Aiming at difficult strain test and unable to accurate strain test for electromagnetic railgun’s special-shaped barrel bore, the strain testing technology of special-shaped barrel was studied. According to electromagnetic railgun strain test characteristics analysis, the back of the rail and the back of insulation support plate are selected as the strain test points, FBG(Fiber Bragg Grating) stain sensor is embedded along the circumference of the barrel to obtain the special-shaped barrel true stain value. At the same time, in order to comparison, The papers studies the rail’s strain simulation technology for electromagnetic railgun, the simulation result is accordance with strain test result, show that stain measurement method is feasible, and measurement results is reliable. The research results can provide data support for location to position of projectile in the special-shaped barrel bore by strain feature.
A compact four-element ultra-wideband (UWB) multiple-input–multiple-output (MIMO) antenna with dual polarization and dual-notched capabilities was developed and fabricated. The MIMO antenna is composed of four orthogonally placed half-cutting UWB antenna elements. This orthogonal placement improves the isolation. Furthermore, an L-shaped slot and a continuous bending slot are etched to realize the band-rejection function in the WiMAX and WLAN bands. The result shows that the antenna achieved operating bands of 2.9–16.5 GHz (140.2%, S11 < −10 dB), fully covering the UWB (3.1–10.6 GHz). The port isolation is greater than 23 dB in the frequency band of interest, excluding two rejected bands. Moreover, the MIMO antenna has excellent diversity performance, such as a low envelope correlation coefficient (<0.004), high diversity gain (approximately 10 dB), and good omnidirectional radiation characteristics.
Aiming at the influence of the attitude angle in the bore of a small calibre electromagnetic weapon on the stability of the projectile, a method for measuring the attitude angle of a projectile in the bore of a small caliber electromagnetic weapon is presented in this paper. According to the launching environment of the electromagnetic weapon and the structural characteristics of body tube, an integrated simulating missiles of anti-high overload is developed to convert the measurement of the attitude angle in the bore of the projectile into the measurement of laser spot displacement, the motion trajectory of the laser beam on the target plate in front of the muzzle is captured by a high-speed camera, and the displacement trajectory of the laser spot is measured by using adaptive spot displacement tracking technology based on centre of mass identification, and then the attitude angle of the projectile is obtained by trigonometric function calculation. Through laboratory verification and the theoretical analysis, the test error is ≤0.1′,it can realize high precision measurement of attitude angle in projectile bore. Finally, through the live firing test, the attitude angle of the projectile in the chamber of a certain electromagnetic weapon is obtained, and the effectiveness of the method is verified.
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