Barometer measurement error modeling and correction for UAH altitude tracking

Altitude is a significant flight parameter for Unmanned Aerial Helicopters(UAH). Traditional vertical damping loop has been used to improve stability of vertical channel of the INS(inertial navigation system) with auxiliary altitude information. Barometer is a common and popular altimeter which can provide the continuous and reliable altitude information, however the measurement performance is rather poor due to several factors, including principle error, drifting behavior and sensitivity to environment changes in pressure uncorrelated with altitude. In this paper, the characteristics of the barometer measurement errors have been thoroughly investigated and we decomposed the barometer measurement errors into three components: principle error, drift error and external disturbance error. We proposed a scheme to estimate and correct the barometer measurement errors. GPS has been utilized in this paper as an auxiliary altimeter. A method has been proposed to estimate and correct the drift error by introducing a factor to change the measurement noise covariance. A serial experiments have been performed to validate the accuracy of the models and illustrate that the proposed method has better performance than normal Kalman filter.