Aerospace Science and Technology
S.H. Jalali Naini; Rahim Asadi; amir hossein Mirzaei
Abstract
A complete miss distance analysis of true proportional navigation is carried out due to initial heading error, step target maneuver, and seeker noise sources assuming a first-order control system using forward and adjoint methods. For this purpose, linearized equations are utilized for deterministic ...
Read More
A complete miss distance analysis of true proportional navigation is carried out due to initial heading error, step target maneuver, and seeker noise sources assuming a first-order control system using forward and adjoint methods. For this purpose, linearized equations are utilized for deterministic and stochastic analyses. Worst case analysis shows that the maximum value of the final time-miss distance plots reduces by increasing the value of the effective navigation ratio due to initial heading error and step target acceleration. The number of peaks of these curves obeys the relation of the effective navigation ratio minus 1 (or 2) due to heading error (or step target maneuver). Moreover, the normalized miss coefficients due to seeker noise sources and miss due to random target maneuver are computed and approximate formulas are presented using the curve fitting method. This leads to an approximate formula for miss distance budget. Therefore, optimum values of the effective navigation ratio and control system time constant are obtained. Finally, the preferred values of these parameters are calculated for increased RMS miss of 5%, 10%, and 20% compared to its minimum value for two scenarios.
Aerospace Science and Technology
Mohammad Yavari; Nemat Allah Ghahremani; Reza Zardashti; Jalal Karimi
Abstract
In this paper a new mid-course guidance algorithm for intercepting high altitude target is proposed. A part of target flight path is outside the atmosphere. The maximum acceleration command is designed as a variable constraint that varies with altitude. This physical limitation is happened for the aerodynamically ...
Read More
In this paper a new mid-course guidance algorithm for intercepting high altitude target is proposed. A part of target flight path is outside the atmosphere. The maximum acceleration command is designed as a variable constraint that varies with altitude. This physical limitation is happened for the aerodynamically control interceptors at high altitudes because of decreasing air density. Based on generalized incremental predictive control approach, a new formulation for parallel navigation guidance law is proposed. Using the nonlinear kinematic equations of target-interceptor, the commands of the new guidance method are computed by optimization of a cost function involved the velocity perpendicular to the line of sight errors and guidance commands. An important feature of the proposed method is the minimization of the line- of - sight angular rate in a finite period of time. The various simulation results of the proposed guidance law shows the higher effectiveness of the designed guidance law in comparison with proportional navigation and sliding mode guidance.
Labid Hassan; M.B. Malaek
Volume 9, Issue 1 , March 2012
Abstract
Based on the idea of Continuous Fuzzy Guidance Law (CFGL), a andldquo;three-phase fuzzy guidanceandrdquo; (TFG) law is proposed for the class of surface to air homing missiles. The current approach enables the guidance law to track a maneuvering target from the beginning of the launch phase up to the ...
Read More
Based on the idea of Continuous Fuzzy Guidance Law (CFGL), a andldquo;three-phase fuzzy guidanceandrdquo; (TFG) law is proposed for the class of surface to air homing missiles. The current approach enables the guidance law to track a maneuvering target from the beginning of the launch phase up to the terminal one while itdynamically attempts to keep miss-distance, flight time and control effort at a minimum acceptable level. The guidance law developed heredepends on four factors:line-of-sight (LOS) angle, LOS rate, LOS angular acceleration, and relative distance to the target. To show the relative superiority of the approach, the performance of the new guidance law has been compared with that of proportional navigation guidance. The results confirm the validity of the idea; as for a TFG,we get quite comparable results. The current approach also shows a relatively good robustness for a wide variety of flight conditions.