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Copyright of Journal of Computer Engineering & Applications is the property of Beijing Journal of Computer Engineering & Applications Journal Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ballistics / Dandao Xuebao is the property of Journal of Ballistics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The attitude of fixed canard dual-spin trajectory correction projectile is changed by adjusting the phase angle of fixed canard to control the direction of correction force. An exact correction force model of precision guidance kit is the key to improve the correction accuracy of the correction projectile. The validity of the numerical calculation is verified on the basis of wind tunnel test. Based on the small disturbance theory, a modified correct force model of guidance kit is established for the correction projectile with four canards. Levenberg-Marquardt algorithm is used to identify the parameters of the modified correction force model based on the data of computational fluid dynamics（CFD）. The results show that y and z directions vary sinusoidally with phase angle in the correction force model based on four canards. The disturbance coefficient of warhead is insensitive to the angle of attack at a given Mach number. The change of disturbance coefficient with angle of attack is less than 4.9%. The residual sum of squares of correction forces in y and z directions in the proposed modified correction force model is smaller than that in the existing model. The calculated results of correction force model of guidance kit are in good agreement with CFD calculations. [ABSTRACT FROM AUTHOR]

The load on dual-spin projectile’s body has an asymmetrical characteristic because of the influence from asymmetrical wake flow of canards. The asymmetrical load on the projectile body is studied.The results form computational fluid dynamics (CFD) simulation and wind tunnel test are compared to prove the effectiveness of the CFD method. The dual-spin projectile models with control surface angles of0°, 2°and 4° are simulated at various Mach numbers and angles of attack. The flow field is qualitatively analyzed by drawing the streamline diagrams of tail flow of canards and the pressure coefficient contour map of projectile body. The asymmetry of force of the projectile body is quantitatively analyzed by comparing the pressure coefficient of body section and the lateral force coefficient of body. The result shows that the body section pressure coefficient of the model with control surface angle of 0° is symmetrical, and the body section pressure coefficients of the model with control surface angles of 2°and 4°are asymmetrical.The projectile body’s normal force coefficient curves of three models coincide with each other as the change in the angle of attack at a given Mach number; and the lateral force coefficient is near 0 for the model with control surface angle of 0°, but is approximately linear with the angle of attack for the modelswith control surface angles of 2° and 4°, and is first ascended and then descended with the Mach number. When the angle of attack is given, the peak value of the model with control surface angle of 4° is about 2 times that of the model with control surface angle of 2°. [ABSTRACT FROM AUTHOR]

A calibration method of magnetometer-aided two-axis gyro sensor is studied for the three-axis calibration of two-axis gyro sensor in the projectile-borne environment. A measurement error model of two-axis gyro sensor is established, and the problem that the roll angular rate of low spinning projectile at x-axis, which is obtained from the single-axis geomagnetic signal, cannot be measured by the gyro sensor due to its limited measurement range is solved. The calibration methods of the linear least square model and the Kalman filter model for calculating the related parameters of two-axis gyro sensor are studied, and the influences of the calculation error of x-axis angular rate of projectile and the measurement noise of gyroscope sensor on the calibrated result are analyzed through numerical simulation. The application of two-axis gyro sensor in engineering is simulated, and the correction effect of calibration method of magnetometer-aided two-axis gyro sensor is studied in the hardware-in-the-loop simulation. The numerically simulated results prove that,when the calculated error of x-axis angular rate of projectile is within 0.261 8 rad/s and the measured noise of gyro sensor is within 0.001 6 rad/s, the corrected errors of the y-axis and z-axis angular rates of projectile are less than 0.01 rad/s. The results of the hardware-in-the-loop simulation show that the two correction models can decrease the measured error range of gyro sensor from -0.30- -0.05 rad/s to -0.02-0.02 rad/s when the calculated error of x-axis angular rate of the projectile is within 0.8 rad/s. The numerical simulation and the hardware-in-the-loop simulation prove that the magnetometer-aided calibration method has a good correction effect on the two-axis gyro sensor. [ABSTRACT FROM AUTHOR]

