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.
Highlights
In the course of the guidance transformation of conventional ammunition, there are some problems such as high rotational speed and high dynamic state in the flight state of the projectile so that the gyro cannot accurately measure the angular velocity of the projectile body roll
Based on the accurate estimation of projectile roll angle and roll angle rate by the Kalman filter, in view of the dynamic characteristics of projectile motion and high speed, appropriate forgetting factor is added for strong tracking, to change the measurement noise and system noise in real time improve the adaptive ability of the algorithm [17]. us, the attitude information of roll angle and roll angle rate necessary for guidance and control of guided munitions under bad onboard environment is obtained
Estimated by pure Kalman filter Estimated by forgetting factor algorithm Estimated by the direct derivation method e error of roll angle rate that the system calculates and the gyro output
Summary
In the course of the guidance transformation of conventional ammunition, there are some problems such as high rotational speed and high dynamic state in the flight state of the projectile so that the gyro cannot accurately measure the angular velocity of the projectile body roll. In the case of a rotating projectile, the maximum axial rotation speed of the projectile can be up to 200 r/s during the launching process, and it is accompanied by a large change In this case of high dynamic and high rotation speed, the ordinary MEMS gyro is already saturated and cannot normally measure angular rate and solve the roll angle. Based on the accurate estimation of projectile roll angle and roll angle rate by the Kalman filter, in view of the dynamic characteristics of projectile motion and high speed, appropriate forgetting factor is added for strong tracking, to change the measurement noise and system noise in real time improve the adaptive ability of the algorithm [17]. Based on the accurate estimation of projectile roll angle and roll angle rate by the Kalman filter, in view of the dynamic characteristics of projectile motion and high speed, appropriate forgetting factor is added for strong tracking, to change the measurement noise and system noise in real time improve the adaptive ability of the algorithm [17]. us, the attitude information of roll angle and roll angle rate necessary for guidance and control of guided munitions under bad onboard environment is obtained
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