Servo System Design for Precise Fin Tip Control in Launch Vehicles Using Electromechanical Actuators

Abstract

This study examines the development and performance of a servo mechanism for fin tip control (FTC) in a launch vehicle, aimed at accurately manipulating rocket fins to achieve efficient steering. The analysis involves both linear and nonlinear modelling of the electromechanical actuator (EMA)-based FTC system, with the goal of developing a compensation strategy based on closed-loop control requirements. These specifications target position control for roll stabilization of launch vehicle during the FTC phase. A compensation approach, incorporating a PID controller and a notch filter, is integrated to meet the system's performance criteria. Friction, particularly Coulomb friction and Stiction, is a critical factor in achieving high-precision control using the EMA. To tackle this, a friction model is developed, and system parameters are determined by reducing the discrepancy between the outputs of the plant and the model, eliminating the need for optimization. The closed-loop performance of the system is then assessed through MATLAB/SIMULINK simulations, demonstrating the ability to meet the desired performance criteria for precise fin tip control.