Optimized Servo Design of SS2 Flex Nozzle Control System for Small Satellite Launch Vehicle

Flex Nozzle Control (FNC) system uses Electro Mechanical Actuators (EMAs) to deflect the rocket nozzle for precise steering of a launch vehicle. The servo analysis and linear modeling of the electromechanical actuation based FNC system are carried out to design a compensation scheme based on the closed loop specifications. Friction plays a crucial role in the high accuracy control of the system using the EMA. A frictional model of the system is developed considering both Coulomb friction and Stiction. An estimator based on I-Ching Algorithm is proposed in this paper, to estimate the unknown Coulomb friction in the system. The estimation is formulated as an optimization problem with the objective of finding a parameter value that minimizes the error between the plant and model outputs. A feedforward controller for friction compensation is also proposed in this paper.The closed loop behavior of the system is evaluated using MATLAB/SIMULINK as the simulation tool.