Roll Angle Estimation for Spinning Projectile Based on Phase-Locked Loop With Geomagnetic Sensor and Gyroscope

Estimation of roll angle is necessary for precision-guidedmunitions. Geomagnetic sensors are widely used in roll angle estimation of spinning projectiles, but their accuracy can be compromised by interference from onboard electromagnetic devices. Therefore, a roll angle estimation for a spinning projectile based on a phase-locked loop (PLL) with a geomagnetic sensor and gyroscope has been proposed. The roll angle data obtained from the gyroscope data in a slide time window (with width ≥ 100) is used to generate cosine and sine sequences, which are, respectively, correlation integrated with the magnetic sensor data sequences within the same time window. The two integration results are subjected to a four-quadrant arc tangent operation to obtain the phase difference between the gyroscope and the geomagnetic sensor, and then the roll angle of the projectile is obtained by Kalman filtering. In order to verify the roll angle estimation method, a semi-physical experiment was carried out, and the experimental results show that expectation of roll angle error of roll angle estimation algorithm based on phase-locked loop (RAEPLL) is 0.139° and the standard deviation (SD) is 0.512°, while the two error characteristics of error state Kalman filter (ESKF) are 0.268 and 0.689 deg, indicating the method proposed in this article can get higher roll angle estimation accuracy only using single-axis geomagnetic sensors and gyroscope comparing with the existing roll angle estimation algorithms.