Development of launch vehicle control algorithm for the initial part of the trajectory using the ACOR method

The control system of a launch vehicle (LV) at the initial phase of flight at altitudes between 0 and 300 meters is the object of investigation in the article. At this phase the flame of the LV jet engine is the cause of a negative impact on facilities of the launch complex. This effect can be reduced by displacing the jet flame in a certain radial direction with increased resistance of the facilities using a specially developed vehicle motion control program. The purpose of the article is to develop an algorithm for the controller of the LV motion control system on the considered “displacement phase” of the trajectory that provides an implementation of such a program. To solve the problem, we developed the modified version of the Letov’s method of analytical construction of regula- tors (ACOR). The peculiarity of the modified statement of the problem solved in the work is that the controlled output vector of the system depends explicitly not only on the LV state vector, but also on the control variable. The quality of control is evaluated using a quadratic terminal-integral optimality criterion. This kind of criterion allows to trace with the specified accuracy the preliminary calculated program for supporting the required position of the trace of the LV jet flame on the launching plane, and also to ensure the vertical position and the zero angular velocity of the vehicle at the end of the displacement phase. To solve the problem of constructing the algorithm, a special linearized model of the LV motion has been developed. The results of simulating the controlled motion of a launch vehicle with the use of the algorithm confirm the operability and demonstrate efficiency of the developed optimal regulator of the LV control system at the displacement phase under consideration. Calculation results show that angular position of the LV at the end of the displacement phase is close to vertical, the angle of the engine nozzle deflection is within the permissible limits and the deviation of the current position of the jet flame track from the program value does not exceed 0.5 meters.