The stability criteria related to the structure parameters of correction fuze are derived based on the simplified model and engineering methods for the aerodynamic characteristics of wing-body combinations, Murphy’s complex variable method and the Hurwitz stability theory. The influence of structure parameters of correction fuze on the stability of spin-stabilized projectile is analyzed for the design and optimization of correction fuze. The stability analysis demonstrates that the forward movement of mass point of the combinations through the balance weight or the structure optimization of correction fuze is in favor of stability when the boundary dimensions of correction fuze (except for the canards) are the same; the increase in the deflection angles of canards is better than the extension of wingspan in order to increase the correction force while reducing the effect on stability. The simulations and experiments verify that the flight stability of projectile can be enhanced by moving the mass point of the combinations forward. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rapid and accurate impact-point prediction is a key to correct or guide a high-spinning projectile， and the impact-point prediction based on perturbation(PP) with base trajectory can balance the calculation efficiency and precision. As the parameters of the perturbation model cannot be calculated rapidly with the variation in environment and target, a method combining the perturbation theory and step approximation method is proposed to calculate the proper launching parameter and base trajectory quickly; and an equation of the model parameters which can be calculated by iteration is deduced to fast modeling under arbitrary destination and condition. Simulations and uncontrolled experiment were carried out to verify the feasibility of the proposed method. The results show that the base trajectory and perturbation model can be established. Compared with the modified point-mass trajectory (MPT) method, the predicted error of ascending trajectory of perturbation method is smaller and the predicted error of descending one is larger. Considering the characteristics of PP and MPT methods, a piecewise prediction method combining PP and MPT is proposed. According to the Monte Carlo simulation, the correcting effect of PW method is better than those of PP or MPT method. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The concept of dual-spinning becomes a new approach to upgrade a conventional spin-stabilized projectile, wherein an actuator is used to control the phase of forward canards. To design and analyze the inner control channel efficiently, a dual-spin ordinary differential equation, including a quasi-steady aerodynamic model and an optimized LuGre friction model, is established. All aerodynamic and kinematic data in time-domain, as input in least square estimation, is obtained in transient numerical model and dynamic wind tunnel test. The results indicate that the side force and roll moment supplied by canards are affected by phase angle and roll rate, and the estimated accuracy of quasi-steady aerodynamics is lower than 4×10-3. The friction between forward and aft parts is a function of axial pressure and relative roll rate, which can be estimated by the optimized LuGre model. The feasibility of using the dual-spin model to predict the canard movement is validated by measurement in a flight test. The proposed approach promotes the pace of engineering application of dual-spin projectiles. [ABSTRACT FROM AUTHOR]

An equivalent force method is proposed to analyze the impact point response of a dual-spin projectile with lateral control force and calculate the correction of impact point conveniently. The influence of lateral force on the mass-center motion of projectile is separated into two parts: the direct influence arose from the control force and the indirect influence caused by the variation of angular motion related to the control force and moment. Based on the seven-degrees-of-freedom rigid-body flight-dynamic-model, the change of angle-of-attack caused by the lateral control force can be derived, thus calculating the equivalent force and the variation of impact point. According to the theoretical analysis, the correction distance is almost in proportion to the length between the origin of control force and the mass center under the same condition. Simulations and experiments demonstrate that the errors of correction and phase angle calculated by the proposed method are less than 10%. [ABSTRACT FROM AUTHOR]

A method of which uses the measured information from onboard laser detectors and GPS to resolve the roll angle of semi-active laser terminal correction projectile is proposed. A formula to calculate the roll angle is deduced by comparing the real target imaging point on imaging planeof laser detector with the calculated target imaging point on non-roll imaging plane.The effects of measured errors of projectile position, projectile velocity and laser detector on the resolving accuracy of roll angle at different quadrant elevation angles are analyzed through the Monte-Carlo simulation. The simulated results show that the maximum error of roll angle is resolved to be less than 4° by the proposed method; the measured error of laser detector has the greatest effect on the resolving accuracy of roll angle among the 3 error sources.The proposed resolving method meets the accuracy and real-time requirements, and is suitable for solving the roll angle of semi-active laser terminal correction projectile with low rolling. [ABSTRACT FROM AUTHOR]