A method for synchronous shock calibration of triaxial accelerometers based on vector decomposition

The triaxial accelerometer can simultaneously detect and measure shock loads along the three coordinate axes in the three-dimensional space. Therefore, it has a wide range of applications in the fields of spatial vibration test, spatial impact test, and so on. Before being put into practical use, triaxial accelerometers must be calibrated for their sensitivity coefficients to ensure the validity and accuracy of measurements. Unlike the calibration of single-axis accelerometers, there is a major difficulty in the calibration technologies of the triaxial accelerometers, that is, how to realize the excitation of three-dimensional shock loads synchronously, since the pulse width of the shock loads are usually as short as a few milliseconds. On the other hand, tracing and measuring the acceleration excited during shock process is also the key to the shock calibration of accelerometers. In order to address the aforementioned problems, a drop table equipped with a shock amplifier was used to excite acceleration loads vertically upward. Then, with the help of an anvil which has a bevel, the vertical acceleration excited on shock amplifier was decomposed to each sensitive axis of the triaxial accelerometer based the principle of vector decomposition. By means of this approach, synchronous shock loading of the triaxial accelerometer was then realized. High-speed camera and image processing based on MATLAB were used to trace and measure the acceleration excited in the synchronous shock calibration of triaxial accelerometers. Experiments were conducted to verify the effectiveness of the motion measurement method based on high-speed camera and MATLAB image processing. The sensitivity matrix of the triaxial accelerometer, which takes into consideration both the main sensitivity coefficients and the coupling sensitivity coefficients, was solved using the least-square method. At last, the measurement accuracy of the accelerometer calibrated using the synchronous method was compared with the measurement accuracy of the accelerometer calibrated using the conventional asynchronous method. The research results indicate that the conventional drop table could excite a wide range (102g～104g) of acceleration by equipping a shock amplifier. In addition, the motion measurement method based on high-speed camera and MATLAB image processing is valid in acceleration traceability or measurement in the shock calibration of accelerometer. Furthermore, compared to the measurement accuracy of the accelerometer calibrated by the asynchronous method, the measurement accuracy of the triaxial accelerometer could be guaranteed and improved by using the synchronous method. Therefore, in engineering, the triaxial accelerometer ought to be calibrated using synchronous methods rather than asynchronous methods to guarantee the validity and accuracy of measurements. © 2023 Explosion and Shock Waves. All rights reserved.