A Real-Time Estimation Method of Roll Angle and Angular Rate Based on Geomagnetic Information

Abstract

In the course of the guidance transformation of the rotating projectile, the accurate acquisition of the roll angle and roll angle rate is very important to the attitude determination and guidance control of the rotating projectile. However, due to the impact of high rotation and high overload of projectile, MEMS gyros have problems such as limited range, saturation, overload, and even performance degradation, which make the roll angle rate unable to be output normally. At the same time, because the MEMS gyro estimation of roll angle is in the form of angular rate integral, the roll angle cannot be estimated normally if the roll angle rate cannot be accurately obtained. In order to solve this problem, a real-time estimation of projectile roll angle and roll rate based on geomagnetic information under high dynamic and high overload conditions is presented. Firstly, according to the motion characteristics of the rotating projectile, the motion model of the projectile is established, and the roll angle and roll angle rate of the projectile are estimated by Kalman filtering algorithm under the conditions of high axial rotation and high overload. Considering the high dynamic characteristics of the rotating projectile, based on the Kalman filter, the algorithm of the forgetting filter with the forgetting factor is further adopted to estimate the roll angle and roll angle rate, so as to reduce the error caused by the estimation delay in the process of high-speed dynamic change. Simulation data and semiphysical test results show that the accuracy of roll angle estimated by this method reaches about 2° in semiphysical test, which is one time higher than that calculated by the system. In the semiphysical experiment, the accuracy of the estimated roll rotation rate reaches 5 °/s, which is more than 6 times higher than that obtained by direct derivation. In the high dynamic stage, compared with the pure Kalman filter, the accuracy of roll angle with forgetting factor estimation is improved by an order of magnitude, and the accuracy of roll angle rate is improved by 4 times, which meets the desired accuracy of rotating projectile.

Roll Angle Estimation Algorithm of Geomagnetic/Gyro Combination Based on an Interacting Multiple‐Model Kalman Filter

“…The core idea of this algorithm is to first use the Kalman filter to process the two-axis signals of the geomagnetic sensor separately and obtain the roll angle information according to formula (4). Then, use the Kalman filter to process the signal of the gyroscope sensor and calculate the angle that the projectile has turned in a short time according to formula (5). Finally, the angle information obtained by the two sensors is fused to obtain the higherprecision roll angle information.…”

“…And H is the projection of T on the horizontal plane. Among them, T, H, I, D, X, Y, and Z are collectively referred to as geomagnetic elements [5]. The geomagnetic element changes with time, usually made up by three elements including magnetic inclination, magnetic declination, and horizontal component, which is used to determine the magnetic field at a certain point.…”

“…Chen et al [3] and Tian et al [4] established a theoretical model to measure the roll angle of the projectile body solely with geomagnetic information and carried out a preliminary simulation experiment, in which the Kalman filter was adopted for data processing. Gao et al conducted a semiphysical simulation experiment under relatively complicated conditions and used the Kalman filter algorithm to estimate the geomagnetic signal, which obtained the roll angle with relatively good accuracy [5]. Yin et al denoised the geomagnetic information, measured through the shooting range experiment, based on the wavelet algorithm, and obtained a relatively clean geomagnetic signal [6].…”