Research And Discussion On Three-dimensional Amplitude Measurement Method

When the projectile is fired,the gunpowder burns sharply to generate strong thrust to eject the projectile.The reverse thrust generated in this process,the expanding airflow and the collision between the projectile and the inner wall of the cylinder will cause the cylinder to vibrate violently.The intensity of the vibration of the cylinder will directly affect the accuracy of the projectile strike and reduce the lethality.Therefore,the three-dimensional amplitude measurement of the cylinder is an indispensable indicator in the field of aerospace.The burning of gunpowder produces strong black smoke instantly,the collision between the projectile and the barrel and the release of pressure when the projectile exits the barrel will produce a largely roar with dazzling fire.In this environment,higher requirements are placed on the instruments and methods for measuring the three-dimensional amplitude.As the projectile pops up,the pressure on the cylinder decreases,resulting in an increase in the angle of inclination between the object and the horizontal plane.The cylinder will have a tendency to rise slowly,it will not return to the starting point.This elevated displacement is a low-frequency signal,which is Permanent displacement.In this paper,the three-dimensional amplitude measurement and the problem of permanent displacement in the above harsh environment are studied,and two methods of amplitude measurement are studied:(1)Based on a rope-type displacement sensor,a vibration displacement measurement platform is build,it converted the change of the three-dimensional space position of the cylinder into the change of three-dimensional coordinates.This method is based on the principle of three-ball intersection positioning.The balls with the cable outlet of the rope-typedisplacement sensor as the center of the sphere and the extension length of the cable as the radius are drew,and finally the three balls will intersect at two points.The equations are listed and solved using MATLAB.Putting the outlet points of the three sensors on the X,Y,Z axes of the three-dimensional space coordinates can greatly reduce the calculation amount of the equation group and improve the calculation efficiency.The calculated data is combined with ORIGIN digital filtering,smoothing curve,zero-removal and other processing,and finally converted into the relative displacement change of the measured object in the three-dimensional space coordinates.The test results show that the measurement method is simple and intuitive to operate,the solution is inexpensive,and the accuracy error is better than 2mm in the range of 0 ~ 100 mm,which better solves the measurement of three-dimensional amplitude displacement changes.(2)Based on the accelerometer sensor,the acceleration of the cylinder is continuously changed,and the vibration displacement curve is obtained by integrating the acceleration in sections.By comparing the traditional frequency domain quadratic integration,time domain quadratic integration,frequency domain-time domain hybrid integration,the data segmentation method based on time domain integration is discussed,and the segmentation integration is performed according to different characteristics of the acceleration perception curve in the time domain to remove the error accumulation of long-term time domain integration.The data is processed differently according to the vibration of each segment of the object,and the displacement curve is finally obtained by time domain integration.The amplitude displacement curve is obtained by integrating the acceleration data is compared with the measured data of the standard displacement meter.The maximum peak error of the displacement curve is better than 16% and the permanent displacement error is better than20%.The experimental results show that the data segmentation method can reflect the true vibration displacement trend of the cylinder.