Hybrid Simulation of Adapte Path Control

Adaptive path control of a two-dimensional maneu ver under lunar attraction is simulated at high speed by a hybrid system comprising general-purpose analog and digital computers and programmable parallel logic and conversion components. The opti mization criterion selected leads to both on-off and continuous control variables. The digital computer performs a high-precision simulation of the rocket motion and transmits velocity and position informa tion to the analog computer at small time intervals. The analog, after each information transfer, solves a boundary value problem by high-speed iteration to obtain the optimum thrust control functions, trans ferring back to the digital computer only that portion of the control functions which is needed until the next information transfer. For any perturbation in the data—such as changes in the goal, the optimiza tion criterion, or operating characteristics of the rocket—a new optimum control will be calculated immediately and the system will adjust. The effective ness of the simulation hinges upon the use of a flex ible linkage system to provide data conversion, tim ing, and parallel logical control. Programming aspects of the hybrid system are emphasized.