压力传感器激波管校准条件下的动态参数估计

激波管是一种关键的压力传感器动态校准装置,但是由于其输出的不稳定性,使得被校准压力传感器的输出数据常常难以直接用于动态建模,且所建模型的准确性也难以表征.提出一种用于激波管校准压力传感器的动态参数估计方法.首先使用基于信息方法处理被校准压力传感器在阶跃激励下的输出数据,得到最优估计值序列、上界序列和下界序列;然后,对所得最优估计值序列、上界序列和下界序列分别进行白化滤波和差分建模,得到最优估计模型、上界模型和下界模型;之后对各个模型进行求解,最优估计模型得出被校准压力传感器的最优特征指标,上界模型和下界模型所得结果构成最优性能指标的估计区间.选用恩德福克200系列压阻传感器进行激波管校准实验,得出时域动态指标的相对误差小于8.17%,频域动态指标相对误差小于9.15%;所有指标均100%位于求得的估计区间内.

Dynamic parameter estimation of pressure transducer in shock tube calibration test

Shock tube is the key device in the pressure transducer dynamic calibration. But as the output of pressure transducer often contains strong interference, which makes it difficult to directly use the output to build the dynamic model of calibrated pressure transducer, in addition, the accuracy of the model is hard to be characterized. A parameter estimation method was proposed which could be applied to pressure transducer in shock tube calibration test. Firstly, the operation of information generation was employed to process the output of calibrated pressure transducer under the pressure of step excitation, and then estimated sequences, upper boundary and lower boundary were obtained. Secondly, the processing methods about filtering and modeling were used to deal with the estimated sequences, upper and lower boundary, and then we could obtain the best estimated value model, the upper boundary model and the lower boundary model. Finally, by solving the obtained models, the indicators obtained by the best estimated model was the best characteristic indicator of the calibrated transducer, the indicators obtained by upper and lower boundary model could compose confidence interval of best indicators, it could show the reliability of the best indicators. A calibration test of shock tube is conducted with the piezoresistive pressure transducer of Endevco 200 series type. The relative errors of dynamic indices of time-domain are no more than 8.17%; the relative errors of dynamic indices of frequency-domain are no more than 9.15%. All the obtained indicators fall in the estimated interval with 100% probability of reliability.