M.Sc Thesis
M.Sc Student Gendler Boris Optimal Pulsed Guidance and its Application to Artillery Rockets Department of Aerospace Engineering Professor Yoseph Ben-Asher Dr. Isaac Yaesh

Abstract

Free rocket accuracy can be dramatically improved by equipping the rocket with a steering device. One such device consists of a ring of Lateral Pulse Jets (LPJ), or small rocket engines, placed on the rocket’s perimeter. Each pulse jet imparts a single, short duration, large force to the rocket in the plane normal to the rocket’s axis of symmetry, resulting in a change in the rocket’s normal velocityA single pulse of finite width may be approximately modeled as a velocity step shaped by a first order low-pass filter. The fact that the steering unit has a finite number of pulsers, and hence a finite number of corrections, demands an optimal guidance law which minimizes the number of corrections. However, the development of such an optimal guidance law is very complicated, since it requires minimization of the sum of absolute values of the discrete-time velocity increments. Therefore, the problem is solved in two steps. First, a continuous time, quadratic problem is formulated and solved, followed by the solution of a discrete time problem.

In the first part of this thesis, a new continuous velocity control law for a first order time lag system was developed for cases of perfect intercept and perfect rendezvous. In the second part, a new discrete quadratic problem was formulated in terms of the sum of absolute velocity increments which reflect the pulser’s energy consumption rate.

The results were compared to other well-known guidance laws and the comparison shows that the new guidance law outperforms existing guidance laws, because of their inapplicability to pulsed guidance.