| Missile’s rotating around its own lengthwise axis while flying can bring many benefits,thus, many kinds of ammunitions are designed to be spinning ammunitions, such asantitank missile, ground-to-air missile, shell and rocket projectile. Taking the spinningammunition with missile-borne inertial measurement unit (IMU) as research object, thenavigation scheme and decoupling control methods suited for spinning ammunition arestudied.Firstly, aiming at the characteristic that the roll rate is difficult to be measured directlyfor high-speed rotating ammunition, the IMU configuration scheme is researched. Based onfeasibility analysis of the gyro aided multi-accelerometer (GAMA) IMU scheme andcombining the advantages of the available configurations, a novel IMU scheme with fiveaccelerometers and two gyros (5A2G) is proposed. The configuration ascertainmentproblem for acquiring the required installation parameters of accelerometers is transformedinto a constraint optimization problem with the objective of minimizing the error of roll rateinformation. The three channels are decoupled during the angular velocity calculationprocedure so that the precision and efficiency are both improved.Secondly, the angular velocity calculation method of spinning ammunition is studied.A general angular velocity calculation modeling method with time-varying process noise isproposed, which is not limited to a certain kind of accelerometer configuration. On thebasis of the angular velocity calculation model, the adaptive unscented Kalman filter(AUKF) algorithm is presented through combining Sage-Husa suboptimal maximum aposteriori (MAP) noise estimator with UKF, to achieve high-precision angular velocitycalculation. Then aiming at the issues of large amount of calculation of UKF, and based onthe characteristics of additive noise and linear state equation, the adaptive simplifiedspherical simplex UKF (ASSSUKF) is proposed to estimate the angular velocity. TheASSSUKF algorithm can effectively improve the angular velocity calculation efficiencyand maintain high-level calculation precision as well.Thirdly, aiming at the characteristic that the outputs of the gyro-free IMU (GF-IMU)and the GAMA-IMU are angular rate and specific force, the navigation algorithm suited for gyro-free inertial navigation system (GF-SINS) and GAMA-SINS is investigated. A set ofimproved navigation algorithm based on angular rate and specific force is derived, in which,the angular rate and specific force output by IMU are directly used to calculate navigationparameters so that the integral errors produced during the process of extracting angle andvelocity increment are avoided. Compared to the conventional navigation algorithm basedon angle and velocity increment and the simplified algorithm based on angular rate andspecific force, the improved algorithm can effectively mitigate error divergence speedunder the condition of angular rate and specific force input.Fourthly, the decoupling control method for spinning ammunition is studied toeliminate the coupling effect between pitching and yawing channels. In the respect ofdouble-channel decoupling control system design, the coupling problem is settled by thedynamic decoupling control method based on linear system geometric theory under theprecondition of constant roll rate. In the respect of three-channel decoupling control systemdesign, the roll rate is modeled as a state variable and a kind of decoupling controller withroll rate feedback is gained owing to the differential geometry method. Then the control lawis further simplified based on the balancing rotating speed. The three-channel decouplingcontrol system can achieve high-precision decoupling control with simply-structuredcontroller, and meanwhile has good adaptability to roll rate variation.Finally, the work that has been done in this paper is summed up and the work need tobe studied further is also pointed out. |
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