טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentAtir Ronen
SubjectTarget Maneuver Adaptive Guidance Law for a Bounded
Acceleration Missile
DepartmentDepartment of Aerospace Engineering
Supervisors Professor Tal Shima
Dr. Haim Weiss
Full Thesis textFull thesis text - English Version


Abstract

A new estimator-guidance law is presented, for a bounded acceleration interceptor pursuing a target performing a sudden step maneuver. The linearized end-game scenario is investigated. The missile's acceleration saturation is represented by the equivalent random input describing function. The estimator proposed for this problem features a mechanism constructed to efficiently identify a sudden target maneuver. Due to the bound on the missile acceleration, the certainty equivalence property in not valid, and so, the resulting controller (guidance law) depends on the measurement noise level, statistics of the target maneuver, and the saturation limit. The derivation of this guidance law proceeds in two stages. In the first simplified stage, it is assumed that the instance that the target issues a step command in its acceleration is known. However, the size of the target maneuver jump must still be estimated. Simulation results show significant improvement over the deterministic optimal guidance law when the jump times vary from 10 to 3 missile time constants prior to the intercept time. If the jump occurs earlier or later than this duration no improvement is gained. In the second stage, a suboptimal guidance law is derived using the multiple model adaptive control formulation for a target performing a single step maneuver near the intercept time. Note that this sub-optimal guidance law does not require a-priory knowledge of the time of the jump in the target acceleration command. Performance improvement in the same order of magnitude as was observed for the jump-time-knowing scheme (that also serves as a performance bound) is achieved, verifying the validity of this approach. Sensitivity analysis to various noise levels and expected target maneuvers was carried out emphasizing the robustness and advantages of this scheme.