1. A trajectory vertex identification method based on three-axis accelerometers is characterized in that two three-axis accelerometers arranged in a mortar shell fuse are used for measuring xy plane and z axis acceleration values borne by a projectile in a trajectory flight process, and whether the projectile is in a launching state and reaches a trajectory vertex is judged through a threshold value + sequence + time window algorithm;

two triaxial accelerometer symmetric arrangement are in projectile body barycenter both sides, and three sensitive axle of triaxial accelerometer is respectively: the x axis points to the direction of the center of mass of the projectile body, the y axis points to the advancing direction of the longitudinal axis of the projectile body, and the z axis points to the tangential direction of the projectile body;

the axis of the fuse is overlapped with the axis of the projectile body, a PCB is fixedly arranged on the fuse, and the installation position of the PCB is vertical to the axis; the PCB is provided with a power module, a CPLD, a triaxial accelerometer and a peripheral circuit;

the specific steps of judging whether the projectile is in a launching state and reaches a ballistic vertex through a threshold value + sequence + time window algorithm are as follows:

setting a threshold A of the combined acceleration of the projectile on a projectile axis xy plane according to the measurement error of the triaxial accelerometer, setting a larger time window T according to the time range of the projectile reaching the ballistic vertex, sampling at a frequency f in the time window T, comparing with the threshold A, and releasing the safety switch if the time meets the logic of a CPLD module;

the specific steps of judging whether the projectile is in a launching state and reaches a ballistic vertex through a threshold value + sequence + time window algorithm are as follows:

step (1): after the mortar shell is launched, the CPLD acquires the accelerations of the x axis, the y axis and the z axis of two three-axis accelerometers every 1ms in a time window T, and the accelerations are respectively marked as a_x1、a_x2、a_y1、a_y2、a_z1、a_z2And calculating the resultant acceleration a of the xy plane_xy；

Step (2): setting the maximum value a of the initial resultant acceleration_xymaxWhen the calculated total acceleration a is 0_xyIs compared with the maximum value if a_xyIf greater than the maximum value, update and overwrite a with the current value_xymax；

And (3): setting initial z-axis acceleration a of two accelerometers_z0A is 0, collected_z1、a_z2Are respectively connected with a_z0By comparison, if a is in T/1ms times_z1、a_z2Are all less than a_z0If the shot is shot, the shot is shot and is off-line; if there is one of times a in T/1ms_z1、a_z2Is greater than or equal to a_z0If the shot is not in a normal launching state, the fuse can not release the safety switch state, and T is a preset time window;

and (4): real-time monitoring a_xymaxWhen a is sampled 3 times in succession_xymaxNot updated, compare it to a threshold A if a_xymaxIf the value is larger than or equal to the threshold value, the projectile reaches the ballistic vertex or just passes the ballistic vertex, and the CPLD sends out a corresponding safety release signal of the safety switch.

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