טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentTaub Ilan
SubjectOptimal Trajectory Shaping Guidance of Time-Varying
Acceleration-Constrained Missiles
DepartmentDepartment of Aerospace Engineering
Supervisor Professor Tal Shima
Full Thesis textFull thesis text - English Version


Abstract

In the following thesis we address the problem of shaping the trajectory of a missile, subject to a varying lateral acceleration constraint, in order to obtain a maximal acceleration margin and avoid entering no-capture zones. The specific problem at hand is of an interceptor with imperfect dynamics intercepting a moving and maneuvering target at a predetermined terminal intercept angle. The problem is treated with the aid of linear quadratic optimization, where the varying acceleration constraint is assumed to be a function of time. The acceleration constraint of aerodynamic steering missiles is usually trajectory dependent rather than time dependent. Transforming the constraint into a time-dependent function by analytical means might not be possible, due to the nonlinear nature of the constraint. The problem is alleviated using a simple iterative calculation. For practical implementation reasons, and in order to improve the guidance performance under model uncertainties and disturbances, the guidance command is decomposed into two separate optimizations; one for the acceleration constraint, where the guidance gains are calculated by a predicted time-to-go, and the other for the autopilot dynamics, where the gains are obtained by a real-time time-to-go calculation, resulting in a sub-optimal guidance law. The performance of the proposed law is investigated using nonlinear planar simulation, for a missile with 1st order autopilot dynamics.